efriedma added a comment.
Two points I'm not sure about in the current version:
- Handling MaterializeTemporaryExpr in ConstExprEmitter doesn't make sense;
ConstExprEmitter is not supposed to visit lvalues. (And I'm not sure what the
new check is supposed to do; `E->isGLValue()` is always true for a
MaterializeTemporaryExpr.) Maybe try something like the following?
diff --git a/clang/lib/CodeGen/CGExprConstant.cpp
b/clang/lib/CodeGen/CGExprConstant.cpp
index b0dd598..51cf69e 100644
--- a/clang/lib/CodeGen/CGExprConstant.cpp
+++ b/clang/lib/CodeGen/CGExprConstant.cpp
@@ -1215,11 +1215,6 @@ public:
return Visit(E->getSubExpr(), T);
}
- llvm::Constant *VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E,
- QualType T) {
- return Visit(E->getSubExpr(), T);
- }
-
llvm::Constant *EmitArrayInitialization(InitListExpr *ILE, QualType T) {
auto *CAT = CGM.getContext().getAsConstantArrayType(ILE->getType());
assert(CAT && "can't emit array init for non-constant-bound array");
@@ -1322,7 +1317,14 @@ public:
assert(CGM.getContext().hasSameUnqualifiedType(Ty, Arg->getType()) &&
"argument to copy ctor is of wrong type");
- return Visit(Arg, Ty);
+ if (auto *MTE = dyn_cast<MaterializeTemporaryExpr>(Arg)) {
+ // Look through the temporary; it's just converting the value to an
+ // lvalue to pass it to the constructor.
+ return Visit(MTE->getSubExpr(), Ty);
+ }
+
+ // Don't try to support arbitrary lvalue-to-rvalue conversions for now.
+ return nullptr;
}
return CGM.EmitNullConstant(Ty);
- HasAnyMaterializeTemporaryExpr shouldn't need to handle
VisitCXXConstructExpr. The EvaluateAsLValue bug only applies to
lifetime-extended temporaries. Any MaterializeTemporaryExpr that's the operand
of a VisitCXXConstructExpr should not be lifetime-extended beyond the end of
the expression. So it won't run into the EvaluateAsLValue issue.
(https://en.cppreference.com/w/cpp/language/reference_initialization#Lifetime_of_a_temporary
should be a complete list of cases where we might need to recurse; none of
those corresponds to a CXXConstructExpr.)
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D151587/new/
https://reviews.llvm.org/D151587
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