[clang-format] Feature Request: FloatingPointLiteralSeparator

[xhrnca00]

Clang-format already has an IntegerLiteralSeparator option that adds separators to integer literals. When I started using it, it confused me there was no alternative for floating point literals.

It would be great to either:

1. Add a new option called FloatingPointLiteralSeparator, which would do the same as its integer alternative, only for floating point literals.
2. Expand the existing IntegerLiteralSeparator to apply the formatting to floating point literals.

I was imagining something like:

# .clang-format
FloatingPointLiteralSeparator:
  Decimal: 3
  DecimalMinDigits: 5
  Hex: 4
  HexMinDigits: 5

The resulting format could look like this:

// Before
double decimal = 12345678.12345678e-50;
double hexa = 0x1234567.89abcdfp-100;

// After
double decimal = 12'345'678.123'456'78e-50;
double hexa = 0x123'4567.89ab'cdfp-100;

[llvmbot]

@llvm/issue-subscribers-clang-format

Author: Adam (xhrnca00)

Clang-format already has an `IntegerLiteralSeparator` option that adds separators to integer literals. When I started using it, it confused me there was no alternative for floating point literals.

It would be great to either:

1. Add a new option called FloatingPointLiteralSeparator, which would do the same as its integer alternative, only for floating point literals.
2. Expand the existing IntegerLiteralSeparator to apply the formatting to floating point literals.

I was imagining something like:

# .clang-format
FloatingPointLiteralSeparator:
  Decimal: 3
  DecimalMinDigits: 5
  Hex: 4
  HexMinDigits: 5

The resulting format could look like this:

// Before
double decimal = 12345678.12345678e-50;
double hexa = 0x1234567.89abcdfp-100;

// After
double decimal = 12'345'678.123'456'78e-50;
double hexa = 0x123'4567.89ab'cdfp-100;