zig/lib/std / Build/Step/Compile.zig

For WebAssembly targets, this will allow for undefined symbols to be imported from the host environment.

const builtin = @import("builtin");
const std = @import("std");
const mem = std.mem;
const fs = std.fs;
const assert = std.debug.assert;
const panic = std.debug.panic;
const StringHashMap = std.StringHashMap;
const Sha256 = std.crypto.hash.sha2.Sha256;
const Allocator = mem.Allocator;
const Step = std.Build.Step;
const LazyPath = std.Build.LazyPath;
const PkgConfigPkg = std.Build.PkgConfigPkg;
const PkgConfigError = std.Build.PkgConfigError;
const RunError = std.Build.RunError;
const Module = std.Build.Module;
const InstallDir = std.Build.InstallDir;
const GeneratedFile = std.Build.GeneratedFile;
const Compile = @This();
const Path = std.Build.Cache.Path;

base_id:

Set via options; intended to be read-only after that.


pub const base_id: Step.Id = .compile;

ExpectedCompileErrors

This step is used to create an include tree that dependent modules can add to their include search paths. Installed headers are copied to this step. This step is created the first time a module links with this artifact and is not created otherwise.


step: Step,
root_module: *Module,

Entry

Behavior of automatic detection of include directories when compiling .rc files. any: Use MSVC if available, fall back to MinGW. msvc: Use MSVC include paths (must be present on the system). gnu: Use MinGW include paths (distributed with Zig). none: Do not use any autodetected include paths.


name: []const u8,
linker_script: ?LazyPath = null,
version_script: ?LazyPath = null,
out_filename: []const u8,
out_lib_filename: []const u8,
linkage: ?std.builtin.LinkMode = null,
version: ?std.SemanticVersion,
kind: Kind,
major_only_filename: ?[]const u8,
name_only_filename: ?[]const u8,
formatted_panics: ?bool = null,
// keep in sync with src/link.zig:CompressDebugSections
compress_debug_sections: enum { none, zlib, zstd } = .none,
verbose_link: bool,
verbose_cc: bool,
bundle_compiler_rt: ?bool = null,
bundle_ubsan_rt: ?bool = null,
rdynamic: bool,
import_memory: bool = false,
export_memory: bool = false,
/// For WebAssembly targets, this will allow for undefined symbols to
/// be imported from the host environment.
import_symbols: bool = false,
import_table: bool = false,
export_table: bool = false,
initial_memory: ?u64 = null,
max_memory: ?u64 = null,
shared_memory: bool = false,
global_base: ?u64 = null,
/// Set via options; intended to be read-only after that.
zig_lib_dir: ?LazyPath,
exec_cmd_args: ?[]const ?[]const u8,
filters: []const []const u8,
test_runner: ?TestRunner,
wasi_exec_model: ?std.builtin.WasiExecModel = null,

Options

(Windows) .manifest file to embed in the compilation Set via options; intended to be read-only after that.


installed_headers: std.array_list.Managed(HeaderInstallation),

Kind

Base address for an executable image.


/// This step is used to create an include tree that dependent modules can add to their include
/// search paths. Installed headers are copied to this step.
/// This step is created the first time a module links with this artifact and is not
/// created otherwise.
installed_headers_include_tree: ?*Step.WriteFile = null,

isTest()

On ELF targets, this will emit a link section called ".note.gnu.build-id" which can be used to coordinate a stripped binary with its debug symbols. As an example, the bloaty project refuses to work unless its inputs have build ids, in order to prevent accidental mismatches. The default is to not include this section because it slows down linking.


// keep in sync with src/Compilation.zig:RcIncludes
/// Behavior of automatic detection of include directories when compiling .rc files.
///  any: Use MSVC if available, fall back to MinGW.
///  msvc: Use MSVC include paths (must be present on the system).
///  gnu: Use MinGW include paths (distributed with Zig).
///  none: Do not use any autodetected include paths.
rc_includes: enum { any, msvc, gnu, none } = .any,

HeaderInstallation

Create a .eh_frame_hdr section and a PT_GNU_EH_FRAME segment in the ELF file.


/// (Windows) .manifest file to embed in the compilation
/// Set via options; intended to be read-only after that.
win32_manifest: ?LazyPath = null,

File

Place every function in its own section so that unused ones may be safely garbage-collected during the linking phase.


installed_path: ?[]const u8,

dupe()

Place every data in its own section so that unused ones may be safely garbage-collected during the linking phase.


/// Base address for an executable image.
image_base: ?u64 = null,

Directory

Remove functions and data that are unreachable by the entry point or exported symbols.


libc_file: ?LazyPath = null,

Options

(Windows) Whether or not to enable ASLR. Maps to the /DYNAMICBASE[:NO] linker argument.


each_lib_rpath: ?bool = null,
/// On ELF targets, this will emit a link section called ".note.gnu.build-id"
/// which can be used to coordinate a stripped binary with its debug symbols.
/// As an example, the bloaty project refuses to work unless its inputs have
/// build ids, in order to prevent accidental mismatches.
/// The default is to not include this section because it slows down linking.
build_id: ?std.zig.BuildId = null,

dupe()

Allow version scripts to refer to undefined symbols.


/// Create a .eh_frame_hdr section and a PT_GNU_EH_FRAME segment in the ELF
/// file.
link_eh_frame_hdr: bool = false,
link_emit_relocs: bool = false,

dupe()

Permit read-only relocations in read-only segments. Disallowed by default.


/// Place every function in its own section so that unused ones may be
/// safely garbage-collected during the linking phase.
link_function_sections: bool = false,

getSource()

Force all relocations to be read-only after processing.


/// Place every data in its own section so that unused ones may be
/// safely garbage-collected during the linking phase.
link_data_sections: bool = false,

dupe()

Allow relocations to be lazily processed after load.


/// Remove functions and data that are unreachable by the entry point or
/// exported symbols.
link_gc_sections: ?bool = null,

TestRunner

Common page size


/// (Windows) Whether or not to enable ASLR. Maps to the /DYNAMICBASE[:NO] linker argument.
linker_dynamicbase: bool = true,

create()

Maximum page size


linker_allow_shlib_undefined: ?bool = null,

installHeader()

(Darwin) Install name for the dylib


/// Allow version scripts to refer to undefined symbols.
linker_allow_undefined_version: ?bool = null,

installHeadersDirectory()

(Darwin) Path to entitlements file


// Enable (or disable) the new DT_RUNPATH tag in the dynamic section.
linker_enable_new_dtags: ?bool = null,

installConfigHeader()

(Darwin) Size of the pagezero segment.


/// Permit read-only relocations in read-only segments. Disallowed by default.
link_z_notext: bool = false,

installLibraryHeaders()

(Darwin) Set size of the padding between the end of load commands and start of __TEXT,__text section.


/// Force all relocations to be read-only after processing.
link_z_relro: bool = true,

getEmittedIncludeTree()

(Darwin) Automatically Set size of the padding between the end of load commands and start of __TEXT,__text section to a value fitting all paths expanded to MAXPATHLEN.


/// Allow relocations to be lazily processed after load.
link_z_lazy: bool = false,

addObjCopy()

(Darwin) Remove dylibs that are unreachable by the entry point or exported symbols.


/// Common page size
link_z_common_page_size: ?u64 = null,

checkObject()

(Darwin) Force load all members of static archives that implement an Objective-C class or category


/// Maximum page size
link_z_max_page_size: ?u64 = null,

setLinkerScript()

Whether local symbols should be discarded from the symbol table.


/// (Darwin) Install name for the dylib
install_name: ?[]const u8 = null,

setVersionScript()

Position Independent Executable


/// (Darwin) Path to entitlements file
entitlements: ?[]const u8 = null,

forceUndefinedSymbol()

Link Time Optimization mode


/// (Darwin) Size of the pagezero segment.
pagezero_size: ?u64 = null,

dependsOnSystemLibrary()

(Windows) When targeting the MinGW ABI, use the unicode entry point (wmain/wWinMain)


/// (Darwin) Set size of the padding between the end of load commands
/// and start of `__TEXT,__text` section.
headerpad_size: ?u32 = null,

isDynamicLibrary()

How the linker must handle the entry point of the executable.


/// (Darwin) Automatically Set size of the padding between the end of load commands
/// and start of `__TEXT,__text` section to a value fitting all paths expanded to MAXPATHLEN.
headerpad_max_install_names: bool = false,

isStaticLibrary()

List of symbols forced as undefined in the symbol table thus forcing their resolution by the linker. Corresponds to -u for ELF/MachO and /include: for COFF/PE.


/// (Darwin) Remove dylibs that are unreachable by the entry point or exported symbols.
dead_strip_dylibs: bool = false,

isDll()

Overrides the default stack size


/// (Darwin) Force load all members of static archives that implement an Objective-C class or category
force_load_objc: bool = false,

producesPdbFile()

Deprecated; prefer using lto.


/// Whether local symbols should be discarded from the symbol table.
discard_local_symbols: bool = false,

producesImplib()

Corresponds to the -fallow-so-scripts / -fno-allow-so-scripts CLI flags, overriding the global user setting provided to the zig build command. The compiler defaults this value to off so that users whose system shared libraries are all ELF files don't have to pay the cost of checking every file to find out if it is a text file instead.


/// Position Independent Executable
pie: ?bool = null,

linkLibC()

This is an advanced setting that can change the intent of this Compile step. If this value is non-null, it means that this Compile step exists to check for compile errors and return *success* if they match, and failure otherwise.


/// Link Time Optimization mode
lto: ?std.zig.LtoMode = null,

linkLibCpp()

The maximum number of distinct errors within a compilation step Defaults to std.math.maxInt(u16)


dll_export_fns: ?bool = null,

linkSystemLibrary()

Computed during make().


subsystem: ?std.Target.SubSystem = null,

linkSystemLibrary2()

Computed during make().


/// (Windows) When targeting the MinGW ABI, use the unicode entry point (wmain/wWinMain)
mingw_unicode_entry_point: bool = false,

linkFramework()

Populated during the make phase when there is a long-lived compiler process. Managed by the build runner, not user build script.


/// How the linker must handle the entry point of the executable.
entry: Entry = .default,

addCSourceFiles()

Enables coverage instrumentation that is only useful if you are using third party fuzzers that depend on it. Otherwise, slows down the instrumented binary with unnecessary function calls. This kind of coverage instrumentation is used by AFLplusplus v4.21c, however, modern fuzzers - including Zig - have switched to using "inline 8-bit counters" or "inline bool flag" which incurs only a single instruction for coverage, along with "trace cmp" which instruments comparisons and reports the operands. To instead enable fuzz testing instrumentation on a compilation using Zig's builtin fuzzer, see the fuzz flag in Module.


/// List of symbols forced as undefined in the symbol table
/// thus forcing their resolution by the linker.
/// Corresponds to `-u <symbol>` for ELF/MachO and `/include:<symbol>` for COFF/PE.
force_undefined_symbols: std.StringHashMap(void),

addCSourceFile()

Let the compiler decide whether to make an entry point and what to name it.


/// Overrides the default stack size
stack_size: ?u64 = null,

addWin32ResourceFile()

The executable will have no entry point.


