[native_toolchain_c] Add linking for macOS (#2360)

Author: goderbauer

pkgs/native_toolchain_c/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.16.4
+
+* Support linking for MacOS.
+
 ## 0.16.3
 
 * Support linking for Android.

pkgs/native_toolchain_c/lib/src/cbuilder/clinker.dart

@@ -53,7 +53,7 @@ class CLinker extends CTool implements Linker {
     required LinkOutputBuilder output,
     required Logger? logger,
   }) async {
-    const supportedTargetOSs = [OS.linux, OS.android];
+    const supportedTargetOSs = [OS.linux, OS.android, OS.macOS];
     if (!supportedTargetOSs.contains(input.config.code.targetOS)) {
       throw UnsupportedError(
         'This feature is only supported when targeting '

pkgs/native_toolchain_c/lib/src/cbuilder/linker_options.dart

@@ -4,6 +4,8 @@
 
 import 'dart:io';
 
+import 'package:code_assets/code_assets.dart';
+
 import '../native_toolchain/tool_likeness.dart';
 import '../tool/tool.dart';
 
@@ -14,7 +16,7 @@ import '../tool/tool.dart';
 /// the [LinkerOptions.treeshake] constructor can be used.
 class LinkerOptions {
   /// The flags to be passed to the linker. As they depend on the linker being
-  /// invoked, the actual usage is via the [postSourcesFlags] method.
+  /// invoked, the actual usage is via the [sourceFilesToFlags] method.
   final List<String> _linkerFlags;
 
   /// Enable garbage collection of unused input sections.
@@ -27,37 +29,38 @@ class LinkerOptions {
   /// See also the `ld` man page at https://linux.die.net/man/1/ld.
   final Uri? linkerScript;
 
-  /// Whether to include all symbols from the sources.
+  /// Whether to strip debugging symbols from the binary.
+  final bool stripDebug;
+
+  /// The symbols to keep in the resulting binaries.
   ///
-  /// This is achieved by setting the `whole-archive` flag before passing the
-  /// sources, and the `no-whole-archive` flag after.
-  final bool _wholeArchiveSandwich;
+  /// If null all symbols will be kept.
+  final List<String>? _symbolsToKeep;
 
   /// Create linking options manually for fine-grained control.
   LinkerOptions.manual({
     List<String>? flags,
     bool? gcSections,
     this.linkerScript,
+    this.stripDebug = true,
+    Iterable<String>? symbolsToKeep,
   }) : _linkerFlags = flags ?? [],
        gcSections = gcSections ?? true,
-       _wholeArchiveSandwich = false;
+       _symbolsToKeep = symbolsToKeep?.toList(growable: false);
 
   /// Create linking options to tree-shake symbols from the input files.
   ///
   /// The [symbols] specify the symbols which should be kept.
   LinkerOptions.treeshake({
     Iterable<String>? flags,
     required Iterable<String>? symbols,
-  }) : _linkerFlags = <String>[
-         ...flags ?? [],
-         '--strip-debug',
-         if (symbols != null) ...symbols.map((e) => '-u,$e'),
-       ].toList(),
+    this.stripDebug = true,
+  }) : _linkerFlags = flags?.toList(growable: false) ?? [],
+       _symbolsToKeep = symbols?.toList(growable: false),
        gcSections = true,
-       _wholeArchiveSandwich = symbols == null,
        linkerScript = _createLinkerScript(symbols);
 
-  Iterable<String> _toLinkerSyntax(Tool linker, List<String> flagList) {
+  Iterable<String> _toLinkerSyntax(Tool linker, Iterable<String> flagList) {
     if (linker.isClangLike) {
       return flagList.map((e) => '-Wl,$e');
     } else if (linker.isLdLike) {
@@ -85,38 +88,48 @@ class LinkerOptions {
 }
 
