fix: linux cross-build require CFLAGS_FOR_BUILD

[SolidFaker]

building bash-5.2 on linux leads to these errors, see this issue.

adding CFLAGS_FOR_BUILD := -std=gnu17 works for me.

[jiegec]

I think we should limit this CFLAGS to bash only. By the way, we use GCC 12(Clang 14.0.5) and the issue does not occur. So it is a requirement for GCC 13 or later?

[jiegec]

By the way, can you post the full error log, or reproduction environment?

[SolidFaker]

I think we should limit this CFLAGS to bash only. By the way, we use GCC 12(Clang 14.0.5) and the issue does not occur. So it is a requirement for GCC 13 or later?

yes, im compiling with GCC 15 on archlinux. but im not sure which version of gcc introduced this issue. based on the discussion in the issue linked by my PR, it has been present at least since GCC 13. P.S., the error log is exactly the same as the one in the issue (i found that issue directly through Google search :P

[jiegec]

I think we should limit this CFLAGS to bash only. By the way, we use GCC 12(Clang 14.0.5) and the issue does not occur. So it is a requirement for GCC 13 or later?

yes, im compiling with GCC 15 on archlinux. but im not sure which version of gcc introduced this issue. based on the discussion in the issue linked by my PR, it has been present at least since GCC 13. P.S., the error log is exactly the same as the one in the issue (i found that issue directly through Google search :P

However, aren't we using cross compilation toolchain (Clang 14.0.5) from HarmonyOS Command Line Tools?

[SolidFaker]

I think we should limit this CFLAGS to bash only. By the way, we use GCC 12(Clang 14.0.5) and the issue does not occur. So it is a requirement for GCC 13 or later?

yes, im compiling with GCC 15 on archlinux. but im not sure which version of gcc introduced this issue. based on the discussion in the issue linked by my PR, it has been present at least since GCC 13. P.S., the error log is exactly the same as the one in the issue (i found that issue directly through Google search :P

However, aren't we using cross compilation toolchain (Clang 14.0.5) from HarmonyOS Command Line Tools?

indeed, but when i run it here, it ends up using the system's gcc. i'll look into the cause and get back to you.

[jiegec]

I think I found the reason: mkbuiltin is a part of the build process: it builds and runs on the x86 machine to generate code for cross compilation.