/// Deprecated; prefer using `lto`.
want_lto: ?bool = null,

setVerboseLink()

The executable will have an entry point with the default symbol name.


use_llvm: ?bool,
use_lld: ?bool,

setVerboseCC()

The executable will have an entry point with the specified symbol name.


/// Corresponds to the `-fallow-so-scripts` / `-fno-allow-so-scripts` CLI
/// flags, overriding the global user setting provided to the `zig build`
/// command.
///
/// The compiler defaults this value to off so that users whose system shared
/// libraries are all ELF files don't have to pay the cost of checking every
/// file to find out if it is a text file instead.
allow_so_scripts: ?bool = null,

setLibCFile()

Embed a .manifest file in the compilation if the object format supports it. https://learn.microsoft.com/en-us/windows/win32/sbscs/manifest-files-reference Manifest files must have the extension .manifest. Can be set regardless of target. The .manifest file will be ignored if the target object format does not support embedded manifests.


/// This is an advanced setting that can change the intent of this Compile step.
/// If this value is non-null, it means that this Compile step exists to
/// check for compile errors and return *success* if they match, and failure
/// otherwise.
expect_errors: ?ExpectedCompileErrors = null,

getEmittedBinDirectory()

File paths that end in any of these suffixes will be excluded from installation.


emit_directory: ?*GeneratedFile,

getEmittedBin()

Only file paths that end in any of these suffixes will be included in installation. null means that all suffixes will be included. exclude_extensions takes precedence over include_extensions.


generated_docs: ?*GeneratedFile,
generated_asm: ?*GeneratedFile,
generated_bin: ?*GeneratedFile,
generated_pdb: ?*GeneratedFile,
generated_implib: ?*GeneratedFile,
generated_llvm_bc: ?*GeneratedFile,
generated_llvm_ir: ?*GeneratedFile,
generated_h: ?*GeneratedFile,

getEmittedImplib()

Test runners can either be "simple", running tests when spawned and terminating when the tests are complete, or they can use std.zig.Server over stdio to interact more closely with the build system.


/// The maximum number of distinct errors within a compilation step
/// Defaults to `std.math.maxInt(u16)`
error_limit: ?u32 = null,

getEmittedH()

Marks the specified header for installation alongside this artifact. When a module links with this artifact, all headers marked for installation are added to that module's include search path.


/// Computed during make().
is_linking_libc: bool = false,
/// Computed during make().
is_linking_libcpp: bool = false,

getEmittedPdb()

Marks headers from the specified directory for installation alongside this artifact. When a module links with this artifact, all headers marked for installation are added to that module's include search path.


/// Populated during the make phase when there is a long-lived compiler process.
/// Managed by the build runner, not user build script.
zig_process: ?*Step.ZigProcess,

getEmittedDocs()

Marks the specified config header for installation alongside this artifact. When a module links with this artifact, all headers marked for installation are added to that module's include search path.


/// Enables coverage instrumentation that is only useful if you are using third
/// party fuzzers that depend on it. Otherwise, slows down the instrumented
/// binary with unnecessary function calls.
///
/// This kind of coverage instrumentation is used by AFLplusplus v4.21c,
/// however, modern fuzzers - including Zig - have switched to using "inline
/// 8-bit counters" or "inline bool flag" which incurs only a single
/// instruction for coverage, along with "trace cmp" which instruments
/// comparisons and reports the operands.
///
/// To instead enable fuzz testing instrumentation on a compilation using Zig's
/// builtin fuzzer, see the `fuzz` flag in `Module`.
sanitize_coverage_trace_pc_guard: ?bool = null,

getEmittedAsm()

Forwards all headers marked for installation from lib to this artifact. When a module links with this artifact, all headers marked for installation are added to that module's include search path.


pub const ExpectedCompileErrors = union(enum) {
    contains: []const u8,
    exact: []const []const u8,
    starts_with: []const u8,
    stderr_contains: []const u8,
};

getEmittedLlvmIr()

Returns whether the library, executable, or object depends on a particular system library. Includes transitive dependencies.


pub const Entry = union(enum) {
    /// Let the compiler decide whether to make an entry point and what to name
    /// it.
    default,
    /// The executable will have no entry point.
    disabled,
    /// The executable will have an entry point with the default symbol name.
    enabled,
    /// The executable will have an entry point with the specified symbol name.
    symbol_name: []const u8,
};

getEmittedLlvmBc()

Deprecated; use compile.root_module.link_libc = true instead. To be removed after 0.15.0 is tagged.


pub const Options = struct {
    name: []const u8,
    root_module: *Module,
    kind: Kind,
    linkage: ?std.builtin.LinkMode = null,
    version: ?std.SemanticVersion = null,
    max_rss: usize = 0,
    filters: []const []const u8 = &.{},
    test_runner: ?TestRunner = null,
    use_llvm: ?bool = null,
    use_lld: ?bool = null,
    zig_lib_dir: ?LazyPath = null,
    /// Embed a `.manifest` file in the compilation if the object format supports it.
    /// https://learn.microsoft.com/en-us/windows/win32/sbscs/manifest-files-reference
    /// Manifest files must have the extension `.manifest`.
    /// Can be set regardless of target. The `.manifest` file will be ignored
    /// if the target object format does not support embedded manifests.
    win32_manifest: ?LazyPath = null,
};

addAssemblyFile()

Deprecated; use compile.root_module.link_libcpp = true instead. To be removed after 0.15.0 is tagged.


pub const Kind = enum {
    exe,
    lib,
    obj,
    @"test",
    test_obj,

addObjectFile()

Run pkg-config for the given library name and parse the output, returning the arguments that should be passed to zig to link the given library.


    pub fn isTest(kind: Kind) bool {
        return switch (kind) {
            .exe, .lib, .obj => false,
            .@"test", .test_obj => true,
        };
    }
};

addObject()

Deprecated; use compile.root_module.linkSystemLibrary(name, .{}) instead. To be removed after 0.15.0 is tagged.


pub const HeaderInstallation = union(enum) {
    file: File,
    directory: Directory,

linkLibrary()

Deprecated; use compile.root_module.linkSystemLibrary(name, options) instead. To be removed after 0.15.0 is tagged.


    pub const File = struct {
        source: LazyPath,
        dest_rel_path: []const u8,

addAfterIncludePath()

Deprecated; use c.root_module.linkFramework(name, .{}) instead. To be removed after 0.15.0 is tagged.


        pub fn dupe(file: File, b: *std.Build) File {
            return .{
                .source = file.source.dupe(b),
                .dest_rel_path = b.dupePath(file.dest_rel_path),
            };
        }
    };

addSystemIncludePath()

Deprecated; use compile.root_module.addCSourceFiles(options) instead. To be removed after 0.15.0 is tagged.


    pub const Directory = struct {
        source: LazyPath,
        dest_rel_path: []const u8,
        options: Directory.Options,

addIncludePath()

Deprecated; use compile.root_module.addCSourceFile(source) instead. To be removed after 0.15.0 is tagged.


        pub const Options = struct {
            /// File paths that end in any of these suffixes will be excluded from installation.
            exclude_extensions: []const []const u8 = &.{},
            /// Only file paths that end in any of these suffixes will be included in installation.
            /// `null` means that all suffixes will be included.
            /// `exclude_extensions` takes precedence over `include_extensions`.
            include_extensions: ?[]const []const u8 = &.{".h"},

addConfigHeader()

Deprecated; use compile.root_module.addWin32ResourceFile(source) instead. To be removed after 0.15.0 is tagged.


            pub fn dupe(opts: Directory.Options, b: *std.Build) Directory.Options {
                return .{
                    .exclude_extensions = b.dupeStrings(opts.exclude_extensions),
                    .include_extensions = if (opts.include_extensions) |incs| b.dupeStrings(incs) else null,
                };
            }
        };

addEmbedPath()

Returns the path to the directory that contains the emitted binary file.


        pub fn dupe(dir: Directory, b: *std.Build) Directory {
            return .{
                .source = dir.source.dupe(b),
                .dest_rel_path = b.dupePath(dir.dest_rel_path),
                .options = dir.options.dupe(b),
            };
        }
    };

addLibraryPath()

Returns the path to the generated executable, library or object file. To run an executable built with zig build, use run, or create an install step and invoke it.


    pub fn getSource(installation: HeaderInstallation) LazyPath {
        return switch (installation) {
            inline .file, .directory => |x| x.source,
        };
    }

addRPath()

Returns the path to the generated import library. This function can only be called for libraries.


    pub fn dupe(installation: HeaderInstallation, b: *std.Build) HeaderInstallation {
        return switch (installation) {
            .file => |f| .{ .file = f.dupe(b) },
            .directory => |d| .{ .directory = d.dupe(b) },
        };
    }
};

addSystemFrameworkPath()

Returns the path to the generated header file. This function can only be called for libraries or objects.


pub const TestRunner = struct {
    path: LazyPath,
    /// Test runners can either be "simple", running tests when spawned and terminating when the
    /// tests are complete, or they can use `std.zig.Server` over stdio to interact more closely
    /// with the build system.
    mode: enum { simple, server },
};

addFrameworkPath()

Returns the generated PDB file. If the compilation does not produce a PDB file, this causes a FileNotFound error at build time.


pub fn create(owner: *std.Build, options: Options) *Compile {
    const name = owner.dupe(options.name);
    if (mem.indexOf(u8, name, "/") != null or mem.indexOf(u8, name, "\\") != null) {
        panic("invalid name: '{s}'. It looks like a file path, but it is supposed to be the library or application name.", .{name});
    }

setExecCmd()

Returns the path to the generated documentation directory.


    const resolved_target = options.root_module.resolved_target orelse
        @panic("the root Module of a Compile step must be created with a known 'target' field");
    const target = &resolved_target.result;

rebuildInFuzzMode()

Returns the path to the generated assembly code.


    const step_name = owner.fmt("compile {s} {s} {s}", .{
        // Avoid the common case of the step name looking like "compile test test".
        if (options.kind.isTest() and mem.eql(u8, name, "test"))
            @tagName(options.kind)
        else
            owner.fmt("{s} {s}", .{ @tagName(options.kind), name }),
        @tagName(options.root_module.optimize orelse .Debug),
        resolved_target.query.zigTriple(owner.allocator) catch @panic("OOM"),
    });

doAtomicSymLinks()

Returns the path to the generated LLVM IR.


    const out_filename = std.zig.binNameAlloc(owner.allocator, .{
        .root_name = name,
        .target = target,
        .output_mode = switch (options.kind) {
            .lib => .Lib,
            .obj, .test_obj => .Obj,
            .exe, .@"test" => .Exe,
        },
        .link_mode = options.linkage,
        .version = options.version,
    }) catch @panic("OOM");

rootModuleTarget()

Returns the path to the generated LLVM BC.


    const compile = owner.allocator.create(Compile) catch @panic("OOM");
    compile.* = .{
        .root_module = options.root_module,
        .verbose_link = false,
        .verbose_cc = false,
        .linkage = options.linkage,
        .kind = options.kind,
        .name = name,
        .step = .init(.{
            .id = base_id,
            .name = step_name,
            .owner = owner,
            .makeFn = make,
            .max_rss = options.max_rss,
        }),
        .version = options.version,
        .out_filename = out_filename,
        .out_lib_filename = undefined,
        .major_only_filename = null,
        .name_only_filename = null,
        .installed_headers = std.array_list.Managed(HeaderInstallation).init(owner.allocator),
        .zig_lib_dir = null,
        .exec_cmd_args = null,
        .filters = options.filters,
        .test_runner = null, // set below
        .rdynamic = false,
        .installed_path = null,
        .force_undefined_symbols = StringHashMap(void).init(owner.allocator),

getCompileDependencies()

Deprecated; use compile.root_module.addAssemblyFile(source) instead. To be removed after 0.15.0 is tagged.


