[flang][OpenMP][Semantics] resolve objects in the flush arg list

flang/lib/Semantics/resolve-directives.cpp

@@ -409,6 +409,26 @@ class OmpAttributeVisitor : DirectiveAttributeVisitor<llvm::omp::Directive> {
   }
   void Post(const parser::OpenMPDepobjConstruct &) { PopContext(); }
 
+  bool Pre(const parser::OpenMPFlushConstruct &x) {
+    PushContext(x.source, llvm::omp::Directive::OMPD_flush);
+    for (auto &arg : x.v.Arguments().v) {
+      if (auto *locator{std::get_if<parser::OmpLocator>(&arg.u)}) {
+        if (auto *object{std::get_if<parser::OmpObject>(&locator->u)}) {
+          if (auto *name{std::get_if<parser::Name>(&object->u)}) {
+            // ResolveOmpCommonBlockName resolves the symbol as a side effect
+            if (!ResolveOmpCommonBlockName(name)) {
+              context_.Say(name->source, // 2.15.3
+                  "COMMON block must be declared in the same scoping unit "
+                  "in which the OpenMP directive or clause appears"_err_en_US);
+            }
+          }
+        }
+      }
+    }
+    return true;
+  }
+  void Post(const parser::OpenMPFlushConstruct &) { PopContext(); }
+
   bool Pre(const parser::OpenMPRequiresConstruct &x) {
     using Flags = WithOmpDeclarative::RequiresFlags;
     using Requires = WithOmpDeclarative::RequiresFlag;

flang/test/Semantics/OpenMP/flush04.f90

@@ -0,0 +1,11 @@
+! RUN: %python %S/../test_errors.py %s %flang_fc1 -fopenmp
+
+! Regression test to ensure that the name /c/ in the flush argument list is
+! resolved to the common block symbol.
+
+  common /c/ x
+  real :: x
+!ERROR: FLUSH argument must be a variable list item
+  !$omp flush(/c/)
+end
+