[flang][directive] Enforce basic semantic check for all clauses

[clementval]

Summary

This patch is a follow up to D94821 to ensure the correct behavior of the
general directive structure checker.
This patch add the generation of the Enter function declaration for clauses in
the TableGen backend.
This helps to ensure each clauses declared in the TableGen file has at least
a basic check.

[kiranchandramohan]

LGTM. A few suggestions. Feel free to skip or submit with changes.

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

474–475

Not of this patch but Nit: seperate -> separate.

474–475

Looks like you have captured more clauses here. Great!

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

131–141

Can these be moved above the clauses?

llvm/utils/TableGen/DirectiveEmitter.cpp

637

Nit: I don't like the name. Also we are only generating the declaration. Would you be OK with GenerateFlangClauseCheckPrototypes? In the comment along it can be mentioned that the checks happen in the Enter stage during traversal.

[clementval]

Address review comments

[clementval]

Thanks for the review.

flang/lib/Semantics/check-acc-structure.h

#include "llvm/Frontend/OpenACC/ACC.inc"
   void Leave(const parser::OpenACCAtomicConstruct &);
   void Enter(const parser::OpenACCCacheConstruct &);
   void Leave(const parser::OpenACCCacheConstruct &);
 
   // Clauses
   void Leave(const parser::AccClauseList &);
   void Enter(const parser::AccClause &);
 
-  void Enter(const parser::AccClause::Auto &);
-  void Enter(const parser::AccClause::Async &);
-  void Enter(const parser::AccClause::Attach &);
-  void Enter(const parser::AccClause::Bind &);
-  void Enter(const parser::AccClause::Capture &);
-  void Enter(const parser::AccClause::Create &);
-  void Enter(const parser::AccClause::Collapse &);
-  void Enter(const parser::AccClause::Copy &);
-  void Enter(const parser::AccClause::Copyin &);
-  void Enter(const parser::AccClause::Copyout &);
-  void Enter(const parser::AccClause::Default &);
-  void Enter(const parser::AccClause::DefaultAsync &);
-  void Enter(const parser::AccClause::Delete &);
-  void Enter(const parser::AccClause::Detach &);
-  void Enter(const parser::AccClause::Device &);
-  void Enter(const parser::AccClause::DeviceNum &);
-  void Enter(const parser::AccClause::Deviceptr &);
-  void Enter(const parser::AccClause::DeviceResident &);
-  void Enter(const parser::AccClause::DeviceType &);
-  void Enter(const parser::AccClause::Finalize &);
-  void Enter(const parser::AccClause::Firstprivate &);
-  void Enter(const parser::AccClause::Gang &);
-  void Enter(const parser::AccClause::Host &);
-  void Enter(const parser::AccClause::If &);
-  void Enter(const parser::AccClause::IfPresent &);
-  void Enter(const parser::AccClause::Independent &);
-  void Enter(const parser::AccClause::Link &);
-  void Enter(const parser::AccClause::NoCreate &);
-  void Enter(const parser::AccClause::Nohost &);
-  void Enter(const parser::AccClause::NumGangs &);
-  void Enter(const parser::AccClause::NumWorkers &);
-  void Enter(const parser::AccClause::Present &);
-  void Enter(const parser::AccClause::Private &);
-  void Enter(const parser::AccClause::Read &);
-  void Enter(const parser::AccClause::Reduction &);
-  void Enter(const parser::AccClause::Self &);
-  void Enter(const parser::AccClause::Seq &);
-  void Enter(const parser::AccClause::Tile &);
-  void Enter(const parser::AccClause::UseDevice &);
-  void Enter(const parser::AccClause::Vector &);
-  void Enter(const parser::AccClause::VectorLength &);
-  void Enter(const parser::AccClause::Wait &);
-  void Enter(const parser::AccClause::Worker &);
-  void Enter(const parser::AccClause::Write &);
+#define GEN_FLANG_CLAUSE_CHECK_ENTER
+#include "llvm/Frontend/OpenACC/ACC.inc"
 
 private:
 
   bool CheckAllowedModifier(llvm::acc::Clause clause);
   bool IsComputeConstruct(llvm::acc::Directive directive) const;
   bool IsInsideComputeConstruct() const;
   void CheckNotInComputeConstruct();
   llvm::StringRef getClauseName(llvm::acc::Clause clause) override;
   llvm::StringRef getDirectiveName(llvm::acc::Directive directive) override;
 };
 
