Revert "Sema: Stop adding Windows implib link inputs for extern "..." syntax."

This reverts commit b461d07.

After some discussion in the team, we've decided that this is too disruptive,
especially because the linker errors are less than helpful. That's a fixable
problem, so we might reconsider this in the future, but revert it for now.

Author: alexrp

build.zig

@@ -452,7 +452,6 @@ pub fn build(b: *std.Build) !void {
         .desc = "Run the behavior tests",
         .optimize_modes = optimization_modes,
         .include_paths = &.{},
-        .windows_libs = &.{},
         .skip_single_threaded = skip_single_threaded,
         .skip_non_native = skip_non_native,
         .skip_freebsd = skip_freebsd,
@@ -475,7 +474,6 @@ pub fn build(b: *std.Build) !void {
         .desc = "Run the @cImport tests",
         .optimize_modes = optimization_modes,
         .include_paths = &.{"test/c_import"},
-        .windows_libs = &.{},
         .skip_single_threaded = true,
         .skip_non_native = skip_non_native,
         .skip_freebsd = skip_freebsd,
@@ -496,7 +494,6 @@ pub fn build(b: *std.Build) !void {
         .desc = "Run the compiler_rt tests",
         .optimize_modes = optimization_modes,
         .include_paths = &.{},
-        .windows_libs = &.{},
         .skip_single_threaded = true,
         .skip_non_native = skip_non_native,
         .skip_freebsd = skip_freebsd,
@@ -518,7 +515,6 @@ pub fn build(b: *std.Build) !void {
         .desc = "Run the zigc tests",
         .optimize_modes = optimization_modes,
         .include_paths = &.{},
-        .windows_libs = &.{},
         .skip_single_threaded = true,
         .skip_non_native = skip_non_native,
         .skip_freebsd = skip_freebsd,
@@ -540,12 +536,6 @@ pub fn build(b: *std.Build) !void {
         .desc = "Run the standard library tests",
         .optimize_modes = optimization_modes,
         .include_paths = &.{},
-        .windows_libs = &.{
-            "advapi32",
-            "crypt32",
-            "iphlpapi",
-            "ws2_32",
-        },
         .skip_single_threaded = skip_single_threaded,
         .skip_non_native = skip_non_native,
         .skip_freebsd = skip_freebsd,
@@ -743,12 +733,6 @@ fn addCompilerMod(b: *std.Build, options: AddCompilerModOptions) *std.Build.Modu
     compiler_mod.addImport("aro", aro_mod);
     compiler_mod.addImport("aro_translate_c", aro_translate_c_mod);
 
-    if (options.target.result.os.tag == .windows) {
-        compiler_mod.linkSystemLibrary("advapi32", .{});
-        compiler_mod.linkSystemLibrary("crypt32", .{});
-        compiler_mod.linkSystemLibrary("ws2_32", .{});
-    }
-
     return compiler_mod;
 }
 
@@ -1446,10 +1430,6 @@ fn generateLangRef(b: *std.Build) std.Build.LazyPath {
         }),
     });
 
-    if (b.graph.host.result.os.tag == .windows) {
-        doctest_exe.root_module.linkSystemLibrary("advapi32", .{});
-    }
-
     var dir = b.build_root.handle.openDir("doc/langref", .{ .iterate = true }) catch |err| {
         std.debug.panic("unable to open '{f}doc/langref' directory: {s}", .{
             b.build_root, @errorName(err),

src/Compilation.zig

@@ -2185,8 +2185,12 @@ pub fn create(gpa: Allocator, arena: Allocator, options: CreateOptions) !*Compil
             .emit_docs = try options.emit_docs.resolve(arena, &options, .docs),
         };
 
-        comp.windows_libs = try std.StringArrayHashMapUnmanaged(void).init(gpa, options.windows_lib_names, &.{});
-        errdefer comp.windows_libs.deinit(gpa);
+        errdefer {
+            for (comp.windows_libs.keys()) |windows_lib| gpa.free(windows_lib);
+            comp.windows_libs.deinit(gpa);
+        }
+        try comp.windows_libs.ensureUnusedCapacity(gpa, options.windows_lib_names.len);
+        for (options.windows_lib_names) |windows_lib| comp.windows_libs.putAssumeCapacity(try gpa.dupe(u8, windows_lib), {});
 
