Add //cc/libc config settings for C standard libraries (#792) Adds a new `//cc/libc` package with `config_setting`s for common C standard libraries, fed by a new `libc_flag` rule that exposes the current CC toolchain's `target_libc` value to `select()`. This mirrors the existing `//cc/compiler` package for compilers. Covered libcs: `glibc`, `musl`, `uclibc`, `bionic`, `macosx` (Apple's libSystem, using the historical value set by toolchains for all Apple platforms), `freebsd`, `netbsd`, `openbsd`, `msvcrt`, `ucrt`, `msys`, `newlib`, `picolibc`, `llvm-libc`, and `wasi-libc`. Toolchains not shipped with Bazel are encouraged to use the same canonical names. Since Bazel documents `target_libc` as "the libc version string (e.g. `glibc-2.2.2`)", `libc_flag` strips a version suffix (everything from the first `-` followed by a digit) before matching, so versioned values still match their family's setting while names like `wasi-libc` and `llvm-libc` are preserved. The following changes make the new constraints usable: * the auto-configured Unix toolchain detects the default libc via preprocessor macros and `-dumpmachine` * the `target_libc` values emitted by the bundled Windows and BSD toolchain configs are changed to the correct values * rule-based `cc_toolchain`s can declare their `target_libc` or fall back to a reasonable default Closes #792 COPYBARA_INTEGRATE_REVIEW=https://github.com/bazelbuild/rules_cc/pull/792 from fmeum:libc-settings 7215a9ced75b2d01816d25b87e76c8387b0eee34 PiperOrigin-RevId: 970542238 Change-Id: Id569a70de73fc51ca8c69ca74169b8ba44cdc1bf
diff --git a/cc/libc/BUILD b/cc/libc/BUILD new file mode 100644 index 0000000..71fdfee --- /dev/null +++ b/cc/libc/BUILD
@@ -0,0 +1,168 @@ +# Copyright 2026 The Bazel Authors. All rights reserved. +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +"""Config settings for C standard libraries identified by Bazel. + +Targets that require libc-specific flags can use the config_settings defined in +this package in their select() statements. + +Toolchains not shipped with Bazel are encouraged to use the same names to +identify C standard libraries as used below, but this is not enforced. A +toolchain's `target_libc` value may carry a semantic version suffix in the form +(e.g. "glibc-2.31"), which is ignored when matching the config settings below. + +Example: + + cc_binary( + name = "foo", + srcs = ["foo.cc"], + copts = select({ + "//cc/libc:glibc": [...], + "//cc/libc:musl": [...], + "//cc/libc:ucrt": [...], + # Fallback case for an undetected C standard library. + "//conditions:default": [...], + }), + ) + +If multiple targets use the same set of conditionally enabled flags, this can be +simplified by extracting the select expression into a Starlark constant. +""" + +load("//cc/toolchains:libc_flag.bzl", "libc_flag") + +package(default_visibility = ["//visibility:public"]) + +licenses(["notice"]) + +libc_flag(name = "libc") + +### Linux + +# The GNU C Library (https://www.gnu.org/software/libc/). +config_setting( + name = "glibc", + flag_values = {":libc": "glibc"}, +) + +# musl libc (https://musl.libc.org). Also used by Emscripten and, in the form +# of the derived wasi-libc, by WASI toolchains. +config_setting( + name = "musl", + flag_values = {":libc": "musl"}, +) + +# uClibc and its successor uClibc-ng (https://uclibc-ng.org). +config_setting( + name = "uclibc", + flag_values = {":libc": "uclibc"}, +) + +### Android + +# Bionic, the C standard library of Android +# (https://android.googlesource.com/platform/bionic/). +config_setting( + name = "bionic", + flag_values = {":libc": "bionic"}, +) + +### Apple + +# On Apple platforms, the C standard library is provided by libSystem. For +# historical reasons, toolchains identify it via the value "macosx" on all +# Apple platforms, not just macOS. +config_setting( + name = "macosx", + flag_values = {":libc": "macosx"}, +) + +### BSDs + +# The C standard libraries developed as part of the respective BSD operating +# system. +config_setting( + name = "freebsd", + flag_values = {":libc": "freebsd"}, +) + +config_setting( + name = "netbsd", + flag_values = {":libc": "netbsd"}, +) + +config_setting( + name = "openbsd", + flag_values = {":libc": "openbsd"}, +) + +### Windows + +# The legacy Microsoft Visual C++ Runtime (msvcrt.dll), which is also targeted +# by MinGW-w64 toolchains by default. +config_setting( + name = "msvcrt", + flag_values = {":libc": "msvcrt"}, +) + +# The Universal C Runtime (ucrtbase.dll), used by MSVC and clang-cl as well as +# the UCRT flavor of MinGW-w64 toolchains. +config_setting( + name = "ucrt", + flag_values = {":libc": "ucrt"}, +) + +# The MSYS2 runtime (msys-2.0.dll), a Cygwin-derived POSIX emulation layer +# targeted by MSYS2's gcc. +config_setting( + name = "msys", + flag_values = {":libc": "msys"}, +) + +### Embedded + +# Newlib (https://sourceware.org/newlib/), commonly used by bare-metal +# toolchains such as arm-none-eabi-gcc. +config_setting( + name = "newlib", + flag_values = {":libc": "newlib"}, +) + +# Picolibc (https://github.com/picolibc/picolibc). +config_setting( + name = "picolibc", + flag_values = {":libc": "picolibc"}, +) + +# LLVM libc (https://libc.llvm.org). +config_setting( + name = "llvm-libc", + flag_values = {":libc": "llvm-libc"}, +) + +### WebAssembly + +# wasi-libc (https://github.com/WebAssembly/wasi-libc), the musl-derived C +# standard library of WASI SDK toolchains. +config_setting( + name = "wasi-libc", + flag_values = {":libc": "wasi-libc"}, +) + +### Generic + +config_setting( + name = "none", + flag_values = {":libc": "none"}, +)
diff --git a/cc/private/toolchain/BUILD.windows.tpl b/cc/private/toolchain/BUILD.windows.tpl index afbc00d..4ce9022 100644 --- a/cc/private/toolchain/BUILD.windows.tpl +++ b/cc/private/toolchain/BUILD.windows.tpl
@@ -218,7 +218,7 @@ compiler = "mingw-gcc", host_system_name = "local", target_system_name = "local", - target_libc = "mingw", + target_libc = "msvcrt", abi_version = "local", abi_libc_version = "local", tool_bin_path = "%{mingw_tool_bin_path}", @@ -267,7 +267,7 @@ compiler = "mingw-gcc", host_system_name = "local", target_system_name = "local", - target_libc = "mingw", + target_libc = "msvcrt", abi_version = "local", abi_libc_version = "local", tool_bin_path = "%{mingw_tool_bin_path}", @@ -318,7 +318,7 @@ compiler = "msvc-cl", host_system_name = "local", target_system_name = "local", - target_libc = "msvcrt", + target_libc = "ucrt", abi_version = "local", abi_libc_version = "local", toolchain_identifier = "msvc_x64", @@ -393,7 +393,7 @@ compiler = "msvc-cl", host_system_name = "local", target_system_name = "local", - target_libc = "msvcrt", + target_libc = "ucrt", abi_version = "local", abi_libc_version = "local", toolchain_identifier = "msvc_x64_x86", @@ -468,7 +468,7 @@ compiler = "msvc-cl", host_system_name = "local", target_system_name = "local", - target_libc = "msvcrt", + target_libc = "ucrt", abi_version = "local", abi_libc_version = "local", toolchain_identifier = "msvc_x64_arm", @@ -543,7 +543,7 @@ compiler = "msvc-cl", host_system_name = "local", target_system_name = "local", - target_libc = "msvcrt", + target_libc = "ucrt", abi_version = "local", abi_libc_version = "local", toolchain_identifier = "msvc_arm64", @@ -618,7 +618,7 @@ compiler = "clang-cl", host_system_name = "local", target_system_name = "local", - target_libc = "msvcrt", + target_libc = "ucrt", abi_version = "local", abi_libc_version = "local", toolchain_identifier = "clang_cl_x64", @@ -691,7 +691,7 @@ compiler = "clang-cl", host_system_name = "local", target_system_name = "aarch64-pc-windows-msvc", - target_libc = "msvcrt", + target_libc = "ucrt", abi_version = "local", abi_libc_version = "local", toolchain_identifier = "clang_cl_arm64",