 } // namespace Fortran::semantics
 
 #endif // FORTRAN_SEMANTICS_CHECK_ACC_STRUCTURE_H_

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

 CHECK_SIMPLE_CLAUSE(Seq, ACCC_seq)
 CHECK_SIMPLE_CLAUSE(Tile, ACCC_tile)
 CHECK_SIMPLE_CLAUSE(UseDevice, ACCC_use_device)
 CHECK_SIMPLE_CLAUSE(Vector, ACCC_vector)
 CHECK_SIMPLE_CLAUSE(VectorLength, ACCC_vector_length)
 CHECK_SIMPLE_CLAUSE(Wait, ACCC_wait)
 CHECK_SIMPLE_CLAUSE(Worker, ACCC_worker)
 CHECK_SIMPLE_CLAUSE(Write, ACCC_write)
+CHECK_SIMPLE_CLAUSE(Unknown, ACCC_unknown)
 
 void AccStructureChecker::Enter(const parser::AccClause::Create &c) {
   CheckAllowed(llvm::acc::Clause::ACCC_create);
   const auto &modifierClause{c.v};
   if (const auto &modifier{
           std::get<std::optional<parser::AccDataModifier>>(modifierClause.t)}) {
     if (modifier->v != parser::AccDataModifier::Modifier::Zero) {
       context_.Say(GetContext().clauseSource,

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

#include "llvm/Frontend/OpenMP/OMP.inc"
   void Leave(const parser::OpenMPCancellationPointConstruct &);
   void Enter(const parser::OpenMPCriticalConstruct &);
   void Leave(const parser::OpenMPCriticalConstruct &);
   void Enter(const parser::OpenMPAtomicConstruct &);
   void Leave(const parser::OpenMPAtomicConstruct &);
 
   void Leave(const parser::OmpClauseList &);
   void Enter(const parser::OmpClause &);
-  void Enter(const parser::OmpClause::Allocate &);
-  void Enter(const parser::OmpClause::Allocator &);
-  void Enter(const parser::OmpClause::Inbranch &);
-  void Enter(const parser::OmpClause::Mergeable &);
-  void Enter(const parser::OmpClause::Nogroup &);
-  void Enter(const parser::OmpClause::Nowait &);
-  void Enter(const parser::OmpClause::Notinbranch &);
-  void Enter(const parser::OmpClause::Untied &);
-  void Enter(const parser::OmpClause::Collapse &);
-  void Enter(const parser::OmpClause::Copyin &);
-  void Enter(const parser::OmpClause::Copyprivate &);
-  void Enter(const parser::OmpClause::Default &);
-  void Enter(const parser::OmpClause::Device &);
-  void Enter(const parser::OmpClause::DistSchedule &);
-  void Enter(const parser::OmpClause::Final &);
-  void Enter(const parser::OmpClause::Firstprivate &);
-  void Enter(const parser::OmpClause::From &);
-  void Enter(const parser::OmpClause::Grainsize &);
-  void Enter(const parser::OmpClause::Lastprivate &);
-  void Enter(const parser::OmpClause::NumTasks &);
-  void Enter(const parser::OmpClause::NumTeams &);
-  void Enter(const parser::OmpClause::NumThreads &);
-  void Enter(const parser::OmpClause::Ordered &);
-  void Enter(const parser::OmpClause::Priority &);
-  void Enter(const parser::OmpClause::Private &);
-  void Enter(const parser::OmpClause::ProcBind &);
-  void Enter(const parser::OmpClause::Reduction &);
-  void Enter(const parser::OmpClause::Safelen &);
-  void Enter(const parser::OmpClause::Shared &);
-  void Enter(const parser::OmpClause::Simdlen &);
-  void Enter(const parser::OmpClause::TaskReduction &);
-  void Enter(const parser::OmpClause::ThreadLimit &);
-  void Enter(const parser::OmpClause::To &);
-  void Enter(const parser::OmpClause::Link &);
-  void Enter(const parser::OmpClause::Uniform &);
-  void Enter(const parser::OmpClause::UseDevicePtr &);
-  void Enter(const parser::OmpClause::IsDevicePtr &);
-  // Memory-order-clause
-  void Enter(const parser::OmpClause::SeqCst &);
-  void Enter(const parser::OmpClause::AcqRel &);
-  void Enter(const parser::OmpClause::Release &);
-  void Enter(const parser::OmpClause::Acquire &);
-  void Enter(const parser::OmpClause::Relaxed &);
-  void Enter(const parser::OmpClause::Hint &);
 
