[clang] [OpenACC][Sema] Implement warning for non-effective 'private' (PR #149004)

[Erich Keane via cfe-commits]

================
@@ -624,6 +624,66 @@ void SemaOpenACC::CheckDeclReference(SourceLocation Loc, Expr *E, Decl *D) {
   // loop (or we aren't in a loop!) so skip the diagnostic.
 }
 
+namespace {
+// Check whether the type of the thing we are referencing is OK for things like
+// private, firstprivate, and reduction, which require certain operators to be
+// available.
+ExprResult CheckVarType(SemaOpenACC &S, OpenACCClauseKind CK, Expr *VarExpr,
+                        Expr *InnerExpr) {
+  // There is nothing to do here, only these three have these sorts of
+  // restrictions.
+  if (CK != OpenACCClauseKind::Private &&
+      CK != OpenACCClauseKind::FirstPrivate &&
+      CK != OpenACCClauseKind::Reduction)
+    return VarExpr;
+
+  // We can't test this if it isn't here, or if the type isn't clear yet.
+  if (!InnerExpr || InnerExpr->isTypeDependent())
+    return VarExpr;
+
+  const auto *RD = InnerExpr->getType()->getAsCXXRecordDecl();
+
+  // if this isn't a C++ record decl, we can create/copy/destroy this thing at
+  // will without problem, so this is a success.
+  if (!RD)
+    return VarExpr;
+
+  // TODO: OpenACC:
+  // Private must have default ctor + dtor in InnerExpr
+  // FirstPrivate must have copyctor + dtor in InnerExpr
+  // Reduction must have copyctor + dtor + operation in InnerExpr
----------------
erichkeane wrote:

It would still need a 'default' constructor though to start its lifetime, right? 

https://github.com/llvm/llvm-project/pull/149004