         // Prevent some footguns by making the "any" fields of config reflect
         // the default Module settings.
@@ -2417,13 +2421,6 @@ pub fn create(gpa: Allocator, arena: Allocator, options: CreateOptions) !*Compil
 
     if (comp.emit_bin != null and target.ofmt != .c) {
         if (!comp.skip_linker_dependencies) {
-            // These DLLs are always loaded into every Windows process.
-            if (target.os.tag == .windows and is_exe_or_dyn_lib) {
-                try comp.windows_libs.ensureUnusedCapacity(gpa, 2);
-                comp.windows_libs.putAssumeCapacity("kernel32", {});
-                comp.windows_libs.putAssumeCapacity("ntdll", {});
-            }
-
             // If we need to build libc for the target, add work items for it.
             // We go through the work queue so that building can be done in parallel.
             // If linking against host libc installation, instead queue up jobs
@@ -2512,7 +2509,7 @@ pub fn create(gpa: Allocator, arena: Allocator, options: CreateOptions) !*Compil
 
                     // When linking mingw-w64 there are some import libs we always need.
                     try comp.windows_libs.ensureUnusedCapacity(gpa, mingw.always_link_libs.len);
-                    for (mingw.always_link_libs) |name| comp.windows_libs.putAssumeCapacity(name, {});
+                    for (mingw.always_link_libs) |name| comp.windows_libs.putAssumeCapacity(try gpa.dupe(u8, name), {});
                 } else {
                     return error.LibCUnavailable;
                 }
@@ -2610,6 +2607,7 @@ pub fn destroy(comp: *Compilation) void {
     comp.c_object_work_queue.deinit();
     comp.win32_resource_work_queue.deinit();
 
+    for (comp.windows_libs.keys()) |windows_lib| gpa.free(windows_lib);
     comp.windows_libs.deinit(gpa);
 
     {
@@ -7795,6 +7793,27 @@ fn getCrtPathsInner(
     };
 }
 
+pub fn addLinkLib(comp: *Compilation, lib_name: []const u8) !void {
+    // Avoid deadlocking on building import libs such as kernel32.lib
+    // This can happen when the user uses `build-exe foo.obj -lkernel32` and
+    // then when we create a sub-Compilation for zig libc, it also tries to
+    // build kernel32.lib.
+    if (comp.skip_linker_dependencies) return;
+    const target = &comp.root_mod.resolved_target.result;
+    if (target.os.tag != .windows or target.ofmt == .c) return;
+
+    // This happens when an `extern "foo"` function is referenced.
+    // If we haven't seen this library yet and we're targeting Windows, we need
+    // to queue up a work item to produce the DLL import library for this.
+    const gop = try comp.windows_libs.getOrPut(comp.gpa, lib_name);
+    if (gop.found_existing) return;
+    {
+        errdefer _ = comp.windows_libs.pop();
+        gop.key_ptr.* = try comp.gpa.dupe(u8, lib_name);
+    }
+    try comp.queueJob(.{ .windows_import_lib = gop.index });
+}
+
 /// This decides the optimization mode for all zig-provided libraries, including
 /// compiler-rt, libcxx, libc, libunwind, etc.
 pub fn compilerRtOptMode(comp: Compilation) std.builtin.OptimizeMode {

src/Sema.zig

@@ -8906,6 +8906,14 @@ fn resolveGenericBody(
     return sema.resolveConstDefinedValue(block, src, result, reason);
 }
 
+/// Given a library name, examines if the library name should end up in
+/// `link.File.Options.windows_libs` table (for example, libc is always
+/// specified via dedicated flag `link_libc` instead),
+/// and puts it there if it doesn't exist.
+/// It also dupes the library name which can then be saved as part of the
+/// respective `Decl` (either `ExternFn` or `Var`).
+/// The liveness of the duped library name is tied to liveness of `Zcu`.
+/// To deallocate, call `deinit` on the respective `Decl` (`ExternFn` or `Var`).
 pub fn handleExternLibName(
     sema: *Sema,
     block: *Block,
@@ -8955,6 +8963,11 @@ pub fn handleExternLibName(
                 .{ lib_name, lib_name },
             );
         }
+        comp.addLinkLib(lib_name) catch |err| {
+            return sema.fail(block, src_loc, "unable to add link lib '{s}': {s}", .{
+                lib_name, @errorName(err),
+            });
+        };
     }
 }
 

src/libs/mingw.zig

@@ -1012,7 +1012,6 @@ const mingw32_winpthreads_src = [_][]const u8{
     "winpthreads" ++ path.sep_str ++ "thread.c",
 };
 