   void Enter(const parser::OmpAtomicRead &);
   void Leave(const parser::OmpAtomicRead &);
   void Enter(const parser::OmpAtomicWrite &);
   void Leave(const parser::OmpAtomicWrite &);
   void Enter(const parser::OmpAtomicUpdate &);
   void Leave(const parser::OmpAtomicUpdate &);
   void Enter(const parser::OmpAtomicCapture &);
   void Leave(const parser::OmpAtomic &);
-  void Enter(const parser::OmpAlignedClause &);
-  void Enter(const parser::OmpDefaultmapClause &);
-  void Enter(const parser::OmpDependClause &);
-  void Enter(const parser::OmpIfClause &);
-  void Enter(const parser::OmpLinearClause &);
-  void Enter(const parser::OmpMapClause &);
-  void Enter(const parser::OmpScheduleClause &);
+
+#define GEN_FLANG_CLAUSE_CHECK_ENTER
+#include "llvm/Frontend/OpenMP/OMP.inc"
 
 private:
   bool HasInvalidWorksharingNesting(
       const parser::CharBlock &, const OmpDirectiveSet &);
 
   // specific clause related
   bool ScheduleModifierHasType(const parser::OmpScheduleClause &,
       const parser::OmpScheduleModifierType::ModType &);

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

void OmpStructureChecker::Leave(const parser::OmpClauseList &) {
   }
 
   CheckRequireAtLeastOneOf();
 }
 
 void OmpStructureChecker::Enter(const parser::OmpClause &x) {
   SetContextClause(x);
 }
 
