Rust multiple crates fail to compile due to permission denied - rust

Question

When I build a project with dependencies, the build script fails with permission denied. This dosent happen with every crate. Here is the output from when trying to build a WGPU project.
error: failed to run custom build command for `objc_exception v0.1.2`
Caused by:
process didn't exit successfully: `/Users/64001830/wgpu-test/target/debug/build/objc_exception-f7c40ee498546635/build-script-build` (exit status: 1)
--- stdout
TARGET = Some("x86_64-apple-darwin")
OPT_LEVEL = Some("0")
HOST = Some("x86_64-apple-darwin")
cargo:rerun-if-env-changed=CC_x86_64-apple-darwin
CC_x86_64-apple-darwin = None
cargo:rerun-if-env-changed=CC_x86_64_apple_darwin
CC_x86_64_apple_darwin = None
cargo:rerun-if-env-changed=HOST_CC
HOST_CC = None
cargo:rerun-if-env-changed=CC
CC = Some("/usr/bin/")
cargo:rerun-if-env-changed=CFLAGS_x86_64-apple-darwin
CFLAGS_x86_64-apple-darwin = None
cargo:rerun-if-env-changed=CFLAGS_x86_64_apple_darwin
CFLAGS_x86_64_apple_darwin = None
cargo:rerun-if-env-changed=HOST_CFLAGS
HOST_CFLAGS = None
cargo:rerun-if-env-changed=CFLAGS
CFLAGS = None
cargo:rerun-if-env-changed=CRATE_CC_NO_DEFAULTS
CRATE_CC_NO_DEFAULTS = None
DEBUG = Some("true")
CARGO_CFG_TARGET_FEATURE = Some("cmpxchg16b,fxsr,llvm14-builtins-abi,sse,sse2,sse3,ssse3")
running: "/usr/bin/" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-gdwarf-2" "-fno-omit-frame-pointer" "-m64" "-arch" "x86_64" "-Wall" "-Wextra" "-o" "/Users/64001830/wgpu-test/target/debug/build/objc_exception-59a44c9c89f7e2b5/out/extern/exception.o" "-c" "extern/exception.m"
--- stderr
error occurred: Command "/usr/bin/" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-gdwarf-2" "-fno-omit-frame-pointer" "-m64" "-arch" "x86_64" "-Wall" "-Wextra" "-o" "/Users/64001830/wgpu-test/target/debug/build/objc_exception-59a44c9c89f7e2b5/out/extern/exception.o" "-c" "extern/exception.m" with args "bin" failed to start: Os { code: 13, kind: PermissionDenied, message: "Permission denied" }
Ive tried restarting, new projects, uninstalling and reinstalling rust.

Answer 1

From the error (specifically this line: CC = Some("/usr/bin/")) you can see that the C compiler environment variable (CC) is set to /usr/bin/ which is not a valid C compiler.
You can either clear the environment variable or set it to something useful like /usr/bin/cc, /usr/bin/gcc or the path to your C compiler of choice.