Use hermetic toolchain on Linux CI

.bazelci/presubmit.yml

@@ -9,32 +9,14 @@ x_defaults:
       - "//..."
     test_targets:
       - "//..."
-  linux_environment: &linux_environment
-    platform: ubuntu2204
-    environment:
-      SWIFT_VERSION: "6.3.3"
-      SWIFT_HOME: "$HOME/swift-$SWIFT_VERSION"
-      PATH: "$SWIFT_HOME/usr/bin:$PATH"
   linux_common: &linux_common
-    <<: *linux_environment
-    build_flags: &linux_flags
-      # On Linux, we look for Swift toolchain binaries on the path. We may be
-      # able to change this when we start auto-downloading toolchains (see
-      # https://github.com/bazelbuild/rules_swift/issues/4).
-      - "--action_env=PATH"
+    platform: ubuntu2204
     build_targets:
       - "//..."
       - "-//examples/apple/..."
-    test_flags: *linux_flags
     test_targets:
       - "//..."
       - "-//examples/apple/..."
-      # The following tests require Swift >5.8.
-      - "-//test:const_values_empty_const_values_multiple_files"
-      - "-//test:const_values_empty_const_values_single_file"
-      - "-//test:const_values_expected_argv"
-      - "-//test:const_values_wmo_single_values_file"
-      - "-//test:output_file_map_default"
   windows_common: &windows_common
     platform: windows
     build_targets:
@@ -75,28 +57,16 @@ tasks:
   ubuntu2204_latest:
     name: "Current LTS"
     bazel: latest
-    shell_commands:
-      - "echo --- Downloading and extracting Swift $SWIFT_VERSION to $SWIFT_HOME"
-      - "mkdir $SWIFT_HOME"
-      - "curl https://download.swift.org/swift-${SWIFT_VERSION}-release/ubuntu2204/swift-${SWIFT_VERSION}-RELEASE/swift-${SWIFT_VERSION}-RELEASE-ubuntu22.04.tar.gz | tar xvz --strip-components=1 -C $SWIFT_HOME"
     <<: *linux_common
 
   ubuntu2204_rolling:
     name: "Latest rolling"
     bazel: rolling
-    shell_commands:
-      - "echo --- Downloading and extracting Swift $SWIFT_VERSION to $SWIFT_HOME"
-      - "mkdir $SWIFT_HOME"
-      - "curl https://download.swift.org/swift-${SWIFT_VERSION}-release/ubuntu2204/swift-${SWIFT_VERSION}-RELEASE/swift-${SWIFT_VERSION}-RELEASE-ubuntu22.04.tar.gz | tar xvz --strip-components=1 -C $SWIFT_HOME"
     <<: *linux_common
 
   ubuntu2204_last_green:
     name: "Last Green Bazel"
     bazel: last_green
-    shell_commands:
-      - "echo --- Downloading and extracting Swift $SWIFT_VERSION to $SWIFT_HOME"
-      - "mkdir $SWIFT_HOME"
-      - "curl https://download.swift.org/swift-${SWIFT_VERSION}-release/ubuntu2204/swift-${SWIFT_VERSION}-RELEASE/swift-${SWIFT_VERSION}-RELEASE-ubuntu22.04.tar.gz | tar xvz --strip-components=1 -C $SWIFT_HOME"
     <<: *linux_common
 
   windows:
@@ -128,11 +98,7 @@ tasks:
   doc_tests:
     name: "Doc tests"
     bazel: latest
-    <<: *linux_environment
-    shell_commands:
-      - "echo --- Downloading and extracting Swift $SWIFT_VERSION to $SWIFT_HOME"
-      - "mkdir $SWIFT_HOME"
-      - "curl https://download.swift.org/swift-${SWIFT_VERSION}-release/ubuntu2204/swift-${SWIFT_VERSION}-RELEASE/swift-${SWIFT_VERSION}-RELEASE-ubuntu22.04.tar.gz | tar xvz --strip-components=1 -C $SWIFT_HOME"
+    platform: ubuntu2204
     test_targets:
       - "doc/..."
 