-// Following clauses do not have a seperate node in parse-tree.h.
-// They fall under 'struct OmpClause' in parse-tree.h.
+// Following clauses do not have a separate node in parse-tree.h.
+CHECK_SIMPLE_CLAUSE(AcqRel, OMPC_acq_rel)
+CHECK_SIMPLE_CLAUSE(Acquire, OMPC_acquire)
+CHECK_SIMPLE_CLAUSE(AtomicDefaultMemOrder, OMPC_atomic_default_mem_order)
+CHECK_SIMPLE_CLAUSE(Affinity, OMPC_affinity)
 CHECK_SIMPLE_CLAUSE(Allocate, OMPC_allocate)
+CHECK_SIMPLE_CLAUSE(Capture, OMPC_capture)
 CHECK_SIMPLE_CLAUSE(Copyin, OMPC_copyin)
 CHECK_SIMPLE_CLAUSE(Copyprivate, OMPC_copyprivate)
 CHECK_SIMPLE_CLAUSE(Default, OMPC_default)
+CHECK_SIMPLE_CLAUSE(Depobj, OMPC_depobj)
+CHECK_SIMPLE_CLAUSE(Destroy, OMPC_destroy)
+CHECK_SIMPLE_CLAUSE(Detach, OMPC_detach)
 CHECK_SIMPLE_CLAUSE(Device, OMPC_device)
+CHECK_SIMPLE_CLAUSE(DeviceType, OMPC_device_type)
+CHECK_SIMPLE_CLAUSE(DistSchedule, OMPC_dist_schedule)
+CHECK_SIMPLE_CLAUSE(DynamicAllocators, OMPC_dynamic_allocators)
+CHECK_SIMPLE_CLAUSE(Exclusive, OMPC_exclusive)
 CHECK_SIMPLE_CLAUSE(Final, OMPC_final)
+CHECK_SIMPLE_CLAUSE(Flush, OMPC_flush)
 CHECK_SIMPLE_CLAUSE(From, OMPC_from)
+CHECK_SIMPLE_CLAUSE(Hint, OMPC_hint)
+CHECK_SIMPLE_CLAUSE(InReduction, OMPC_in_reduction)
+CHECK_SIMPLE_CLAUSE(Inclusive, OMPC_inclusive)
+CHECK_SIMPLE_CLAUSE(Match, OMPC_match)
+CHECK_SIMPLE_CLAUSE(Nontemporal, OMPC_nontemporal)
+CHECK_SIMPLE_CLAUSE(Order, OMPC_order)
+CHECK_SIMPLE_CLAUSE(Read, OMPC_read)
+CHECK_SIMPLE_CLAUSE(ReverseOffload, OMPC_reverse_offload)
+CHECK_SIMPLE_CLAUSE(Threadprivate, OMPC_threadprivate)
+CHECK_SIMPLE_CLAUSE(Threads, OMPC_threads)
 CHECK_SIMPLE_CLAUSE(Inbranch, OMPC_inbranch)
 CHECK_SIMPLE_CLAUSE(IsDevicePtr, OMPC_is_device_ptr)
 CHECK_SIMPLE_CLAUSE(Lastprivate, OMPC_lastprivate)
 CHECK_SIMPLE_CLAUSE(Link, OMPC_link)
 CHECK_SIMPLE_CLAUSE(Mergeable, OMPC_mergeable)
 CHECK_SIMPLE_CLAUSE(Nogroup, OMPC_nogroup)
 CHECK_SIMPLE_CLAUSE(Notinbranch, OMPC_notinbranch)
 CHECK_SIMPLE_CLAUSE(Nowait, OMPC_nowait)
+CHECK_SIMPLE_CLAUSE(ProcBind, OMPC_proc_bind)
 CHECK_SIMPLE_CLAUSE(Reduction, OMPC_reduction)
+CHECK_SIMPLE_CLAUSE(Release, OMPC_release)
+CHECK_SIMPLE_CLAUSE(Relaxed, OMPC_relaxed)
+CHECK_SIMPLE_CLAUSE(SeqCst, OMPC_seq_cst)
+CHECK_SIMPLE_CLAUSE(Simd, OMPC_simd)
 CHECK_SIMPLE_CLAUSE(TaskReduction, OMPC_task_reduction)
 CHECK_SIMPLE_CLAUSE(To, OMPC_to)
+CHECK_SIMPLE_CLAUSE(UnifiedAddress, OMPC_unified_address)
+CHECK_SIMPLE_CLAUSE(UnifiedSharedMemory, OMPC_unified_shared_memory)
 CHECK_SIMPLE_CLAUSE(Uniform, OMPC_uniform)
+CHECK_SIMPLE_CLAUSE(Unknown, OMPC_unknown)
 CHECK_SIMPLE_CLAUSE(Untied, OMPC_untied)
 CHECK_SIMPLE_CLAUSE(UseDevicePtr, OMPC_use_device_ptr)
-CHECK_SIMPLE_CLAUSE(AcqRel, OMPC_acq_rel)
-CHECK_SIMPLE_CLAUSE(Acquire, OMPC_acquire)
-CHECK_SIMPLE_CLAUSE(SeqCst, OMPC_seq_cst)
-CHECK_SIMPLE_CLAUSE(Release, OMPC_release)
-CHECK_SIMPLE_CLAUSE(Relaxed, OMPC_relaxed)
-CHECK_SIMPLE_CLAUSE(Hint, OMPC_hint)
-CHECK_SIMPLE_CLAUSE(ProcBind, OMPC_proc_bind)
-CHECK_SIMPLE_CLAUSE(DistSchedule, OMPC_dist_schedule)
+CHECK_SIMPLE_CLAUSE(UsesAllocators, OMPC_uses_allocators)
+CHECK_SIMPLE_CLAUSE(Update, OMPC_update)
+CHECK_SIMPLE_CLAUSE(UseDeviceAddr, OMPC_use_device_addr)
+CHECK_SIMPLE_CLAUSE(Write, OMPC_write)
 