        .emit_directory = null,
        .generated_docs = null,
        .generated_asm = null,
        .generated_bin = null,
        .generated_pdb = null,
        .generated_implib = null,
        .generated_llvm_bc = null,
        .generated_llvm_ir = null,
        .generated_h = null,

        .use_llvm = options.use_llvm,
        .use_lld = options.use_lld,

        .zig_process = null,
    };

    if (options.zig_lib_dir) |lp| {
        compile.zig_lib_dir = lp.dupe(compile.step.owner);
        lp.addStepDependencies(&compile.step);
    }

    if (options.test_runner) |runner| {
        compile.test_runner = .{
            .path = runner.path.dupe(compile.step.owner),
            .mode = runner.mode,
        };
        runner.path.addStepDependencies(&compile.step);
    }

    // Only the PE/COFF format has a Resource Table which is where the manifest
    // gets embedded, so for any other target the manifest file is just ignored.
    if (target.ofmt == .coff) {
        if (options.win32_manifest) |lp| {
            compile.win32_manifest = lp.dupe(compile.step.owner);
            lp.addStepDependencies(&compile.step);
        }
    }

    if (compile.kind == .lib) {
        if (compile.linkage != null and compile.linkage.? == .static) {
            compile.out_lib_filename = compile.out_filename;
        } else if (compile.version) |version| {
            if (target.os.tag.isDarwin()) {
                compile.major_only_filename = owner.fmt("lib{s}.{d}.dylib", .{
                    compile.name,
                    version.major,
                });
                compile.name_only_filename = owner.fmt("lib{s}.dylib", .{compile.name});
                compile.out_lib_filename = compile.out_filename;
            } else if (target.os.tag == .windows) {
                compile.out_lib_filename = owner.fmt("{s}.lib", .{compile.name});
            } else {
                compile.major_only_filename = owner.fmt("lib{s}.so.{d}", .{ compile.name, version.major });
                compile.name_only_filename = owner.fmt("lib{s}.so", .{compile.name});
                compile.out_lib_filename = compile.out_filename;
            }
        } else {
            if (target.os.tag.isDarwin()) {
                compile.out_lib_filename = compile.out_filename;
            } else if (target.os.tag == .windows) {
                compile.out_lib_filename = owner.fmt("{s}.lib", .{compile.name});
            } else {
                compile.out_lib_filename = compile.out_filename;
            }
        }
    }

    return compile;
}

/// Marks the specified header for installation alongside this artifact.
/// When a module links with this artifact, all headers marked for installation are added to that
/// module's include search path.
pub fn installHeader(cs: *Compile, source: LazyPath, dest_rel_path: []const u8) void {
    const b = cs.step.owner;
    const installation: HeaderInstallation = .{ .file = .{
        .source = source.dupe(b),
        .dest_rel_path = b.dupePath(dest_rel_path),
    } };
    cs.installed_headers.append(installation) catch @panic("OOM");
    cs.addHeaderInstallationToIncludeTree(installation);
    installation.getSource().addStepDependencies(&cs.step);
}

/// Marks headers from the specified directory for installation alongside this artifact.
/// When a module links with this artifact, all headers marked for installation are added to that
/// module's include search path.
pub fn installHeadersDirectory(
    cs: *Compile,
    source: LazyPath,
    dest_rel_path: []const u8,
    options: HeaderInstallation.Directory.Options,
) void {
    const b = cs.step.owner;
    const installation: HeaderInstallation = .{ .directory = .{
        .source = source.dupe(b),
        .dest_rel_path = b.dupePath(dest_rel_path),
        .options = options.dupe(b),
    } };
    cs.installed_headers.append(installation) catch @panic("OOM");
    cs.addHeaderInstallationToIncludeTree(installation);
    installation.getSource().addStepDependencies(&cs.step);
}

/// Marks the specified config header for installation alongside this artifact.
/// When a module links with this artifact, all headers marked for installation are added to that
/// module's include search path.
pub fn installConfigHeader(cs: *Compile, config_header: *Step.ConfigHeader) void {
    cs.installHeader(config_header.getOutput(), config_header.include_path);
}

/// Forwards all headers marked for installation from `lib` to this artifact.
/// When a module links with this artifact, all headers marked for installation are added to that
/// module's include search path.
pub fn installLibraryHeaders(cs: *Compile, lib: *Compile) void {
    assert(lib.kind == .lib);
    for (lib.installed_headers.items) |installation| {
        const installation_copy = installation.dupe(lib.step.owner);
        cs.installed_headers.append(installation_copy) catch @panic("OOM");
        cs.addHeaderInstallationToIncludeTree(installation_copy);
        installation_copy.getSource().addStepDependencies(&cs.step);
    }
}

fn addHeaderInstallationToIncludeTree(cs: *Compile, installation: HeaderInstallation) void {
    if (cs.installed_headers_include_tree) |wf| switch (installation) {
        .file => |file| {
            _ = wf.addCopyFile(file.source, file.dest_rel_path);
        },
        .directory => |dir| {
            _ = wf.addCopyDirectory(dir.source, dir.dest_rel_path, .{
                .exclude_extensions = dir.options.exclude_extensions,
                .include_extensions = dir.options.include_extensions,
            });
        },
    };
}

pub fn getEmittedIncludeTree(cs: *Compile) LazyPath {
    if (cs.installed_headers_include_tree) |wf| return wf.getDirectory();
    const b = cs.step.owner;
    const wf = b.addWriteFiles();
    cs.installed_headers_include_tree = wf;
    for (cs.installed_headers.items) |installation| {
        cs.addHeaderInstallationToIncludeTree(installation);
    }
    // The compile step itself does not need to depend on the write files step,
    // only dependent modules do.
    return wf.getDirectory();
}

pub fn addObjCopy(cs: *Compile, options: Step.ObjCopy.Options) *Step.ObjCopy {
    const b = cs.step.owner;
    var copy = options;
    if (copy.basename == null) {
        if (options.format) |f| {
            copy.basename = b.fmt("{s}.{s}", .{ cs.name, @tagName(f) });
        } else {
            copy.basename = cs.name;
        }
    }
    return b.addObjCopy(cs.getEmittedBin(), copy);
}

pub fn checkObject(compile: *Compile) *Step.CheckObject {
    return Step.CheckObject.create(compile.step.owner, compile.getEmittedBin(), compile.rootModuleTarget().ofmt);
}

pub fn setLinkerScript(compile: *Compile, source: LazyPath) void {
    const b = compile.step.owner;
    compile.linker_script = source.dupe(b);
    source.addStepDependencies(&compile.step);
}

pub fn setVersionScript(compile: *Compile, source: LazyPath) void {
    const b = compile.step.owner;
    compile.version_script = source.dupe(b);
    source.addStepDependencies(&compile.step);
}

pub fn forceUndefinedSymbol(compile: *Compile, symbol_name: []const u8) void {
    const b = compile.step.owner;
    compile.force_undefined_symbols.put(b.dupe(symbol_name), {}) catch @panic("OOM");
}

/// Returns whether the library, executable, or object depends on a particular system library.
/// Includes transitive dependencies.
pub fn dependsOnSystemLibrary(compile: *Compile, name: []const u8) bool {
    var is_linking_libc = false;
    var is_linking_libcpp = false;

    for (compile.getCompileDependencies(true)) |some_compile| {
        for (some_compile.root_module.getGraph().modules) |mod| {
            for (mod.link_objects.items) |lo| {
                switch (lo) {
                    .system_lib => |lib| if (mem.eql(u8, lib.name, name)) return true,
                    else => {},
                }
            }
            if (mod.link_libc orelse false) is_linking_libc = true;
            if (mod.link_libcpp orelse false) is_linking_libcpp = true;
        }
    }

    const target = compile.rootModuleTarget();

    if (std.zig.target.isLibCLibName(target, name)) {
        return is_linking_libc;
    }

    if (std.zig.target.isLibCxxLibName(target, name)) {
        return is_linking_libcpp;
    }

    return false;
}

pub fn isDynamicLibrary(compile: *const Compile) bool {
    return compile.kind == .lib and compile.linkage == .dynamic;
}

pub fn isStaticLibrary(compile: *const Compile) bool {
    return compile.kind == .lib and compile.linkage != .dynamic;
}

pub fn isDll(compile: *Compile) bool {
    return compile.isDynamicLibrary() and compile.rootModuleTarget().os.tag == .windows;
}

pub fn producesPdbFile(compile: *Compile) bool {
    const target = compile.rootModuleTarget();
    // TODO: Is this right? Isn't PDB for *any* PE/COFF file?
    // TODO: just share this logic with the compiler, silly!
    switch (target.os.tag) {
        .windows, .uefi => {},
        else => return false,
    }
    if (target.ofmt == .c) return false;
    if (compile.use_llvm == false) return false;
    if (compile.root_module.strip == true or
        (compile.root_module.strip == null and compile.root_module.optimize == .ReleaseSmall))
    {
        return false;
    }
    return compile.isDynamicLibrary() or compile.kind == .exe or compile.kind == .@"test";
}

pub fn producesImplib(compile: *Compile) bool {
    return compile.isDll();
}

/// Deprecated; use `compile.root_module.link_libc = true` instead.
/// To be removed after 0.15.0 is tagged.
pub fn linkLibC(compile: *Compile) void {
    compile.root_module.link_libc = true;
}

/// Deprecated; use `compile.root_module.link_libcpp = true` instead.
/// To be removed after 0.15.0 is tagged.
pub fn linkLibCpp(compile: *Compile) void {
    compile.root_module.link_libcpp = true;
}

const PkgConfigResult = struct {
    cflags: []const []const u8,
    libs: []const []const u8,
};

/// Run pkg-config for the given library name and parse the output, returning the arguments
/// that should be passed to zig to link the given library.
fn runPkgConfig(compile: *Compile, lib_name: []const u8) !PkgConfigResult {
    const wl_rpath_prefix = "-Wl,-rpath,";

    const b = compile.step.owner;
    const pkg_name = match: {
        // First we have to map the library name to pkg config name. Unfortunately,
        // there are several examples where this is not straightforward:
        // -lSDL2 -> pkg-config sdl2
        // -lgdk-3 -> pkg-config gdk-3.0
        // -latk-1.0 -> pkg-config atk
        // -lpulse -> pkg-config libpulse
        const pkgs = try getPkgConfigList(b);

        // Exact match means instant winner.
        for (pkgs) |pkg| {
            if (mem.eql(u8, pkg.name, lib_name)) {
                break :match pkg.name;
            }
        }

        // Next we'll try ignoring case.
        for (pkgs) |pkg| {
            if (std.ascii.eqlIgnoreCase(pkg.name, lib_name)) {
                break :match pkg.name;
            }
        }