MODULE.bazel

@@ -9,6 +9,7 @@ module(
 
 bazel_dep(name = "abseil-cpp", version = "20250814.1")
 bazel_dep(name = "apple_support", version = "2.6.1")
+bazel_dep(name = "bazel_linux_packages", version = "0.3.1")
 bazel_dep(name = "bazel_features", version = "1.51.0")
 bazel_dep(name = "bazel_skylib", version = "1.7.1")
 bazel_dep(name = "nlohmann_json", version = "3.12.0.bcr.1")
@@ -18,6 +19,21 @@ bazel_dep(name = "rules_cc", version = "0.2.14")
 bazel_dep(name = "rules_shell", version = "0.3.0")
 bazel_dep(name = "swift_argument_parser", version = "1.7.0")
 
+# Regenerate lockfile: bazel run @swift_ubuntu22.04_sysroot//:lock
+apt = use_extension("@bazel_linux_packages//apt:extensions.bzl", "apt")
+apt.ubuntu(
+    name = "swift_ubuntu22.04_sysroot",
+    lockfile = "//swift/internal/extensions:ubuntu22.04_sysroot.lock.json",
+    packages = [
+        "libc6-dev",
+        "libstdc++-11-dev",
+        "linux-libc-dev",
+        "zlib1g-dev",
+    ],
+    suites = ["jammy"],
+)
+use_repo(apt, "swift_ubuntu22.04_sysroot")
+
 swift_autoconfiguration = use_repo_rule("//swift/internal:swift_autoconfiguration.bzl", "swift_autoconfiguration")
 
 swift_autoconfiguration(name = "rules_swift_local_config")
@@ -145,8 +161,6 @@ http_archive(
     urls = ["https://github.com/MobileNativeFoundation/index-import/releases/download/6.1.0.1/index-import.tar.gz"],
 )
 
-register_toolchains("//swift/toolchains:all")
-
 system_sdk = use_extension("//swift:extensions.bzl", "system_sdk")
 system_sdk.configure_sdks(
     # NOTE: This doesn't apply to downstream repos
@@ -209,14 +223,18 @@ register_toolchains(
     # Anyway, for now we will need to update this every time we update the CI environment. Contributors might also
     # have to update this list if they're testing on a different Linux distribution.
     "@swift_toolchain//:cc_toolchain_embedded_ubuntu22.04",
+    "@swift_toolchain//:cc_toolchain_exec_ubuntu22.04",
     "@swift_toolchain//:cc_toolchain_embedded_ubuntu22.04-aarch64",
     "@swift_toolchain//:cc_toolchain_embedded_xcode",
     "@swift_toolchain//:swift_toolchain_embedded_ubuntu22.04",
+    "@swift_toolchain//:swift_toolchain_exec_ubuntu22.04",
     "@swift_toolchain//:swift_toolchain_embedded_ubuntu22.04-aarch64",
     "@swift_toolchain//:swift_toolchain_embedded_xcode",
     dev_dependency = True,
 )
 
+register_toolchains("//swift/toolchains:all")
+
 include("//examples/cross_compilation/android_app:android.MODULE.bazel")
 include("//examples/cross_compilation/wasm:wasm.MODULE.bazel")
 
@@ -240,3 +258,21 @@ single_version_override(
     patch_strip = 1,
     patches = ["//third_party/patches:stardoc-revert-load-statements-in-docs.patch"],
 )
+
+# FIXME: Delete after testing
+
+archive_override(
+    module_name = "apple_support",
+    integrity = "sha256-4YQ7nCqSJ4QcfTF8RLDRQseKtfFS1MTtWKnLlS3bg/U=",
+    strip_prefix = "apple_support-c268c90e7d1efe0d656081e29b11ab05ada9bdda",
+    urls = [
+        "https://github.com/bazelbuild/apple_support/archive/c268c90e7d1efe0d656081e29b11ab05ada9bdda.tar.gz",
+    ],
+)
+
+single_version_override(
+    module_name = "bazel_linux_packages",
+    patch_strip = 1,
+    patches = ["//third_party/patches:bazel-linux-packages-bazel-9.patch"],
+    version = "0.3.1",
+)

