[flang][OpenMP] Use OmpDirectiveSpecification in REQUIRES

flang/include/flang/Parser/openmp-utils.h

@@ -41,7 +41,6 @@ struct ConstructId {
 MAKE_CONSTR_ID(OpenMPDeclarativeAllocate, D::OMPD_allocate);
 MAKE_CONSTR_ID(OpenMPDeclareReductionConstruct, D::OMPD_declare_reduction);
 MAKE_CONSTR_ID(OpenMPExecutableAllocate, D::OMPD_allocate);
-MAKE_CONSTR_ID(OpenMPRequiresConstruct, D::OMPD_requires);
 
 #undef MAKE_CONSTR_ID
 
@@ -94,8 +93,7 @@ struct DirectiveNameScope {
         return std::get<OmpBeginDirective>(x.t).DirName();
       } else if constexpr (std::is_same_v<T, OpenMPDeclarativeAllocate> ||
           std::is_same_v<T, OpenMPDeclareReductionConstruct> ||
-          std::is_same_v<T, OpenMPExecutableAllocate> ||
-          std::is_same_v<T, OpenMPRequiresConstruct>) {
+          std::is_same_v<T, OpenMPExecutableAllocate>) {
         return MakeName(std::get<Verbatim>(x.t).source, ConstructId<T>::id);
       } else {
         return GetFromTuple(

flang/include/flang/Parser/parse-tree.h

@@ -4991,9 +4991,8 @@ struct OpenMPGroupprivate {
 
 // 2.4 requires -> REQUIRES requires-clause[ [ [,] requires-clause]...]
 struct OpenMPRequiresConstruct {
-  TUPLE_CLASS_BOILERPLATE(OpenMPRequiresConstruct);
+  WRAPPER_CLASS_BOILERPLATE(OpenMPRequiresConstruct, OmpDirectiveSpecification);
   CharBlock source;
-  std::tuple<Verbatim, OmpClauseList> t;
 };
 
 // 2.15.2 threadprivate -> THREADPRIVATE (variable-name-list)

flang/lib/Parser/openmp-parsers.cpp

@@ -1836,7 +1836,9 @@ TYPE_PARSER(sourced( //
 
 // 2.4 Requires construct
 TYPE_PARSER(sourced(construct<OpenMPRequiresConstruct>(
-    verbatim("REQUIRES"_tok), Parser<OmpClauseList>{})))
+    predicated(OmpDirectiveNameParser{},
+        IsDirective(llvm::omp::Directive::OMPD_requires)) >=
+    Parser<OmpDirectiveSpecification>{})))
 
 // 2.15.2 Threadprivate directive
 TYPE_PARSER(sourced( //

flang/lib/Parser/unparse.cpp

@@ -2594,10 +2594,10 @@ class UnparseVisitor {
     Put("\n");
     EndOpenMP();
   }
-  void Unparse(const OpenMPRequiresConstruct &y) {
+  void Unparse(const OpenMPRequiresConstruct &x) {
     BeginOpenMP();
-    Word("!$OMP REQUIRES ");
-    Walk(std::get<OmpClauseList>(y.t));
+    Word("!$OMP ");
+    Walk(x.v);
     Put("\n");
     EndOpenMP();
   }

flang/lib/Semantics/check-omp-structure.cpp

@@ -624,10 +624,6 @@ template <typename Checker> struct DirectiveSpellingVisitor {
     checker_(x.v.DirName().source, Directive::OMPD_groupprivate);
     return false;
   }
-  bool Pre(const parser::OpenMPRequiresConstruct &x) {
-    checker_(std::get<parser::Verbatim>(x.t).source, Directive::OMPD_requires);
-    return false;
-  }
   bool Pre(const parser::OmpBeginDirective &x) {
     checker_(x.DirName().source, x.DirId());
     return false;
@@ -1498,14 +1494,13 @@ void OmpStructureChecker::Leave(const parser::OpenMPDepobjConstruct &x) {
 }
 
