[build] Patch rules_cc to recognize cc as gcc

CMakeLists.txt

@@ -288,26 +288,29 @@ if(NOT PYTHON_VERSION_MAJOR_MINOR VERSION_EQUAL SUPPORTED_PYTHON_VERSION)
   )
 endif()
 
+# We need to run Bazel in a dedicated temporary directory. The particular
+# name `drake_build_cwd` isn't important, it just needs to be unique. Note,
+# however, that the macOS wheel builds also need to know this path, so if it
+# ever changes, tools/wheel/macos/build-wheel.sh will also need to be updated.
+set(DRAKE_BAZEL_BUILD_DIR "${CMAKE_BINARY_DIR}/drake_build_cwd")
+file(MAKE_DIRECTORY "${DRAKE_BAZEL_BUILD_DIR}")
+
 set(BAZEL_REPO_ENV)
 
+# Put this patch where `cmake/MODULE.bazel.in` expects it during its call to
+# `single_version_override`.
+file(CREATE_LINK
+  "${PROJECT_SOURCE_DIR}/tools/workspace/rules_cc/patches/upstream/cc-as-gcc.patch"
+  "${DRAKE_BAZEL_BUILD_DIR}/cc-as-gcc.patch"
+  SYMBOLIC
+)
 if(NOT APPLE)
+  # N.B. Bazel does its own compiler-chasing with Xcode, which we shouldn't
+  # interfere with here.
   string(APPEND BAZEL_REPO_ENV
     " --repo_env=CC=${CMAKE_C_COMPILER}"
     " --repo_env=CXX=${CMAKE_CXX_COMPILER}"
   )
-  # Pass a Bazel flag which enforces the underlying compiler so that
-  # compiler- and version-specific logic (e.g., warnings) is enforced in the
-  # build, since rules_cc's support for compiler identification is not as
-  # robust as using CMake's CMAKE_<LANG>_COMPILER_ID.
-  if(CMAKE_C_COMPILER_ID STREQUAL Clang)
-    string(APPEND BAZEL_REPO_ENV
-      " --@drake//tools/cc_toolchain:compiler=clang"
-    )
-  elseif(CMAKE_C_COMPILER_ID STREQUAL GNU)
-    string(APPEND BAZEL_REPO_ENV
-      " --@drake//tools/cc_toolchain:compiler=gcc"
-    )
-  endif()
 endif()
 
 get_filename_component(PROJECT_BINARY_DIR_REALPATH
@@ -815,15 +818,11 @@ foreach(import IN LISTS BAZELRC_IMPORTS)
   string(APPEND BAZELRC_IMPORT "import ${PROJECT_SOURCE_DIR}/${import}\n")
 endforeach()
 
-# We need to run Bazel in a dedicated temporary directory. The particular
-# name `drake_build_cwd` isn't important, it just needs to be unique. Note,
-# however, that the macOS wheel builds also need to know this path, so if it
-# ever changes, tools/wheel/macos/build-wheel.sh will also need to be updated.
-configure_file(cmake/bazel.rc.in drake_build_cwd/.bazelrc @ONLY)
-configure_file(cmake/MODULE.bazel.in drake_build_cwd/MODULE.bazel @ONLY)
-configure_file(cmake/BUILD.bazel.in drake_build_cwd/BUILD.bazel @ONLY)
-file(CREATE_LINK "${PROJECT_SOURCE_DIR}/.bazeliskrc" drake_build_cwd/.bazeliskrc SYMBOLIC)
-file(CREATE_LINK "${PROJECT_SOURCE_DIR}/.bazelversion" drake_build_cwd/.bazelversion SYMBOLIC)
+configure_file(cmake/bazel.rc.in "${DRAKE_BAZEL_BUILD_DIR}/.bazelrc" @ONLY)
+configure_file(cmake/MODULE.bazel.in "${DRAKE_BAZEL_BUILD_DIR}/MODULE.bazel" @ONLY)
+configure_file(cmake/BUILD.bazel.in "${DRAKE_BAZEL_BUILD_DIR}/BUILD.bazel" @ONLY)
+file(CREATE_LINK "${PROJECT_SOURCE_DIR}/.bazeliskrc" "${DRAKE_BAZEL_BUILD_DIR}/.bazeliskrc" SYMBOLIC)
+file(CREATE_LINK "${PROJECT_SOURCE_DIR}/.bazelversion" "${DRAKE_BAZEL_BUILD_DIR}/.bazelversion" SYMBOLIC)
 
 find_package(Git)
 
