[clang] [OpenMP] Fix OpenMP reduction segfault with non-copyable types and user initializers. (PR #219265)

[Zahira Ammarguellat via cfe-commits]

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@@ -24377,6 +24378,39 @@ VarDecl *SemaOpenMP::ActOnOpenMPDeclareReductionInitializerStart(Scope *S,
 void SemaOpenMP::ActOnOpenMPDeclareReductionInitializerEnd(
     Decl *D, Expr *Initializer, VarDecl *OmpPrivParm) {
   auto *DRD = cast<OMPDeclareReductionDecl>(D);
+
+  // For non-trivial types with user initializers, build an AST that
+  // includes default construction first to initialize members before user
+  // initializer. This must be done before popping contexts.
+  if (Initializer && !DRD->getDeclContext()->isDependentContext()) {
+    QualType ReductionType = DRD->getType();
+    if (const auto *RD = ReductionType->getAsCXXRecordDecl()) {
+      CXXConstructorDecl *DefaultCtor =
+          SemaRef.LookupDefaultConstructor(const_cast<CXXRecordDecl *>(RD));
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zahiraam wrote:

Applied.

https://github.com/llvm/llvm-project/pull/219265