 void OmpStructureChecker::Enter(const parser::OpenMPRequiresConstruct &x) {
-  const auto &dir{std::get<parser::Verbatim>(x.t)};
-  PushContextAndClauseSets(dir.source, llvm::omp::Directive::OMPD_requires);
+  const auto &dirName{x.v.DirName()};
+  PushContextAndClauseSets(dirName.source, dirName.v);
 
   if (visitedAtomicSource_.empty()) {
     return;
   }
-  const auto &clauseList{std::get<parser::OmpClauseList>(x.t)};
-  for (const parser::OmpClause &clause : clauseList.v) {
+  for (const parser::OmpClause &clause : x.v.Clauses().v) {
     llvm::omp::Clause id{clause.Id()};
     if (id == llvm::omp::Clause::OMPC_atomic_default_mem_order) {
       parser::MessageFormattedText txt(

flang/lib/Semantics/resolve-directives.cpp

@@ -523,7 +523,7 @@ class OmpAttributeVisitor : DirectiveAttributeVisitor<llvm::omp::Directive> {
     // Gather information from the clauses.
     Flags flags;
     std::optional<common::OmpMemoryOrderType> memOrder;
-    for (const auto &clause : std::get<parser::OmpClauseList>(x.t).v) {
+    for (const parser::OmpClause &clause : x.v.Clauses().v) {
       flags |= common::visit(
           common::visitors{
               [&memOrder](

flang/test/Parser/OpenMP/requires.f90

@@ -0,0 +1,33 @@
+!RUN: %flang_fc1 -fdebug-unparse -fopenmp -fopenmp-version=50 %s | FileCheck --ignore-case --check-prefix="UNPARSE" %s
+!RUN: %flang_fc1 -fdebug-dump-parse-tree -fopenmp -fopenmp-version=50 %s | FileCheck --check-prefix="PARSE-TREE" %s
+
+!$omp requires atomic_default_mem_order(seq_cst)
+
+!UNPARSE: !$OMP REQUIRES ATOMIC_DEFAULT_MEM_ORDER(SEQ_CST)
+
+!PARSE-TREE: OpenMPDeclarativeConstruct -> OpenMPRequiresConstruct -> OmpDirectiveSpecification
+!PARSE-TREE: | OmpDirectiveName -> llvm::omp::Directive = requires
+!PARSE-TREE: | OmpClauseList -> OmpClause -> AtomicDefaultMemOrder -> OmpAtomicDefaultMemOrderClause -> OmpMemoryOrderType = Seq_Cst
+!PARSE-TREE: | Flags = None
+
+!$omp requires unified_shared_memory unified_address
+
+!UNPARSE: !$OMP REQUIRES UNIFIED_SHARED_MEMORY UNIFIED_ADDRESS
+
+!PARSE-TREE: OpenMPDeclarativeConstruct -> OpenMPRequiresConstruct -> OmpDirectiveSpecification
+!PARSE-TREE: | OmpDirectiveName -> llvm::omp::Directive = requires
+!PARSE-TREE: | OmpClauseList -> OmpClause -> UnifiedSharedMemory
+!PARSE-TREE: | OmpClause -> UnifiedAddress
+!PARSE-TREE: | Flags = None
+
+!$omp requires dynamic_allocators reverse_offload
+
+!UNPARSE: !$OMP REQUIRES DYNAMIC_ALLOCATORS REVERSE_OFFLOAD
+
+!PARSE-TREE: OpenMPDeclarativeConstruct -> OpenMPRequiresConstruct -> OmpDirectiveSpecification
+!PARSE-TREE: | OmpDirectiveName -> llvm::omp::Directive = requires
+!PARSE-TREE: | OmpClauseList -> OmpClause -> DynamicAllocators
+!PARSE-TREE: | OmpClause -> ReverseOffload
+!PARSE-TREE: | Flags = None
+
+end