-// Note: kernel32 and ntdll are always linked even without targeting MinGW-w64.
 pub const always_link_libs = [_][]const u8{
     "api-ms-win-crt-conio-l1-1-0",
     "api-ms-win-crt-convert-l1-1-0",
@@ -1030,6 +1029,8 @@ pub const always_link_libs = [_][]const u8{
     "api-ms-win-crt-time-l1-1-0",
     "api-ms-win-crt-utility-l1-1-0",
     "advapi32",
+    "kernel32",
+    "ntdll",
     "shell32",
     "user32",
 };

src/main.zig

@@ -312,7 +312,6 @@ fn mainArgs(gpa: Allocator, arena: Allocator, args: []const []const u8) !void {
         return jitCmd(gpa, arena, cmd_args, .{
             .cmd_name = "resinator",
             .root_src_path = "resinator/main.zig",
-            .windows_libs = &.{"advapi32"},
             .depend_on_aro = true,
             .prepend_zig_lib_dir_path = true,
             .server = use_server,
@@ -337,7 +336,6 @@ fn mainArgs(gpa: Allocator, arena: Allocator, args: []const []const u8) !void {
         return jitCmd(gpa, arena, cmd_args, .{
             .cmd_name = "std",
             .root_src_path = "std-docs.zig",
-            .windows_libs = &.{"ws2_32"},
             .prepend_zig_lib_dir_path = true,
             .prepend_zig_exe_path = true,
             .prepend_global_cache_path = true,
@@ -3659,6 +3657,7 @@ fn buildOutputType(
             } else if (target.os.tag == .windows) {
                 try test_exec_args.appendSlice(arena, &.{
                     "--subsystem", "console",
+                    "-lkernel32",  "-lntdll",
                 });
             }
 
@@ -3862,8 +3861,7 @@ fn createModule(
                     .only_compiler_rt => continue,
                 }
 
-                // We currently prefer import libraries provided by MinGW-w64 even for MSVC.
-                if (target.os.tag == .windows) {
+                if (target.isMinGW()) {
                     const exists = mingw.libExists(arena, target, create_module.dirs.zig_lib, lib_name) catch |err| {
                         fatal("failed to check zig installation for DLL import libs: {s}", .{
                             @errorName(err),
@@ -5375,14 +5373,6 @@ fn cmdBuild(gpa: Allocator, arena: Allocator, args: []const []const u8) !void {
 
             try root_mod.deps.put(arena, "@build", build_mod);
 
-            var windows_libs: std.StringArrayHashMapUnmanaged(void) = .empty;
-
-            if (resolved_target.result.os.tag == .windows) {
-                try windows_libs.ensureUnusedCapacity(arena, 2);
-                windows_libs.putAssumeCapacity("advapi32", {});
-                windows_libs.putAssumeCapacity("ws2_32", {}); // for `--listen` (web interface)
-            }
-
             const comp = Compilation.create(gpa, arena, .{
                 .libc_installation = libc_installation,
                 .dirs = dirs,
@@ -5405,7 +5395,6 @@ fn cmdBuild(gpa: Allocator, arena: Allocator, args: []const []const u8) !void {
                 .cache_mode = .whole,
                 .reference_trace = reference_trace,
                 .debug_compile_errors = debug_compile_errors,
-                .windows_lib_names = windows_libs.keys(),
             }) catch |err| {
                 fatal("unable to create compilation: {s}", .{@errorName(err)});
             };
@@ -5509,7 +5498,6 @@ fn cmdBuild(gpa: Allocator, arena: Allocator, args: []const []const u8) !void {
 const JitCmdOptions = struct {
     cmd_name: []const u8,
     root_src_path: []const u8,
-    windows_libs: []const []const u8 = &.{},
     prepend_zig_lib_dir_path: bool = false,
     prepend_global_cache_path: bool = false,
     prepend_zig_exe_path: bool = false,
@@ -5626,13 +5614,6 @@ fn jitCmd(
             try root_mod.deps.put(arena, "aro", aro_mod);
         }
 
