Restored CheckHelper::CheckGlobalName() to original implementation.

Instead, added IsAlternateEntry() and modified IsExternalProcedureDefinition().

Author: eugeneepshteyn

flang/include/flang/Evaluate/tools.h

@@ -1531,6 +1531,15 @@ class Scope;
 // point to its subprogram.
 const Symbol *GetMainEntry(const Symbol *);
 
+inline bool IsAlternateEntry(const Symbol *symbol) {
+  // If symbol is not alternate entry symbol, GetMainEntry() returns the same
+  // symbol.
+  return symbol && GetMainEntry(symbol) != symbol;
+}
+inline bool IsAlternateEntry(const Symbol &symbol) {
+  return IsAlternateEntry(&symbol);
+}
+
 // These functions are used in Evaluate so they are defined here rather than in
 // Semantics to avoid a link-time dependency on Semantics.
 // All of these apply GetUltimate() or ResolveAssociations() to their arguments.

flang/lib/Semantics/check-declarations.cpp

@@ -2950,7 +2950,7 @@ static bool IsSubprogramDefinition(const Symbol &symbol) {
 
 static bool IsExternalProcedureDefinition(const Symbol &symbol) {
   return IsBlockData(symbol) ||
-      (IsSubprogramDefinition(symbol) &&
+      ((IsSubprogramDefinition(symbol) || IsAlternateEntry(symbol)) &&
           (IsExternal(symbol) || symbol.GetBindName()));
 }
 
@@ -2997,12 +2997,9 @@ void CheckHelper::CheckGlobalName(const Symbol &symbol) {
         // they're not in the same scope.
       } else if ((IsProcedure(symbol) || IsBlockData(symbol)) &&
           (IsProcedure(other) || IsBlockData(other)) &&
-          (!(IsExternalProcedureDefinition(symbol) || GetMainEntry(&symbol)) ||
-              !(IsExternalProcedureDefinition(other) ||
-                  GetMainEntry(&other)))) {
-        // Both are procedures/BLOCK DATA, not both definitions.
-        // Note: GetMainEntry() above returns non-null in case symbol
-        // is an alternate entry.
+          (!IsExternalProcedureDefinition(symbol) ||
+              !IsExternalProcedureDefinition(other))) {
+        // both are procedures/BLOCK DATA, not both definitions
       } else if (IsSameSymbolFromHermeticModule(symbol, other)) {
         // Both symbols are the same thing.
       } else if (symbol.has<ModuleDetails>()) {