@@ -851,7 +850,7 @@ add_custom_target(drake_version ALL
 
 add_custom_target(drake_install ALL
   COMMAND "${Bazel_EXECUTABLE}" build ${BAZEL_INSTALL_TARGET}
-  WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/drake_build_cwd"
+  WORKING_DIRECTORY "${DRAKE_BAZEL_BUILD_DIR}"
   USES_TERMINAL
 )
 add_dependencies(drake_install drake_version)
@@ -861,7 +860,7 @@ install(CODE
     COMMAND
       \"${Bazel_EXECUTABLE}\" run ${BAZEL_INSTALL_TARGET}
       -- ${BAZEL_INSTALL_ARGS}
-    WORKING_DIRECTORY \"${CMAKE_CURRENT_BINARY_DIR}/drake_build_cwd\"
+    WORKING_DIRECTORY \"${DRAKE_BAZEL_BUILD_DIR}\"
   )"
   ALL_COMPONENTS
 )

MODULE.bazel

@@ -24,6 +24,13 @@ bazel_dep(name = "rules_python", version = "1.6.3")  # Keep this in sync with cm
 bazel_dep(name = "rules_rust", version = "0.67.0")
 bazel_dep(name = "rules_shell", version = "0.6.1")
 
+single_version_override(
+    module_name = "rules_cc",
+    patches = [
+        "@drake//tools/workspace/rules_cc:patches/upstream/cc-as-gcc.patch",
+    ],
+)
+
 # Customize our toolchains.
 
 cc_configure = use_extension(

cmake/MODULE.bazel.in

@@ -24,3 +24,8 @@ python_repository(
 )
 
 register_toolchains("@python//:all")
+
+single_version_override(
+    module_name = "rules_cc",
+    patches = ["//:cc-as-gcc.patch"],
+)

tools/cc_toolchain/BUILD.bazel

@@ -26,28 +26,16 @@ string_flag(
     ],
 )
 
-# In our developer builds and CMake installs, we use the following two flags
-# as optional hints for configuring compiler warnings. It's not strictly
-# necessary to set these, but doing so will tweak the compiler flags and
-# reduce warning spam during the build.
+# In our developer builds and CMake installs, we use the following flag as
+# an optional hint for configuring compiler warnings. It's not strictly
+# necessary to set, but doing so will tweak the compiler flags and reduce
+# warning spam during the build.
 #
-# These are intended for internal use only, not for users to configure.
+# This is intended for internal use only, not for users to configure.
 #
-# TODO(jwnimmer-tri) Ideally, rules_cc would provide,
-# * for 'compiler', a check for the real underlying compiler by invoking it
-#   (akin to CMake) instead of just parsing the filename; and
-# * for 'compiler_major', some toolchain attribute that we could query.
-# Neither of these seem to exist yet.
-string_flag(
-    name = "compiler",
-    build_setting_default = "",
-    values = [
-        "",
-        "gcc",
-        "clang",
-    ],
-)
-
+# TODO(jwnimmer-tri) Ideally, rules_cc would provide some toolchain attribute
+# that we could query for the version of the compiler, but that doesn't seem to
+# exist yet.
 int_flag(
     name = "compiler_major",
     build_setting_default = 0,
@@ -73,37 +61,11 @@ config_setting(
     flag_values = {":error_severity": "error"},
 )
 
-config_setting(
-    name = "compiler_clang",
-    flag_values = {":compiler": "clang"},
-)
-
-config_setting(
-    name = "compiler_gcc",
-    flag_values = {":compiler": "gcc"},
-)
-
-selects.config_setting_group(
-    name = "clang",
-    match_any = [
-        "@rules_cc//cc/compiler:clang",
-        ":compiler_clang",
-    ],
-)
-
-selects.config_setting_group(
-    name = "gcc",
-    match_any = [
-        "@rules_cc//cc/compiler:gcc",
-        ":compiler_gcc",
-    ],
-)
-
 selects.config_setting_group(
     name = "apple_clang_with_warnings",
     match_all = [
         ":apple",
-        ":clang",
+        "@rules_cc//cc/compiler:clang",
         ":error_severity_warning",
     ],
 )
@@ -112,23 +74,23 @@ selects.config_setting_group(
     name = "apple_clang_with_errors",
     match_all = [
         ":apple",
-        ":clang",
+        "@rules_cc//cc/compiler:clang",
         ":error_severity_error",
     ],
 )
 
