tree a888c340baf297fa82b13a4511c2409de5697893
parent a99a3c6de1522cf420350f856368954338b6eba6
author Pavel Labath <pavel@labath.sk> 1547815923 +0000
committer Pavel Labath <pavel@labath.sk> 1547815923 +0000

[ADT] Add streaming operators for llvm::Optional

Summary:
The operators simply print the underlying value or "None".

The trickier part of this patch is making sure the streaming operators
work even in unit tests (which was my primary motivation, though I can
also see them being useful elsewhere). Since the stream operator was a
template, implicit conversions did not kick in, and our gtest glue code
was explicitly introducing an implicit conversion to make sure other
implicit conversions do not kick in :P. I resolve that by specializing
llvm_gtest::StreamSwitch for llvm:Optional<T>.

Reviewers: sammccall, dblaikie

Reviewed By: sammccall

Subscribers: mgorny, dexonsmith, kristina, llvm-commits

Differential Revision: https://reviews.llvm.org/D56795

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@351548 91177308-0d34-0410-b5e6-96231b3b80d8