[OpenMP][clang] declare mapper: fix handling of nested types (llvm#143504)

Fix a crash that happened during parsing of a "declare mapper" construct
for a struct that contains an element for which we also declared a
custom default mapper.

Author: ro-i

clang/include/clang/Sema/SemaOpenMP.h

@@ -283,7 +283,7 @@ class SemaOpenMP : public SemaBase {
   /// mapper' construct.
   QualType ActOnOpenMPDeclareMapperType(SourceLocation TyLoc,
                                         TypeResult ParsedType);
-  /// Called on start of '#pragma omp declare mapper'.
+  /// Called for '#pragma omp declare mapper'.
   DeclGroupPtrTy ActOnOpenMPDeclareMapperDirective(
       Scope *S, DeclContext *DC, DeclarationName Name, QualType MapperType,
       SourceLocation StartLoc, DeclarationName VN, AccessSpecifier AS,

clang/lib/Parse/ParseOpenMP.cpp

@@ -576,6 +576,7 @@ Parser::ParseOpenMPDeclareMapperDirective(AccessSpecifier AS) {
     return DeclGroupPtrTy();
   }
 
+  Scope *OuterScope = getCurScope();
   // Enter scope.
   DeclarationNameInfo DirName;
   SourceLocation Loc = Tok.getLocation();
@@ -614,12 +615,17 @@ Parser::ParseOpenMPDeclareMapperDirective(AccessSpecifier AS) {
     IsCorrect = false;
   }
 
+  // This needs to be called within the scope because
+  // processImplicitMapsWithDefaultMappers may add clauses when analyzing nested
+  // types. The scope used for calling ActOnOpenMPDeclareMapperDirective,
+  // however, needs to be the outer one, otherwise declared mappers don't become
+  // visible.
+  DeclGroupPtrTy DG = Actions.OpenMP().ActOnOpenMPDeclareMapperDirective(
+      OuterScope, Actions.getCurLexicalContext(), MapperId, MapperType,
+      Range.getBegin(), VName, AS, MapperVarRef.get(), Clauses);
   // Exit scope.
   Actions.OpenMP().EndOpenMPDSABlock(nullptr);
   OMPDirectiveScope.Exit();
-  DeclGroupPtrTy DG = Actions.OpenMP().ActOnOpenMPDeclareMapperDirective(
-      getCurScope(), Actions.getCurLexicalContext(), MapperId, MapperType,
-      Range.getBegin(), VName, AS, MapperVarRef.get(), Clauses);
   if (!IsCorrect)
     return DeclGroupPtrTy();
 

clang/test/OpenMP/declare_mapper_ast_print.c

@@ -49,6 +49,23 @@ struct dat {
 #pragma omp declare mapper(struct dat d) map(to: d.d)
 // CHECK: #pragma omp declare mapper (default : struct dat d) map(to: d.d){{$}}
 
+// Verify that nested default mappers do not lead to a crash during parsing / sema.
+// CHECK: struct inner {
+struct inner {
+  int size;
+  int *data;
+};
+#pragma omp declare mapper(struct inner i) map(i, i.data[0 : i.size])
+// CHECK: #pragma omp declare mapper (default : struct inner i) map(tofrom: default::i,i.data[0:i.size]){{$}}
+
+// CHECK: struct outer {
+struct outer {
+  int a;
+  struct inner i;
+};
+#pragma omp declare mapper(struct outer o) map(o)
+// CHECK: #pragma omp declare mapper (default : struct outer o) map(tofrom: default::o) map(tofrom: o.i){{$}}
+
 // CHECK: int main(void) {
 int main(void) {
 #pragma omp declare mapper(id: struct vec v) map(v.len)
@@ -77,6 +94,14 @@ int main(void) {
 #pragma omp declare mapper(id1: struct vec vvec) map(iterator(it=0:vvec.len:2), tofrom:vvec.data[it])
 // OMP52: #pragma omp declare mapper (id1 : struct vec vvec) map(iterator(int it = 0:vvec.len:2),tofrom: vvec.data[it]);
 #endif
+
+  {
+    struct outer outer;
+#pragma omp target map(outer)
+// CHECK: #pragma omp target map(tofrom: outer)
+    { }
+  }
+
   return 0;
 }
 // CHECK: }

clang/test/OpenMP/declare_mapper_ast_print.cpp

@@ -34,6 +34,28 @@ class vecchild : public vec {
 // CHECK: }
 // CHECK: ;
 
+// Verify that nested default mappers do not lead to a crash during parsing / sema.
+// CHECK: namespace N2 {
+namespace N2
+{
+// CHECK: struct inner {
+struct inner {
+  int size;
+  int *data;
+};
+#pragma omp declare mapper(struct inner i) map(i, i.data[0 : i.size])
+// CHECK: #pragma omp declare mapper (default : struct inner i) map(tofrom: N2::default::i,i.data[0:i.size]){{$}}
+
+// CHECK: struct outer {
+struct outer {
+  int a;
+  struct inner i;
+};
+#pragma omp declare mapper(struct outer o) map(o)
+// CHECK: #pragma omp declare mapper (default : struct outer o) map(tofrom: N2::default::o) map(tofrom: o.i){{$}}
+} // namespace N2
+// CHECK: }
+
 template <class T>
 class dat {
 public:
@@ -122,6 +144,7 @@ T foo(T a) {
 int main() {
   N1::vec vv, vvv;
   N1::vecchild vc;
+  N2::outer outer;
   dat<double> dd;
 #pragma omp target map(mapper(N1::id) tofrom: vv) map(mapper(dat<double>::id) alloc: vvv)
 // CHECK: #pragma omp target map(mapper(N1::id),tofrom: vv) map(mapper(dat<double>::id),alloc: vvv)
@@ -132,6 +155,9 @@ int main() {
 #pragma omp target map(mapper(default) tofrom: dd)
 // CHECK: #pragma omp target map(mapper(default),tofrom: dd)
   { dd.d++; }
+#pragma omp target map(outer)
+// CHECK: #pragma omp target map(tofrom: outer)
+  { }
 
 #pragma omp target update to(mapper(N1::id) : vc)
 // CHECK: #pragma omp target update to(mapper(N1::id): vc)