Use llvm-libtool-darwin instead of llvm-ar

This removes the need to provide `--features=-libtool` on macOS.

.github/workflows/release_notes_template.txt

@@ -1,4 +1,4 @@
-Minimum bazel version: **6.0.0** (6.1.0 if using blzmod)
+Minimum bazel version: **7.0.0**
 
 If you're using `bzlmod`, add the following to `MODULE.bazel`:
 
@@ -53,19 +53,3 @@ load("@llvm_toolchain//:toolchains.bzl", "llvm_register_toolchains")
 
 llvm_register_toolchains()
 ```
-
-And add the following section to your .bazelrc file:
-
-```sh
-# Not needed after https://github.com/bazelbuild/bazel/issues/7260 is closed
-build --incompatible_enable_cc_toolchain_resolution
-
-# For macOS only:
-
-# Needed for Bazel versions before 7.
-# Without this, one can use `--linkopt='-undefined dynamic_lookup'`.
-# This feature is intentionally not supported on macOS.
-build --features=-supports_dynamic_linker
-# Not needed after https://github.com/bazel-contrib/toolchains_llvm/pull/229.
-build --features=-libtool
-```

.github/workflows/tests.yml

@@ -28,14 +28,8 @@ jobs:
       fail-fast: false
       matrix:
         os: [macos-latest, ubuntu-latest]
-        bazel_version: [6.0.0, 6.1.0, latest]
+        bazel_version: [7.0.0, latest] # Minimum supported Bazel version is 7.0.0.
         bzlmod: [true, false]
-        # bzlmod needs 6.1.0 (issue unrelated to this project)
-        exclude:
-          - bazel_version: 6.0.0
-            bzlmod: true
-          - bazel_version: 6.1.0
-            bzlmod: false
     runs-on: ${{ matrix.os }}
     steps:
       - if: startsWith(matrix.os, 'ubuntu')

MODULE.bazel

@@ -16,6 +16,7 @@ module(
     name = "toolchains_llvm",
     version = "0.0.0",
     compatibility_level = 0,
+    bazel_compatibility = [">=7.0.0"],
 )
 
 bazel_dep(name = "bazel_skylib", version = "1.4.2")

README.md

@@ -98,9 +98,6 @@ For specifying unregistered toolchains on the command line, please use the
 `--extra_toolchains` flag. For example,
 `--extra_toolchains=@llvm_toolchain//:cc-toolchain-x86_64-linux`.
 
-We no longer support the `--crosstool_top=@llvm_toolchain//:toolchain` flag,
-and instead rely on the `--incompatible_enable_cc_toolchain_resolution` flag.
-
 ### Bring Your Own LLVM
 
 The following mechanisms are available for using an LLVM toolchain:

tests/.bazelrc

@@ -1,2 +1 @@
-build --incompatible_enable_cc_toolchain_resolution
 build --features=layering_check

tests/scripts/bazel.sh

@@ -40,27 +40,16 @@ common_args=(
   "--enable_bzlmod=${USE_BZLMOD:-false}"
 )
 
+# shellcheck disable=SC2034
 common_test_args=(
   "${common_args[@]}"
   "--symlink_prefix=/"
-  "--incompatible_enable_cc_toolchain_resolution"
   "--color=yes"
   "--show_progress_rate_limit=30"
   "--keep_going"
   "--test_output=errors"
 )
 
-if [[ ${short_uname} == 'Darwin' ]]; then
-  common_test_args+=(
-    # Needed for Bazel versions before 7.
-    # Without this, one can use `--linkopt='-undefined dynamic_lookup'`.
-    # This feature is intentionally not supported on macOS.
-    --features=-supports_dynamic_linker
-    # Not needed after https://github.com/bazel-contrib/toolchains_llvm/pull/229.
-    --features=-libtool
-  )
-fi
-
 # Do not run autoconf to configure local CC toolchains.
 export BAZEL_DO_NOT_DETECT_CPP_TOOLCHAIN=1
 

tests/scripts/run_xcompile_tests.sh

@@ -29,13 +29,13 @@ check_with_image() {
     return
   fi
   local image="$1"
-  docker run --rm --mount "type=bind,source=${binpath},target=/stdlib_test" "${image}" /stdlib_test
+  docker run --rm -it --platform=linux/amd64 \