 extension LinkerOptionsExt on LinkerOptions {
-  /// The flags for the specified [linker], which are inserted _before_ the
-  /// sources.
-  ///
-  /// This is mainly used for the whole-archive ... no-whole-archive
-  /// trick, which includes all symbols when linking object files.
-  ///
-  /// Throws if the [linker] is not supported.
-  Iterable<String> preSourcesFlags(Tool linker, Iterable<String> sourceFiles) =>
-      _toLinkerSyntax(
-        linker,
-        sourceFiles.any((source) => source.endsWith('.a')) ||
-                _wholeArchiveSandwich
-            ? ['--whole-archive']
-            : [],
-      );
-
-  /// The flags for the specified [linker], which are inserted _after_ the
-  /// sources.
-  ///
-  /// This is mainly used for the whole-archive ... no-whole-archive
-  /// trick, which includes all symbols when linking object files.
-  ///
-  /// Throws if the [linker] is not supported.
-  Iterable<String> postSourcesFlags(
-    Tool linker,
+  /// Takes [sourceFiles] and turns it into flags for the compiler driver while
+  /// considering the current [LinkerOptions].
+  Iterable<String> sourceFilesToFlags(
+    Tool tool,
     Iterable<String> sourceFiles,
-  ) => _toLinkerSyntax(linker, [
-    ..._linkerFlags,
-    if (gcSections) '--gc-sections',
-    if (linkerScript != null) '--version-script=${linkerScript!.toFilePath()}',
-    if (sourceFiles.any((source) => source.endsWith('.a')) ||
-        _wholeArchiveSandwich)
-      '--no-whole-archive',
-  ]);
+    OS targetOS,
+  ) {
+    final includeAllSymbols = _symbolsToKeep == null;
+
+    switch (targetOS) {
+      case OS.macOS:
+        return [
+          if (!includeAllSymbols) ...sourceFiles,
+          ..._toLinkerSyntax(tool, [
+            if (includeAllSymbols) ...sourceFiles.map((e) => '-force_load,$e'),
+            ..._linkerFlags,
+            ..._symbolsToKeep?.map((symbol) => '-u,_$symbol') ?? [],
+            if (stripDebug) '-S',
+            if (gcSections) '-dead_strip',
+          ]),
+        ];
+
+      case OS.android || OS.linux:
+        final wholeArchiveSandwich =
+            sourceFiles.any((source) => source.endsWith('.a')) ||
+            includeAllSymbols;
+        return [
+          if (wholeArchiveSandwich)
+            ..._toLinkerSyntax(tool, ['--whole-archive']),
+          ...sourceFiles,
+          ..._toLinkerSyntax(tool, [
+            ..._linkerFlags,
+            ..._symbolsToKeep?.map((symbol) => '-u,$symbol') ?? [],
+            if (stripDebug) '--strip-debug',
+            if (gcSections) '--gc-sections',
+            if (linkerScript != null)
+              '--version-script=${linkerScript!.toFilePath()}',
+            if (wholeArchiveSandwich) '--no-whole-archive',
+          ]),
+        ];
+      case OS():
+        throw UnimplementedError();
+    }
+  }
 }

pkgs/native_toolchain_c/lib/src/cbuilder/run_cbuilder.dart

@@ -262,9 +262,9 @@ class RunCBuilder {
               if (dynamicLibrary != null) '-fPIC',
               // Using PIC for static libraries allows them to be linked into
               // any executable, but it is not necessarily the best option in
-              // terms of overhead. We would have to know wether the target into
-              // which the static library is linked is PIC, PIE or neither. Then
-              // we could use the same option for the static library.
+              // terms of overhead. We would have to know whether the target
+              // into which the static library is linked is PIC, PIE or neither.
+              // Then we could use the same option for the static library.
               if (staticLibrary != null) '-fPIC',
               if (executable != null) ...[
                 // Generate position-independent code for executables.
@@ -296,7 +296,6 @@ class RunCBuilder {
         ],
         if (optimizationLevel != OptimizationLevel.unspecified)
           optimizationLevel.clangFlag(),
-        ...linkerOptions?.preSourcesFlags(toolInstance.tool, sourceFiles) ?? [],
         // Support Android 15 page size by default, can be overridden by
         // passing [flags].
         if (codeConfig.targetOS == OS.android) '-Wl,-z,max-page-size=16384',
@@ -306,7 +305,14 @@ class RunCBuilder {
         for (final include in includes) '-I${include.toFilePath()}',
         for (final forcedInclude in forcedIncludes)
           '-include${forcedInclude.toFilePath()}',
-        ...sourceFiles,
+        if (linkerOptions != null)
+          ...linkerOptions!.sourceFilesToFlags(
+            toolInstance.tool,
+            sourceFiles,
+            codeConfig.targetOS,
+          )
+        else
+          ...sourceFiles,
         if (language == Language.objectiveC) ...[
           for (final framework in frameworks) ...['-framework', framework],
         ],
@@ -322,8 +328,6 @@ class RunCBuilder {
           '-o',
           outFile!.toFilePath(),
         ],
-        ...linkerOptions?.postSourcesFlags(toolInstance.tool, sourceFiles) ??
-            [],
         if (executable != null || dynamicLibrary != null) ...[
           if (codeConfig.targetOS case OS.android || OS.linux)
             // During bundling code assets are all placed in the same directory.

pkgs/native_toolchain_c/pubspec.yaml

@@ -1,7 +1,7 @@
 name: native_toolchain_c
 description: >-
   A library to invoke the native C compiler installed on the host machine.
-version: 0.16.3
+version: 0.16.4
 repository: https://github.com/dart-lang/native/tree/main/pkgs/native_toolchain_c
 
 topics:

pkgs/native_toolchain_c/test/cbuilder/cbuilder_cross_android_test.dart

@@ -43,7 +43,7 @@ void main() {
             linkMode,
             optimizationLevel: optimizationLevel,
           );
-          await expectMachineArchitecture(libUri, target);
+          await expectMachineArchitecture(libUri, target, OS.android);
           if (linkMode == DynamicLoadingBundled()) {
             await expectPageSize(libUri, 16 * 1024);
           }

