Add custom toolchain to generated project

test/internal/custom_toolchain/BUILD

@@ -0,0 +1,26 @@
+# buildifier: disable=bzl-visibility
+load("//xcodeproj/internal:custom_toolchain.bzl", "custom_toolchain")
+
+# Example swiftc override for testing
+filegroup(
+    name = "test_swiftc",
+    srcs = ["test_swiftc.sh"],
+    visibility = ["//visibility:public"],
+)
+
+# Test target for custom_toolchain
+custom_toolchain(
+    name = "test_toolchain",
+    overrides = {
+        ":test_swiftc": "swiftc",
+    },
+    toolchain_name = "TestCustomToolchain",
+)
+
+# Add a simple test rule that depends on the toolchain
+sh_test(
+    name = "custom_toolchain_test",
+    srcs = ["custom_toolchain_test.sh"],
+    args = ["$(location :test_toolchain)"],
+    data = [":test_toolchain"],
+)

test/internal/custom_toolchain/custom_toolchain_test.sh

@@ -0,0 +1,46 @@
+#!/bin/bash
+
+set -euo pipefail
+
+# The first argument should be the path to the toolchain directory
+TOOLCHAIN_DIR="$1"
+
+echo "Verifying toolchain at: $TOOLCHAIN_DIR"
+
+# Check that the toolchain directory exists
+if [[ ! -d "$TOOLCHAIN_DIR" ]]; then
+  echo "ERROR: Toolchain directory does not exist: $TOOLCHAIN_DIR"
+  exit 1
+fi
+
+# Check that ToolchainInfo.plist exists
+if [[ ! -f "$TOOLCHAIN_DIR/ToolchainInfo.plist" ]]; then
+  echo "ERROR: ToolchainInfo.plist not found in toolchain"
+  exit 1
+fi
+
+# Check for correct identifiers in the plist
+if ! grep -q "TestCustomToolchain" "$TOOLCHAIN_DIR/ToolchainInfo.plist"; then
+  echo "ERROR: ToolchainInfo.plist doesn't contain TestCustomToolchain"
+  exit 1
+fi
+
+# Check that our custom swiftc is properly linked/copied
+if [[ ! -f "$TOOLCHAIN_DIR/usr/bin/swiftc" ]]; then
+  echo "ERROR: swiftc not found in toolchain"
+  exit 1
+fi
+
+# Ensure swiftc is executable
+if [[ ! -x "$TOOLCHAIN_DIR/usr/bin/swiftc" ]]; then
+  echo "ERROR: swiftc is not executable"
+  exit 1
+fi
+
+# Test if the swiftc actually runs
+if ! "$TOOLCHAIN_DIR/usr/bin/swiftc" --version > /dev/null 2>&1; then
+  echo "WARN: swiftc doesn't run correctly, but this is expected in tests"
+fi
+
+echo "Custom toolchain validation successful!"
+exit 0

test/internal/custom_toolchain/test_swiftc.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+# This is a test script that simulates a custom Swift compiler
+# It will be used as an override in the custom toolchain
+
+# Print inputs for debugging
+echo "Custom swiftc called with args: $@" >&2
+
+# In a real override, you would do something meaningful with the args
+# For testing, just exit successfully
+exit 0

test/internal/pbxproj_partials/write_pbxproj_prefix_tests.bzl

@@ -266,6 +266,8 @@ def write_pbxproj_prefix_test_suite(name):
             "some/path/to/index_import",
             # resolvedRepositoriesFile
             "some/path/to/resolved_repositories_file",
+            # customToolchainID
+            "com.rules_xcodeproj.BazelRulesXcodeProj.16B40",
             # minimumXcodeVersion
             "14.2.1",
             # importIndexBuildIndexstores
@@ -332,6 +334,8 @@ def write_pbxproj_prefix_test_suite(name):
             "some/path/to/index_import",
             # resolvedRepositoriesFile
             "some/path/to/resolved_repositories_file",
+            # customToolchainID
+            "com.rules_xcodeproj.BazelRulesXcodeProj.16B40",
             # minimumXcodeVersion
             "14.2.1",
             # importIndexBuildIndexstores

