If RUST_LIB_SRC is defined in the top-level Makefile (via an environment variable or command line), it is already exported. The only situation where it is defined but not exported is when the top-level Makefile is wrapped by another Makefile (e.g., GNUmakefile). I cannot think of any other use cases. I know some people use this tip to define custom variables. However, even in that case, you can export it directly in the wrapper Makefile. Example GNUmakefile: export RUST_LIB_SRC = /path/to/your/sysroot/lib/rustlib/src/rust/library include Makefile Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx> --- This code was added by this commit: https://github.com/Rust-for-Linux/linux/commit/3f46885dc03ed2d750085b2237078a1628323964 Please me know if I am missing something. Makefile | 4 ---- 1 file changed, 4 deletions(-) diff --git a/Makefile b/Makefile index d57cfc6896b8..b194b7702a2e 100644 --- a/Makefile +++ b/Makefile @@ -578,10 +578,6 @@ else RUSTC_OR_CLIPPY = $(RUSTC) endif -ifdef RUST_LIB_SRC - export RUST_LIB_SRC -endif - # Allows the usage of unstable features in stable compilers. export RUSTC_BOOTSTRAP := 1 -- 2.43.0