-        var windows_libs: std.StringArrayHashMapUnmanaged(void) = .empty;
-
-        if (resolved_target.result.os.tag == .windows) {
-            try windows_libs.ensureUnusedCapacity(arena, options.windows_libs.len);
-            for (options.windows_libs) |lib| windows_libs.putAssumeCapacity(lib, {});
-        }
-
         const comp = Compilation.create(gpa, arena, .{
             .dirs = dirs,
             .root_name = options.cmd_name,
@@ -5643,7 +5624,6 @@ fn jitCmd(
             .self_exe_path = self_exe_path,
             .thread_pool = &thread_pool,
             .cache_mode = .whole,
-            .windows_lib_names = windows_libs.keys(),
         }) catch |err| {
             fatal("unable to create compilation: {s}", .{@errorName(err)});
         };

test/standalone/simple/build.zig

@@ -50,10 +50,6 @@ pub fn build(b: *std.Build) void {
                 });
                 if (case.link_libc) exe.root_module.link_libc = true;
 
-                if (resolved_target.result.os.tag == .windows) {
-                    exe.root_module.linkSystemLibrary("advapi32", .{});
-                }
-
                 _ = exe.getEmittedBin();
 
                 step.dependOn(&exe.step);
@@ -70,10 +66,6 @@ pub fn build(b: *std.Build) void {
                 });
                 if (case.link_libc) exe.root_module.link_libc = true;
 
-                if (resolved_target.result.os.tag == .windows) {
-                    exe.root_module.linkSystemLibrary("advapi32", .{});
-                }
-
                 const run = b.addRunArtifact(exe);
                 step.dependOn(&run.step);
             }

test/standalone/windows_argv/build.zig

@@ -47,8 +47,6 @@ pub fn build(b: *std.Build) !void {
         }),
     });
 
-    fuzz.root_module.linkSystemLibrary("advapi32", .{});
-
     const fuzz_max_iterations = b.option(u64, "iterations", "The max fuzz iterations (default: 100)") orelse 100;
     const fuzz_iterations_arg = std.fmt.allocPrint(b.allocator, "{}", .{fuzz_max_iterations}) catch @panic("oom");
 

test/standalone/windows_bat_args/build.zig

@@ -28,8 +28,6 @@ pub fn build(b: *std.Build) !void {
         }),
     });
 
-    test_exe.root_module.linkSystemLibrary("advapi32", .{});
-
     const run = b.addRunArtifact(test_exe);
     run.addArtifactArg(echo_args);
     run.expectExitCode(0);
@@ -46,8 +44,6 @@ pub fn build(b: *std.Build) !void {
         }),
     });
 
-    fuzz.root_module.linkSystemLibrary("advapi32", .{});
-
     const fuzz_max_iterations = b.option(u64, "iterations", "The max fuzz iterations (default: 100)") orelse 100;
     const fuzz_iterations_arg = std.fmt.allocPrint(b.allocator, "{}", .{fuzz_max_iterations}) catch @panic("oom");
 

test/standalone/windows_spawn/build.zig

@@ -28,8 +28,6 @@ pub fn build(b: *std.Build) void {
         }),
     });
 
-    main.root_module.linkSystemLibrary("advapi32", .{});
-
     const run = b.addRunArtifact(main);
     run.addArtifactArg(hello);
     run.expectExitCode(0);

test/tests.zig

@@ -2238,7 +2238,6 @@ const ModuleTestOptions = struct {
     desc: []const u8,
     optimize_modes: []const OptimizeMode,
     include_paths: []const []const u8,
-    windows_libs: []const []const u8,
     skip_single_threaded: bool,
     skip_non_native: bool,
     skip_freebsd: bool,
@@ -2373,10 +2372,6 @@ pub fn addModuleTests(b: *std.Build, options: ModuleTestOptions) *Step {
 
         for (options.include_paths) |include_path| these_tests.root_module.addIncludePath(b.path(include_path));
 
-        if (target.os.tag == .windows) {
-            for (options.windows_libs) |lib| these_tests.root_module.linkSystemLibrary(lib, .{});
-        }
-
         const qualified_name = b.fmt("{s}-{s}-{s}-{s}{s}{s}{s}{s}{s}{s}", .{
             options.name,
             triple_txt,
@@ -2672,10 +2667,6 @@ pub fn addIncrementalTests(b: *std.Build, test_step: *Step) !void {
         }),
     });
 
-    if (b.graph.host.result.os.tag == .windows) {
-        incr_check.root_module.linkSystemLibrary("advapi32", .{});
-    }
-
     var dir = try b.build_root.handle.openDir("test/incremental", .{ .iterate = true });
     defer dir.close();