Feature request: Two different indentation width options, one for code, one for pre-processor directives

[hartwork]

Bugzilla Link	42919
Version	unspecified
OS	All
CC	@claudiusaiz

Extended Description

It seems like option "IndentWidth" effects both C/C++ code indentation width as well as pre-processor indentation width. What I have seen a few times is that pre-processor indentation uses a single space per level while the C/C++ code in the same file uses 2 or 4 spaces. "IndentWidth" seems to affect both widths which also means that pre-processor code will look very noise when "IndentWidth" is more than 2.

So it would be great to have two options, "IndentWidth" and a new one "IndentWidthPP"(?), thinking of existing "IndentPPDirectives".

Would that be possible?

Thanks in advance!

[MaskRay]

The feature will be useful for compiler-rt and glibc (https://sourceware.org/pipermail/libc-alpha/2022-March/137362.html).

[hartwork]

Update: Controlling preprocessor indentation separately is apparently possible since clang-format 13, the key related options are:

• PPIndentWidth
• IndentPPDirectives

The defaults seem to be:

$ clang-format --version
clang-format version 21.1.1

$ clang-format --dump-config | grep 'IndentPPDirectives\|PPIndentWidth'
IndentPPDirectives: None
PPIndentWidth:   -1

Before adjusting config:

$ clang-format -i demo.c && cat demo.c
#if 1
// PPIndentWidth rules here:
#if 0
#error Dead code here
#endif
#endif

int main(void) {
  // IndentWidth rules here:
  return 0; //
}

With custom indentation:

$ clang-format -style='{IndentWidth: 4, PPIndentWidth: 2, IndentPPDirectives: AfterHash}' -i demo.c && cat demo.c 
#if 1
// PPIndentWidth rules here:
#  if 0
#    error Dead code here
#  endif
#endif

int main(void) {
    // IndentWidth rules here:
    return 0; //
}

I'll be closing this as fixed…