Building rustc without using the system defaults

[marcbowes]

There are use-cases where one might want to build rustc from source without having the build process use the default system gcc/glibc.

Right now, I can't see a way to achieve this with a flag. One possible solution is to create a wrapper script for the stage0 rustc which calls the real stage0 rustc with --link-args, --linker and so forth.

The reason I don't like this is it essentially involves a prebuild/patch step - these are usually quite brittle and difficult to maintain.

A possible future solution might be to have some env var, STAGE0_FLAGS or similar, which one could export before running make.

/cc @cmr

[marcbowes]

I'm attempting:

export PATH="$PATH_THAT_ONLY_INCLUDES_TOOLS_YOU_WANT_TO_USE"
export RUSTFLAGS="--linker-args -L $LIBRARIES_YOU_WANT_RUSTC_TO_BE_LINKED_TO"`
VERBOSE=1 make

.. based on feedback in IRC - will update once I know if it works or not.

[alexcrichton]

Closing, the recent changes to the configure script and the makefiles should allow for the standard CC and friends environment variables to configure the build process. If some support is still missing, however, feel free to reopen!