clang-format: C++17 deduction guides are wrongly formatted

[mkurdej]

Bugzilla Link	35518
Resolution	FIXED
Resolved on	Nov 06, 2019 08:16
Version	trunk
OS	Windows NT
CC	@mkurdej,@elvenfighter,@lichray,@mydeveloperday
Fixed by commit(s)	76ec6b1

Extended Description

The following snippet:

template <class... Ts>
S(Ts...) -> S<Ts...>;

is formatted to:

template <class... Ts>
S(Ts...)->S<Ts...>;

Which seems to me to be wrong as the spaces are missing around -> (arrow operator).

Version: trunk from 2017-11-22.

[lichray]

Please prioritize this, this is harmful.

https://github.com/taocpp/PEGTL/blob/54e4c0e8835b07e90245edc65d679696020d1921/include/tao/pegtl/argv_input.hpp#L46-L47

[elvenfighter]

This should be consistent with spaces around arrow in the trailing return type declarations.

So, for example this snippet (newlines to force formatting):

template
S(T)
->
S;

auto f(int, int)
->
double;

By running clang-format -style=llvm test.hpp produces the following:

template S(T)->S;

auto f(int, int) -> double;

I.e. it is inconsistent, and as of now (LLVM-10, git master) there is no way to directly influence the behavior for user-defined template deduction guidelines.

[mydeveloperday]

Tentative revision https://reviews.llvm.org/D69577

[mydeveloperday]

Please help review your own bugs. Adding all as reviewers.

[mydeveloperday]

Landed in trunk, November 6th 2019

https://reviews.llvm.org/rG76ec6b1ef69fcbd27cb0d587a5eb2d51a135a6bb