Only accept ompx_bare on a combined "TARGET TEAMS" construct

Author: kparzysz

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

@@ -2433,6 +2433,7 @@ CHECK_SIMPLE_CLAUSE(CancellationConstructType, OMPC_cancellation_construct_type)
 CHECK_SIMPLE_CLAUSE(Doacross, OMPC_doacross)
 CHECK_SIMPLE_CLAUSE(OmpxAttribute, OMPC_ompx_attribute)
 CHECK_SIMPLE_CLAUSE(OmpxBare, OMPC_ompx_bare)
+CHECK_SIMPLE_CLAUSE(Enter, OMPC_enter)
 CHECK_SIMPLE_CLAUSE(Fail, OMPC_fail)
 CHECK_SIMPLE_CLAUSE(Weak, OMPC_weak)
 
@@ -3439,6 +3440,17 @@ void OmpStructureChecker::Enter(const parser::OmpClause::To &x) {
   }
 }
 
+void OmpStructureChecker::Enter(const parser::OmpClause::OmpxBare &x) {
+  // Don't call CheckAllowedClause, because it allows "ompx_bare" on
+  // a non-combined "target" directive (for reasons of splitting combined
+  // directives). In source code it's only allowed on "target teams".
+  if (GetContext().directive != llvm::omp::Directive::OMPD_target_teams) {
+    context_.Say(GetContext().clauseSource,
+        "%s clause is only allowed on combined TARGET TEAMS"_err_en_US,
+        parser::ToUpperCaseLetters(getClauseName(llvm::omp::OMPC_ompx_bare)));
+  }
+}
+
 llvm::StringRef OmpStructureChecker::getClauseName(llvm::omp::Clause clause) {
   return llvm::omp::getOpenMPClauseName(clause);
 }

flang/test/Semantics/OpenMP/ompx-bare.f90

@@ -0,0 +1,21 @@
+!RUN: %python %S/../test_errors.py %s %flang -fopenmp -fopenmp-version=51
+
+subroutine test1
+!ERROR: OMPX_BARE clause is only allowed on combined TARGET TEAMS
+  !$omp target ompx_bare
+  !$omp end target
+end
+
+subroutine test2
+  !$omp target
+!ERROR: OMPX_BARE clause is only allowed on combined TARGET TEAMS
+  !$omp teams ompx_bare
+  !$omp end teams
+  !$omp end target
+end
+
+subroutine test3
+!No errors
+  !$omp target teams ompx_bare
+  !$omp end target teams
+end