[flang] Fix an assert on duplicate initializations

[PeteSteinfeld]

Summary

When declaring the same variable twice with an initialization, we were failing
an internal check. I fixed this by checking to see if the associated symbol
already had an error.

I added tests for pointer and non-pointer initialization of duplicate names.

[klausler]

flang/lib/Semantics/resolve-names.cpp

5683–5700

Might be more clear as if (context().HasError(ultimate)) { } else if (auto *details...)

flang/lib/Semantics/resolve-names.cpp

if (name.symbol) {
     }
   }
 }
 
 void DeclarationVisitor::NonPointerInitialization(const parser::Name &name,
     const parser::ConstantExpr &expr, bool inComponentDecl) {
   if (name.symbol) {
     Symbol &ultimate{name.symbol->GetUltimate()};
+    if (!context().HasError(ultimate)) {
       if (IsPointer(ultimate)) {
-      Say(name, "'%s' is a pointer but is not initialized like one"_err_en_US);
+        Say(name,
+            "'%s' is a pointer but is not initialized like one"_err_en_US);
       } else if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
         CHECK(!details->init());
         Walk(expr);
         // TODO: check C762 - all bounds and type parameters of component
         // are colons or constant expressions if component is initialized
         if (inComponentDecl) {
           // Can't convert to type of component, which might not yet
           // be known; that's done later during instantiation.
           if (MaybeExpr value{EvaluateExpr(expr)}) {
             details->set_init(std::move(*value));
           }
         } else if (MaybeExpr folded{EvaluateConvertedExpr(
                        ultimate, expr, expr.thing.value().source)}) {
           details->set_init(std::move(*folded));
         }
       }
     }
   }
+}
 
 void ResolveNamesVisitor::HandleCall(
     Symbol::Flag procFlag, const parser::Call &call) {
   std::visit(
       common::visitors{
           [&](const parser::Name &x) { HandleProcedureName(procFlag, x); },
           [&](const parser::ProcComponentRef &x) { Walk(x); },
       },

flang/test/Semantics/resolve91.f90

module m6
   character(len=ubound(iarray)(1)) :: first
 end module m6
 
 module m7
   integer, dimension(2) :: iarray
   !ERROR: Derived type 'ubound' not found
   integer :: ivar = ubound(iarray)(1)
 end module m7
+
+module m8
+  integer :: iVar = 3
+  !ERROR: The type of 'ivar' has already been declared
+  integer :: iVar = 4
+  integer, target :: jVar = 5
+  integer, target :: kVar = 5
+  integer, pointer :: pVar => jVar
+  !ERROR: The type of 'pvar' has already been declared
+  integer, pointer :: pVar => kVar
+end module m8