diff --git a/cc/private/toolchain/armeabi_cc_toolchain_config.bzl b/cc/private/toolchain/armeabi_cc_toolchain_config.bzl index b35e43f..30cb09f 100644 --- a/cc/private/toolchain/armeabi_cc_toolchain_config.bzl +++ b/cc/private/toolchain/armeabi_cc_toolchain_config.bzl
@@ -26,7 +26,7 @@ host_system_name = "armeabi-v7a" target_system_name = "armeabi-v7a" target_cpu = "armeabi-v7a" - target_libc = "armeabi-v7a" + target_libc = "unknown" compiler = "compiler" abi_version = "armeabi-v7a" abi_libc_version = "armeabi-v7a"
diff --git a/cc/private/toolchain/bsd_cc_toolchain_config.bzl b/cc/private/toolchain/bsd_cc_toolchain_config.bzl index 83b9313..ced21ba 100644 --- a/cc/private/toolchain/bsd_cc_toolchain_config.bzl +++ b/cc/private/toolchain/bsd_cc_toolchain_config.bzl
@@ -62,7 +62,7 @@ toolchain_identifier = "local_{}".format(cpu) if is_bsd else "stub_armeabi-v7a" host_system_name = "local" if is_bsd else "armeabi-v7a" target_system_name = "local" if is_bsd else "armeabi-v7a" - target_libc = "local" if is_bsd else "armeabi-v7a" + target_libc = cpu if is_bsd else "unknown" abi_version = "local" if is_bsd else "armeabi-v7a" abi_libc_version = "local" if is_bsd else "armeabi-v7a"
diff --git a/cc/private/toolchain/empty_cc_toolchain_config.bzl b/cc/private/toolchain/empty_cc_toolchain_config.bzl index 5b2e49c..f5ca6fe 100644 --- a/cc/private/toolchain/empty_cc_toolchain_config.bzl +++ b/cc/private/toolchain/empty_cc_toolchain_config.bzl
@@ -26,7 +26,7 @@ host_system_name = "local", target_system_name = "local", target_cpu = "local", - target_libc = "local", + target_libc = "unknown", compiler = "compiler", abi_version = "local", abi_libc_version = "local",
diff --git a/cc/private/toolchain/unix_cc_configure.bzl b/cc/private/toolchain/unix_cc_configure.bzl index a1bbd83..283ef0b 100644 --- a/cc/private/toolchain/unix_cc_configure.bzl +++ b/cc/private/toolchain/unix_cc_configure.bzl
@@ -59,6 +59,58 @@ return path[len(repo_root):] return path +def _get_target_libc(repository_ctx, cc, darwin, compile_opts): + """Detect the C standard library targeted by the compiler. + + Returns one of the canonical names used by the config_settings in + @rules_cc//cc/libc if the C standard library is recognized and "unknown" + otherwise. Can be overridden via the BAZEL_TARGET_LIBC environment + variable. + + Args: + repository_ctx: The repository context. + cc: Path of the compiler. + darwin: Whether the target platform is macOS. + compile_opts: User-configured C compile flags, which may affect the + targeted libc (e.g. via --sysroot or --target). + """ + if darwin: + return "macosx" + libc = get_env_var(repository_ctx, "BAZEL_TARGET_LIBC", "", False) + if libc: + return escape_string(libc) + + # Preprocessing any standard library header defines macros that identify + # most implementations. + repository_ctx.file("tools/cpp/detect_libc.c", "#include <string.h>\n") + result = repository_ctx.execute([cc] + compile_opts + ["-E", "-dM", "tools/cpp/detect_libc.c"]) + if result.return_code == 0: + for macro, libc in [ + # uClibc also defines __GLIBC__ for compatibility, so check for it + # first. + ("__UCLIBC__", "uclibc"), + ("__GLIBC__", "glibc"), + ("__BIONIC__", "bionic"), + ("__LLVM_LIBC__", "llvm-libc"), + ("__FreeBSD__", "freebsd"), + ("__NetBSD__", "netbsd"), + ("__OpenBSD__", "openbsd"), + ]: + if ("#define %s " % macro) in result.stdout: + return libc + + # musl intentionally doesn't define an identifying macro, but is usually + # mentioned in the compiler's target triple. + result = repository_ctx.execute([cc] + compile_opts + ["-dumpmachine"]) + if result.return_code == 0: + triple = result.stdout.strip() + if "musl" in triple: + return "musl" + if "android" in triple: + return "bionic" + + return "unknown" + def _find_tool(repository_ctx, tool, overridden_tools): """Find a tool for repository, taking overridden tools into account.""" if tool in overridden_tools: @@ -772,12 +824,7 @@ cpu_value, False, )), - "%{target_libc}": "macosx" if darwin else escape_string(get_env_var( - repository_ctx, - "BAZEL_TARGET_LIBC", - "local", - False, - )), + "%{target_libc}": _get_target_libc(repository_ctx, cc, darwin, all_compile_opts + conly_opts), "%{target_system_name}": escape_string(get_env_var( repository_ctx, "BAZEL_TARGET_SYSTEM",
