Why does the C++ STL mix tabs and spaces?

[BrandonPacewic]

When looking at the source code for STL containers like vector I realized that most of the formatting makes no sense to me. It appears that the indent width of class functions is 6 spaces. Then once inside the function it switches to 1 tab? Then for anything nested inside that function it adds 2 spaces?

This causes some problems in my editor where it looks like the first items nested in a class function
have no indentation at all. So why is this done?

[miscco]

That looks like libstdc++ code.

This is MSVC stl and the code here looks much different

[StephanTLavavej]

Yep. In fact, we have automated validation that rejects tabs in virtually all files (see

STL/tools/validate/validate.cpp

Lines 227 to 229 in 313aa59

	static constexpr array tabby_filenames{
	L".gitmodules"sv,
	};

for the current lone exception).

We converted from tabs to spaces in VS 2019 16.0, when we switched to clang-formatting everything.

[BrandonPacewic]

Looking again I realized that this is only true for the GNU ISO C++ Library. I suppose that my question would then be why does GNU do this? But yes the MSVC STL does not do this. My apologies for not realizing that I was looking at the wrong library.

[miscco]

This forum is only about MSVC stl. Moreover, all maintainers are explicitly forbidden to even look at libstdc++ source code due to lisencing issues.

So it would be nice if you would both remove the snippet in question and pose the question in their mailing list