pkgs/native_toolchain_c/test/clinker/build_testfiles.dart

@@ -16,8 +16,15 @@ Future<Uri> buildTestArchive(
   OS targetOS,
   Architecture architecture, {
   int? androidTargetNdkApi, // Must be specified iff targetOS is OS.android.
+  int? macOSTargetVersion, // Must be specified iff targetOS is OS.macos.
 }) async {
-  assert((targetOS != OS.android) == (androidTargetNdkApi == null));
+  if (targetOS == OS.android) {
+    ArgumentError.checkNotNull(androidTargetNdkApi, 'androidTargetNdkApi');
+  }
+  if (targetOS == OS.macOS) {
+    ArgumentError.checkNotNull(macOSTargetVersion, 'macOSTargetVersion');
+  }
+
   final test1Uri = packageUri.resolve('test/clinker/testfiles/linker/test1.c');
   final test2Uri = packageUri.resolve('test/clinker/testfiles/linker/test2.c');
   if (!await File.fromUri(test1Uri).exists() ||
@@ -46,6 +53,9 @@ Future<Uri> buildTestArchive(
         android: androidTargetNdkApi != null
             ? AndroidCodeConfig(targetNdkApi: androidTargetNdkApi)
             : null,
+        macOS: macOSTargetVersion != null
+            ? MacOSCodeConfig(targetVersion: macOSTargetVersion)
+            : null,
       ),
     );
 

pkgs/native_toolchain_c/test/clinker/objects_cross_android_test.dart

@@ -9,15 +9,8 @@ import '../helpers.dart';
 import 'objects_helper.dart';
 
 void main() {
-  final architectures = [
-    Architecture.arm,
-    Architecture.arm64,
-    Architecture.ia32,
-    Architecture.x64,
-    Architecture.riscv64,
-  ];
-
   const targetOS = OS.android;
+  final architectures = supportedArchitecturesFor(targetOS);
 
   for (final apiLevel in [
     flutterAndroidNdkVersionLowestSupported,

pkgs/native_toolchain_c/test/clinker/objects_cross_test.dart

@@ -2,31 +2,31 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-//TODO(mosuem): Enable for windows and mac.
+// TODO(mosuem): Enable for windows.
 // See https://github.com/dart-lang/native/issues/1376.
-@TestOn('linux')
+@TestOn('linux || mac-os')
 library;
 
 import 'dart:io';
 
 import 'package:code_assets/code_assets.dart';
 import 'package:test/test.dart';
 
+import '../helpers.dart';
 import 'objects_helper.dart';
 
 void main() {
-  if (!Platform.isLinux) {
+  if (!Platform.isLinux && !Platform.isMacOS) {
     // Avoid needing status files on Dart SDK CI.
     return;
   }
 
-  final architectures = [
-    Architecture.arm,
-    Architecture.arm64,
-    Architecture.ia32,
-    Architecture.x64,
-    Architecture.riscv64,
-  ]..remove(Architecture.current);
+  final architectures = supportedArchitecturesFor(OS.current)
+    ..remove(Architecture.current); // See objects_test.dart for current arch.
 
-  runObjectsTests(OS.current, architectures);
+  runObjectsTests(
+    OS.current,
+    architectures,
+    macOSTargetVersion: OS.current == OS.macOS ? defaultMacOSVersion : null,
+  );
 }

pkgs/native_toolchain_c/test/clinker/objects_helper.dart

@@ -16,8 +16,15 @@ void runObjectsTests(
   OS targetOS,
   List<Architecture> architectures, {
   int? androidTargetNdkApi, // Must be specified iff targetOS is OS.android.
+  int? macOSTargetVersion, // Must be specified iff targetOS is OS.macos.
 }) {
-  assert((targetOS != OS.android) == (androidTargetNdkApi == null));
+  if (targetOS == OS.android) {
+    ArgumentError.checkNotNull(androidTargetNdkApi, 'androidTargetNdkApi');
+  }
+  if (targetOS == OS.macOS) {
+    ArgumentError.checkNotNull(macOSTargetVersion, 'macOSTargetVersion');
+  }
+
   const name = 'mylibname';
 
   for (final architecture in architectures) {
@@ -31,6 +38,7 @@ void runObjectsTests(
         targetOS,
         architecture,
         androidTargetNdkApi: androidTargetNdkApi,
+        macOSTargetVersion: macOSTargetVersion,
       );
 
       final linkInputBuilder = LinkInputBuilder()
@@ -50,6 +58,9 @@ void runObjectsTests(
             android: androidTargetNdkApi != null
                 ? AndroidCodeConfig(targetNdkApi: androidTargetNdkApi)
                 : null,
+            macOS: macOSTargetVersion != null
+                ? MacOSCodeConfig(targetVersion: macOSTargetVersion)
+                : null,
           ),
         );
 
@@ -70,7 +81,7 @@ void runObjectsTests(
       final asset = codeAssets.first;
       expect(asset, isA<CodeAsset>());
       expect(
-        await nmReadSymbols(asset),
+        await nmReadSymbols(asset, targetOS),
         stringContainsInOrder(['my_func', 'my_other_func']),
       );
     });