experimenting

cuda/private/rules/cuda_library.bzl

@@ -1,10 +1,10 @@
-load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "find_cpp_toolchain")
-load("//cuda/private:cuda_helper.bzl", "cuda_helper")
-load("//cuda/private:providers.bzl", "CudaInfo")
-load("//cuda/private:toolchain.bzl", "find_cuda_toolchain", "use_cpp_toolchain", "use_cuda_toolchain")
+load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "find_cpp_toolchain", "use_cpp_toolchain")
 load("//cuda/private:actions/compile.bzl", "compile")
 load("//cuda/private:actions/dlink.bzl", "device_link")
+load("//cuda/private:cuda_helper.bzl", "cuda_helper")
+load("//cuda/private:providers.bzl", "CudaInfo")
 load("//cuda/private:rules/common.bzl", "ALLOW_CUDA_HDRS", "ALLOW_CUDA_SRCS")
+load("//cuda/private:toolchain.bzl", "find_cuda_toolchain", "use_cuda_toolchain")
 
 def _cuda_library_impl(ctx):
     """cuda_library is a rule that perform device link.
@@ -175,6 +175,6 @@ cuda_library = rule(
         "_default_cuda_archs": attr.label(default = "//cuda:archs"),
     },
     fragments = ["cpp"],
-    toolchains = use_cpp_toolchain() + use_cuda_toolchain(),
+    toolchains = use_cpp_toolchain(mandatory = True) + use_cuda_toolchain(),
     provides = [DefaultInfo, OutputGroupInfo, CcInfo, CudaInfo],
 )

cuda/private/rules/cuda_objects.bzl

@@ -1,9 +1,9 @@
-load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "find_cpp_toolchain")
+load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "find_cpp_toolchain", "use_cpp_toolchain")
+load("//cuda/private:actions/compile.bzl", "compile")
 load("//cuda/private:cuda_helper.bzl", "cuda_helper")
 load("//cuda/private:providers.bzl", "CudaInfo")
-load("//cuda/private:toolchain.bzl", "find_cuda_toolchain", "use_cpp_toolchain", "use_cuda_toolchain")
-load("//cuda/private:actions/compile.bzl", "compile")
 load("//cuda/private:rules/common.bzl", "ALLOW_CUDA_HDRS", "ALLOW_CUDA_SRCS")
+load("//cuda/private:toolchain.bzl", "find_cuda_toolchain", "use_cuda_toolchain")
 
 def _cuda_objects_impl(ctx):
     attr = ctx.attr
@@ -110,6 +110,6 @@ code and device link time optimization source files.""",
         "_default_cuda_archs": attr.label(default = "//cuda:archs"),
     },
     fragments = ["cpp"],
-    toolchains = use_cpp_toolchain() + use_cuda_toolchain(),
+    toolchains = use_cpp_toolchain(mandatory = True) + use_cuda_toolchain(),
     provides = [DefaultInfo, OutputGroupInfo, CcInfo, CudaInfo],
 )

cuda/private/toolchain.bzl

@@ -42,15 +42,6 @@ cuda_toolchain = rule(
 CPP_TOOLCHAIN_TYPE = "@bazel_tools//tools/cpp:toolchain_type"
 CUDA_TOOLCHAIN_TYPE = "//cuda:toolchain_type"
 
-# buildifier: disable=unused-variable
-def use_cpp_toolchain(mandatory = True):
-    """Helper to depend on the C++ toolchain.
-
-    Notes:
-        Copied from [toolchain_utils.bzl](https://github.com/bazelbuild/bazel/blob/ac48e65f70/tools/cpp/toolchain_utils.bzl#L53-L72)
-    """
-    return [CPP_TOOLCHAIN_TYPE]
-
 def use_cuda_toolchain():
     """Helper to depend on the CUDA toolchain."""
     return [CUDA_TOOLCHAIN_TYPE]

cuda/private/toolchain_configs/clang.bzl

@@ -1,10 +1,9 @@
 load("@bazel_skylib//lib:paths.bzl", "paths")
 load("@bazel_tools//tools/build_defs/cc:action_names.bzl", CC_ACTION_NAMES = "ACTION_NAMES")
-load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "find_cpp_toolchain")
+load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "find_cpp_toolchain", "use_cpp_toolchain")
 load("//cuda/private:action_names.bzl", "ACTION_NAMES")
 load("//cuda/private:artifact_categories.bzl", "ARTIFACT_CATEGORIES")
 load("//cuda/private:providers.bzl", "CudaToolchainConfigInfo", "CudaToolkitInfo")
-load("//cuda/private:toolchain.bzl", "use_cpp_toolchain")
 load(
     "//cuda/private:toolchain_config_lib.bzl",
     "action_config",
@@ -516,5 +515,5 @@ cuda_toolchain_config = rule(
         "_cc_toolchain": attr.label(default = "@bazel_tools//tools/cpp:current_cc_toolchain"),  # legacy behaviour
     },
     provides = [CudaToolchainConfigInfo],
-    toolchains = use_cpp_toolchain(),
+    toolchains = use_cpp_toolchain(mandatory = True),
 )

