Add custom toolchain handling

Karim Alweheshy · Karim Alweheshy · commit e77be93a405b · 2025-03-21T10:30:46.000+01:00
Signed-off-by: Karim Alweheshy &lt;karim.alweheshy@reddit.com&gt;
diff --git a/tools/generators/legacy/src/Extensions/XCScheme+Extensions.swift b/tools/generators/legacy/src/Extensions/XCScheme+Extensions.swift
@@ -35,7 +35,7 @@ extension XCScheme {
                 .first
             {
                 otherPreActions.append(
-                    .symlinkDefaultToolchainUsrLibDirectory(
+                    .symlinkToolchainUsrLibDirectory(
                         buildableReference: launchableTarget.targetInfo
                             .buildableReference
                     )
@@ -201,10 +201,10 @@ touch "$BUILD_MARKER_FILE"
         )
     }
 
-    /// Symlinks `$DEVELOPER_DIR/Toolchains/XcodeDefault.xctoolchain/usr/lib` to
+    /// Symlinks `$TOOLCHAIN_DIR/usr/lib` to
     /// `$(BAZEL_INTEGRATION_DIR)/../lib` so that Xcode can copy sanitizers'
     /// dylibs.
-    static func symlinkDefaultToolchainUsrLibDirectory(
+    static func symlinkToolchainUsrLibDirectory(
         buildableReference: XCScheme.BuildableReference
     ) -> XCScheme.ExecutionAction {
         return .init(
@@ -215,9 +215,12 @@ if [[ "${ENABLE_ADDRESS_SANITIZER:-}" == "YES" || \
       "${ENABLE_THREAD_SANITIZER:-}" == "YES" || \
       "${ENABLE_UNDEFINED_BEHAVIOR_SANITIZER:-}" == "YES" ]]
 then
-    # TODO: Support custom toolchains once clang.sh supports them
     cd "$INTERNAL_DIR" || exit 1
-    ln -shfF "$DEVELOPER_DIR/Toolchains/XcodeDefault.xctoolchain/usr/lib" lib
+    if [[ -n "${TOOLCHAIN_DIR:-}" ]]; then
+        ln -shfF "$TOOLCHAIN_DIR/usr/lib" lib
+    else
+        ln -shfF "$DEVELOPER_DIR/Toolchains/XcodeDefault.xctoolchain/usr/lib" lib
+    fi
 fi
 """#,
             title: "Prepare BazelDependencies",
diff --git a/tools/generators/legacy/test/CreateAutogeneratedXCSchemesTests.swift b/tools/generators/legacy/test/CreateAutogeneratedXCSchemesTests.swift
@@ -178,7 +178,7 @@ class CreateAutogeneratedXCSchemesTests: XCTestCase {
            expectedTargetInfo.productType.isLaunchable
         {
             expectedBuildPreActions.append(
-                .symlinkDefaultToolchainUsrLibDirectory(
+                .symlinkToolchainUsrLibDirectory(
                 buildableReference: expectedTargetInfo.buildableReference
                 )
             )
diff --git a/tools/generators/xcschemes/README.md b/tools/generators/xcschemes/README.md
@@ -78,7 +78,7 @@ Here is an example output:
             ActionType = "Xcode.IDEStandardExecutionActionsCore.ExecutionActionType.ShellScriptAction">
             <ActionContent
                title = "Prepare BazelDependencies"
-               scriptText = "mkdir -p &quot;$PROJECT_DIR&quot;&#10;&#10;if [[ &quot;${ENABLE_ADDRESS_SANITIZER:-}&quot; == &quot;YES&quot; || \&#10;      &quot;${ENABLE_THREAD_SANITIZER:-}&quot; == &quot;YES&quot; || \&#10;      &quot;${ENABLE_UNDEFINED_BEHAVIOR_SANITIZER:-}&quot; == &quot;YES&quot; ]]&#10;then&#10;    # TODO: Support custom toolchains once clang.sh supports them&#10;    cd &quot;$INTERNAL_DIR&quot; || exit 1&#10;    ln -shfF &quot;$DEVELOPER_DIR/Toolchains/XcodeDefault.xctoolchain/usr/lib&quot; lib&#10;fi&#10;">
+               scriptText = "mkdir -p &quot;$PROJECT_DIR&quot;&#10;&#10;if [[ &quot;${ENABLE_ADDRESS_SANITIZER:-}&quot; == &quot;YES&quot; || \&#10;      &quot;${ENABLE_THREAD_SANITIZER:-}&quot; == &quot;YES&quot; || \&#10;      &quot;${ENABLE_UNDEFINED_BEHAVIOR_SANITIZER:-}&quot; == &quot;YES&quot; ]]&#10;then&#10;    $INTERNAL_DIR&quot; || exit 1&#10;    ln -shfF &quot;$DEVELOPER_DIR/Toolchains/XcodeDefault.xctoolchain/usr/lib&quot; lib&#10;fi&#10;">
                <EnvironmentBuildable>
                   <BuildableReference
                      BuildableIdentifier = "primary"
diff --git a/tools/generators/xcschemes/src/Generator/CreateScheme.swift b/tools/generators/xcschemes/src/Generator/CreateScheme.swift
@@ -478,14 +478,17 @@ if [[ "${ENABLE_ADDRESS_SANITIZER:-}" == "YES" || \
       "${ENABLE_THREAD_SANITIZER:-}" == "YES" || \
       "${ENABLE_UNDEFINED_BEHAVIOR_SANITIZER:-}" == "YES" ]]
 then
-    # TODO: Support custom toolchains once clang.sh supports them
     cd "$INTERNAL_DIR" || exit 1
-    ln -shfF "$DEVELOPER_DIR/Toolchains/XcodeDefault.xctoolchain/usr/lib" lib
+    if [[ -n "${TOOLCHAIN_DIR:-}" ]]; then
+        ln -shfF "$TOOLCHAIN_DIR/usr/lib" lib
+    else
+        ln -shfF "$DEVELOPER_DIR/Toolchains/XcodeDefault.xctoolchain/usr/lib" lib
+    fi
 fi
 
