[flang] Catch inconsistent function/subroutine usage of procedure pointer components

[klausler]

Summary

When a derived type has a procedure pointer component with no interface,
we can't do a lot of checking on its call sites, but we can at least require
that the same procedure pointer component be used consistently as either
a function or as a subroutine, but not both.

flang/lib/Semantics/resolve-names.cpp

void DeclarationVisitor::NonPointerInitialization(
   }
 }
 
 void ResolveNamesVisitor::HandleCall(
     Symbol::Flag procFlag, const parser::Call &call) {
   common::visit(
       common::visitors{
           [&](const parser::Name &x) { HandleProcedureName(procFlag, x); },
-          [&](const parser::ProcComponentRef &x) { Walk(x); },
+          [&](const parser::ProcComponentRef &x) {
+            Walk(x);
+            const parser::Name &name{x.v.thing.component};
+            if (Symbol * symbol{name.symbol}) {
+              if (IsProcedure(*symbol)) {
+                SetProcFlag(name, *symbol, procFlag);
+              }
+            }
+          },
       },
       std::get<parser::ProcedureDesignator>(call.t).u);
   Walk(std::get<std::list<parser::ActualArgSpec>>(call.t));
 }
 
 void ResolveNamesVisitor::HandleProcedureName(
     Symbol::Flag flag, const parser::Name &name) {
   CHECK(flag == Symbol::Flag::Function || flag == Symbol::Flag::Subroutine);

flang/test/Semantics/resolve09.f90

subroutine s8
   call a8()
   x = b8()
 end
 subroutine a8()
 end
 function b8()
   b8 = 0.0
 end
+
+subroutine s9
+  type t
+    procedure(), nopass, pointer :: p1, p2
+  end type
+  type(t) x
+  print *, x%p1()
+  call x%p2
+  !ERROR: Cannot call function 'p1' like a subroutine
+  call x%p1
+  !ERROR: Cannot call subroutine 'p2' like a function
+  print *, x%p2()
+end subroutine