 CHECK_REQ_SCALAR_INT_CLAUSE(Allocator, OMPC_allocator)
 CHECK_REQ_SCALAR_INT_CLAUSE(Grainsize, OMPC_grainsize)
 CHECK_REQ_SCALAR_INT_CLAUSE(NumTasks, OMPC_num_tasks)
 CHECK_REQ_SCALAR_INT_CLAUSE(NumTeams, OMPC_num_teams)
 CHECK_REQ_SCALAR_INT_CLAUSE(NumThreads, OMPC_num_threads)
 CHECK_REQ_SCALAR_INT_CLAUSE(Priority, OMPC_priority)
 CHECK_REQ_SCALAR_INT_CLAUSE(ThreadLimit, OMPC_thread_limit)
void OmpStructureChecker::Leave(const parser::OmpAtomic &) {
   }
   if (const auto *clause{FindClause(llvm::omp::Clause::OMPC_acq_rel)}) {
     context_.Say(clause->source,
         "Clause ACQ_REL is not allowed on the ATOMIC directive"_err_en_US);
   }
 }
 // Restrictions specific to each clause are implemented apart from the
 // generalized restrictions.
-void OmpStructureChecker::Enter(const parser::OmpAlignedClause &x) {
+void OmpStructureChecker::Enter(const parser::OmpClause::Aligned &x) {
   CheckAllowed(llvm::omp::Clause::OMPC_aligned);
 
   if (const auto &expr{
-          std::get<std::optional<parser::ScalarIntConstantExpr>>(x.t)}) {
+          std::get<std::optional<parser::ScalarIntConstantExpr>>(x.v.t)}) {
     RequiresConstantPositiveParameter(llvm::omp::Clause::OMPC_aligned, *expr);
   }
   // 2.8.1 TODO: list-item attribute check
 }
-void OmpStructureChecker::Enter(const parser::OmpDefaultmapClause &x) {
+void OmpStructureChecker::Enter(const parser::OmpClause::Defaultmap &x) {
   CheckAllowed(llvm::omp::Clause::OMPC_defaultmap);
   using VariableCategory = parser::OmpDefaultmapClause::VariableCategory;
-  if (!std::get<std::optional<VariableCategory>>(x.t)) {
+  if (!std::get<std::optional<VariableCategory>>(x.v.t)) {
     context_.Say(GetContext().clauseSource,
         "The argument TOFROM:SCALAR must be specified on the DEFAULTMAP "
         "clause"_err_en_US);
   }
 }
-void OmpStructureChecker::Enter(const parser::OmpIfClause &x) {
+void OmpStructureChecker::Enter(const parser::OmpClause::If &x) {
   CheckAllowed(llvm::omp::Clause::OMPC_if);
-
   using dirNameModifier = parser::OmpIfClause::DirectiveNameModifier;
   static std::unordered_map<dirNameModifier, OmpDirectiveSet>
       dirNameModifierMap{{dirNameModifier::Parallel, llvm::omp::parallelSet},
           {dirNameModifier::Target, llvm::omp::targetSet},
           {dirNameModifier::TargetEnterData,
               {llvm::omp::Directive::OMPD_target_enter_data}},
           {dirNameModifier::TargetExitData,
               {llvm::omp::Directive::OMPD_target_exit_data}},
           {dirNameModifier::TargetData,
               {llvm::omp::Directive::OMPD_target_data}},
           {dirNameModifier::TargetUpdate,
               {llvm::omp::Directive::OMPD_target_update}},
           {dirNameModifier::Task, {llvm::omp::Directive::OMPD_task}},
           {dirNameModifier::Taskloop, llvm::omp::taskloopSet}};
   if (const auto &directiveName{
-          std::get<std::optional<dirNameModifier>>(x.t)}) {
+          std::get<std::optional<dirNameModifier>>(x.v.t)}) {
     auto search{dirNameModifierMap.find(*directiveName)};
     if (search == dirNameModifierMap.end() ||
         !search->second.test(GetContext().directive)) {
       context_
           .Say(GetContext().clauseSource,
               "Unmatched directive name modifier %s on the IF clause"_err_en_US,
               parser::ToUpperCaseLetters(
                   parser::OmpIfClause::EnumToString(*directiveName)))
           .Attach(
               GetContext().directiveSource, "Cannot apply to directive"_en_US);
     }
   }
 }
 
