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Add header_modules feature #403

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1 change: 1 addition & 0 deletions toolchain/cc_toolchain.bzl
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Original file line number Diff line number Diff line change
Expand Up @@ -61,6 +61,7 @@ def cc_toolchain(name, tool_map, module_map = None, extra_args = []):
"@llvm//toolchain/features:dbg",
"@llvm//toolchain/features:archive_param_file",
"@llvm//toolchain/features:parse_headers",
"@llvm//toolchain/features/header_modules:all_header_module_features",
"@llvm//toolchain/features/legacy:all_legacy_builtin_features",
# Always last (contains user_compile_flags and user_link_flags who should apply last).
"@llvm//toolchain/features/legacy:experimental_replace_legacy_action_config_features",
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142 changes: 142 additions & 0 deletions toolchain/features/header_modules/BUILD.bazel
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Original file line number Diff line number Diff line change
@@ -0,0 +1,142 @@
load("@rules_cc//cc/toolchains:args.bzl", "cc_args")
load("@rules_cc//cc/toolchains:feature.bzl", "cc_feature")
load("@rules_cc//cc/toolchains:feature_set.bzl", "cc_feature_set")

package(default_visibility = ["//visibility:public"])

# Based on https://github.com/bazelbuild/bazel/issues/4005#issuecomment-1212952697.
#
# Features that control header modules.
#
# We have different features for module consumers and producers:
# 'header_modules' is enabled for targets that support being compiled as a
# header module.
# 'use_header_modules' is enabled for targets that want to use the provided
# header modules from their transitive closure. We enable this globally and
# disable it for targets that do not support builds with header modules.
#
# Allow switching off header modules completely by specifying
# features=["-use_header_modules"] in a rule.

cc_args(
name = "header_module_compile_args",
actions = ["@rules_cc//cc/toolchains/actions:cpp_module_compile"],
args = [
"-xc++",
"-Xclang",
"-emit-module",
"-Xclang",
"-fmodules-embed-all-files",
"-Xclang",
"-fmodules-local-submodule-visibility",
],
)

cc_feature(
name = "header_module_compile",
args = [":header_module_compile_args"],
feature_name = "header_module_compile",
)

cc_feature(
name = "header_modules",
feature_name = "header_modules",
implies = [":header_module_compile"],
requires_any_of = [":use_header_modules"],
)

cc_feature(
name = "header_module_codegen",
feature_name = "header_module_codegen",
requires_any_of = [":header_modules"],
)

cc_args(
name = "header_modules_codegen_functions_args",
actions = ["@rules_cc//cc/toolchains/actions:cpp_module_compile"],
args = [
"-Xclang",
"-fmodules-codegen",
],
)

cc_feature(
name = "header_modules_codegen_functions",
args = [":header_modules_codegen_functions_args"],
feature_name = "header_modules_codegen_functions",
implies = [":header_module_codegen"],
)

cc_args(
name = "header_modules_codegen_debuginfo_args",
actions = ["@rules_cc//cc/toolchains/actions:cpp_module_compile"],
args = [
"-Xclang",
"-fmodules-debuginfo",
],
)

cc_feature(
name = "header_modules_codegen_debuginfo",
args = [":header_modules_codegen_debuginfo_args"],
feature_name = "header_modules_codegen_debuginfo",
implies = [":header_module_codegen"],
)

cc_args(
name = "use_header_modules_args",
actions = [
"@rules_cc//cc/toolchains/actions:cpp_compile",
"@rules_cc//cc/toolchains/actions:cpp_header_parsing",
"@rules_cc//cc/toolchains/actions:cpp_module_compile",
],
args = [
"-fmodules",
"-fmodule-file-deps",
"-fno-implicit-modules",
"-fno-implicit-module-maps",
"-Wno-modules-ambiguous-internal-linkage",
"-Wno-module-import-in-extern-c",
"-Wno-modules-import-nested-redundant",
],
)

cc_args(
name = "use_header_modules_module_files_args",
actions = [
"@rules_cc//cc/toolchains/actions:cpp_compile",
"@rules_cc//cc/toolchains/actions:cpp_header_parsing",
"@rules_cc//cc/toolchains/actions:cpp_module_compile",
],
args = [
"-Xclang",
"-fmodule-file={module_files}",
],
format = {
"module_files": "@rules_cc//cc/toolchains/variables:module_files",
},
iterate_over = "@rules_cc//cc/toolchains/variables:module_files",
requires_not_none = "@rules_cc//cc/toolchains/variables:module_files",
)

cc_feature(
name = "use_header_modules",
args = [
":use_header_modules_args",
":use_header_modules_module_files_args",
],
feature_name = "use_header_modules",
implies = ["@rules_cc//cc/toolchains/args/layering_check:use_module_maps"],
)

cc_feature_set(
name = "all_header_module_features",
all_of = [
":header_module_compile",
":header_modules",
":header_module_codegen",
":header_modules_codegen_functions",
":header_modules_codegen_debuginfo",
":use_header_modules",
],
)
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