[RFC] Improve newlib source code compatibility with LLVM clang

Hello,

LLVM Embedded Toolchain for Arm [1] uses newlib as one of libraries for embedded development, with a lot of interest from users. Unfortunately, newlib cannot be built with LLVM clang out-of-box, because of minor source code issues, so the project has to maintain a rather big patch [2] on top of newlib.

Most of the issues are in the assembly syntax, straightforward to fix in a way to be supported by both GCC and clang.

We want to share a series of small patches to update the syntax to improve compatibility with both compilers. I will send individual patches to the mail list as separate emails for further discussion.

Note that if there is interest from the newlib community, we would be happy to setup a CI that would try to build latest version of newlib to show if any new incompatibilities are introduced, however we would not have time to fix all of them in timely manner as our focus is on LLVM development.

References:

  1.  https://github.com/ARM-software/LLVM-embedded-toolchain-for-Arm
  2.  https://github.com/ARM-software/LLVM-embedded-toolchain-for-Arm/blob/main/patches/newlib/0001-Enable-newlib-build.patch

Sincerely,

Volodymyr Turanskyy | Principal Software Engineer | CE SW LLVM Team