[PATCH] D42343: [coroutines] Fix application of NRVO to Coroutine "Gro" or return object.

[Eric Fiselier via Phabricator via cfe-commits]

EricWF created this revision.
EricWF added reviewers: rsmith, GorNishanov, nicholas.

Fix NRVO for Gro variable.

      

Previously, we only marked the GRO declaration as an NRVO variable
when its QualType and the function return's QualType matched exactly
(using operator==). However, this was incorrect for two reasons:

1. We were marking non-class types, such as ints, as being NRVO variables.

This was incorrect.

2. We failed to  handle cases where the canonical types were the same, but

the actual `QualType` objects were different. For example, if  one was represented by a typedef.
(Example: https://godbolt.org/g/3UFgsL)

This patch fixes these bugs by marking the Gro variable as supporting NRVO only
when `Sema::isCopyElisionCandidate` is true.


https://reviews.llvm.org/D42343

Files:
  lib/Sema/SemaCoroutine.cpp
  test/CodeGenCoroutines/coro-alloc.cpp
  test/CodeGenCoroutines/coro-gro-nrvo.cpp

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