+    --mount "type=bind,source=${binpath},target=/stdlib_test" "${image}" /stdlib_test
 }
 
 echo ""
 echo "Testing static linked user libraries and dynamic linked system libraries"
 build_args=(
-  --incompatible_enable_cc_toolchain_resolution
   --platforms=@toolchains_llvm//platforms:linux-x86_64
   --extra_toolchains=@llvm_toolchain_with_sysroot//:cc-toolchain-x86_64-linux
   --symlink_prefix=/
@@ -44,7 +44,7 @@ build_args=(
 )
 "${bazel}" --bazelrc=/dev/null build "${build_args[@]}" //:stdlib_test
 file "${binpath}" | tee /dev/stderr | grep -q ELF
-check_with_image "frolvlad/alpine-glibc" # Need glibc image for system libraries.
+check_with_image "gcr.io/distroless/cc-debian11" # Need glibc image for system libraries.
 
 echo ""
 echo "Testing static linked user and system libraries"
@@ -53,4 +53,4 @@ build_args+=(
 )
 "${bazel}" --bazelrc=/dev/null build "${build_args[@]}" //:stdlib_test
 file "${binpath}" | tee /dev/stderr | grep -q ELF
-check_with_image "alpine"
+check_with_image "gcr.io/distroless/static-debian11"

tests/transitions.bzl

@@ -95,5 +95,4 @@ dwp_file = rule(
             default = "@bazel_tools//tools/allowlists/function_transition_allowlist",
         ),
     },
-    incompatible_use_toolchain_transition = True,
 )

toolchain/cc_toolchain_config.bzl

@@ -263,7 +263,7 @@ def cc_toolchain_config(
     # The tool names come from [here](https://github.com/bazelbuild/bazel/blob/c7e58e6ce0a78fdaff2d716b4864a5ace8917626/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java#L76-L90):
     # NOTE: Ensure these are listed in toolchain_tools in toolchain/internal/common.bzl.
     tool_paths = {
-        "ar": tools_path_prefix + "llvm-ar",
+        "ar": tools_path_prefix + ("llvm-ar" if (host_os != "darwin" or is_xcompile) else "llvm-libtool-darwin"),
         "cpp": tools_path_prefix + "clang-cpp",
         "dwp": tools_path_prefix + "llvm-dwp",
         "gcc": wrapper_bin_prefix + "cc_wrapper.sh",

toolchain/internal/common.bzl

@@ -14,7 +14,7 @@
 
 SUPPORTED_TARGETS = [("linux", "x86_64"), ("linux", "aarch64"), ("darwin", "x86_64"), ("darwin", "aarch64")]
 
-toolchain_tools = [
+_toolchain_tools = [
     "clang-cpp",
     "ld.lld",
     "llvm-ar",
@@ -27,6 +27,10 @@ toolchain_tools = [
     "llvm-strip",
 ]
 
+_toolchain_tools_darwin = [
+    "llvm-libtool-darwin",
+]
+
 def host_os_key(rctx):
     (os, version, arch) = os_version_arch(rctx)
     if version == "":
@@ -191,6 +195,12 @@ def attr_dict(attr):
 
     return dict(tuples)
 
+def toolchain_tools(os):
+    tools = list(_toolchain_tools)
+    if os == "darwin":
+        tools.extend(_toolchain_tools_darwin)
+    return tools
+
 def _get_host_tool_info(rctx, tool_path, tool_key = None):
     if tool_key == None:
         tool_key = tool_path

toolchain/internal/configure.bzl

@@ -105,11 +105,12 @@ def llvm_register_toolchains():
         # symlinked path from the wrapper.
         wrapper_bin_prefix = "bin/"
         tools_path_prefix = "bin/"
-        for tool_name in _toolchain_tools:
+        tools = _toolchain_tools(os)
+        for tool_name in tools:
             rctx.symlink(llvm_dist_rel_path + "bin/" + tool_name, tools_path_prefix + tool_name)
         symlinked_tools_str = "".join([
-            "\n" + (" " * 8) + "\"" + tools_path_prefix + name + "\","
-            for name in _toolchain_tools
+            "\n" + (" " * 8) + "\"" + tools_path_prefix + tool_name + "\","
+            for tool_name in tools
         ])
     else:
         llvm_dist_rel_path = llvm_dist_path_prefix