[clang-format] Allow excluding preproccesor directives from `IntegerLiteralSeparator`

[Alunderin]

Given the config

IntegerLiteralSeparator:
    Decimal:                3
    DecimalMinDigits:       5

all numbers, including numbers inside of preprocessor directives, will have separators inserted:

#if __cpp_constexpr >= 201'603L  // i.e 2016-03

I believe that there is a legitimate use-case for wanting directives to be left as-is, e.g. for feature testing (like above) or if someone wanted to use a C99 preprocessor for their C23/C++14 code.

---

I was thinking the option for it could look something like this:

IntegerLiteralSeparator:
    Decimal:                3
    DecimalMinDigits:       5
    PPDirectives:           true

One could also consider something more fine-grained like Always/Never/Leave, although I can't imagine that being very beneficial.

[llvmbot]

@llvm/issue-subscribers-clang-format

Author: None (Alunderin)

Given the config

IntegerLiteralSeparator:
    Decimal:                3
    DecimalMinDigits:       5

all numbers, including numbers inside of preprocessor directives, will have separators inserted:

#if __cpp_constexpr >= 201'603L  // i.e 2016-03

I believe that there is a legitimate use-case for wanting directives to be left as-is, e.g. for feature testing (like above) or if someone wanted to use a C99 preprocessor for their C23/C++14 code.

---

I was thinking the option for it could look something like this:

IntegerLiteralSeparator:
    Decimal:                3
    DecimalMinDigits:       5
    PPDirectives:           true

One could also consider something more fine-grained like Always/Never/Leave, although I can't imagine that being very beneficial.