        // Prefixed "lib" or suffixed ".0".
        for (pkgs) |pkg| {
            if (std.ascii.indexOfIgnoreCase(pkg.name, lib_name)) |pos| {
                const prefix = pkg.name[0..pos];
                const suffix = pkg.name[pos + lib_name.len ..];
                if (prefix.len > 0 and !mem.eql(u8, prefix, "lib")) continue;
                if (suffix.len > 0 and !mem.eql(u8, suffix, ".0")) continue;
                break :match pkg.name;
            }
        }

        // Trimming "-1.0".
        if (mem.endsWith(u8, lib_name, "-1.0")) {
            const trimmed_lib_name = lib_name[0 .. lib_name.len - "-1.0".len];
            for (pkgs) |pkg| {
                if (std.ascii.eqlIgnoreCase(pkg.name, trimmed_lib_name)) {
                    break :match pkg.name;
                }
            }
        }

        return error.PackageNotFound;
    };

    var code: u8 = undefined;
    const pkg_config_exe = b.graph.env_map.get("PKG_CONFIG") orelse "pkg-config";
    const stdout = if (b.runAllowFail(&[_][]const u8{
        pkg_config_exe,
        pkg_name,
        "--cflags",
        "--libs",
    }, &code, .Ignore)) |stdout| stdout else |err| switch (err) {
        error.ProcessTerminated => return error.PkgConfigCrashed,
        error.ExecNotSupported => return error.PkgConfigFailed,
        error.ExitCodeFailure => return error.PkgConfigFailed,
        error.FileNotFound => return error.PkgConfigNotInstalled,
        else => return err,
    };

    var zig_cflags = std.array_list.Managed([]const u8).init(b.allocator);
    defer zig_cflags.deinit();
    var zig_libs = std.array_list.Managed([]const u8).init(b.allocator);
    defer zig_libs.deinit();

    var arg_it = mem.tokenizeAny(u8, stdout, " \r\n\t");
    while (arg_it.next()) |arg| {
        if (mem.eql(u8, arg, "-I")) {
            const dir = arg_it.next() orelse return error.PkgConfigInvalidOutput;
            try zig_cflags.appendSlice(&[_][]const u8{ "-I", dir });
        } else if (mem.startsWith(u8, arg, "-I")) {
            try zig_cflags.append(arg);
        } else if (mem.eql(u8, arg, "-L")) {
            const dir = arg_it.next() orelse return error.PkgConfigInvalidOutput;
            try zig_libs.appendSlice(&[_][]const u8{ "-L", dir });
        } else if (mem.startsWith(u8, arg, "-L")) {
            try zig_libs.append(arg);
        } else if (mem.eql(u8, arg, "-l")) {
            const lib = arg_it.next() orelse return error.PkgConfigInvalidOutput;
            try zig_libs.appendSlice(&[_][]const u8{ "-l", lib });
        } else if (mem.startsWith(u8, arg, "-l")) {
            try zig_libs.append(arg);
        } else if (mem.eql(u8, arg, "-D")) {
            const macro = arg_it.next() orelse return error.PkgConfigInvalidOutput;
            try zig_cflags.appendSlice(&[_][]const u8{ "-D", macro });
        } else if (mem.startsWith(u8, arg, "-D")) {
            try zig_cflags.append(arg);
        } else if (mem.startsWith(u8, arg, wl_rpath_prefix)) {
            try zig_cflags.appendSlice(&[_][]const u8{ "-rpath", arg[wl_rpath_prefix.len..] });
        } else if (b.debug_pkg_config) {
            return compile.step.fail("unknown pkg-config flag '{s}'", .{arg});
        }
    }

    return .{
        .cflags = try zig_cflags.toOwnedSlice(),
        .libs = try zig_libs.toOwnedSlice(),
    };
}

/// Deprecated; use `compile.root_module.linkSystemLibrary(name, .{})` instead.
/// To be removed after 0.15.0 is tagged.
pub fn linkSystemLibrary(compile: *Compile, name: []const u8) void {
    return compile.root_module.linkSystemLibrary(name, .{});
}

/// Deprecated; use `compile.root_module.linkSystemLibrary(name, options)` instead.
/// To be removed after 0.15.0 is tagged.
pub fn linkSystemLibrary2(
    compile: *Compile,
    name: []const u8,
    options: Module.LinkSystemLibraryOptions,
) void {
    return compile.root_module.linkSystemLibrary(name, options);
}

/// Deprecated; use `c.root_module.linkFramework(name, .{})` instead.
/// To be removed after 0.15.0 is tagged.
pub fn linkFramework(c: *Compile, name: []const u8) void {
    c.root_module.linkFramework(name, .{});
}

/// Deprecated; use `compile.root_module.addCSourceFiles(options)` instead.
/// To be removed after 0.15.0 is tagged.
pub fn addCSourceFiles(compile: *Compile, options: Module.AddCSourceFilesOptions) void {
    compile.root_module.addCSourceFiles(options);
}

/// Deprecated; use `compile.root_module.addCSourceFile(source)` instead.
/// To be removed after 0.15.0 is tagged.
pub fn addCSourceFile(compile: *Compile, source: Module.CSourceFile) void {
    compile.root_module.addCSourceFile(source);
}

/// Deprecated; use `compile.root_module.addWin32ResourceFile(source)` instead.
/// To be removed after 0.15.0 is tagged.
pub fn addWin32ResourceFile(compile: *Compile, source: Module.RcSourceFile) void {
    compile.root_module.addWin32ResourceFile(source);
}

pub fn setVerboseLink(compile: *Compile, value: bool) void {
    compile.verbose_link = value;
}

pub fn setVerboseCC(compile: *Compile, value: bool) void {
    compile.verbose_cc = value;
}

pub fn setLibCFile(compile: *Compile, libc_file: ?LazyPath) void {
    const b = compile.step.owner;
    if (libc_file) |f| {
        compile.libc_file = f.dupe(b);
        f.addStepDependencies(&compile.step);
    } else {
        compile.libc_file = null;
    }
}

fn getEmittedFileGeneric(compile: *Compile, output_file: *?*GeneratedFile) LazyPath {
    if (output_file.*) |file| return .{ .generated = .{ .file = file } };
    const arena = compile.step.owner.allocator;
    const generated_file = arena.create(GeneratedFile) catch @panic("OOM");
    generated_file.* = .{ .step = &compile.step };
    output_file.* = generated_file;
    return .{ .generated = .{ .file = generated_file } };
}

/// Returns the path to the directory that contains the emitted binary file.
pub fn getEmittedBinDirectory(compile: *Compile) LazyPath {
    _ = compile.getEmittedBin();
    return compile.getEmittedFileGeneric(&compile.emit_directory);
}

/// Returns the path to the generated executable, library or object file.
/// To run an executable built with zig build, use `run`, or create an install step and invoke it.
pub fn getEmittedBin(compile: *Compile) LazyPath {
    return compile.getEmittedFileGeneric(&compile.generated_bin);
}

/// Returns the path to the generated import library.
/// This function can only be called for libraries.
pub fn getEmittedImplib(compile: *Compile) LazyPath {
    assert(compile.kind == .lib);
    return compile.getEmittedFileGeneric(&compile.generated_implib);
}

/// Returns the path to the generated header file.
/// This function can only be called for libraries or objects.
pub fn getEmittedH(compile: *Compile) LazyPath {
    assert(compile.kind != .exe and compile.kind != .@"test");
    return compile.getEmittedFileGeneric(&compile.generated_h);
}

/// Returns the generated PDB file.
/// If the compilation does not produce a PDB file, this causes a FileNotFound error
/// at build time.
pub fn getEmittedPdb(compile: *Compile) LazyPath {
    _ = compile.getEmittedBin();
    return compile.getEmittedFileGeneric(&compile.generated_pdb);
}

/// Returns the path to the generated documentation directory.
pub fn getEmittedDocs(compile: *Compile) LazyPath {
    return compile.getEmittedFileGeneric(&compile.generated_docs);
}

/// Returns the path to the generated assembly code.
pub fn getEmittedAsm(compile: *Compile) LazyPath {
    return compile.getEmittedFileGeneric(&compile.generated_asm);
}

/// Returns the path to the generated LLVM IR.
pub fn getEmittedLlvmIr(compile: *Compile) LazyPath {
    return compile.getEmittedFileGeneric(&compile.generated_llvm_ir);
}

/// Returns the path to the generated LLVM BC.
pub fn getEmittedLlvmBc(compile: *Compile) LazyPath {
    return compile.getEmittedFileGeneric(&compile.generated_llvm_bc);
}

/// Deprecated; use `compile.root_module.addAssemblyFile(source)` instead.
/// To be removed after 0.15.0 is tagged.
pub fn addAssemblyFile(compile: *Compile, source: LazyPath) void {
    compile.root_module.addAssemblyFile(source);
}

/// Deprecated; use `compile.root_module.addObjectFile(source)` instead.
/// To be removed after 0.15.0 is tagged.
pub fn addObjectFile(compile: *Compile, source: LazyPath) void {
    compile.root_module.addObjectFile(source);
}

/// Deprecated; use `compile.root_module.addObject(object)` instead.
/// To be removed after 0.15.0 is tagged.
pub fn addObject(compile: *Compile, object: *Compile) void {
    compile.root_module.addObject(object);
}

/// Deprecated; use `compile.root_module.linkLibrary(library)` instead.
/// To be removed after 0.15.0 is tagged.
pub fn linkLibrary(compile: *Compile, library: *Compile) void {
    compile.root_module.linkLibrary(library);
}

/// Deprecated; use `compile.root_module.addAfterIncludePath(lazy_path)` instead.
/// To be removed after 0.15.0 is tagged.
pub fn addAfterIncludePath(compile: *Compile, lazy_path: LazyPath) void {
    compile.root_module.addAfterIncludePath(lazy_path);
}

/// Deprecated; use `compile.root_module.addSystemIncludePath(lazy_path)` instead.
/// To be removed after 0.15.0 is tagged.
pub fn addSystemIncludePath(compile: *Compile, lazy_path: LazyPath) void {
    compile.root_module.addSystemIncludePath(lazy_path);
}

/// Deprecated; use `compile.root_module.addIncludePath(lazy_path)` instead.
/// To be removed after 0.15.0 is tagged.
pub fn addIncludePath(compile: *Compile, lazy_path: LazyPath) void {
    compile.root_module.addIncludePath(lazy_path);
}

/// Deprecated; use `compile.root_module.addConfigHeader(config_header)` instead.
/// To be removed after 0.15.0 is tagged.
pub fn addConfigHeader(compile: *Compile, config_header: *Step.ConfigHeader) void {
    compile.root_module.addConfigHeader(config_header);
}

/// Deprecated; use `compile.root_module.addEmbedPath(lazy_path)` instead.
/// To be removed after 0.15.0 is tagged.
pub fn addEmbedPath(compile: *Compile, lazy_path: LazyPath) void {
    compile.root_module.addEmbedPath(lazy_path);
}

/// Deprecated; use `compile.root_module.addLibraryPath(directory_path)` instead.
/// To be removed after 0.15.0 is tagged.
pub fn addLibraryPath(compile: *Compile, directory_path: LazyPath) void {
    compile.root_module.addLibraryPath(directory_path);
}

