[NFC] Refactor representation of materialized temporaries

Summary:
this patch refactor representation of materialized temporaries to prevent an issue raised by rsmith in https://reviews.llvm.org/D63640#inline-612718

Reviewers: rsmith, martong, shafik

Reviewed By: rsmith

Subscribers: rnkovacs, arphaman, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D69360

1 files changed, 28 insertions, 0 deletions

diff --git a/clang/lib/AST/DeclCXX.cpp b/clang/lib/AST/DeclCXX.cpp
index 58b50de944e..bca560c40ae 100644
--- a/clang/lib/AST/DeclCXX.cpp
+++ b/clang/lib/AST/DeclCXX.cpp
@@ -2796,6 +2796,34 @@ NamespaceAliasDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
                                         SourceLocation(), nullptr);
 }
 
+void LifetimeExtendedTemporaryDecl::anchor() {}
+
+/// Retrieve the storage duration for the materialized temporary.
+StorageDuration LifetimeExtendedTemporaryDecl::getStorageDuration() const {
+  const ValueDecl *ExtendingDecl = getExtendingDecl();
+  if (!ExtendingDecl)
+    return SD_FullExpression;
+  // FIXME: This is not necessarily correct for a temporary materialized
+  // within a default initializer.
+  if (isa<FieldDecl>(ExtendingDecl))
+    return SD_Automatic;
+  // FIXME: This only works because storage class specifiers are not allowed
+  // on decomposition declarations.
+  if (isa<BindingDecl>(ExtendingDecl))
+    return ExtendingDecl->getDeclContext()->isFunctionOrMethod() ? SD_Automatic
+                                                                 : SD_Static;
+  return cast<VarDecl>(ExtendingDecl)->getStorageDuration();
+}
+
+APValue *LifetimeExtendedTemporaryDecl::getOrCreateValue(bool MayCreate) const {
+  assert(getStorageDuration() == SD_Static &&
+         "don't need to cache the computed value for this temporary");
+  if (MayCreate && !Value)
+    Value = (new (getASTContext()) APValue);
+  assert(Value && "may not be null");
+  return Value;
+}
+
 void UsingShadowDecl::anchor() {}
 
 UsingShadowDecl::UsingShadowDecl(Kind K, ASTContext &C, DeclContext *DC,