-void OmpStructureChecker::Enter(const parser::OmpLinearClause &x) {
+void OmpStructureChecker::Enter(const parser::OmpClause::Linear &x) {
   CheckAllowed(llvm::omp::Clause::OMPC_linear);
 
   // 2.7 Loop Construct Restriction
   if ((llvm::omp::doSet | llvm::omp::simdSet).test(GetContext().directive)) {
-    if (std::holds_alternative<parser::OmpLinearClause::WithModifier>(x.u)) {
+    if (std::holds_alternative<parser::OmpLinearClause::WithModifier>(x.v.u)) {
       context_.Say(GetContext().clauseSource,
           "A modifier may not be specified in a LINEAR clause "
           "on the %s directive"_err_en_US,
           ContextDirectiveAsFortran());
     }
   }
 }
 
llvm::interleave(
         [&] { commaSeperatedMapTypes.append(", "); });
     context_.Say(GetContext().clauseSource,
         "Only the %s map types are permitted "
         "for MAP clauses on the %s directive"_err_en_US,
         commaSeperatedMapTypes, ContextDirectiveAsFortran());
   }
 }
 
-void OmpStructureChecker::Enter(const parser::OmpMapClause &x) {
+void OmpStructureChecker::Enter(const parser::OmpClause::Map &x) {
   CheckAllowed(llvm::omp::Clause::OMPC_map);
-  if (const auto &maptype{std::get<std::optional<parser::OmpMapType>>(x.t)}) {
+
+  if (const auto &maptype{std::get<std::optional<parser::OmpMapType>>(x.v.t)}) {
     using Type = parser::OmpMapType::Type;
     const Type &type{std::get<Type>(maptype->t)};
     switch (GetContext().directive) {
     case llvm::omp::Directive::OMPD_target:
     case llvm::omp::Directive::OMPD_target_teams:
     case llvm::omp::Directive::OMPD_target_teams_distribute:
     case llvm::omp::Directive::OMPD_target_teams_distribute_simd:
     case llvm::omp::Directive::OMPD_target_teams_distribute_parallel_do:
const auto &modType2{
         std::get<std::optional<parser::OmpScheduleModifier::Modifier2>>(
             modifier->t)};
     if (modType1.v.v == type || (modType2 && modType2->v.v == type)) {
       return true;
     }
   }
   return false;
 }
-void OmpStructureChecker::Enter(const parser::OmpScheduleClause &x) {
+void OmpStructureChecker::Enter(const parser::OmpClause::Schedule &x) {
   CheckAllowed(llvm::omp::Clause::OMPC_schedule);
+  const parser::OmpScheduleClause &scheduleClause = x.v;
 
   // 2.7 Loop Construct Restriction
   if (llvm::omp::doSet.test(GetContext().directive)) {
-    const auto &kind{std::get<1>(x.t)};
-    const auto &chunk{std::get<2>(x.t)};
+    const auto &kind{std::get<1>(scheduleClause.t)};
+    const auto &chunk{std::get<2>(scheduleClause.t)};
     if (chunk) {
       if (kind == parser::OmpScheduleClause::ScheduleType::Runtime ||
           kind == parser::OmpScheduleClause::ScheduleType::Auto) {
         context_.Say(GetContext().clauseSource,
             "When SCHEDULE clause has %s specified, "
             "it must not have chunk size specified"_err_en_US,
             parser::ToUpperCaseLetters(
                 parser::OmpScheduleClause::EnumToString(kind)));
       }
-      if (const auto &chunkExpr{
-              std::get<std::optional<parser::ScalarIntExpr>>(x.t)}) {
+      if (const auto &chunkExpr{std::get<std::optional<parser::ScalarIntExpr>>(
+              scheduleClause.t)}) {
         RequiresPositiveParameter(
             llvm::omp::Clause::OMPC_schedule, *chunkExpr, "chunk size");
       }
     }
 