/// Deprecated; use `compile.root_module.addRPath(directory_path)` instead.
/// To be removed after 0.15.0 is tagged.
pub fn addRPath(compile: *Compile, directory_path: LazyPath) void {
    compile.root_module.addRPath(directory_path);
}

/// Deprecated; use `compile.root_module.addSystemFrameworkPath(directory_path)` instead.
/// To be removed after 0.15.0 is tagged.
pub fn addSystemFrameworkPath(compile: *Compile, directory_path: LazyPath) void {
    compile.root_module.addSystemFrameworkPath(directory_path);
}

/// Deprecated; use `compile.root_module.addFrameworkPath(directory_path)` instead.
/// To be removed after 0.15.0 is tagged.
pub fn addFrameworkPath(compile: *Compile, directory_path: LazyPath) void {
    compile.root_module.addFrameworkPath(directory_path);
}

pub fn setExecCmd(compile: *Compile, args: []const ?[]const u8) void {
    const b = compile.step.owner;
    assert(compile.kind == .@"test");
    const duped_args = b.allocator.alloc(?[]u8, args.len) catch @panic("OOM");
    for (args, 0..) |arg, i| {
        duped_args[i] = if (arg) |a| b.dupe(a) else null;
    }
    compile.exec_cmd_args = duped_args;
}

const CliNamedModules = struct {
    modules: std.AutoArrayHashMapUnmanaged(*Module, void),
    names: std.StringArrayHashMapUnmanaged(void),

    /// Traverse the whole dependency graph and give every module a unique
    /// name, ideally one named after what it's called somewhere in the graph.
    /// It will help here to have both a mapping from module to name and a set
    /// of all the currently-used names.
    fn init(arena: Allocator, root_module: *Module) Allocator.Error!CliNamedModules {
        var compile: CliNamedModules = .{
            .modules = .{},
            .names = .{},
        };
        const graph = root_module.getGraph();
        {
            assert(graph.modules[0] == root_module);
            try compile.modules.put(arena, root_module, {});
            try compile.names.put(arena, "root", {});
        }
        for (graph.modules[1..], graph.names[1..]) |mod, orig_name| {
            var name = orig_name;
            var n: usize = 0;
            while (true) {
                const gop = try compile.names.getOrPut(arena, name);
                if (!gop.found_existing) {
                    try compile.modules.putNoClobber(arena, mod, {});
                    break;
                }
                name = try std.fmt.allocPrint(arena, "{s}{d}", .{ orig_name, n });
                n += 1;
            }
        }
        return compile;
    }
};

fn getGeneratedFilePath(compile: *Compile, comptime tag_name: []const u8, asking_step: ?*Step) []const u8 {
    const maybe_path: ?*GeneratedFile = @field(compile, tag_name);

    const generated_file = maybe_path orelse {
        const w = std.debug.lockStderrWriter(&.{});
        std.Build.dumpBadGetPathHelp(&compile.step, w, .detect(.stderr()), compile.step.owner, asking_step) catch {};
        std.debug.unlockStderrWriter();
        @panic("missing emit option for " ++ tag_name);
    };

    const path = generated_file.path orelse {
        const w = std.debug.lockStderrWriter(&.{});
        std.Build.dumpBadGetPathHelp(&compile.step, w, .detect(.stderr()), compile.step.owner, asking_step) catch {};
        std.debug.unlockStderrWriter();
        @panic(tag_name ++ " is null. Is there a missing step dependency?");
    };

    return path;
}

fn getZigArgs(compile: *Compile, fuzz: bool) ![][]const u8 {
    const step = &compile.step;
    const b = step.owner;
    const arena = b.allocator;

    var zig_args = std.array_list.Managed([]const u8).init(arena);
    defer zig_args.deinit();

    try zig_args.append(b.graph.zig_exe);

    const cmd = switch (compile.kind) {
        .lib => "build-lib",
        .exe => "build-exe",
        .obj => "build-obj",
        .@"test" => "test",
        .test_obj => "test-obj",
    };
    try zig_args.append(cmd);

    if (b.reference_trace) |some| {
        try zig_args.append(try std.fmt.allocPrint(arena, "-freference-trace={d}", .{some}));
    }
    try addFlag(&zig_args, "allow-so-scripts", compile.allow_so_scripts orelse b.graph.allow_so_scripts);

    try addFlag(&zig_args, "llvm", compile.use_llvm);
    try addFlag(&zig_args, "lld", compile.use_lld);

    if (compile.root_module.resolved_target.?.query.ofmt) |ofmt| {
        try zig_args.append(try std.fmt.allocPrint(arena, "-ofmt={s}", .{@tagName(ofmt)}));
    }

    switch (compile.entry) {
        .default => {},
        .disabled => try zig_args.append("-fno-entry"),
        .enabled => try zig_args.append("-fentry"),
        .symbol_name => |entry_name| {
            try zig_args.append(try std.fmt.allocPrint(arena, "-fentry={s}", .{entry_name}));
        },
    }

    {
        var symbol_it = compile.force_undefined_symbols.keyIterator();
        while (symbol_it.next()) |symbol_name| {
            try zig_args.append("--force_undefined");
            try zig_args.append(symbol_name.*);
        }
    }

    if (compile.stack_size) |stack_size| {
        try zig_args.append("--stack");
        try zig_args.append(try std.fmt.allocPrint(arena, "{}", .{stack_size}));
    }

    if (fuzz) {
        try zig_args.append("-ffuzz");
    }

    {
        // Stores system libraries that have already been seen for at least one
        // module, along with any arguments that need to be passed to the
        // compiler for each module individually.
        var seen_system_libs: std.StringHashMapUnmanaged([]const []const u8) = .empty;
        var frameworks: std.StringArrayHashMapUnmanaged(Module.LinkFrameworkOptions) = .empty;

        var prev_has_cflags = false;
        var prev_has_rcflags = false;
        var prev_search_strategy: Module.SystemLib.SearchStrategy = .paths_first;
        var prev_preferred_link_mode: std.builtin.LinkMode = .dynamic;
        // Track the number of positional arguments so that a nice error can be
        // emitted if there is nothing to link.
        var total_linker_objects: usize = @intFromBool(compile.root_module.root_source_file != null);

        // Fully recursive iteration including dynamic libraries to detect
        // libc and libc++ linkage.
        for (compile.getCompileDependencies(true)) |some_compile| {
            for (some_compile.root_module.getGraph().modules) |mod| {
                if (mod.link_libc == true) compile.is_linking_libc = true;
                if (mod.link_libcpp == true) compile.is_linking_libcpp = true;
            }
        }

        var cli_named_modules = try CliNamedModules.init(arena, compile.root_module);

        // For this loop, don't chase dynamic libraries because their link
        // objects are already linked.
        for (compile.getCompileDependencies(false)) |dep_compile| {
            for (dep_compile.root_module.getGraph().modules) |mod| {
                // While walking transitive dependencies, if a given link object is
                // already included in a library, it should not redundantly be
                // placed on the linker line of the dependee.
                const my_responsibility = dep_compile == compile;
                const already_linked = !my_responsibility and dep_compile.isDynamicLibrary();

                // Inherit dependencies on darwin frameworks.
                if (!already_linked) {
                    for (mod.frameworks.keys(), mod.frameworks.values()) |name, info| {
                        try frameworks.put(arena, name, info);
                    }
                }

                // Inherit dependencies on system libraries and static libraries.
                for (mod.link_objects.items) |link_object| {
                    switch (link_object) {
                        .static_path => |static_path| {
                            if (my_responsibility) {
                                try zig_args.append(static_path.getPath2(mod.owner, step));
                                total_linker_objects += 1;
                            }
                        },
                        .system_lib => |system_lib| {
                            const system_lib_gop = try seen_system_libs.getOrPut(arena, system_lib.name);
                            if (system_lib_gop.found_existing) {
                                try zig_args.appendSlice(system_lib_gop.value_ptr.*);
                                continue;
                            } else {
                                system_lib_gop.value_ptr.* = &.{};
                            }

                            if (already_linked)
                                continue;

                            if ((system_lib.search_strategy != prev_search_strategy or
                                system_lib.preferred_link_mode != prev_preferred_link_mode) and
                                compile.linkage != .static)
                            {
                                switch (system_lib.search_strategy) {
                                    .no_fallback => switch (system_lib.preferred_link_mode) {
                                        .dynamic => try zig_args.append("-search_dylibs_only"),
                                        .static => try zig_args.append("-search_static_only"),
                                    },
                                    .paths_first => switch (system_lib.preferred_link_mode) {
                                        .dynamic => try zig_args.append("-search_paths_first"),
                                        .static => try zig_args.append("-search_paths_first_static"),
                                    },
                                    .mode_first => switch (system_lib.preferred_link_mode) {
                                        .dynamic => try zig_args.append("-search_dylibs_first"),
                                        .static => try zig_args.append("-search_static_first"),
                                    },
                                }
                                prev_search_strategy = system_lib.search_strategy;
                                prev_preferred_link_mode = system_lib.preferred_link_mode;
                            }

                            const prefix: []const u8 = prefix: {
                                if (system_lib.needed) break :prefix "-needed-l";
                                if (system_lib.weak) break :prefix "-weak-l";
                                break :prefix "-l";
                            };
                            switch (system_lib.use_pkg_config) {
                                .no => try zig_args.append(b.fmt("{s}{s}", .{ prefix, system_lib.name })),
                                .yes, .force => {
                                    if (compile.runPkgConfig(system_lib.name)) |result| {
                                        try zig_args.appendSlice(result.cflags);
                                        try zig_args.appendSlice(result.libs);
                                        try seen_system_libs.put(arena, system_lib.name, result.cflags);
                                    } else |err| switch (err) {
                                        error.PkgConfigInvalidOutput,
                                        error.PkgConfigCrashed,
                                        error.PkgConfigFailed,
                                        error.PkgConfigNotInstalled,
                                        error.PackageNotFound,
                                        => switch (system_lib.use_pkg_config) {
                                            .yes => {
                                                // pkg-config failed, so fall back to linking the library
                                                // by name directly.
                                                try zig_args.append(b.fmt("{s}{s}", .{
                                                    prefix,
                                                    system_lib.name,
                                                }));
                                            },
                                            .force => {
                                                panic("pkg-config failed for library {s}", .{system_lib.name});
                                            },
                                            .no => unreachable,
                                        },

                                        else => |e| return e,
                                    }
                                },
                            }
                        },
                        .other_step => |other| {
                            switch (other.kind) {
                                .exe => return step.fail("cannot link with an executable build artifact", .{}),
                                .@"test" => return step.fail("cannot link with a test", .{}),
                                .obj, .test_obj => {
                                    const included_in_lib_or_obj = !my_responsibility and
                                        (dep_compile.kind == .lib or dep_compile.kind == .obj or dep_compile.kind == .test_obj);
                                    if (!already_linked and !included_in_lib_or_obj) {
                                        try zig_args.append(other.getEmittedBin().getPath2(b, step));
                                        total_linker_objects += 1;
                                    }
                                },
                                .lib => l: {
                                    const other_produces_implib = other.producesImplib();
                                    const other_is_static = other_produces_implib or other.isStaticLibrary();