tools/generators/files_and_groups/src/Generator/CreateBuildFileObject.swift

@@ -42,7 +42,7 @@ extension Generator.CreateBuildFileObject {
             settings = #"settings = {COMPILER_FLAGS = "-fno-objc-arc"; }; "#
         case .compileStub, .source:
             settings = ""
-        case .product, .watchKitExtension:
+        case .product, .watchKitExtension, .framework:
             // Handled in `CreateProductBuildFileObject` and
             // `CreateProductObject`
             preconditionFailure()

tools/generators/legacy/src/Generator/CreateProject.swift

@@ -137,8 +137,6 @@ $(PROJECT_TEMP_DIR)/$(BAZEL_PACKAGE_BIN_DIR)/$(COMPILE_TARGET_NAME)
                 "LD": "$(BAZEL_INTEGRATION_DIR)/ld",
                 "LDPLUSPLUS": "$(BAZEL_INTEGRATION_DIR)/ld",
                 "LIBTOOL": "$(BAZEL_INTEGRATION_DIR)/libtool",
-                "SWIFT_EXEC": "$(BAZEL_INTEGRATION_DIR)/swiftc",
-                "SWIFT_USE_INTEGRATED_DRIVER": false,
                 "TAPI_EXEC": "/usr/bin/true",
             ], uniquingKeysWith: { _, r in r })
         } else {

tools/generators/legacy/test/CreateProjectTests.swift

@@ -232,11 +232,9 @@ $(BUILD_DIR)/$(BAZEL_PACKAGE_BIN_DIR)
             "RULES_XCODEPROJ_BUILD_MODE": "bazel",
             "SRCROOT": directories.workspace.string,
             "SUPPORTS_MACCATALYST": false,
-            "SWIFT_EXEC": "$(BAZEL_INTEGRATION_DIR)/swiftc",
             "TAPI_EXEC": "/usr/bin/true",
             "SWIFT_OBJC_INTERFACE_HEADER_NAME": "",
             "SWIFT_OPTIMIZATION_LEVEL": "-Onone",
-            "SWIFT_USE_INTEGRATED_DRIVER": false,
             "SWIFT_VERSION": "5.0",
             "TARGET_TEMP_DIR": """
 $(PROJECT_TEMP_DIR)/$(BAZEL_PACKAGE_BIN_DIR)/$(COMPILE_TARGET_NAME)

tools/generators/lib/PBXProj/src/BuildPhase.swift

@@ -5,6 +5,7 @@ public enum BuildPhase {
     case sources
     case copySwiftGeneratedHeader
     case embedAppExtensions
+    case linkBinaryWithLibraries
 
     public var name: String {
         switch self {
@@ -16,6 +17,7 @@ Copy Bazel Outputs / Generate Bazel Dependencies (Index Build)
         case .sources: return "Sources"
         case .copySwiftGeneratedHeader: return "Copy Swift Generated Header"
         case .embedAppExtensions: return "Embed App Extensions"
+        case .linkBinaryWithLibraries: return "Frameworks"
         }
     }
 }

tools/generators/lib/PBXProj/src/Identifiers.swift

@@ -89,6 +89,9 @@ FF01000000000000000001\#(byteHexStrings[index]!) \#
             /// The product reference for a target.
             case product = "P"
 
+            /// The framework reference for a target in libraries to link build phase.
+            case framework = "f"
+
             /// A normal file referenced in a `BuildPhase.sources` build phase.
             case source = "0"
 
