clang-format does not remove spaces in front of `::`

[nico]

% cat format.cc 
void f() {
  A::    B    ::C d;
}

Actual:

% out/gn/bin/clang-format format.cc
void f() { A::B ::C d; }

Expected:

void f() { A::B::C d; }

(i.e. no space after ::B)

I suppose clang-format isn't sure if ::C is a qualified global symbol or a continuation of a qualified name (?) Is there ever a situation where a globally-qualified identifier follows an identifier? (That heuristic would get it wrong after templates, but it'd still be a progression.)

[llvmbot]

@llvm/issue-subscribers-clang-format

Author: Nico Weber (nico)

``` % cat format.cc void f() { A:: B ::C d; } ```

Actual:

% out/gn/bin/clang-format format.cc
void f() { A::B ::C d; }

Expected:

void f() { A::B::C d; }

(i.e. no space after ::B)

I suppose clang-format isn't sure if ::C is a qualified global symbol or a continuation of a qualified name (?) Is there ever a situation where a globally-qualified identifier follows an identifier? (That heuristic would get it wrong after templates, but it'd still be a progression.)

[nico]

Oh, I suppose A::B ::C() {} is a construct where keeping the space is actually correct, hmm! You'd have to scan past the parens (and possibly initializer lists) and see if there's a { or not to decide if you can remove the space. This is pretty tricky.

[nico]

Oh ,and even if there's no { but a ; that could be a function declaration (if there are parens after the A::B ::C)