diff --git a/cc/toolchains/impl/libc_version.bzl b/cc/toolchains/impl/libc_version.bzl new file mode 100644 index 0000000..c3f8ef6 --- /dev/null +++ b/cc/toolchains/impl/libc_version.bzl
@@ -0,0 +1,34 @@ +# Copyright 2026 The Bazel Authors. All rights reserved. +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +"""Helper function for parsing target_libc values.""" + +visibility([ + "//cc/toolchains", + "//tests/libc_settings", +]) + +def libc_without_version(libc): + """Strips a version suffix from a target_libc value. + + Args: + libc: (str) The value of cc_toolchain.libc. + + Returns: + The name of the C standard library without a version suffix. + """ + for i in range(1, len(libc) - 1): + if libc[i] == "-" and libc[i + 1].isdigit(): + return libc[:i] + return libc
diff --git a/cc/toolchains/libc_flag.bzl b/cc/toolchains/libc_flag.bzl new file mode 100644 index 0000000..e06db80 --- /dev/null +++ b/cc/toolchains/libc_flag.bzl
@@ -0,0 +1,28 @@ +# Copyright 2026 The Bazel Authors. All rights reserved. +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +"""Rule that allows select() to differentiate between C standard libraries.""" + +load("//cc:find_cc_toolchain.bzl", "CC_TOOLCHAIN_ATTRS", "find_cpp_toolchain", "use_cc_toolchain") +load("//cc/toolchains/impl:libc_version.bzl", "libc_without_version") + +def _libc_flag_impl(ctx): + toolchain = find_cpp_toolchain(ctx) + return [config_common.FeatureFlagInfo(value = libc_without_version(toolchain.libc))] + +libc_flag = rule( + implementation = _libc_flag_impl, + attrs = CC_TOOLCHAIN_ATTRS, + toolchains = use_cc_toolchain(), +)
diff --git a/cc/toolchains/toolchain.bzl b/cc/toolchains/toolchain.bzl index 0c9ab94..1202040 100644 --- a/cc/toolchains/toolchain.bzl +++ b/cc/toolchains/toolchain.bzl
@@ -53,6 +53,7 @@ supports_param_files = False, compiler = "", cpu = "", + target_libc = None, target_system_name = None, **kwargs): """A C/C++ toolchain configuration. @@ -151,6 +152,11 @@ through the `target_cpu` attribute of the toolchain configuration. We should not add new readers of this value, but there are many existing ones in the wild. + target_libc: (str) The name of the C standard library targeted by this toolchain + (e.g. "glibc", "musl"), optionally followed by a version suffix (e.g. + "glibc-2.2.2"). The current toolchain's C standard library is exposed to + `select()` statements via the config settings in `@rules_cc//cc/libc`. If not provided, + a best effort default is selected. target_system_name: (str) The target system name for this toolchain. Bazel doesn't use this but starlark rules can read this value through `toolchain_info.target_gnu_system_name`. This string is commonly the target triple you would pass to `clang -target` (e.g. "x86_64-unknown-linux-gnu"). @@ -175,8 +181,10 @@ "//conditions:default": "", }) - target_libc = select({ + target_libc = target_libc or select({ Label("//cc/settings:apple_constraint"): "macosx", + Label("@platforms//os:linux"): "glibc", + Label("@platforms//os:windows"): "ucrt", "//conditions:default": "", })
diff --git a/docs/toolchain_api.md b/docs/toolchain_api.md index 6e2fb70..bd03ee9 100644 --- a/docs/toolchain_api.md +++ b/docs/toolchain_api.md
