Add fastbuild_compile_flags (#536)

This includes updating and using
bazelbuild/rules_cc@ff06b70 and
bazelbuild/rules_cc@eed7e63
which is also [used by
`bazel_tools`](https://github.com/bazelbuild/bazel/blob/4f46e8265313078b8afbf9d6b832711b2d75cfc2/tools/cpp/unix_cc_toolchain_config.bzl#L17).

Usage example:
```starlark
# MODULE.bazel
llvm = use_extension("@toolchains_llvm//toolchain/extensions:llvm.bzl", "llvm")
llvm.toolchain(
    compile_flags = {
        "fastbuild_compile_flags": [
            "-O1",
        ],
    },
    llvm_version = "20.1.2",
)
```

---------

Co-authored-by: Tom Rybka <[email protected]>

Author: mering

.github/workflows/release_notes_template.txt

@@ -43,6 +43,14 @@ load("@toolchains_llvm//toolchain:deps.bzl", "bazel_toolchain_dependencies")
 
 bazel_toolchain_dependencies()
 
+load("@bazel_features//:deps.bzl", "bazel_features_deps")
+
+bazel_features_deps()
+
+load("@rules_cc//cc:extensions.bzl", "compatibility_proxy_repo")
+
+compatibility_proxy_repo()
+
 load("@toolchains_llvm//toolchain:rules.bzl", "llvm_toolchain")
 
 llvm_toolchain(

MODULE.bazel

@@ -20,7 +20,7 @@ module(
 )
 
 bazel_dep(name = "bazel_skylib", version = "1.5.0")
-bazel_dep(name = "rules_cc", version = "0.0.17")
+bazel_dep(name = "rules_cc", version = "0.2.2")
 bazel_dep(name = "platforms", version = "0.0.8")
 
 # TODO: Remove when protobuf is released with a version of rules_python that supports 8.x

tests/WORKSPACE

@@ -325,9 +325,12 @@ rules_foreign_cc_dependencies()
 
 load("@bazel_features//:deps.bzl", "bazel_features_deps")
 
-# Dep of `rules_foreign_cc`.
 bazel_features_deps()
 
+load("@rules_cc//cc:extensions.bzl", "compatibility_proxy_repo")
+
+compatibility_proxy_repo()
+
 _ALL_CONTENT = """\
 filegroup(
     name = "all_srcs",

toolchain/cc_toolchain_config.bzl

@@ -12,8 +12,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+# buildifier: disable=bzl-visibility
 load(
-    "@bazel_tools//tools/cpp:unix_cc_toolchain_config.bzl",
+    "@rules_cc//cc/private/toolchain:unix_cc_toolchain_config.bzl",
     unix_cc_toolchain_config = "cc_toolchain_config",
 )
 load(
@@ -178,6 +179,8 @@ def cc_toolchain_config(
 
     dbg_compile_flags = ["-g", "-fstandalone-debug"]
 
+    fastbuild_compile_flags = []
+
     opt_compile_flags = [
         "-g0",
         "-O2",
@@ -399,6 +402,8 @@ def cc_toolchain_config(
         opt_link_flags = _fmt_flags(compiler_configuration["opt_link_flags"], toolchain_path_prefix)
     if compiler_configuration["dbg_compile_flags"] != None:
         dbg_compile_flags = _fmt_flags(compiler_configuration["dbg_compile_flags"], toolchain_path_prefix)
+    if compiler_configuration["fastbuild_compile_flags"] != None:
+        fastbuild_compile_flags = _fmt_flags(compiler_configuration["fastbuild_compile_flags"], toolchain_path_prefix)
     if compiler_configuration["coverage_compile_flags"] != None:
         coverage_compile_flags = _fmt_flags(compiler_configuration["coverage_compile_flags"], toolchain_path_prefix)
     if compiler_configuration["coverage_link_flags"] != None:
@@ -420,6 +425,7 @@ def cc_toolchain_config(
         cxx_builtin_include_directories = cxx_builtin_include_directories,
         tool_paths = tool_paths,
         compile_flags = compile_flags,
+        fastbuild_compile_flags = fastbuild_compile_flags,
         dbg_compile_flags = dbg_compile_flags,
         opt_compile_flags = opt_compile_flags,
         conly_flags = conly_flags,

