[Flang] Introduce FortranSupport

Author: Meinersbur

Diff for: flang/include/flang/ISO_Fortran_binding_wrapper.h renamed to flang/include/flang/Common/ISO_Fortran_binding_wrapper.h

@@ -1,14 +1,13 @@
-/*===-- include/flang/ISO_Fortran_binding_wrapper.h ---------------*- C++ -*-===
+/*===-- include/flang/Common/ISO_Fortran_binding_wrapper.h ----------*- C -*-===
  *
  * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  * See https://llvm.org/LICENSE.txt for license information.
  * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  *
- * ===-----------------------------------------------------------------------===
- */
+ *===----------------------------------------------------------------------===*/
 
-#ifndef FORTRAN_ISO_FORTRAN_BINDING_WRAPPER_H_
-#define FORTRAN_ISO_FORTRAN_BINDING_WRAPPER_H_
+#ifndef FORTRAN_COMMON_ISO_FORTRAN_BINDING_WRAPPER_H_
+#define FORTRAN_COMMON_ISO_FORTRAN_BINDING_WRAPPER_H_
 
 /* A thin wrapper around flang/include/ISO_Fortran_binding.h
  * This header file must be included when ISO_Fortran_binding.h
@@ -23,17 +22,17 @@
 
 /* clang-format off */
 #include <stddef.h>
-#include "Common/api-attrs.h"
+#include "flang/Common/api-attrs.h"
 #ifdef __cplusplus
 namespace Fortran {
 namespace ISO {
 #define FORTRAN_ISO_NAMESPACE_ ::Fortran::ISO
 #endif /* __cplusplus */
-#include "ISO_Fortran_binding.h"
+#include "flang/ISO_Fortran_binding.h"
 #ifdef __cplusplus
 } // namespace ISO
 } // namespace Fortran
 #endif /* __cplusplus */
 /* clang-format on */
 
-#endif /* FORTRAN_ISO_FORTRAN_BINDING_WRAPPER_H_ */
+#endif /* FORTRAN_COMMON_ISO_FORTRAN_BINDING_WRAPPER_H_ */

Diff for: flang/include/flang/Common/fast-int-set.h

@@ -24,7 +24,7 @@
 #ifndef FORTRAN_COMMON_FAST_INT_SET_H_
 #define FORTRAN_COMMON_FAST_INT_SET_H_
 
-#include <optional>
+#include "optional.h"
 
 namespace Fortran::common {
 
@@ -83,9 +83,9 @@ template <int N> class FastIntSet {
     }
   }
 
-  std::optional<int> PopValue() {
+  optional<int> PopValue() {
     if (IsEmpty()) {
-      return std::nullopt;
+      return nullopt;
     } else {
       return value_[--size_];
     }