@@ -795,7 +795,7 @@ cc_toolchain(*, <a href="#cc_toolchain-name">name</a>, <a href="#cc_toolchain-tool_map">tool_map</a>, <a href="#cc_toolchain-args">args</a>, <a href="#cc_toolchain-artifact_name_patterns">artifact_name_patterns</a>, <a href="#cc_toolchain-make_variables">make_variables</a>, <a href="#cc_toolchain-legacy_tools">legacy_tools</a>, <a href="#cc_toolchain-known_features">known_features</a>, <a href="#cc_toolchain-enabled_features">enabled_features</a>, <a href="#cc_toolchain-grep_includes">grep_includes</a>, <a href="#cc_toolchain-libc_top">libc_top</a>, <a href="#cc_toolchain-module_map">module_map</a>, <a href="#cc_toolchain-dynamic_runtime_lib">dynamic_runtime_lib</a>, <a href="#cc_toolchain-static_runtime_lib">static_runtime_lib</a>, <a href="#cc_toolchain-supports_header_parsing">supports_header_parsing</a>, <a href="#cc_toolchain-supports_param_files">supports_param_files</a>, - <a href="#cc_toolchain-compiler">compiler</a>, <a href="#cc_toolchain-cpu">cpu</a>, <a href="#cc_toolchain-target_system_name">target_system_name</a>, <a href="#cc_toolchain-kwargs">**kwargs</a>) + <a href="#cc_toolchain-compiler">compiler</a>, <a href="#cc_toolchain-cpu">cpu</a>, <a href="#cc_toolchain-target_libc">target_libc</a>, <a href="#cc_toolchain-target_system_name">target_system_name</a>, <a href="#cc_toolchain-kwargs">**kwargs</a>) </pre> A C/C++ toolchain configuration. @@ -860,6 +860,7 @@ | <a id="cc_toolchain-supports_param_files"></a>supports_param_files | (bool) Whether or not this toolchain supports linking via param files. See [`cc_toolchain.supports_param_files`](https://bazel.build/reference/be/c-cpp#cc_toolchain.supports_param_files) for more information. | `False` | | <a id="cc_toolchain-compiler"></a>compiler | (str) The type of compiler used by this toolchain (e.g. "gcc", "clang"). The current toolchain's compiler is exposed to `@rules_cc//cc/private/toolchain:compiler (compiler_flag)` as a flag value. | `""` | | <a id="cc_toolchain-cpu"></a>cpu | (str) DEPRECATED: CPU string (ex: "darwin_arm64", "k8") exposed through the `target_cpu` attribute of the toolchain configuration. We should not add new readers of this value, but there are many existing ones in the wild. | `""` | +| <a id="cc_toolchain-target_libc"></a>target_libc | (str) The name of the C standard library targeted by this toolchain (e.g. "glibc", "musl"), optionally followed by a version suffix (e.g. "glibc-2.2.2"). The current toolchain's C standard library is exposed to `select()` statements via the config settings in `@rules_cc//cc/libc`. If not provided, a best effort default is selected. | `None` | | <a id="cc_toolchain-target_system_name"></a>target_system_name | (str) The target system name for this toolchain. Bazel doesn't use this but starlark rules can read this value through `toolchain_info.target_gnu_system_name`. This string is commonly the target triple you would pass to `clang -target` (e.g. "x86_64-unknown-linux-gnu"). If not provided, a best effort default is selected. | `None` | | <a id="cc_toolchain-kwargs"></a>kwargs | [common attributes](https://bazel.build/reference/be/common-definitions#common-attributes) that should be applied to all rules created by this macro. | none |
diff --git a/tests/builtins_bzl/cc/cc_static_library/test/mock_toolchain.bzl b/tests/builtins_bzl/cc/cc_static_library/test/mock_toolchain.bzl index 5aa1201..58b3c01 100644 --- a/tests/builtins_bzl/cc/cc_static_library/test/mock_toolchain.bzl +++ b/tests/builtins_bzl/cc/cc_static_library/test/mock_toolchain.bzl
@@ -100,7 +100,7 @@ host_system_name = "local", target_system_name = "local", target_cpu = "local", - target_libc = "local", + target_libc = "unknown", compiler = "compiler", )
diff --git a/tests/cc/testutil/toolchains/BUILD b/tests/cc/testutil/toolchains/BUILD index 45dd6af..2ca081c 100644 --- a/tests/cc/testutil/toolchains/BUILD +++ b/tests/cc/testutil/toolchains/BUILD
@@ -311,7 +311,7 @@ feature_names = [], host_system_name = "local", make_variables = {}, - target_libc = "local", + target_libc = "glibc", target_system_name = "local", tool_paths = {}, toolchain_identifier = "mock-toolchain-k8",
