[drahnr]

Fall back to the environment passed to NVCC when dry-run output omits PATH, while preserving explicit dry-run overrides. Return executable lookup errors instead of panicking when PATH is absent.

nvcc --version
nvcc: NVIDIA (R) Cuda compiler driver
Copyright (c) 2005-2026 NVIDIA Corporation
Built on Mon_Aug_03_13:24:11_PDT_2026
Cuda compilation tools, release 13.4, V13.4.59
Build cuda_13.4.r13.4/compiler.38657139_0

/usr/bin/nvcc --dryrun --keep -c tests/test_a.cu -o /tmp/sccache-nvcc-path-repro.o
#$ _NVVM_BRANCH_=nvvm
#$ _SPACE_=
#$ _CUDART_=cudart
#$ CUDA_ROOT=/usr
#$ _HERE_=/usr/bin
#$ _THERE_=/usr/bin
#$ _TARGET_SIZE_=
#$ _TARGET_DIR_=
#$ _TARGET_SIZE_=64
#$ CICC_PATH=/usr/bin
#$ NVVMIR_LIBRARY_DIR=/usr/nvvm/libdevice
#$ INCLUDES="-I/usr/include/cccl"
#$ LIBRARIES="-L/usr/lib64"
#$ CUDAFE_FLAGS=
#$ PTXAS_FLAGS=
#$ g++-15 -D__CUDA_ARCH_LIST__=750 -E -x c++ -D__CUDACC__ -D__NVCC__  "-I/usr/include/cccl"  -D__CUDACC_VER_MAJOR__=13 -D__CUDACC_VER_MINOR__=4 -D__CUDACC_VER_BUILD__=59 -D__CUDA_API_VER_MAJOR__=13 -D__CUDA_API_VER_MINOR__=4 -D__NVCC_DIAG_PRAGMA_SUPPORT__=1 -D__CUDACC_DEVICE_ATOMIC_BUILTINS__=1 -include "cuda_runtime.h" -m64 "tests/test_a.cu" -o "test_a.cpp4.ii"
#$ cudafe++ --c++17 --static-host-stub --device-hidden-visibility --gnu_version=150301 --display_error_number --orig_src_file_name "tests/test_a.cu" --orig_src_path_name "/media/humpback/projects/worktrees/sccache/zephyr-stone/sccache/tests/test_a.cu" --allow_managed  --m64 --parse_templates --gen_c_file_name "test_a.cudafe1.cpp" --stub_file_name "test_a.cudafe1.stub.c" --gen_module_id_file --module_id_file_name "test_a.module_id" --simt-only "test_a.cpp4.ii"
#$ g++-15 -D__CUDA_ARCH__=750 -D__CUDA_ARCH_LIST__=750 -E -x c++  -DCUDA_DOUBLE_MATH_FUNCTIONS -D__CUDACC__ -D__NVCC__  "-I/usr/include/cccl"  -D__CUDACC_VER_MAJOR__=13 -D__CUDACC_VER_MINOR__=4 -D__CUDACC_VER_BUILD__=59 -D__CUDA_API_VER_MAJOR__=13 -D__CUDA_API_VER_MINOR__=4 -D__NVCC_DIAG_PRAGMA_SUPPORT__=1 -D__CUDACC_DEVICE_ATOMIC_BUILTINS__=1 -include "cuda_runtime.h" -m64 "tests/test_a.cu" -o "test_a.cpp1.ii"
#$ "$CICC_PATH/cicc" --c++17 --static-host-stub --device-hidden-visibility --gnu_version=150301 --display_error_number --orig_src_file_name "tests/test_a.cu" --orig_src_path_name "/media/humpback/projects/worktrees/sccache/zephyr-stone/sccache/tests/test_a.cu" --allow_managed   -arch compute_75 -m64 --no-version-ident -ftz=0 -prec_div=1 -prec_sqrt=1 -fmad=1 --include_file_name "test_a.fatbin.c"  -tused --module_id_file_name "test_a.module_id" --gen_c_file_name "test_a.cudafe1.c" --stub_file_name "test_a.cudafe1.stub.c" --gen_device_file_name "test_a.cudafe1.gpu"  "test_a.cpp1.ii" --simt-only -o "test_a.ptx"
#$ ptxas -arch=sm_75 -m64  "test_a.ptx"  -o "test_a.sm_75.cubin"
#$ fatbinary --create="test_a.fatbin" -64 --cicc-cmdline="-ftz=0 -prec_div=1 -prec_sqrt=1 -fmad=1 " "--image3=kind=elf,sm=75,file=test_a.sm_75.cubin" "--image3=kind=ptx,sm=75,file=test_a.ptx" --embedded-fatbin="test_a.fatbin.c"
#$ g++-15 -D__CUDA_ARCH__=750 -D__CUDA_ARCH_LIST__=750 -c -x c++  -DCUDA_DOUBLE_MATH_FUNCTIONS -Wno-psabi "-I/usr/include/cccl" -m64 "test_a.cudafe1.cpp" -o "/tmp/sccache-nvcc-path-repro.o"

So the core issue is the missing $# PATH which is not present in all distributions, hence we also use the inherited_env_vars we (the sccache wrapper process) pass to the nvcc binary and also search that.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.84%. Comparing base (33d12fb) to head (0b3eadf).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3012      +/-   ##
==========================================
+ Coverage   78.81%   78.84%   +0.03%     
==========================================
  Files          75       75              
  Lines       45354    45433      +79     
==========================================
+ Hits        35745    35823      +78     
- Misses       9609     9610       +1     

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[Copilot]

🟡 Changes recommended

The case-sensitive PATH lookup ignores inherited Path on Windows, causing bare compiler names to remain unresolved when the dry run omits PATH.

1 open issue

• Resolve Windows PATH environment names case-insensitively · New

What changed in this PR

Updates NVCC dry-run parsing to support distributions that omit PATH assignments, using the environment passed to NVCC for executable lookup.

Changes:

• Falls back to inherited PATH while preserving explicit dry-run overrides.
• Returns executable lookup errors instead of panicking when PATH is absent.
• Adds tests for PATH fallback, override precedence, absolute executable paths, and missing-PATH errors.

File	Description
src/​compiler/​nvcc.rs	Updates subcommand executable lookup and adds regression tests.

_{Review effort: Balanced}