                                    if (compile.isStaticLibrary() and other_is_static) {
                                        // Avoid putting a static library inside a static library.
                                        break :l;
                                    }

                                    // For DLLs, we must link against the implib.
                                    // For everything else, we directly link
                                    // against the library file.
                                    const full_path_lib = if (other_produces_implib)
                                        other.getGeneratedFilePath("generated_implib", &compile.step)
                                    else
                                        other.getGeneratedFilePath("generated_bin", &compile.step);

                                    try zig_args.append(full_path_lib);
                                    total_linker_objects += 1;

                                    if (other.linkage == .dynamic and
                                        compile.rootModuleTarget().os.tag != .windows)
                                    {
                                        if (fs.path.dirname(full_path_lib)) |dirname| {
                                            try zig_args.append("-rpath");
                                            try zig_args.append(dirname);
                                        }
                                    }
                                },
                            }
                        },
                        .assembly_file => |asm_file| l: {
                            if (!my_responsibility) break :l;

                            if (prev_has_cflags) {
                                try zig_args.append("-cflags");
                                try zig_args.append("--");
                                prev_has_cflags = false;
                            }
                            try zig_args.append(asm_file.getPath2(mod.owner, step));
                            total_linker_objects += 1;
                        },

                        .c_source_file => |c_source_file| l: {
                            if (!my_responsibility) break :l;

                            if (prev_has_cflags or c_source_file.flags.len != 0) {
                                try zig_args.append("-cflags");
                                for (c_source_file.flags) |arg| {
                                    try zig_args.append(arg);
                                }
                                try zig_args.append("--");
                            }
                            prev_has_cflags = (c_source_file.flags.len != 0);

                            if (c_source_file.language) |lang| {
                                try zig_args.append("-x");
                                try zig_args.append(lang.internalIdentifier());
                            }

                            try zig_args.append(c_source_file.file.getPath2(mod.owner, step));

                            if (c_source_file.language != null) {
                                try zig_args.append("-x");
                                try zig_args.append("none");
                            }
                            total_linker_objects += 1;
                        },

                        .c_source_files => |c_source_files| l: {
                            if (!my_responsibility) break :l;

                            if (prev_has_cflags or c_source_files.flags.len != 0) {
                                try zig_args.append("-cflags");
                                for (c_source_files.flags) |arg| {
                                    try zig_args.append(arg);
                                }
                                try zig_args.append("--");
                            }
                            prev_has_cflags = (c_source_files.flags.len != 0);

                            if (c_source_files.language) |lang| {
                                try zig_args.append("-x");
                                try zig_args.append(lang.internalIdentifier());
                            }

                            const root_path = c_source_files.root.getPath2(mod.owner, step);
                            for (c_source_files.files) |file| {
                                try zig_args.append(b.pathJoin(&.{ root_path, file }));
                            }

                            if (c_source_files.language != null) {
                                try zig_args.append("-x");
                                try zig_args.append("none");
                            }

                            total_linker_objects += c_source_files.files.len;
                        },

                        .win32_resource_file => |rc_source_file| l: {
                            if (!my_responsibility) break :l;

                            if (rc_source_file.flags.len == 0 and rc_source_file.include_paths.len == 0) {
                                if (prev_has_rcflags) {
                                    try zig_args.append("-rcflags");
                                    try zig_args.append("--");
                                    prev_has_rcflags = false;
                                }
                            } else {
                                try zig_args.append("-rcflags");
                                for (rc_source_file.flags) |arg| {
                                    try zig_args.append(arg);
                                }
                                for (rc_source_file.include_paths) |include_path| {
                                    try zig_args.append("/I");
                                    try zig_args.append(include_path.getPath2(mod.owner, step));
                                }
                                try zig_args.append("--");
                                prev_has_rcflags = true;
                            }
                            try zig_args.append(rc_source_file.file.getPath2(mod.owner, step));
                            total_linker_objects += 1;
                        },
                    }
                }

                // We need to emit the --mod argument here so that the above link objects
                // have the correct parent module, but only if the module is part of
                // this compilation.
                if (!my_responsibility) continue;
                if (cli_named_modules.modules.getIndex(mod)) |module_cli_index| {
                    const module_cli_name = cli_named_modules.names.keys()[module_cli_index];
                    try mod.appendZigProcessFlags(&zig_args, step);

                    // --dep arguments
                    try zig_args.ensureUnusedCapacity(mod.import_table.count() * 2);
                    for (mod.import_table.keys(), mod.import_table.values()) |name, import| {
                        const import_index = cli_named_modules.modules.getIndex(import).?;
                        const import_cli_name = cli_named_modules.names.keys()[import_index];
                        zig_args.appendAssumeCapacity("--dep");
                        if (std.mem.eql(u8, import_cli_name, name)) {
                            zig_args.appendAssumeCapacity(import_cli_name);
                        } else {
                            zig_args.appendAssumeCapacity(b.fmt("{s}={s}", .{ name, import_cli_name }));
                        }
                    }

                    // When the CLI sees a -M argument, it determines whether it
                    // implies the existence of a Zig compilation unit based on
                    // whether there is a root source file. If there is no root
                    // source file, then this is not a zig compilation unit - it is
                    // perhaps a set of linker objects, or C source files instead.
                    // Linker objects are added to the CLI globally, while C source
                    // files must have a module parent.
                    if (mod.root_source_file) |lp| {
                        const src = lp.getPath2(mod.owner, step);
                        try zig_args.append(b.fmt("-M{s}={s}", .{ module_cli_name, src }));
                    } else if (moduleNeedsCliArg(mod)) {
                        try zig_args.append(b.fmt("-M{s}", .{module_cli_name}));
                    }
                }
            }
        }

        if (total_linker_objects == 0) {
            return step.fail("the linker needs one or more objects to link", .{});
        }

        for (frameworks.keys(), frameworks.values()) |name, info| {
            if (info.needed) {
                try zig_args.append("-needed_framework");
            } else if (info.weak) {
                try zig_args.append("-weak_framework");
            } else {
                try zig_args.append("-framework");
            }
            try zig_args.append(name);
        }

        if (compile.is_linking_libcpp) {
            try zig_args.append("-lc++");
        }

        if (compile.is_linking_libc) {
            try zig_args.append("-lc");
        }
    }

    if (compile.win32_manifest) |manifest_file| {
        try zig_args.append(manifest_file.getPath2(b, step));
    }

    if (compile.image_base) |image_base| {
        try zig_args.append("--image-base");
        try zig_args.append(b.fmt("0x{x}", .{image_base}));
    }

    for (compile.filters) |filter| {
        try zig_args.append("--test-filter");
        try zig_args.append(filter);
    }

    if (compile.test_runner) |test_runner| {
        try zig_args.append("--test-runner");
        try zig_args.append(test_runner.path.getPath2(b, step));
    }

    for (b.debug_log_scopes) |log_scope| {
        try zig_args.append("--debug-log");
        try zig_args.append(log_scope);
    }

    if (b.debug_compile_errors) {
        try zig_args.append("--debug-compile-errors");
    }

    if (b.debug_incremental) {
        try zig_args.append("--debug-incremental");
    }

    if (b.verbose_cimport) try zig_args.append("--verbose-cimport");
    if (b.verbose_air) try zig_args.append("--verbose-air");
    if (b.verbose_llvm_ir) |path| try zig_args.append(b.fmt("--verbose-llvm-ir={s}", .{path}));
    if (b.verbose_llvm_bc) |path| try zig_args.append(b.fmt("--verbose-llvm-bc={s}", .{path}));
    if (b.verbose_link or compile.verbose_link) try zig_args.append("--verbose-link");
    if (b.verbose_cc or compile.verbose_cc) try zig_args.append("--verbose-cc");
    if (b.verbose_llvm_cpu_features) try zig_args.append("--verbose-llvm-cpu-features");
    if (b.graph.time_report) try zig_args.append("--time-report");

    if (compile.generated_asm != null) try zig_args.append("-femit-asm");
    if (compile.generated_bin == null) try zig_args.append("-fno-emit-bin");
    if (compile.generated_docs != null) try zig_args.append("-femit-docs");
    if (compile.generated_implib != null) try zig_args.append("-femit-implib");
    if (compile.generated_llvm_bc != null) try zig_args.append("-femit-llvm-bc");
    if (compile.generated_llvm_ir != null) try zig_args.append("-femit-llvm-ir");
    if (compile.generated_h != null) try zig_args.append("-femit-h");

    try addFlag(&zig_args, "formatted-panics", compile.formatted_panics);

    switch (compile.compress_debug_sections) {
        .none => {},
        .zlib => try zig_args.append("--compress-debug-sections=zlib"),
        .zstd => try zig_args.append("--compress-debug-sections=zstd"),
    }

    if (compile.link_eh_frame_hdr) {
        try zig_args.append("--eh-frame-hdr");
    }
    if (compile.link_emit_relocs) {
        try zig_args.append("--emit-relocs");
    }
    if (compile.link_function_sections) {
        try zig_args.append("-ffunction-sections");
    }
    if (compile.link_data_sections) {
        try zig_args.append("-fdata-sections");
    }
    if (compile.link_gc_sections) |x| {
        try zig_args.append(if (x) "--gc-sections" else "--no-gc-sections");
    }
    if (!compile.linker_dynamicbase) {
        try zig_args.append("--no-dynamicbase");
    }
    if (compile.linker_allow_shlib_undefined) |x| {
        try zig_args.append(if (x) "-fallow-shlib-undefined" else "-fno-allow-shlib-undefined");
    }
    if (compile.link_z_notext) {
        try zig_args.append("-z");
        try zig_args.append("notext");
    }
    if (!compile.link_z_relro) {
        try zig_args.append("-z");
        try zig_args.append("norelro");
    }
    if (compile.link_z_lazy) {
        try zig_args.append("-z");
        try zig_args.append("lazy");
    }
    if (compile.link_z_common_page_size) |size| {
        try zig_args.append("-z");
        try zig_args.append(b.fmt("common-page-size={d}", .{size}));
    }
    if (compile.link_z_max_page_size) |size| {
        try zig_args.append("-z");
        try zig_args.append(b.fmt("max-page-size={d}", .{size}));
    }

    if (compile.libc_file) |libc_file| {
        try zig_args.append("--libc");
        try zig_args.append(libc_file.getPath2(b, step));
    } else if (b.libc_file) |libc_file| {
        try zig_args.append("--libc");
        try zig_args.append(libc_file);
    }

    try zig_args.append("--cache-dir");
    try zig_args.append(b.cache_root.path orelse ".");

    try zig_args.append("--global-cache-dir");
    try zig_args.append(b.graph.global_cache_root.path orelse ".");

    if (b.graph.debug_compiler_runtime_libs) try zig_args.append("--debug-rt");

    try zig_args.append("--name");
    try zig_args.append(compile.name);

    if (compile.linkage) |some| switch (some) {
        .dynamic => try zig_args.append("-dynamic"),
        .static => try zig_args.append("-static"),
    };
    if (compile.kind == .lib and compile.linkage != null and compile.linkage.? == .dynamic) {
        if (compile.version) |version| {
            try zig_args.append("--version");
            try zig_args.append(b.fmt("{f}", .{version}));
        }