diff --git a/tests/cc/testutil/toolchains/cc_toolchain_config.bzl b/tests/cc/testutil/toolchains/cc_toolchain_config.bzl index 894e0fb..74bbc04 100644 --- a/tests/cc/testutil/toolchains/cc_toolchain_config.bzl +++ b/tests/cc/testutil/toolchains/cc_toolchain_config.bzl
@@ -2135,7 +2135,7 @@ "toolchain_identifier": attr.string(default = "mock-llvm-toolchain-k8"), "host_system_name": attr.string(default = "local"), "target_system_name": attr.string(default = "local"), - "target_libc": attr.string(default = "local"), + "target_libc": attr.string(default = "unknown"), "abi_version": attr.string(default = "local"), "abi_libc_version": attr.string(default = "local"), "feature_names": attr.string_list(),
diff --git a/tests/libc_settings/BUILD b/tests/libc_settings/BUILD new file mode 100644 index 0000000..a2f263b --- /dev/null +++ b/tests/libc_settings/BUILD
@@ -0,0 +1,37 @@ +# Copyright 2026 The Bazel Authors. All rights reserved. +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +load("//cc:cc_binary.bzl", "cc_binary") +load(":libc_flag_test.bzl", "libc_flag_test_suite") + +licenses(["notice"]) + +libc_flag_test_suite(name = "libc_flag_tests") + +cc_binary( + name = "main", + srcs = ["main.cc"], + local_defines = select( + { + "//cc/libc:bionic": ["LIBC=bionic"], + "//cc/libc:glibc": ["LIBC=glibc"], + "//cc/libc:macosx": ["LIBC=macosx"], + "//cc/libc:msvcrt": ["LIBC=msvcrt"], + "//cc/libc:msys": ["LIBC=msys"], + "//cc/libc:musl": ["LIBC=musl"], + "//cc/libc:ucrt": ["LIBC=ucrt"], + "//conditions:default": [], + }, + ), +)
diff --git a/tests/libc_settings/libc_flag_test.bzl b/tests/libc_settings/libc_flag_test.bzl new file mode 100644 index 0000000..2ad1703 --- /dev/null +++ b/tests/libc_settings/libc_flag_test.bzl
@@ -0,0 +1,52 @@ +# Copyright 2026 The Bazel Authors. All rights reserved. +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +"""Unit tests for libc_without_version()""" + +load("@bazel_skylib//lib:unittest.bzl", "asserts", "unittest") +load("//cc/toolchains/impl:libc_version.bzl", "libc_without_version") + +def _libc_without_version_impl(ctx): + env = unittest.begin(ctx) + + # Unversioned values are returned unchanged. + asserts.equals(env, "glibc", libc_without_version("glibc")) + asserts.equals(env, "macosx", libc_without_version("macosx")) + asserts.equals(env, "unknown", libc_without_version("unknown")) + asserts.equals(env, "", libc_without_version("")) + + # Version suffixes in the "glibc-2.2.2" format documented for + # cc_common.create_cc_toolchain_config_info are stripped. + asserts.equals(env, "glibc", libc_without_version("glibc-2.2.2")) + asserts.equals(env, "glibc", libc_without_version("glibc-2")) + asserts.equals(env, "musl", libc_without_version("musl-1.2.4")) + asserts.equals(env, "newlib", libc_without_version("newlib-4.3.0.20230120")) + + # A "-" followed by a non-digit is part of the name, not a version suffix. + asserts.equals(env, "wasi-libc", libc_without_version("wasi-libc")) + asserts.equals(env, "llvm-libc", libc_without_version("llvm-libc")) + asserts.equals(env, "wasi-libc", libc_without_version("wasi-libc-25")) + + # A trailing "-" is not a version suffix. + asserts.equals(env, "glibc-", libc_without_version("glibc-")) + + return unittest.end(env) + +libc_without_version_test = unittest.make(_libc_without_version_impl) + +def libc_flag_test_suite(name): + unittest.suite( + name, + libc_without_version_test, + )
diff --git a/tests/libc_settings/main.cc b/tests/libc_settings/main.cc new file mode 100644 index 0000000..ee5b1bf --- /dev/null +++ b/tests/libc_settings/main.cc
@@ -0,0 +1,22 @@ +// Copyright 2026 The Bazel Authors. All rights reserved. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +#include <iostream> + +#define STRINGIFY(x) #x +#define TO_STRING(x) STRINGIFY(x) + +int main() { + std::cout << "Hello, " << TO_STRING(LIBC) << "!" << std::endl; +}