doc/providers.md

@@ -268,9 +268,9 @@ SwiftToolchainInfo(<a href="#SwiftToolchainInfo-action_configs">action_configs</
                    <a href="#SwiftToolchainInfo-const_protocols_to_gather">const_protocols_to_gather</a>, <a href="#SwiftToolchainInfo-cross_import_overlays">cross_import_overlays</a>, <a href="#SwiftToolchainInfo-debug_outputs_provider">debug_outputs_provider</a>,
                    <a href="#SwiftToolchainInfo-developer_dirs">developer_dirs</a>, <a href="#SwiftToolchainInfo-entry_point_linkopts_provider">entry_point_linkopts_provider</a>, <a href="#SwiftToolchainInfo-feature_allowlists">feature_allowlists</a>,
                    <a href="#SwiftToolchainInfo-generated_header_module_implicit_deps_providers">generated_header_module_implicit_deps_providers</a>, <a href="#SwiftToolchainInfo-implicit_deps_providers">implicit_deps_providers</a>,
-                   <a href="#SwiftToolchainInfo-module_aliases">module_aliases</a>, <a href="#SwiftToolchainInfo-package_configurations">package_configurations</a>, <a href="#SwiftToolchainInfo-requested_features">requested_features</a>, <a href="#SwiftToolchainInfo-root_dir">root_dir</a>, <a href="#SwiftToolchainInfo-runtime">runtime</a>,
-                   <a href="#SwiftToolchainInfo-swift_worker">swift_worker</a>, <a href="#SwiftToolchainInfo-system_modules">system_modules</a>, <a href="#SwiftToolchainInfo-implicit_system_modules">implicit_system_modules</a>, <a href="#SwiftToolchainInfo-test_configuration">test_configuration</a>,
-                   <a href="#SwiftToolchainInfo-tool_configs">tool_configs</a>, <a href="#SwiftToolchainInfo-unsupported_features">unsupported_features</a>)
+                   <a href="#SwiftToolchainInfo-module_aliases">module_aliases</a>, <a href="#SwiftToolchainInfo-package_configurations">package_configurations</a>, <a href="#SwiftToolchainInfo-requested_features">requested_features</a>, <a href="#SwiftToolchainInfo-root_dir">root_dir</a>, <a href="#SwiftToolchainInfo-swift_worker">swift_worker</a>,
+                   <a href="#SwiftToolchainInfo-system_modules">system_modules</a>, <a href="#SwiftToolchainInfo-implicit_system_modules">implicit_system_modules</a>, <a href="#SwiftToolchainInfo-test_configuration">test_configuration</a>, <a href="#SwiftToolchainInfo-tool_configs">tool_configs</a>,
+                   <a href="#SwiftToolchainInfo-unsupported_features">unsupported_features</a>)
 </pre>
 