 """#.schemeXmlEscaped
 
-    /// Symlinks `$DEVELOPER_DIR/Toolchains/XcodeDefault.xctoolchain/usr/lib` to
+    /// Symlinks `$TOOLCHAIN_DIR/XcodeDefault.xctoolchain/usr/lib` to
     /// `$(BAZEL_INTEGRATION_DIR)/../lib` so that Xcode can copy sanitizers'
     /// dylibs.
     mutating func appendPrepareBazelDependencies(
diff --git a/tools/swiftc_stub/main.swift b/tools/swiftc_stub/main.swift
@@ -62,6 +62,38 @@ func processArgs(
     )
 }
 
+let swiftcPath: String = {
+    guard let path = ProcessInfo.processInfo.environment["PATH"] else {
+        fputs("error: PATH not set", stderr)
+        exit(1)
+    }
+
+    var result: String?
+    
+    if let toolchainDir = ProcessInfo.processInfo.environment["TOOLCHAIN_DIR"] {
+        result = "\(toolchainDir)/usr/bin/swiftc"
+    } else {
+        // /Applications/Xcode-15.0.0-Beta.app/Contents/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin -> /Applications/Xcode-15.0.0-Beta.app/Contents/Developer/usr/bin
+        let pathComponents = path.split(separator: ":", maxSplits: 1)
+        let xcodeBinPath = pathComponents[0]
+        guard xcodeBinPath.hasSuffix("/Contents/Developer/usr/bin") else {
+            fputs("Xcode based bin PATH not set \(path)", stderr)
+            fputs("error: Xcode based bin PATH not set", stderr)
+            exit(1)
+        }
+        // /Applications/Xcode-15.0.0-Beta.app/Contents/Developer/usr/bin -> /Applications/Xcode-15.0.0-Beta.app/Contents/Developer
+        let developerDir = xcodeBinPath.dropLast(8)
+        result = "\(developerDir)/Toolchains/XcodeDefault.xctoolchain/usr/bin/swiftc"
+    }
+
+    guard let result else {
+        fputs("error: Failed to determine swiftc path", stderr)
+        exit(1)
+    }
+
+    return result
+}()
+
 extension URL {
     mutating func touch() throws {
         let fileManager = FileManager.default
@@ -138,67 +170,14 @@ func runSubProcess(executable: String, args: [String]) throws -> Int32 {
 }
 
 func handleXcodePreviewThunk(args: [String], paths: [PathKey: URL]) throws -> Never {
-    guard let sdkPath = paths[PathKey.sdk]?.path else {
-        fputs(
-            "error: No such argument '-sdk'. Using /usr/bin/swiftc.",
-            stderr
-        )
-        exit(1)
-    }
-
-    // TODO: Make this work with custom toolchains
-    // We could produce this file at the start of the build?
-    let fullRange = NSRange(sdkPath.startIndex..., in: sdkPath)
-    let matches = try NSRegularExpression(
-        pattern: #"(.*?/Contents/Developer)/.*"#
-    ).matches(in: sdkPath, range: fullRange)
-    guard let match = matches.first,
-        let range = Range(match.range(at: 1), in: sdkPath)
-    else {
-        fputs(
-            """
-error: Failed to parse DEVELOPER_DIR from '-sdk'. Using /usr/bin/swiftc.
-""",
-            stderr
-        )
-        exit(1)
-    }
-    let developerDir = sdkPath[range]
-
-    try exit(runSubProcess(
-        executable: """
-\(developerDir)/Toolchains/XcodeDefault.xctoolchain/usr/bin/swiftc
-""",
-        args: Array(args.dropFirst())
-    ))
+    try exit(runSubProcess(executable: swiftcPath, args: Array(args.dropFirst())))
 }
 