        if (compile.rootModuleTarget().os.tag.isDarwin()) {
            const install_name = compile.install_name orelse b.fmt("@rpath/{s}{s}{s}", .{
                compile.rootModuleTarget().libPrefix(),
                compile.name,
                compile.rootModuleTarget().dynamicLibSuffix(),
            });
            try zig_args.append("-install_name");
            try zig_args.append(install_name);
        }
    }

    if (compile.entitlements) |entitlements| {
        try zig_args.appendSlice(&[_][]const u8{ "--entitlements", entitlements });
    }
    if (compile.pagezero_size) |pagezero_size| {
        const size = try std.fmt.allocPrint(arena, "{x}", .{pagezero_size});
        try zig_args.appendSlice(&[_][]const u8{ "-pagezero_size", size });
    }
    if (compile.headerpad_size) |headerpad_size| {
        const size = try std.fmt.allocPrint(arena, "{x}", .{headerpad_size});
        try zig_args.appendSlice(&[_][]const u8{ "-headerpad", size });
    }
    if (compile.headerpad_max_install_names) {
        try zig_args.append("-headerpad_max_install_names");
    }
    if (compile.dead_strip_dylibs) {
        try zig_args.append("-dead_strip_dylibs");
    }
    if (compile.force_load_objc) {
        try zig_args.append("-ObjC");
    }
    if (compile.discard_local_symbols) {
        try zig_args.append("--discard-all");
    }

    try addFlag(&zig_args, "compiler-rt", compile.bundle_compiler_rt);
    try addFlag(&zig_args, "ubsan-rt", compile.bundle_ubsan_rt);
    try addFlag(&zig_args, "dll-export-fns", compile.dll_export_fns);
    if (compile.rdynamic) {
        try zig_args.append("-rdynamic");
    }
    if (compile.import_memory) {
        try zig_args.append("--import-memory");
    }
    if (compile.export_memory) {
        try zig_args.append("--export-memory");
    }
    if (compile.import_symbols) {
        try zig_args.append("--import-symbols");
    }
    if (compile.import_table) {
        try zig_args.append("--import-table");
    }
    if (compile.export_table) {
        try zig_args.append("--export-table");
    }
    if (compile.initial_memory) |initial_memory| {
        try zig_args.append(b.fmt("--initial-memory={d}", .{initial_memory}));
    }
    if (compile.max_memory) |max_memory| {
        try zig_args.append(b.fmt("--max-memory={d}", .{max_memory}));
    }
    if (compile.shared_memory) {
        try zig_args.append("--shared-memory");
    }
    if (compile.global_base) |global_base| {
        try zig_args.append(b.fmt("--global-base={d}", .{global_base}));
    }

    if (compile.wasi_exec_model) |model| {
        try zig_args.append(b.fmt("-mexec-model={s}", .{@tagName(model)}));
    }
    if (compile.linker_script) |linker_script| {
        try zig_args.append("--script");
        try zig_args.append(linker_script.getPath2(b, step));
    }

    if (compile.version_script) |version_script| {
        try zig_args.append("--version-script");
        try zig_args.append(version_script.getPath2(b, step));
    }
    if (compile.linker_allow_undefined_version) |x| {
        try zig_args.append(if (x) "--undefined-version" else "--no-undefined-version");
    }

    if (compile.linker_enable_new_dtags) |enabled| {
        try zig_args.append(if (enabled) "--enable-new-dtags" else "--disable-new-dtags");
    }

    if (compile.kind == .@"test") {
        if (compile.exec_cmd_args) |exec_cmd_args| {
            for (exec_cmd_args) |cmd_arg| {
                if (cmd_arg) |arg| {
                    try zig_args.append("--test-cmd");
                    try zig_args.append(arg);
                } else {
                    try zig_args.append("--test-cmd-bin");
                }
            }
        }
    }

    if (b.sysroot) |sysroot| {
        try zig_args.appendSlice(&[_][]const u8{ "--sysroot", sysroot });
    }

    // -I and -L arguments that appear after the last --mod argument apply to all modules.
    for (b.search_prefixes.items) |search_prefix| {
        var prefix_dir = fs.cwd().openDir(search_prefix, .{}) catch |err| {
            return step.fail("unable to open prefix directory '{s}': {s}", .{
                search_prefix, @errorName(err),
            });
        };
        defer prefix_dir.close();

        // Avoid passing -L and -I flags for nonexistent directories.
        // This prevents a warning, that should probably be upgraded to an error in Zig's
        // CLI parsing code, when the linker sees an -L directory that does not exist.

        if (prefix_dir.accessZ("lib", .{})) |_| {
            try zig_args.appendSlice(&.{
                "-L", b.pathJoin(&.{ search_prefix, "lib" }),
            });
        } else |err| switch (err) {
            error.FileNotFound => {},
            else => |e| return step.fail("unable to access '{s}/lib' directory: {s}", .{
                search_prefix, @errorName(e),
            }),
        }

        if (prefix_dir.accessZ("include", .{})) |_| {
            try zig_args.appendSlice(&.{
                "-I", b.pathJoin(&.{ search_prefix, "include" }),
            });
        } else |err| switch (err) {
            error.FileNotFound => {},
            else => |e| return step.fail("unable to access '{s}/include' directory: {s}", .{
                search_prefix, @errorName(e),
            }),
        }
    }

    if (compile.rc_includes != .any) {
        try zig_args.append("-rcincludes");
        try zig_args.append(@tagName(compile.rc_includes));
    }

    try addFlag(&zig_args, "each-lib-rpath", compile.each_lib_rpath);

    if (compile.build_id orelse b.build_id) |build_id| {
        try zig_args.append(switch (build_id) {
            .hexstring => |hs| b.fmt("--build-id=0x{x}", .{hs.toSlice()}),
            .none, .fast, .uuid, .sha1, .md5 => b.fmt("--build-id={s}", .{@tagName(build_id)}),
        });
    }

    const opt_zig_lib_dir = if (compile.zig_lib_dir) |dir|
        dir.getPath2(b, step)
    else if (b.graph.zig_lib_directory.path) |_|
        b.fmt("{f}", .{b.graph.zig_lib_directory})
    else
        null;

    if (opt_zig_lib_dir) |zig_lib_dir| {
        try zig_args.append("--zig-lib-dir");
        try zig_args.append(zig_lib_dir);
    }

    try addFlag(&zig_args, "PIE", compile.pie);

    if (compile.lto) |lto| {
        try zig_args.append(switch (lto) {
            .full => "-flto=full",
            .thin => "-flto=thin",
            .none => "-fno-lto",
        });
    } else try addFlag(&zig_args, "lto", compile.want_lto);

    try addFlag(&zig_args, "sanitize-coverage-trace-pc-guard", compile.sanitize_coverage_trace_pc_guard);

    if (compile.subsystem) |subsystem| {
        try zig_args.append("--subsystem");
        try zig_args.append(switch (subsystem) {
            .Console => "console",
            .Windows => "windows",
            .Posix => "posix",
            .Native => "native",
            .EfiApplication => "efi_application",
            .EfiBootServiceDriver => "efi_boot_service_driver",
            .EfiRom => "efi_rom",
            .EfiRuntimeDriver => "efi_runtime_driver",
        });
    }

    if (compile.mingw_unicode_entry_point) {
        try zig_args.append("-municode");
    }

    if (compile.error_limit) |err_limit| try zig_args.appendSlice(&.{
        "--error-limit", b.fmt("{d}", .{err_limit}),
    });

    try addFlag(&zig_args, "incremental", b.graph.incremental);

    try zig_args.append("--listen=-");

    // Windows has an argument length limit of 32,766 characters, macOS 262,144 and Linux
    // 2,097,152. If our args exceed 30 KiB, we instead write them to a "response file" and
    // pass that to zig, e.g. via 'zig build-lib @args.rsp'
    // See @file syntax here: https://gcc.gnu.org/onlinedocs/gcc/Overall-Options.html
    var args_length: usize = 0;
    for (zig_args.items) |arg| {
        args_length += arg.len + 1; // +1 to account for null terminator
    }
    if (args_length >= 30 * 1024) {
        try b.cache_root.handle.makePath("args");

        const args_to_escape = zig_args.items[2..];
        var escaped_args = try std.array_list.Managed([]const u8).initCapacity(arena, args_to_escape.len);
        arg_blk: for (args_to_escape) |arg| {
            for (arg, 0..) |c, arg_idx| {
                if (c == '\\' or c == '"') {
                    // Slow path for arguments that need to be escaped. We'll need to allocate and copy
                    var escaped: std.ArrayListUnmanaged(u8) = .empty;
                    try escaped.ensureTotalCapacityPrecise(arena, arg.len + 1);
                    try escaped.appendSlice(arena, arg[0..arg_idx]);
                    for (arg[arg_idx..]) |to_escape| {
                        if (to_escape == '\\' or to_escape == '"') try escaped.append(arena, '\\');
                        try escaped.append(arena, to_escape);
                    }
                    escaped_args.appendAssumeCapacity(escaped.items);
                    continue :arg_blk;
                }
            }
            escaped_args.appendAssumeCapacity(arg); // no escaping needed so just use original argument
        }

        // Write the args to zig-cache/args/<SHA256 hash of args> to avoid conflicts with
        // other zig build commands running in parallel.
        const partially_quoted = try std.mem.join(arena, "\" \"", escaped_args.items);
        const args = try std.mem.concat(arena, u8, &[_][]const u8{ "\"", partially_quoted, "\"" });

        var args_hash: [Sha256.digest_length]u8 = undefined;
        Sha256.hash(args, &args_hash, .{});
        var args_hex_hash: [Sha256.digest_length * 2]u8 = undefined;
        _ = try std.fmt.bufPrint(&args_hex_hash, "{x}", .{&args_hash});

        const args_file = "args" ++ fs.path.sep_str ++ args_hex_hash;
        try b.cache_root.handle.writeFile(.{ .sub_path = args_file, .data = args });

        const resolved_args_file = try mem.concat(arena, u8, &.{
            "@",
            try b.cache_root.join(arena, &.{args_file}),
        });

        zig_args.shrinkRetainingCapacity(2);
        try zig_args.append(resolved_args_file);
    }

    return try zig_args.toOwnedSlice();
}

fn make(step: *Step, options: Step.MakeOptions) !void {
    const b = step.owner;
    const compile: *Compile = @fieldParentPtr("step", step);

    const zig_args = try getZigArgs(compile, false);

    const maybe_output_dir = step.evalZigProcess(
        zig_args,
        options.progress_node,
        (b.graph.incremental == true) and (options.watch or options.web_server != null),
        options.web_server,
        options.gpa,
    ) catch |err| switch (err) {
        error.NeedCompileErrorCheck => {
            assert(compile.expect_errors != null);
            try checkCompileErrors(compile);
            return;
        },
        else => |e| return e,
    };

    // Update generated files
    if (maybe_output_dir) |output_dir| {
        if (compile.emit_directory) |lp| {
            lp.path = b.fmt("{f}", .{output_dir});
        }