 Propagates information about a Swift toolchain to compilation and linking rules
@@ -296,7 +296,6 @@ that use the toolchain.
 | <a id="SwiftToolchainInfo-package_configurations"></a>package_configurations |  A list of `SwiftPackageConfigurationInfo` providers that specify additional compilation configuration options that are applied to targets on a per-package basis.    |
 | <a id="SwiftToolchainInfo-requested_features"></a>requested_features |  `List` of `string`s. Features that should be implicitly enabled by default for targets built using this toolchain, unless overridden by the user by listing their negation in the `features` attribute of a target/package or in the `--features` command line flag.<br><br>These features determine various compilation and debugging behaviors of the Swift build rules, and they are also passed to the C++ APIs used when linking (so features defined in CROSSTOOL may be used here).    |
 | <a id="SwiftToolchainInfo-root_dir"></a>root_dir |  `String`. The workspace-relative root directory of the toolchain.    |
-| <a id="SwiftToolchainInfo-runtime"></a>runtime |  `List` of `File`s. Files required at runtime by compiled executables. They will be added to the input root at execution time.    |
 | <a id="SwiftToolchainInfo-swift_worker"></a>swift_worker |  `File`. The executable representing the worker executable used to invoke the compiler and other Swift tools (for both incremental and non-incremental compiles).    |
 | <a id="SwiftToolchainInfo-system_modules"></a>system_modules |  A `struct` with the following fields, which represent providers from targets that should be added as implicit dependencies of any compilation or linking target:<br><br>*   `cc_infos`: A list of `CcInfo` providers from targets specified as the     toolchain's implicit dependencies.<br><br>*   `swift_infos`: A list of `SwiftInfo` providers from targets specified as the     toolchain's implicit dependencies.<br><br>For ease of use, this field is never `None`; it will always be a valid `struct` containing the fields described above, even if those lists are empty.    |
 | <a id="SwiftToolchainInfo-implicit_system_modules"></a>implicit_system_modules |  A `struct` with in the same shape as `system_modules` for the system modules that every Swift compilation implicitly requires.    |

swift/internal/extensions/toolchain.BUILD

@@ -1,8 +1,11 @@
+load("@apple_support//toolchain:cc_toolchain.bzl", apple_cc_toolchain = "cc_toolchain")
 load("@rules_cc//cc/toolchains:args.bzl", "cc_args")
+load("@rules_cc//cc/toolchains:feature.bzl", "cc_feature")
 load("@rules_cc//cc/toolchains:make_variable.bzl", "cc_make_variable")
 load("@rules_cc//cc/toolchains:tool.bzl", "cc_tool")
 load("@rules_cc//cc/toolchains:tool_map.bzl", "cc_tool_map")
 load("@rules_cc//cc/toolchains:toolchain.bzl", "cc_toolchain")
+load("@rules_cc//cc/toolchains/args:sysroot.bzl", "cc_sysroot")
 load("@rules_swift//swift/toolchains:swift_toolchain.bzl", "swift_toolchain")
 load("@rules_swift//swift/toolchains:swift_tools.bzl", "swift_tools")
 
@@ -76,12 +79,32 @@ cc_tool(
 cc_tool(
     name = "clang",
     src = "usr/bin/clang",
+    data = [":swift_sdk_linker_inputs"],
     tags = ["manual"],
 )
 
 cc_tool(
     name = "clang++",
     src = "usr/bin/clang++",
+    data = [":swift_sdk_linker_inputs"],
+    tags = ["manual"],
+)
+
+cc_tool(
+    name = "llvm_cov",
+    src = "usr/bin/llvm-cov",
+    tags = ["manual"],
+)
+
+cc_tool(
+    name = "llvm_objcopy",
+    src = "usr/bin/llvm-objcopy",
+    tags = ["manual"],
+)
+
+cc_tool(
+    name = "llvm_profdata",
+    src = "usr/bin/llvm-profdata",
     tags = ["manual"],
 )
 
@@ -93,10 +116,42 @@ cc_tool_map(
         "@rules_cc//cc/toolchains/actions:assembly_actions": ":clang",
         "@rules_cc//cc/toolchains/actions:c_compile": ":clang",
         "@rules_cc//cc/toolchains/actions:cpp_compile_actions": ":clang++",
-        "@rules_cc//cc/toolchains/actions:link_actions": ":clang",
+        "@rules_cc//cc/toolchains/actions:link_actions": ":clang++",
+        "@rules_cc//cc/toolchains/actions:llvm_cov": ":llvm_cov",
+        "@rules_cc//cc/toolchains/actions:llvm_profdata": ":llvm_profdata",
+        "@rules_cc//cc/toolchains/actions:objcopy_embed_data": ":llvm_objcopy",
+        "@rules_cc//cc/toolchains/actions:strip": ":llvm_objcopy",
     },
 )
 