cuda/private/toolchain_configs/nvcc.bzl

@@ -1,10 +1,9 @@
 load("@bazel_skylib//lib:paths.bzl", "paths")
 load("@bazel_tools//tools/build_defs/cc:action_names.bzl", CC_ACTION_NAMES = "ACTION_NAMES")
-load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "find_cpp_toolchain")
+load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "find_cpp_toolchain", "use_cpp_toolchain")
 load("//cuda/private:action_names.bzl", "ACTION_NAMES")
 load("//cuda/private:artifact_categories.bzl", "ARTIFACT_CATEGORIES")
 load("//cuda/private:providers.bzl", "CudaToolchainConfigInfo", "CudaToolkitInfo")
-load("//cuda/private:toolchain.bzl", "use_cpp_toolchain")
 load(
     "//cuda/private:toolchain_config_lib.bzl",
     "action_config",
@@ -526,5 +525,5 @@ cuda_toolchain_config = rule(
         "_cc_toolchain": attr.label(default = "@bazel_tools//tools/cpp:current_cc_toolchain"),  # legacy behaviour
     },
     provides = [CudaToolchainConfigInfo],
-    toolchains = use_cpp_toolchain(),
+    toolchains = use_cpp_toolchain(mandatory = True),
 )

cuda/private/toolchain_configs/nvcc_msvc.bzl

@@ -1,10 +1,9 @@
 load("@bazel_skylib//lib:paths.bzl", "paths")
 load("@bazel_tools//tools/build_defs/cc:action_names.bzl", CC_ACTION_NAMES = "ACTION_NAMES")
-load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "find_cpp_toolchain")
+load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "find_cpp_toolchain", "use_cpp_toolchain")
 load("//cuda/private:action_names.bzl", "ACTION_NAMES")
 load("//cuda/private:artifact_categories.bzl", "ARTIFACT_CATEGORIES")
 load("//cuda/private:providers.bzl", "CudaToolchainConfigInfo", "CudaToolkitInfo")
-load("//cuda/private:toolchain.bzl", "use_cpp_toolchain")
 load(
     "//cuda/private:toolchain_config_lib.bzl",
     "action_config",
@@ -614,5 +613,5 @@ cuda_toolchain_config = rule(
         "_cc_toolchain": attr.label(default = "@bazel_tools//tools/cpp:current_cc_toolchain"),  # legacy behaviour
     },
     provides = [CudaToolchainConfigInfo],
-    toolchains = use_cpp_toolchain(),
+    toolchains = use_cpp_toolchain(mandatory = True),
 )

docs/developer_docs.bzl

@@ -1,25 +1,23 @@
-load("@rules_cuda//cuda/private:cuda_helper.bzl", _cuda_helper = "cuda_helper")
 load("@rules_cuda//cuda/private:actions/compile.bzl", _compile = "compile")
 load("@rules_cuda//cuda/private:actions/dlink.bzl", _device_link = "device_link")
-load(
-    "@rules_cuda//cuda/private:toolchain.bzl",
-    _find_cuda_toolchain = "find_cuda_toolchain",
-    _find_cuda_toolkit = "find_cuda_toolkit",
-    _use_cpp_toolchain = "use_cpp_toolchain",
-    _use_cuda_toolchain = "use_cuda_toolchain",
-)
-load("@rules_cuda//cuda/private:toolchain_config_lib.bzl", _config_helper = "config_helper")
+load("@rules_cuda//cuda/private:cuda_helper.bzl", _cuda_helper = "cuda_helper")
 load(
     "@rules_cuda//cuda/private:repositories.bzl",
     _config_clang = "config_clang",
     _config_cuda_toolkit_and_nvcc = "config_cuda_toolkit_and_nvcc",
     _detect_clang = "detect_clang",
     _detect_cuda_toolkit = "detect_cuda_toolkit",
 )
+load(
+    "@rules_cuda//cuda/private:toolchain.bzl",
+    _find_cuda_toolchain = "find_cuda_toolchain",
+    _find_cuda_toolkit = "find_cuda_toolkit",
+    _use_cuda_toolchain = "use_cuda_toolchain",
+)
+load("@rules_cuda//cuda/private:toolchain_config_lib.bzl", _config_helper = "config_helper")
 
 # create a struct to group toolchain symbols semantically
 toolchain = struct(
-    use_cpp_toolchain = _use_cpp_toolchain,
     use_cuda_toolchain = _use_cuda_toolchain,
     find_cuda_toolchain = _find_cuda_toolchain,
     find_cuda_toolkit = _find_cuda_toolkit,