        // zig fmt: off
        if (compile.generated_bin)     |lp| lp.path = compile.outputPath(output_dir, .bin);
        if (compile.generated_pdb)     |lp| lp.path = compile.outputPath(output_dir, .pdb);
        if (compile.generated_implib)  |lp| lp.path = compile.outputPath(output_dir, .implib);
        if (compile.generated_h)       |lp| lp.path = compile.outputPath(output_dir, .h);
        if (compile.generated_docs)    |lp| lp.path = compile.outputPath(output_dir, .docs);
        if (compile.generated_asm)     |lp| lp.path = compile.outputPath(output_dir, .@"asm");
        if (compile.generated_llvm_ir) |lp| lp.path = compile.outputPath(output_dir, .llvm_ir);
        if (compile.generated_llvm_bc) |lp| lp.path = compile.outputPath(output_dir, .llvm_bc);
        // zig fmt: on
    }

    if (compile.kind == .lib and compile.linkage != null and compile.linkage.? == .dynamic and
        compile.version != null and std.Build.wantSharedLibSymLinks(compile.rootModuleTarget()))
    {
        try doAtomicSymLinks(
            step,
            compile.getEmittedBin().getPath2(b, step),
            compile.major_only_filename.?,
            compile.name_only_filename.?,
        );
    }
}
fn outputPath(c: *Compile, out_dir: std.Build.Cache.Path, ea: std.zig.EmitArtifact) []const u8 {
    const arena = c.step.owner.graph.arena;
    const name = ea.cacheName(arena, .{
        .root_name = c.name,
        .target = &c.root_module.resolved_target.?.result,
        .output_mode = switch (c.kind) {
            .lib => .Lib,
            .obj, .test_obj => .Obj,
            .exe, .@"test" => .Exe,
        },
        .link_mode = c.linkage,
        .version = c.version,
    }) catch @panic("OOM");
    return out_dir.joinString(arena, name) catch @panic("OOM");
}

pub fn rebuildInFuzzMode(c: *Compile, gpa: Allocator, progress_node: std.Progress.Node) !Path {
    c.step.result_error_msgs.clearRetainingCapacity();
    c.step.result_stderr = "";

    c.step.result_error_bundle.deinit(gpa);
    c.step.result_error_bundle = std.zig.ErrorBundle.empty;

    const zig_args = try getZigArgs(c, true);
    const maybe_output_bin_path = try c.step.evalZigProcess(zig_args, progress_node, false, null, gpa);
    return maybe_output_bin_path.?;
}

pub fn doAtomicSymLinks(
    step: *Step,
    output_path: []const u8,
    filename_major_only: []const u8,
    filename_name_only: []const u8,
) !void {
    const b = step.owner;
    const out_dir = fs.path.dirname(output_path) orelse ".";
    const out_basename = fs.path.basename(output_path);
    // sym link for libfoo.so.1 to libfoo.so.1.2.3
    const major_only_path = b.pathJoin(&.{ out_dir, filename_major_only });
    fs.cwd().atomicSymLink(out_basename, major_only_path, .{}) catch |err| {
        return step.fail("unable to symlink {s} -> {s}: {s}", .{
            major_only_path, out_basename, @errorName(err),
        });
    };
    // sym link for libfoo.so to libfoo.so.1
    const name_only_path = b.pathJoin(&.{ out_dir, filename_name_only });
    fs.cwd().atomicSymLink(filename_major_only, name_only_path, .{}) catch |err| {
        return step.fail("Unable to symlink {s} -> {s}: {s}", .{
            name_only_path, filename_major_only, @errorName(err),
        });
    };
}

fn execPkgConfigList(b: *std.Build, out_code: *u8) (PkgConfigError || RunError)![]const PkgConfigPkg {
    const pkg_config_exe = b.graph.env_map.get("PKG_CONFIG") orelse "pkg-config";
    const stdout = try b.runAllowFail(&[_][]const u8{ pkg_config_exe, "--list-all" }, out_code, .Ignore);
    var list = std.array_list.Managed(PkgConfigPkg).init(b.allocator);
    errdefer list.deinit();
    var line_it = mem.tokenizeAny(u8, stdout, "\r\n");
    while (line_it.next()) |line| {
        if (mem.trim(u8, line, " \t").len == 0) continue;
        var tok_it = mem.tokenizeAny(u8, line, " \t");
        try list.append(PkgConfigPkg{
            .name = tok_it.next() orelse return error.PkgConfigInvalidOutput,
            .desc = tok_it.rest(),
        });
    }
    return list.toOwnedSlice();
}

fn getPkgConfigList(b: *std.Build) ![]const PkgConfigPkg {
    if (b.pkg_config_pkg_list) |res| {
        return res;
    }
    var code: u8 = undefined;
    if (execPkgConfigList(b, &code)) |list| {
        b.pkg_config_pkg_list = list;
        return list;
    } else |err| {
        const result = switch (err) {
            error.ProcessTerminated => error.PkgConfigCrashed,
            error.ExecNotSupported => error.PkgConfigFailed,
            error.ExitCodeFailure => error.PkgConfigFailed,
            error.FileNotFound => error.PkgConfigNotInstalled,
            error.InvalidName => error.PkgConfigNotInstalled,
            error.PkgConfigInvalidOutput => error.PkgConfigInvalidOutput,
            else => return err,
        };
        b.pkg_config_pkg_list = result;
        return result;
    }
}

fn addFlag(args: *std.array_list.Managed([]const u8), comptime name: []const u8, opt: ?bool) !void {
    const cond = opt orelse return;
    try args.ensureUnusedCapacity(1);
    if (cond) {
        args.appendAssumeCapacity("-f" ++ name);
    } else {
        args.appendAssumeCapacity("-fno-" ++ name);
    }
}

fn checkCompileErrors(compile: *Compile) !void {
    // Clear this field so that it does not get printed by the build runner.
    const actual_eb = compile.step.result_error_bundle;
    compile.step.result_error_bundle = .empty;

    const arena = compile.step.owner.allocator;

    const actual_errors = ae: {
        var aw: std.io.Writer.Allocating = .init(arena);
        defer aw.deinit();
        try actual_eb.renderToWriter(.{
            .ttyconf = .no_color,
            .include_reference_trace = false,
            .include_source_line = false,
        }, &aw.writer);
        break :ae try aw.toOwnedSlice();
    };

    // Render the expected lines into a string that we can compare verbatim.
    var expected_generated: std.ArrayListUnmanaged(u8) = .empty;
    const expect_errors = compile.expect_errors.?;

    var actual_line_it = mem.splitScalar(u8, actual_errors, '\n');

    // TODO merge this with the testing.expectEqualStrings logic, and also CheckFile
    switch (expect_errors) {
        .starts_with => |expect_starts_with| {
            if (std.mem.startsWith(u8, actual_errors, expect_starts_with)) return;
            return compile.step.fail(
                \\
                \\========= should start with: ============
                \\{s}
                \\========= but not found: ================
                \\{s}
                \\=========================================
            , .{ expect_starts_with, actual_errors });
        },
        .contains => |expect_line| {
            while (actual_line_it.next()) |actual_line| {
                if (!matchCompileError(actual_line, expect_line)) continue;
                return;
            }

            return compile.step.fail(
                \\
                \\========= should contain: ===============
                \\{s}
                \\========= but not found: ================
                \\{s}
                \\=========================================
            , .{ expect_line, actual_errors });
        },
        .stderr_contains => |expect_line| {
            const actual_stderr: []const u8 = if (compile.step.result_error_msgs.items.len > 0)
                compile.step.result_error_msgs.items[0]
            else
                &.{};
            compile.step.result_error_msgs.clearRetainingCapacity();

            var stderr_line_it = mem.splitScalar(u8, actual_stderr, '\n');

            while (stderr_line_it.next()) |actual_line| {
                if (!matchCompileError(actual_line, expect_line)) continue;
                return;
            }

            return compile.step.fail(
                \\
                \\========= should contain: ===============
                \\{s}
                \\========= but not found: ================
                \\{s}
                \\=========================================
            , .{ expect_line, actual_stderr });
        },
        .exact => |expect_lines| {
            for (expect_lines) |expect_line| {
                const actual_line = actual_line_it.next() orelse {
                    try expected_generated.appendSlice(arena, expect_line);
                    try expected_generated.append(arena, '\n');
                    continue;
                };
                if (matchCompileError(actual_line, expect_line)) {
                    try expected_generated.appendSlice(arena, actual_line);
                    try expected_generated.append(arena, '\n');
                    continue;
                }
                try expected_generated.appendSlice(arena, expect_line);
                try expected_generated.append(arena, '\n');
            }

            if (mem.eql(u8, expected_generated.items, actual_errors)) return;

            return compile.step.fail(
                \\
                \\========= expected: =====================
                \\{s}
                \\========= but found: ====================
                \\{s}
                \\=========================================
            , .{ expected_generated.items, actual_errors });
        },
    }
}

fn matchCompileError(actual: []const u8, expected: []const u8) bool {
    if (mem.endsWith(u8, actual, expected)) return true;
    if (mem.startsWith(u8, expected, ":?:?: ")) {
        if (mem.endsWith(u8, actual, expected[":?:?: ".len..])) return true;
    }
    // We scan for /?/ in expected line and if there is a match, we match everything
    // up to and after /?/.
    const expected_trim = mem.trim(u8, expected, " ");
    if (mem.indexOf(u8, expected_trim, "/?/")) |index| {
        const actual_trim = mem.trim(u8, actual, " ");
        const lhs = expected_trim[0..index];
        const rhs = expected_trim[index + "/?/".len ..];
        if (mem.startsWith(u8, actual_trim, lhs) and mem.endsWith(u8, actual_trim, rhs)) return true;
    }
    return false;
}

pub fn rootModuleTarget(c: *Compile) std.Target {
    // The root module is always given a target, so we know this to be non-null.
    return c.root_module.resolved_target.?.result;
}

fn moduleNeedsCliArg(mod: *const Module) bool {
    return for (mod.link_objects.items) |o| switch (o) {
        .c_source_file, .c_source_files, .assembly_file, .win32_resource_file => break true,
        else => continue,
    } else false;
}

/// Return the full set of `Step.Compile` which `start` depends on, recursively. `start` itself is
/// always returned as the first element. If `chase_dynamic` is `false`, then dynamic libraries are
/// not included, and their dependencies are not considered; if `chase_dynamic` is `true`, dynamic
/// libraries are treated the same as other linked `Compile`s.
pub fn getCompileDependencies(start: *Compile, chase_dynamic: bool) []const *Compile {
    const arena = start.step.owner.graph.arena;

    var compiles: std.AutoArrayHashMapUnmanaged(*Compile, void) = .empty;
    var next_idx: usize = 0;

    compiles.putNoClobber(arena, start, {}) catch @panic("OOM");

    while (next_idx < compiles.count()) {
        const compile = compiles.keys()[next_idx];
        next_idx += 1;

        for (compile.root_module.getGraph().modules) |mod| {
            for (mod.link_objects.items) |lo| {
                switch (lo) {
                    .other_step => |other_compile| {
                        if (!chase_dynamic and other_compile.isDynamicLibrary()) continue;
                        compiles.put(arena, other_compile, {}) catch @panic("OOM");
                    },
                    else => {},
                }
            }
        }
    }

    return compiles.keys();
}