toolchain/deps.bzl

@@ -19,9 +19,9 @@ def bazel_toolchain_dependencies():
     if not native.existing_rule("rules_cc"):
         http_archive(
             name = "rules_cc",
-            urls = ["https://github.com/bazelbuild/rules_cc/releases/download/0.0.17/rules_cc-0.0.17.tar.gz"],
-            sha256 = "abc605dd850f813bb37004b77db20106a19311a96b2da1c92b789da529d28fe1",
-            strip_prefix = "rules_cc-0.0.17",
+            urls = ["https://github.com/bazelbuild/rules_cc/releases/download/0.2.2/rules_cc-0.2.2.tar.gz"],
+            sha256 = "e50f24506011841e2ac83d9733a0c7e058eb3a10a6e3e10baa9c7942ff5f4767",
+            strip_prefix = "rules_cc-0.2.2",
         )
 
     # Load bazel_skylib if the user has not defined them.
@@ -36,3 +36,12 @@ def bazel_toolchain_dependencies():
         )
 
         # Skip bazel_skylib_workspace because we are not using lib/unittest.bzl
+
+    # Load bazel_features if the user has not defined them.
+    if not native.existing_rule("bazel_features"):
+        http_archive(
+            name = "bazel_features",
+            sha256 = "ba1282c1aa1d1fffdcf994ab32131d7c7551a9bc960fbf05f42d55a1b930cbfb",
+            strip_prefix = "bazel_features-1.15.0",
+            url = "https://github.com/bazel-contrib/bazel_features/releases/download/v1.15.0/bazel_features-v1.15.0.tar.gz",
+        )

toolchain/internal/configure.bzl

@@ -165,6 +165,7 @@ def llvm_config_impl(rctx):
         link_flags_dict = rctx.attr.link_flags,
         archive_flags_dict = rctx.attr.archive_flags,
         link_libs_dict = rctx.attr.link_libs,
+        fastbuild_compile_flags_dict = rctx.attr.fastbuild_compile_flags,
         opt_compile_flags_dict = rctx.attr.opt_compile_flags,
         opt_link_flags_dict = rctx.attr.opt_link_flags,
         dbg_compile_flags_dict = rctx.attr.dbg_compile_flags,
@@ -396,6 +397,7 @@ cc_toolchain_config(
       "link_flags": {link_flags},
       "archive_flags": {archive_flags},
       "link_libs": {link_libs},
+      "fastbuild_compile_flags": {fastbuild_compile_flags},
       "opt_compile_flags": {opt_compile_flags},
       "opt_link_flags": {opt_link_flags},
       "dbg_compile_flags": {dbg_compile_flags},
@@ -570,6 +572,7 @@ cc_toolchain(
         link_flags = _list_to_string(_dict_value(toolchain_info.link_flags_dict, target_pair)),
         archive_flags = _list_to_string(_dict_value(toolchain_info.archive_flags_dict, target_pair)),
         link_libs = _list_to_string(_dict_value(toolchain_info.link_libs_dict, target_pair)),
+        fastbuild_compile_flags = _list_to_string(_dict_value(toolchain_info.fastbuild_compile_flags_dict, target_pair)),
         opt_compile_flags = _list_to_string(_dict_value(toolchain_info.opt_compile_flags_dict, target_pair)),
         opt_link_flags = _list_to_string(_dict_value(toolchain_info.opt_link_flags_dict, target_pair)),
         dbg_compile_flags = _list_to_string(_dict_value(toolchain_info.dbg_compile_flags_dict, target_pair)),

toolchain/internal/repo.bzl

@@ -209,6 +209,14 @@ _compiler_configuration_attrs = {
                "target OS and arch pair you want to override " +
                "({}); empty key overrides all.".format(_target_pairs)),
     ),
+    "fastbuild_compile_flags": attr.string_list_dict(
+        mandatory = False,
+        doc = ("Override for fastbuild_compile_flags, replacing the default values. " +
+               "`{toolchain_path_prefix}` in the flags will be substituted by the path " +
+               "to the root LLVM distribution directory. Provide one list for each " +
+               "target OS and arch pair you want to override " +
+               "({}); empty key overrides all.".format(_target_pairs)),
+    ),
     "opt_compile_flags": attr.string_list_dict(
         mandatory = False,
         doc = ("Override for opt_compile_flags, replacing the default values. " +