adding static and dynamic ZigEquivalent enums so that zig cc can force static or dynamic linking.

[cod1r]

When adding the flag -dynamic, zig cc would still statically link by default because link_mode was set to null.

Adding the ZigEquivalent enums static and dynamic allows us to branch properly to set link_mode when we iterate over the arguments passed into ClangArgIterator when arg_mode is equivalent to .cc.

This should close#11909.

Documentation used: Clang CLI Reference and zig's source code.

[kubkon]

Thanks for this change! In order to land this, we need to fix how changes to src/clang_options_data.zig are generated which actually happens automatically via running the tool tools/update_clang_options.zig. Have a look at the review comments and lemme know if that makes sense to you!

[cod1r]

apologies for the messy commits. there are a lot of git features I have yet to use. I think I made the right changes in the right files like you asked. if not, I'll be happy to do more. :)

[andrewrk]

Reverted in 4f9345d.

[andrewrk]

This change may have been correct as is. If so, it exposed a bug in LLVM's cmake configuration which incorrectly adds -static to the CXX flags on Windows when doing -DLLVM_BUILD_STATIC=ON.

However, even if this is the case, more investigation is needed. An upstream bug report needs to be created, and we need a workaround so that zig-bootstrap continues to work.

Another possibility is that the -static flag of C compilers does not influence whether the resulting binary is statically linked, but rather influences what search paths -l arguments look for, i.e., it would make -lfoo only look for libfoo.a. On Windows, this could still be an import lib, and the executable is still dynamically linked. This would mean that setting link_mode, as done in this PR, would be incorrect.