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Support C++20 modules, MSVC part #836

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2 changes: 1 addition & 1 deletion cc/private/toolchain/msvc_deps_scanner_wrapper.bat.tpl
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Original file line number Diff line number Diff line change
Expand Up @@ -13,4 +13,4 @@
:: limitations under the License.

@echo OFF
"%{cc}" /scanDependencies- /TP %* >%DEPS_SCANNER_OUTPUT_FILE%
"%{cc}" /scanDependencies %DEPS_SCANNER_OUTPUT_FILE% /TP %*
55 changes: 51 additions & 4 deletions cc/private/toolchain/windows_cc_toolchain_config.bzl
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@
# limitations under the License.
"""A Starlark cc_toolchain configuration rule for Windows"""

load("@bazel_features//private:util.bzl", "ge")
load("@rules_cc//cc:action_names.bzl", "ACTION_NAMES")
load(
"@rules_cc//cc:cc_toolchain_config_lib.bzl",
Expand Down Expand Up @@ -67,6 +68,19 @@ all_cpp_compile_actions = [
ACTION_NAMES.clif_match,
]

# Actions that must carry the MSVC runtime library flag (/MT or /MD). Module
# interface compiles (cpp*_module_compile/codegen) must receive the same CRT
# flag as importing TUs; otherwise cl.exe falls back to the static CRT for the
# module unit, and importing TUs get C5050 while the linker gets LNK4098.
msvcrt_compile_actions = [
ACTION_NAMES.c_compile,
ACTION_NAMES.cpp_compile,
ACTION_NAMES.cpp_module_compile,
ACTION_NAMES.cpp_module_codegen,
ACTION_NAMES.cpp20_module_compile,
ACTION_NAMES.cpp20_module_codegen,
]

preprocessor_compile_actions = [
ACTION_NAMES.c_compile,
ACTION_NAMES.cpp_compile,
Expand Down Expand Up @@ -102,6 +116,16 @@ lto_index_actions = [
ACTION_NAMES.lto_index_for_nodeps_dynamic_library,
]

def _cpp_module_extension(compiler):
"""Returns the BMI/CMI file extension for cpp_module artifact_name_pattern."""

# Bazel only allows the .ifc extension for cpp_module artifacts on
# Bazel 9.0.0 and later; older versions only accept .pcm. This mirrors
# the Unix toolchain, which selects .gcm for GCC on Bazel 9+.
if compiler == "msvc-cl" and ge("9.0.0"):
return ".ifc"
return ".pcm"

def _use_msvc_toolchain(ctx):
return ctx.attr.cpu in ["x64_windows", "arm64_windows"] and (ctx.attr.compiler == "msvc-cl" or ctx.attr.compiler == "clang-cl")

Expand Down Expand Up @@ -140,6 +164,11 @@ def _impl(ctx):
prefix = "",
extension = ".if.lib",
),
artifact_name_pattern(
category_name = "cpp_module",
prefix = "",
extension = _cpp_module_extension(ctx.attr.compiler),
),
]
else:
artifact_name_patterns = [
Expand Down Expand Up @@ -662,12 +691,12 @@ def _impl(ctx):
name = "static_link_msvcrt",
flag_sets = [
flag_set(
actions = [ACTION_NAMES.c_compile, ACTION_NAMES.cpp_compile],
actions = msvcrt_compile_actions,
flag_groups = [flag_group(flags = ["/MT"])],
with_features = [with_feature_set(not_features = ["dbg"])],
),
flag_set(
actions = [ACTION_NAMES.c_compile, ACTION_NAMES.cpp_compile],
actions = msvcrt_compile_actions,
flag_groups = [flag_group(flags = ["/MTd"])],
with_features = [with_feature_set(features = ["dbg"])],
),
Expand All @@ -689,12 +718,12 @@ def _impl(ctx):
enabled = True,
flag_sets = [
flag_set(
actions = [ACTION_NAMES.c_compile, ACTION_NAMES.cpp_compile],
actions = msvcrt_compile_actions,
flag_groups = [flag_group(flags = ["/MD"])],
with_features = [with_feature_set(not_features = ["dbg", "static_link_msvcrt"])],
),
flag_set(
actions = [ACTION_NAMES.c_compile, ACTION_NAMES.cpp_compile],
actions = msvcrt_compile_actions,
flag_groups = [flag_group(flags = ["/MDd"])],
with_features = [with_feature_set(features = ["dbg"], not_features = ["static_link_msvcrt"])],
),
Expand Down Expand Up @@ -1048,6 +1077,10 @@ def _impl(ctx):
ACTION_NAMES.cpp_compile,
ACTION_NAMES.cpp_header_parsing,
ACTION_NAMES.cpp_module_compile,
ACTION_NAMES.cpp_module_codegen,
ACTION_NAMES.cpp_module_deps_scanning,
ACTION_NAMES.cpp20_module_compile,
ACTION_NAMES.cpp20_module_codegen,
],
flag_groups = [
flag_group(
Expand Down Expand Up @@ -1203,6 +1236,20 @@ def _impl(ctx):
],
),
],
env_sets = [
env_set(
actions = [
ACTION_NAMES.cpp_module_deps_scanning,
],
env_entries = [
env_entry(
key = "DEPS_SCANNER_OUTPUT_FILE",
value = "%{output_file}",
expand_if_available = "output_file",
),
],
),
],
)

nologo_feature = feature(
Expand Down