Check for "$ENV{NIX_CC}", with quotes, not without #194929
Description
In this commit: 871cf9f#diff-ff2a2145cf58008275b3e5299c8bdcd31a88541c74f23127aa4f5468de69b80eR25, the code IS_DIRECTORY ${ENV(NIX_CC} checks the env var without quotes, which means an unset or empty variables can cause build errors, eg this one for the boring-sys Rust crate in a nix shell:
"IS_DIRECTORY" "AND" "EXISTS" "/nix-support/orig-libc" "AND" "EXISTS" "/nix-support/orig-libc-dev"
^
Nothing here, should have at least an empty string
I'm not sure it's missing quotes though, I don't know how CMake works in this situation, but since that looks like a bash-inspired syntax, I suppose it has bash-inspired bugs too
Full error:
running: "cmake" "[CARGO_HOME]/registry/src/github.com-1ecc6299db9ec823/boring-sys-2.1.0/deps/boringssl" "-G" "Ninja" "-DCMAKE_TOOLCHAIN_FILE=/nix/store/x25lgahqpdygym97i6kqcy82bif2f89n-macos.arm64.cmake" "-DCMAKE_INSTALL_PREFIX=[CWD]/target/aarch64-apple-darwin/debug/build/boring-sys-400f6fa962fd5ab3/out" "-DCMAKE_C_FLAGS= -ffunction-sections -fdata-sections -fPIC --target=arm64-apple-darwin" "-DCMAKE_CXX_FLAGS= -ffunction-sections -fdata-sections -fPIC --target=arm64-apple-darwin" "-DCMAKE_ASM_FLAGS= -ffunction-sections -fdata-sections -fPIC --target=arm64-apple-darwin" "-DCMAKE_BUILD_TYPE=Debug"
-- The C compiler identification is Clang 14.0.6
-- The CXX compiler identification is Clang 14.0.6
-- Configuring incomplete, errors occurred!
See also "[CWD]/target/aarch64-apple-darwin/debug/build/boring-sys-400f6fa962fd5ab3/out/build/CMakeFiles/CMakeOutput.log".
--- stderr
CMake Error at /nix/store/dz5jcmsfmi4hi6lkajvdfcv8g9dcnvds-cmake-3.24.1/share/cmake-3.24/Modules/Platform/UnixPaths.cmake:51 (if):
if given arguments:
"IS_DIRECTORY" "AND" "EXISTS" "/nix-support/orig-libc" "AND" "EXISTS" "/nix-support/orig-libc-dev"
Unknown arguments specified
Call Stack (most recent call first):
/nix/store/dz5jcmsfmi4hi6lkajvdfcv8g9dcnvds-cmake-3.24.1/share/cmake-3.24/Modules/Platform/Darwin.cmake:241 (include)
/nix/store/dz5jcmsfmi4hi6lkajvdfcv8g9dcnvds-cmake-3.24.1/share/cmake-3.24/Modules/CMakeSystemSpecificInformation.cmake:37 (include)
CMakeLists.txt:9 (project)
thread 'main' panicked at '
command did not execute successfully, got: exit status: 1
build script failed, must exit now', [CARGO_HOME]/registry/src/github.com-1ecc6299db9ec823/cmake-0.1.48/src/lib.rs:975:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Temporary workaround:
Set NIX_CC to garbage, like /does-not-exists, and it will build and run correctly