 selects.config_setting_group(
     name = "gcc_with_warnings",
     match_all = [
-        ":gcc",
+        "@rules_cc//cc/compiler:gcc",
         ":error_severity_warning",
     ],
 )
 
 selects.config_setting_group(
     name = "gcc_with_errors",
     match_all = [
-        ":gcc",
+        "@rules_cc//cc/compiler:gcc",
         ":error_severity_error",
     ],
 )
@@ -137,7 +99,7 @@ selects.config_setting_group(
     name = "linux_clang_with_warnings",
     match_all = [
         ":linux",
-        ":clang",
+        "@rules_cc//cc/compiler:clang",
         ":error_severity_warning",
     ],
 )
@@ -146,7 +108,7 @@ selects.config_setting_group(
     name = "linux_clang_with_errors",
     match_all = [
         ":linux",
-        ":clang",
+        "@rules_cc//cc/compiler:clang",
         ":error_severity_error",
     ],
 )
@@ -191,7 +153,7 @@ config_setting(
 selects.config_setting_group(
     name = "gcc_13_with_warnings",
     match_all = [
-        ":gcc",
+        "@rules_cc//cc/compiler:gcc",
         ":compiler_major_13",
         ":error_severity_warning",
     ],
@@ -200,7 +162,7 @@ selects.config_setting_group(
 selects.config_setting_group(
     name = "gcc_13_with_errors",
     match_all = [
-        ":gcc",
+        "@rules_cc//cc/compiler:gcc",
         ":compiler_major_13",
         ":error_severity_error",
     ],

tools/skylark/drake_cc.bzl

@@ -141,8 +141,8 @@ def _platform_copts(rule_copts, rule_gcc_copts, rule_clang_copts, cc_test = 0):
     test_gcc_copts = (CC_TEST_FLAGS + GCC_CC_TEST_FLAGS) if cc_test else []
     test_clang_copts = CC_TEST_FLAGS if cc_test else []
     return BASE_COPTS + rule_copts + select({
-        "//tools/cc_toolchain:gcc": rule_gcc_copts + test_gcc_copts,
-        "//tools/cc_toolchain:clang": rule_clang_copts + test_clang_copts,
+        "@rules_cc//cc/compiler:gcc": rule_gcc_copts + test_gcc_copts,
+        "@rules_cc//cc/compiler:clang": rule_clang_copts + test_clang_copts,
         "//conditions:default": [],
     })
 

tools/skylark/pybind.bzl

@@ -5,7 +5,7 @@ load("//tools/skylark:drake_py.bzl", "drake_py_library", "drake_py_test")
 load("//tools/skylark:py.bzl", "py_library")
 
 EXTRA_PYBIND_COPTS = select({
-    "@drake//tools/cc_toolchain:clang": [
+    "@rules_cc//cc/compiler:clang": [
         # GCC and Clang don't always agree / succeed when inferring storage
         # duration (#9600). Workaround it for now.
         "-Wno-unused-lambda-capture",

tools/workspace/rules_cc/BUILD.bazel

@@ -0,0 +1,3 @@
+load("//tools/lint:lint.bzl", "add_lint_tests")
+
+add_lint_tests()

tools/workspace/rules_cc/patches/upstream/cc-as-gcc.patch

@@ -0,0 +1,19 @@
+[rules_cc] Recognize CC as GCC when applicable
+
+Running `cc -v` when CC is really GCC under the hood will still print GCC
+information, similar to the logic with Clang immediately above.
+
+--- cc/private/toolchain/unix_cc_configure.bzl
++++ cc/private/toolchain/unix_cc_configure.bzl
+@@ -273,10 +273,7 @@ def _is_clang(repository_ctx, cc):
+     return "clang" in repository_ctx.execute([cc, "-v"]).stderr
+
+ def _is_gcc(repository_ctx, cc):
+-    # GCC's version output uses the basename of argv[0] as the program name:
+-    # https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/gcc.cc;h=158461167951c1b9540322fb19be6a89d6da07fc;hb=HEAD#l8728
+-    cc_stdout = repository_ctx.execute([cc, "--version"]).stdout
+-    return cc_stdout.startswith("gcc ") or cc_stdout.startswith("gcc-")
++    return "gcc version " in repository_ctx.execute([cc, "-v"]).stderr.split('\n')[-2]
+
+ def _get_compiler_name(repository_ctx, cc):
+     if _is_clang(repository_ctx, cc):