Hermetic toolchain tries to use host libraries.

[turmanticant]

When I try to use the hermetic toolchain I get complication errors that originate from libraries from my host distribution instead of using the hermetic libraries. Am I holding it wrong, or is this a bug?

Error

The /usr/bin... path is the host library path.

clang: warning: CUDA version is newer than the latest partially supported version 12.8 [-Wunknown-cuda-version]
In file included from <built-in>:1:
/usr/bin/../lib/clang/21/include/__clang_cuda_runtime_wrapper.h:388:10: fatal error: 'texture_fetch_functions.h' file not found
  388 | #include "texture_fetch_functions.h"
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated when compiling for sm_52.
Use --verbose_failures to see the command lines of failed build steps.

Reproduction

git clone https://github.com/bazel-contrib/rules_cuda.git .
cd examples

I modified the examples MODULE.bazel to point to the latest version of rules_cude, and set the redist toolchain.

diff --git a/examples/MODULE.bazel b/examples/MODULE.bazel
index 0a8becc..47297d7 100644
--- a/examples/MODULE.bazel
+++ b/examples/MODULE.bazel
@@ -4,16 +4,12 @@ module(
     compatibility_level = 1,
 )

-bazel_dep(name = "rules_cuda", version = "0.2.3")
-local_path_override(
-    module_name = "rules_cuda",
-    path = "..",
-)
+bazel_dep(name = "rules_cuda", version = "0.3.0")

 cuda = use_extension("@rules_cuda//cuda:extensions.bzl", "toolchain")
-cuda.toolkit(
-    name = "cuda",
-    toolkit_path = "",
+cuda.redist_json(
+    name = "rules_cuda_redist_json",
+    version = "12.6.3",
 )
 use_repo(cuda, "cuda")

Running one of the tests triggers the error.

bazel test //basic_macros/... --config clang

Host Env

$ uname -a
Linux phobos 7.0.11-100.fc43.x86_64 #1 SMP PREEMPT_DYNAMIC Mon Jun  1 22:51:40 UTC 2026 x86_64 GNU/Linux
$ bazel --version
bazel 9.1.1

[cloudhan]

examples/ are not configured for hermetic toolchain and libraries, they always use locally install ctk and toolchain.

See https://github.com/bazel-contrib/rules_cuda/blob/249c9e897b6c5f29adba8a2195abadc21b4f771c/tests/integration/toolchain_redist_json_multi/MODULE.bazel for a hermetic config.

[turmanticant]

I have seen those tests, and based my hermetic config on them. I modified the examples to use the hermitc toolchain (see the diff in OP) to get a more complex example (more like what I am doing in my own monorepo) as a simple reproduction.

The problem still exists.

[cloudhan]

/usr/bin indicate you are using a non-hermetic clang. Hermetic toolchain in this repo only handles ctk only. The hermetic llvm is a separate concern, you need some other rules to help you with the hermetic clang toolchain.

[AustinSchuh]

If you are looking for an example, RealtimeRoboticsGroup/aos@9232536 uses toolchains_llvm + rules_cuda to create a fully hermetic clang + cuda setup. It properly handles those cuda clang includes. That implements both host builds + cross compilation.