Sema: Forbid more than one-level OSSArraySections with pointers

Fixes llvm#24

Author: mikaoP

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -9745,6 +9745,8 @@ def err_oss_section_length_negative : Error<
   "section length is evaluated to a negative value %0">;
 def err_oss_section_length_undefined : Error<
   "section length is unspecified and cannot be inferred because subscripted value is %select{not an array|an array of unknown bound}0">;
+def err_oss_section_only_one_pointer_level : Error<
+  "pointer types only allow one-level array sections">;
 def err_oss_typecheck_shaping_base_no_ptr_or_array: Error<
   "shaping expression base is not a pointer or array">;
 def err_oss_shape_incomplete_type : Error<

clang/lib/Sema/SemaExpr.cpp

@@ -4635,6 +4635,11 @@ ExprResult Sema::ActOnOSSArraySectionExpr(Expr *Base, SourceLocation LBLoc,
   QualType OriginalTy = OSSArraySectionExpr::getBaseOriginalType(Base);
   QualType ResultTy;
   if (OriginalTy->isAnyPointerType()) {
+    if (const auto *OASE = dyn_cast<OSSArraySectionExpr>(Base)) {
+      Diag(OASE->getExprLoc(), diag::err_oss_section_only_one_pointer_level)
+        << OASE->getSourceRange();
+      return ExprError();
+    }
     ResultTy = OriginalTy->getPointeeType();
   } else if (OriginalTy->isArrayType()) {
     ResultTy = OriginalTy->getAsArrayTypeUnsafe()->getElementType();

clang/test/OmpSs/Sema/task_depend.cpp

@@ -51,7 +51,7 @@ int main(int argc, char **argv, char *env[]) {
   #pragma oss task depend(in:argv[argv[:2]:1]) // expected-error {{OmpSs-2 array section is not allowed here}}
   #pragma oss task depend(in:argv[0:][:]) // expected-error {{section length is unspecified and cannot be inferred because subscripted value is not an array}}
   #pragma oss task depend(in:env[0:][:]) // expected-error {{section length is unspecified and cannot be inferred because subscripted value is an array of unknown bound}}
-  #pragma oss task depend(in : argv[ : argc][1 : argc - 1])
+  #pragma oss task depend(in : argv[ : argc][1 : argc - 1]) // expected-error {{pointer types only allow one-level array sections}}
   #pragma oss task depend(in : arr[0])
   #pragma oss task depend(, // expected-error {{expected 'in', 'out', 'inout' or 'weak' in OmpSs-2 clause 'depend'}} expected-error {{expected ')'}} expected-note {{to match this '('}} expected-warning {{missing ':' after dependency type - ignoring}}
   #pragma oss task depend(, : // expected-error {{expected 'in', 'out', 'inout' or 'weak' in OmpSs-2 clause 'depend'}} expected-error {{expected ')'}} expected-note {{to match this '('}}