-    if (ScheduleModifierHasType(
-            x, parser::OmpScheduleModifierType::ModType::Nonmonotonic)) {
+    if (ScheduleModifierHasType(scheduleClause,
+            parser::OmpScheduleModifierType::ModType::Nonmonotonic)) {
       if (kind != parser::OmpScheduleClause::ScheduleType::Dynamic &&
           kind != parser::OmpScheduleClause::ScheduleType::Guided) {
         context_.Say(GetContext().clauseSource,
             "The NONMONOTONIC modifier can only be specified with "
             "SCHEDULE(DYNAMIC) or SCHEDULE(GUIDED)"_err_en_US);
       }
     }
   }
 }
 
-void OmpStructureChecker::Enter(const parser::OmpDependClause &x) {
+void OmpStructureChecker::Enter(const parser::OmpClause::Depend &x) {
   CheckAllowed(llvm::omp::Clause::OMPC_depend);
-  if (const auto *inOut{std::get_if<parser::OmpDependClause::InOut>(&x.u)}) {
+  if (const auto *inOut{std::get_if<parser::OmpDependClause::InOut>(&x.v.u)}) {
     const auto &designators{std::get<std::list<parser::Designator>>(inOut->t)};
     for (const auto &ele : designators) {
       if (const auto *dataRef{std::get_if<parser::DataRef>(&ele.u)}) {
         CheckDependList(*dataRef);
         if (const auto *arr{
                 std::get_if<common::Indirection<parser::ArrayElement>>(
                     &dataRef->u)}) {
           CheckDependArraySection(*arr, GetLastName(*dataRef));

llvm/utils/TableGen/DirectiveEmitter.cpp

for (const auto &C : DirLang.getClauses()) {
     } else {
       OS << "void Before(const " << DirLang.getFlangClauseBaseClass()
          << "::" << Clause.getFormattedParserClassName() << " &) { Word(\""
          << Clause.getName().upper() << "\"); }\n";
     }
   }
 }
 
+// Generate check in the Enter functions for clauses classes.
+void GenerateFlangClauseCheckPrototypes(const DirectiveLanguage &DirLang,
+                                        raw_ostream &OS) {
+
+  IfDefScope Scope("GEN_FLANG_CLAUSE_CHECK_ENTER", OS);
+
+  OS << "\n";
+  for (const auto &C : DirLang.getClauses()) {
+    Clause Clause{C};
+    OS << "void Enter(const parser::" << DirLang.getFlangClauseBaseClass()
+       << "::" << Clause.getFormattedParserClassName() << " &);\n";
+  }
+}
+
 // Generate the implementation section for the enumeration in the directive
 // language
 void EmitDirectivesFlangImpl(const DirectiveLanguage &DirLang,
                              raw_ostream &OS) {
 
   GenerateDirectiveClauseSets(DirLang, OS);
 
   GenerateDirectiveClauseMap(DirLang, OS);
 
   GenerateFlangClauseParserClass(DirLang, OS);
 
   GenerateFlangClauseParserClassList(DirLang, OS);
 
   GenerateFlangClauseDump(DirLang, OS);
 
   GenerateFlangClauseUnparse(DirLang, OS);
+
+  GenerateFlangClauseCheckPrototypes(DirLang, OS);
 }
 
 void GenerateClauseClassMacro(const DirectiveLanguage &DirLang,
                               raw_ostream &OS) {
   // Generate macros style information for legacy code in clang
   IfDefScope Scope("GEN_CLANG_CLAUSE_CLASS", OS);
 
   OS << "\n";