[CFG] [analyzer] Simplify lifetime-extended temporary construction contexts.

When a temporary object is materialized and through that obtain lifetime that
is longer than the duration of the full-expression, it does not require a
temporary object destructor; it will be destroyed in a different manner.

Therefore it's not necessary to include CXXBindTemporaryExpr into the
construction context for such temporary in the CFG only to make clients
throw it away.

Differential Revision: https://reviews.llvm.org/D47667

llvm-svn: 335798

1 files changed, 7 insertions, 0 deletions

diff --git a/clang/lib/Analysis/ConstructionContext.cpp b/clang/lib/Analysis/ConstructionContext.cpp
index de003753367..ed1e6324321 100644
--- a/clang/lib/Analysis/ConstructionContext.cpp
+++ b/clang/lib/Analysis/ConstructionContext.cpp
@@ -76,6 +76,13 @@ const ConstructionContext *ConstructionContext::createFromLayers(
         // both destruction and materialization info attached to it in the AST.
         if ((MTE = dyn_cast<MaterializeTemporaryExpr>(
                  ParentLayer->getTriggerStmt()))) {
+          if (MTE->getStorageDuration() != SD_FullExpression) {
+            // If the temporary is lifetime-extended, don't save the BTE,
+            // because we don't need a temporary destructor, but an automatic
+            // destructor.
+            BTE = nullptr;
+          }
+
           // Handle pre-C++17 copy and move elision.
           const CXXConstructExpr *ElidedCE = nullptr;
           const ConstructionContext *ElidedCC = nullptr;