[coroutines] Fix application of NRVO to Coroutine "Gro" or return object.
Summary:
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.
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 `BuildReturnStmt` marks the Gro variable as a coroutine candidate.
Reviewers: rsmith, GorNishanov, nicholas
Reviewed By: GorNishanov
Subscribers: majnemer, cfe-commits
Differential Revision: https://reviews.llvm.org/D42343
llvm-svn: 324037
diff --git a/clang/lib/Sema/SemaCoroutine.cpp b/clang/lib/Sema/SemaCoroutine.cpp
index f05a94e..67c8b9b 100644
--- a/clang/lib/Sema/SemaCoroutine.cpp
+++ b/clang/lib/Sema/SemaCoroutine.cpp
@@ -1316,10 +1316,6 @@
if (Res.isInvalid())
return false;
- if (GroType == FnRetType) {
- GroDecl->setNRVOVariable(true);
- }
-
S.AddInitializerToDecl(GroDecl, Res.get(),
/*DirectInit=*/false);
@@ -1343,6 +1339,8 @@
noteMemberDeclaredHere(S, ReturnValue, Fn);
return false;
}
+ if (cast<clang::ReturnStmt>(ReturnStmt.get())->getNRVOCandidate() == GroDecl)
+ GroDecl->setNRVOVariable(true);
this->ReturnStmt = ReturnStmt.get();
return true;