Fix edge case in declare target initializer expression

[RitanyaB]

Summary

This patch adds support for the following edge cases in declare target -
#pragma omp declare target(variable)
#pragma omp declare target to(variable)

[ABataev]

LG

clang/lib/Sema/SemaOpenMP.cpp

void Sema::ActOnOpenMPDeclareTargetName(NamedDecl *ND, SourceLocation Loc,
   }
   auto *A = OMPDeclareTargetDeclAttr::CreateImplicit(
       Context, MT, DTCI.DT, IndirectE, IsIndirect, Level,
       SourceRange(Loc, Loc));
   ND->addAttr(A);
   if (ASTMutationListener *ML = Context.getASTMutationListener())
     ML->DeclarationMarkedOpenMPDeclareTarget(ND, A);
   checkDeclIsAllowedInOpenMPTarget(nullptr, ND, Loc);
+  if (auto *VD = dyn_cast<VarDecl>(ND);
+      LangOpts.OpenMP && VD && VD->hasAttr<OMPDeclareTargetDeclAttr>() &&
+      VD->hasGlobalStorage())
+    ActOnOpenMPDeclareTargetInitializer(ND);
 }
 
 static void checkDeclInTargetContext(SourceLocation SL, SourceRange SR,
                                      Sema &SemaRef, Decl *D) {
   if (!D || !isa<VarDecl>(D))
     return;
   auto *VD = cast<VarDecl>(D);
   std::optional<OMPDeclareTargetDeclAttr::MapTypeTy> MapTy =

clang/test/OpenMP/declare_target_variables_ast_print.cpp

 declare *obj2 = &obj1;
 
 struct target{
   int x;
   void print();
 };
 static target S;
 
+static int var3 = 100;
+static int *ptr_3 = &var3;
+static char c = 'a';
+
 #pragma omp declare target
 int target_var = variable;
 float target_var1 = variable2;
 int *ptr = &var;
 int ***ptr2 = &ptr1;
 int (**ptr3)[2] = &arrptr;
 declare **obj3 = &obj2;
 target *S1 = &S;
 #pragma omp end declare target
+#pragma omp declare target(ptr_3)
+#pragma omp declare target to(c)
+
 // CHECK: #pragma omp declare target
 // CHECK-NEXT: static int variable = 100;
 // CHECK-NEXT: #pragma omp end declare target
 
 // CHECK-NEXT: #pragma omp declare target
 // CHECK-NEXT: static float variable1 = 200;
 // CHECK-NEXT: #pragma omp end declare target
 // CHECK-NEXT: #pragma omp declare target

 
 // CHECK-NEXT: struct target {
 // CHECK-NEXT:  int x;
 // CHECK-NEXT:  void print();
 // CHECK-NEXT: };
 // CHECK-NEXT: #pragma omp declare target
 // CHECK-NEXT: static target S;
 // CHECK-NEXT: #pragma omp end declare target
-
+// CHECK-NEXT: #pragma omp declare target
+// CHECK-NEXT: static int var3 = 100;
+// CHECK-NEXT: #pragma omp end declare target
+// CHECK-NEXT: #pragma omp declare target
+// CHECK-NEXT: static int *ptr_3 = &var3;
+// CHECK-NEXT: #pragma omp end declare target
+// CHECK-NEXT: #pragma omp declare target
+// CHECK-NEXT: static char c = 'a';
+// CHECK-NEXT: #pragma omp end declare target
 // CHECK-NEXT: #pragma omp declare target
 // CHECK-NEXT: int target_var = variable;
 // CHECK-NEXT: #pragma omp end declare target
 // CHECK-NEXT: #pragma omp declare target
 // CHECK-NEXT: float target_var1 = variable2;
 // CHECK-NEXT: #pragma omp end declare target
 // CHECK-NEXT: #pragma omp declare target
 // CHECK-NEXT: int *ptr = &var;