 // MARK: - Main
 
 let args = CommandLine.arguments
 // Xcode 16.0 Beta 3 began using "--version" over "-v". Support both.
 if args.count == 2, args.last == "--version" || args.last == "-v" {
-    guard let path = ProcessInfo.processInfo.environment["PATH"] else {
-        fputs("error: PATH not set", stderr)
-        exit(1)
-    }
-
-    // /Applications/Xcode-15.0.0-Beta.app/Contents/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin -> /Applications/Xcode-15.0.0-Beta.app/Contents/Developer/usr/bin
-    let pathComponents = path.split(separator: ":", maxSplits: 1)
-    let xcodeBinPath = pathComponents[0]
-    guard xcodeBinPath.hasSuffix("/Contents/Developer/usr/bin") else {
-        fputs("error: Xcode based bin PATH not set", stderr)
-        exit(1)
-    }
-
-    // /Applications/Xcode-15.0.0-Beta.app/Contents/Developer/usr/bin -> /Applications/Xcode-15.0.0-Beta.app/Contents/Developer
-    let developerDir = xcodeBinPath.dropLast(8)
-
-    // TODO: Make this work with custom toolchains
-    let swiftcPath = """
-\(developerDir)/Toolchains/XcodeDefault.xctoolchain/usr/bin/swiftc
-"""
-
     // args.last allows passing in -v (Xcode < 16b3) and --version (>= 16b3)
     try exit(runSubProcess(executable: swiftcPath, args: [args.last!]))
 }
diff --git a/xcodeproj/internal/bazel_integration_files/clang.sh b/xcodeproj/internal/bazel_integration_files/clang.sh
@@ -17,9 +17,15 @@ do
     break
     ;;
   -v)
-    # TODO: Make this work with custom toolchains
-    DEV_DIR_PREFIX=$(awk '{ sub(/.*-isysroot /, ""); sub(/.Contents\/Developer.*/, ""); print}' <<< "${@:1}")
-    clang="$DEV_DIR_PREFIX/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang"
+    if [[ -n "${TOOLCHAIN_DIR:-}" ]]; then
+      # Use the toolchain's clang
+      clang="$TOOLCHAIN_DIR/usr/bin/clang"
+    else
+      # Use default Xcode default toolchain if no toolchain is provided
+      DEV_DIR_PREFIX=$(awk '{ sub(/.*-isysroot /, ""); sub(/.Contents\/Developer.*/, ""); print}' <<< "${@:1}")
+      clang="$DEV_DIR_PREFIX/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang"
+    fi
+
     "$clang" "${@:1}"
     break
     ;;
diff --git a/xcodeproj/internal/bazel_integration_files/ld b/xcodeproj/internal/bazel_integration_files/ld
@@ -22,8 +22,14 @@ do
 
   *.preview-thunk.dylib)
     # Pass through for SwiftUI Preview thunk compilation
-    # TODO: Make this work with custom toolchains
-    exec "$developer_dir/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang" "${passthrough_args[@]}"
+    if [[ -n "${TOOLCHAIN_DIR:-}" ]]; then
+      # Use the toolchain's ld
+      ld="$TOOLCHAIN_DIR/usr/bin/ld"
+    else
+      # Use default Xcode default toolchain if no toolchain is provided
+      ld="$developer_dir/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld"
+    fi
+    exec "$ld" "${passthrough_args[@]}"
     ;;
   esac
   shift

Original file line number	Diff line number	Diff line change
`@@ -178,7 +178,7 @@ class CreateAutogeneratedXCSchemesTests: XCTestCase {`
`178`	`178`	`expectedTargetInfo.productType.isLaunchable`
`179`	`179`	`{`
`180`	`180`	`expectedBuildPreActions.append(`
`181`		`- .symlinkDefaultToolchainUsrLibDirectory(`
	`181`	`+ .symlinkToolchainUsrLibDirectory(`
`182`	`182`	`buildableReference: expectedTargetInfo.buildableReference`
`183`	`183`	`)`
`184`	`184`	`)`