+cc_sysroot(
+    name = "linux_sysroot_args",
+    actions = [
+        "@rules_cc//cc/toolchains/actions:link_actions",
+        "@rules_cc//cc/toolchains/actions:compile_actions",
+    ],
+    data = ["@swift_ubuntu22.04_sysroot//:root"],
+    sysroot = "@swift_ubuntu22.04_sysroot//:root",
+)
+
+cc_feature(
+    name = "linux_sysroot",
+    args = [":linux_sysroot_args"],
+    feature_name = "sysroot",
+)
+
+apple_cc_toolchain(
+    name = "cc_toolchain_exec",
+    module_map = None,
+    supports_header_parsing = False,
+    sysroot_feature = ":linux_sysroot",
+    target = select({
+        "@platforms//cpu:aarch64": "aarch64-unknown-linux-gnu",
+        "@platforms//cpu:x86_64": "x86_64-unknown-linux-gnu",
+    }),
+    tool_map = ":all_tools",
+)
+
 ### Make variables ###
 # Used in _swift_toolchain_impl() in swift/toolchain/swift_toolchain.bzl
 cc_make_variable(
@@ -227,6 +282,12 @@ swift_toolchain(
         "swift._supports_upcoming_features",
         "swift.no_embed_debug_module",
         "swift.use_autolink_extract",
+        "swift.lld_gc_workaround",
+        "swift.use_module_wrap",
+        # TODO: This should be removed so that private headers can be used with
+        # explicit modules, but the build targets for CgRPC need to be cleaned up
+        # first because they contain C++ code.
+        "swift.module_map_no_private_headers",
     ],
     os = select({
         "@platforms//os:linux": "linux",
@@ -235,8 +296,8 @@ swift_toolchain(
     parsed_version = "{swift_version}",
     runtime = glob(
         [
-            "usr/lib/swift/**/*.dylib",  # On MacOS
-            "usr/lib/swift/**/*.so",  # On Linux
+            "usr/lib/swift/linux/*.so",
+            "usr/lib/swift/macosx/*.dylib",
         ],
         allow_empty = True,
     ),

swift/internal/extensions/toolchains.bzl

@@ -43,6 +43,18 @@ toolchain(
 
 """
 
+_CC_EXEC_TOOLCHAIN_PLATFORM = """
+# C++ exec toolchain from repository: `{toolchain_repository}`
+toolchain(
+    name = "cc_toolchain_exec_{platform}",
+    exec_compatible_with = {exec_compatible_with},
+    target_compatible_with = {exec_compatible_with},
+    toolchain = "@{toolchain_repository}//:cc_toolchain_exec",
+    toolchain_type = "@bazel_tools//tools/cpp:toolchain_type",
+    visibility = ["//visibility:public"],
+)
+"""
+
 _SDK_TOOLCHAIN_PLATFORM = """
 # Swift SDK toolchain from repository: `{sdk_repository}`
 toolchain(
@@ -94,12 +106,26 @@ def _exec_compatible_with_for_platform(platform):
     ]
 
 def toolchains_for_platform(platform, toolchain_repository):
-    return _TOOLCHAIN_PLATFORM.format(
+    content = _TOOLCHAIN_PLATFORM.format(
         exec_compatible_with = _exec_compatible_with_for_platform(platform),
         platform = platform,
         toolchain_repository = toolchain_repository,
     )
 
+    # TODO: Expand based on sysroot compatibility, maybe we should allow users to pass them
+    if platform in (
+        "ubuntu22.04",
+        "ubuntu22.04-aarch64",
+        "ubuntu24.04",
+        "ubuntu24.04-aarch64",
+    ):
+        content += _CC_EXEC_TOOLCHAIN_PLATFORM.format(
+            exec_compatible_with = _exec_compatible_with_for_platform(platform),
+            platform = platform,
+            toolchain_repository = toolchain_repository,
+        )
+    return content
+
 def android_sdk_toolchains_for_platform(platform, sdk_repository, archs):
     """Returns Swift `toolchain` declarations for an Android Swift SDK.