@@ -186,6 +189,14 @@ FF01000000000000000001\#(byteHexStrings[index]!) \#
                 return #"""
 \#(subIdentifier.shard)00\#(subIdentifier.hash)0000000000FF \#
 /* \#(subIdentifier.path.path) */
+"""#
+
+            case .framework:
+                let basename = subIdentifier.path.path
+                    .split(separator: "/").last!
+                return #"""
+\#(subIdentifier.shard)A8\#(subIdentifier.hash) \#
+/* \#(basename) in Frameworks */
 """#
 
             case .compileStub:
@@ -535,6 +546,7 @@ private extension Identifiers.BuildFiles.FileType {
     var buildPhase: BuildPhase {
         switch self {
         case .product: preconditionFailure() // product reference used as build file
+        case .framework: return .linkBinaryWithLibraries
         case .source: return .sources
         case .nonArcSource: return .sources
         case .compileStub: return .sources
@@ -566,6 +578,7 @@ extension BuildPhase {
         case .sources: return "06"
         case .copySwiftGeneratedHeader: return "07"
         case .embedAppExtensions: return "08"
+        case .linkBinaryWithLibraries: return "09"
         }
     }
 }

tools/generators/pbxnativetargets/src/Generator/CalculatePlatformVariantBuildSettings.swift

@@ -183,6 +183,24 @@ extension Generator.CalculatePlatformVariantBuildSettings {
             )
         }
 
+        buildSettings.append(
+            .init(
+                key: "LIBRARY_SEARCH_PATHS",
+                value: (
+                    platformVariant.librarySearchPaths
+                        .map {
+                            let path = $0.path.split(separator: "/").dropFirst().joined(separator: "/")
+                            return "\"$(BAZEL_OUT)/\(path)\""
+                        } + [
+                            "\"/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/lib/darwin\""
+                        ]
+                    )
+                    .sorted()
+                    .joined(separator: " ")
+                    .pbxProjEscaped
+            )
+        )
+
         buildSettings.append(contentsOf: platformVariant.buildSettingsFromFile)
 
         return buildSettings

tools/generators/pbxnativetargets/src/Generator/CalculatePlatformVariants.swift

@@ -59,6 +59,7 @@ extension Generator.CalculatePlatformVariants {
     ) {
         var srcs: [[BazelPath]] = []
         var nonArcSrcs: [[BazelPath]] = []
+        var librariesToLinkPaths: [[BazelPath]] = []
         var excludableFilesKeysWithValues: [(TargetID, Set<BazelPath>)] = []
         for id in ids {
             let targetArguments = try targetArguments.value(
@@ -68,6 +69,7 @@ extension Generator.CalculatePlatformVariants {
 
             srcs.append(targetArguments.srcs)
             nonArcSrcs.append(targetArguments.nonArcSrcs)
+            librariesToLinkPaths.append(targetArguments.librariesToLinkPaths)
 
             excludableFilesKeysWithValues.append(
                 (
@@ -134,14 +136,16 @@ extension Generator.CalculatePlatformVariants {
                         .flatMap { unitTestHosts[$0] },
                     dSYMPathsBuildSetting:
                         targetArguments.dSYMPathsBuildSetting.isEmpty ?
-                    nil : targetArguments.dSYMPathsBuildSetting
+                    nil : targetArguments.dSYMPathsBuildSetting,
+                    librarySearchPaths: Set(targetArguments.librarySearchPaths)
                 )
             )
         }
 
         let consolidatedInputs = Target.ConsolidatedInputs(
             srcs: consolidatePaths(srcs),
-            nonArcSrcs: consolidatePaths(nonArcSrcs)
+            nonArcSrcs: consolidatePaths(nonArcSrcs),
+            librariesToLinkPaths: consolidatePaths(librariesToLinkPaths)
         )
 
         return (platformVariants, allConditionalFiles, consolidatedInputs)

tools/generators/pbxnativetargets/src/Generator/CalculateXcodeConfigurationBuildSettings.swift

@@ -236,7 +236,7 @@ private extension Platform {
     }
 }
 
-private extension String {
+extension String {
     var quoteIfNeeded: String {
         guard !contains(" ") else {
             return #""\#(self)""#