[OpenACC] Ensure clause expressions side-effects don't happen

The OpenACC standard says side-effects/ordering of expressions in
clauses and constructs (not yet, but PR for constructs) cannot be
depended on.  We already had infrastructure to ensure constructs, and
non-template clauses did this right, but we had the ordering of a call
vs transform of the clauses happened in tree transform.

This patch ensures that the evaluation context put together for the
construct covers the clauses as well in tree transform.

clang/lib/Sema/TreeTransform.h

@@ -11859,13 +11859,14 @@ StmtResult TreeTransform<Derived>::TransformOpenACCComputeConstruct(
     OpenACCComputeConstruct *C) {
   getSema().OpenACC().ActOnConstruct(C->getDirectiveKind(), C->getBeginLoc());
 
+  llvm::SmallVector<OpenACCClause *> TransformedClauses =
+      getDerived().TransformOpenACCClauseList(C->getDirectiveKind(),
+                                              C->clauses());
+
   if (getSema().OpenACC().ActOnStartStmtDirective(C->getDirectiveKind(),
                                                   C->getBeginLoc()))
     return StmtError();
 
-  llvm::SmallVector<OpenACCClause *> TransformedClauses =
-      getDerived().TransformOpenACCClauseList(C->getDirectiveKind(),
-                                              C->clauses());
   // Transform Structured Block.
   SemaOpenACC::AssociatedStmtRAII AssocStmtRAII(getSema().OpenACC(),
                                                 C->getDirectiveKind());
@@ -11884,14 +11885,14 @@ TreeTransform<Derived>::TransformOpenACCLoopConstruct(OpenACCLoopConstruct *C) {
 
   getSema().OpenACC().ActOnConstruct(C->getDirectiveKind(), C->getBeginLoc());
 
-  if (getSema().OpenACC().ActOnStartStmtDirective(C->getDirectiveKind(),
-                                                  C->getBeginLoc()))
-    return StmtError();
-
   llvm::SmallVector<OpenACCClause *> TransformedClauses =
       getDerived().TransformOpenACCClauseList(C->getDirectiveKind(),
                                               C->clauses());
 
+  if (getSema().OpenACC().ActOnStartStmtDirective(C->getDirectiveKind(),
+                                                  C->getBeginLoc()))
+    return StmtError();
+
   // Transform Loop.
   SemaOpenACC::AssociatedStmtRAII AssocStmtRAII(getSema().OpenACC(),
                                                 C->getDirectiveKind());

clang/test/SemaOpenACC/compute-construct-intexpr-clause-ast.cpp

@@ -435,7 +435,6 @@ void TemplUses(T t, U u) {
   // CHECK-NEXT: CXXBoolLiteralExpr
   // CHECK-NEXT: CompoundStmt
 
-
   // CHECK-NEXT: DeclStmt
   // CHECK-NEXT: VarDecl{{.*}}EndMarker
   int EndMarker;
@@ -490,7 +489,6 @@ void TemplUses(T t, U u) {
   // CHECK-NEXT: CXXFunctionalCastExpr{{.*}} 'CorrectConvert' functional cast to struct CorrectConvert <NoOp>
   // CHECK-NEXT: InitListExpr{{.*}}'CorrectConvert'
   // CHECK-NEXT: WhileStmt
-  // CHECK-NEXT: ExprWithCleanups
   // CHECK-NEXT: CXXBoolLiteralExpr
   // CHECK-NEXT: CompoundStmt
 
@@ -503,7 +501,6 @@ void TemplUses(T t, U u) {
   // CHECK-NEXT: CXXFunctionalCastExpr{{.*}} 'HasInt' functional cast to struct HasInt <NoOp>
   // CHECK-NEXT: InitListExpr{{.*}}'HasInt'
   // CHECK-NEXT: WhileStmt
-  // CHECK-NEXT: ExprWithCleanups
   // CHECK-NEXT: CXXBoolLiteralExpr
   // CHECK-NEXT: CompoundStmt