[clang][OpenMP] Improve handling of non-C/C++ directives

clang/lib/Parse/ParseOpenMP.cpp

@@ -2613,9 +2613,8 @@ StmtResult Parser::ParseOpenMPDeclarativeOrExecutableDirective(
     Diag(Tok, diag::err_omp_unknown_directive);
     return StmtError();
   }
-  if (DKind == OMPD_workshare) {
-    // "workshare" is an executable, Fortran-only directive. Treat it
-    // as unknown.
+  if (!(getDirectiveLanguages(DKind) & SourceLanguage::C)) {
+    // Treat directives that are not allowed in C/C++ as unknown.
     DKind = OMPD_unknown;
   }
 

clang/test/OpenMP/openmp_non_c_directives.c

@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -verify -fopenmp -ferror-limit 100 -o - %s
+
+// Test the reaction to some Fortran-only directives.
+
+void foo() {
+#pragma omp allocators // expected-error {{expected an OpenMP directive}}
+#pragma omp do // expected-error {{expected an OpenMP directive}}
+#pragma omp end workshare // expected-error {{expected an OpenMP directive}}
+#pragma omp parallel workshare // expected-warning {{extra tokens at the end of '#pragma omp parallel' are ignored}}
+#pragma omp workshare // expected-error {{expected an OpenMP directive}}
+}
+

llvm/include/llvm/ADT/BitmaskEnum.h

@@ -92,6 +92,7 @@
   using ::llvm::BitmaskEnumDetail::operator^=;                                 \
   using ::llvm::BitmaskEnumDetail::operator<<=;                                \
   using ::llvm::BitmaskEnumDetail::operator>>=;                                \
+  using ::llvm::BitmaskEnumDetail::operator!;                                  \
   /* Force a semicolon at the end of this macro. */                            \
   using ::llvm::BitmaskEnumDetail::any
 
@@ -141,6 +142,11 @@ constexpr unsigned bitWidth(uint64_t Value) {
   return Value ? 1 + bitWidth(Value >> 1) : 0;
 }
 
+template <typename E, typename = std::enable_if_t<is_bitmask_enum<E>::value>>
+constexpr bool operator!(E Val) {
+  return Val == static_cast<E>(0);
+}
+
 template <typename E, typename = std::enable_if_t<is_bitmask_enum<E>::value>>
 constexpr bool any(E Val) {
   return Val != static_cast<E>(0);

llvm/include/llvm/Frontend/Directive/DirectiveBase.td

@@ -172,6 +172,15 @@ def CA_Meta: Category<"Meta"> {}
 def CA_Subsidiary: Category<"Subsidiary"> {}
 def CA_Utility: Category<"Utility"> {}
 
+class SourceLanguage<string n> {
+  string name = n;  // Name of the enum value in enum class Association.
+}
+
+// The C languages also implies C++ until there is a reason to add C++
+// separately.
+def L_C : SourceLanguage<"C"> {}
+def L_Fortran : SourceLanguage<"Fortran"> {}
+
 // Information about a specific directive.
 class Directive<string d> {
   // Name of the directive. Can be composite directive sepearted by whitespace.
@@ -205,4 +214,7 @@ class Directive<string d> {
 
   // The category of the directive.
   Category category = ?;
+
+  // The languages that allow this directive. Default: all languages.
+  list<SourceLanguage> languages = [L_C, L_Fortran];
 }