[flang] Catch name conflict between generic TBP and inherited non-generic

[klausler]

Summary

A generic procedure binding in an extended derived type may not have the
same name as a symbol inherited from an ancestor type unless that inherited
symbol is also a generic TBP. Since generic names can be things like
"ASSIGNMENT(=)", name resolution doesn't use OkToAddComponent() for
generic TBPs, which would have caught this error as it does for other
symbols in derived types, so it must be special-cased.

flang/lib/Semantics/resolve-names.cpp

if (currScope().IsDerivedType() && currScope().symbol()) {
     }
   }
 }
 
 bool DeclarationVisitor::Pre(const parser::TypeBoundGenericStmt &x) {
   const auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)};
   const auto &genericSpec{std::get<Indirection<parser::GenericSpec>>(x.t)};
   const auto &bindingNames{std::get<std::list<parser::Name>>(x.t)};
-  auto info{GenericSpecInfo{genericSpec.value()}};
+  GenericSpecInfo info{genericSpec.value()};
   SourceName symbolName{info.symbolName()};
   bool isPrivate{accessSpec ? accessSpec->v == parser::AccessSpec::Kind::Private
                             : derivedTypeInfo_.privateBindings};
   auto *genericSymbol{FindInScope(symbolName)};
   if (genericSymbol) {
     if (!genericSymbol->has<GenericDetails>()) {
       genericSymbol = nullptr; // MakeTypeSymbol will report the error below
     }
   } else {
-    // look in parent types:
-    Symbol *inheritedSymbol{nullptr};
+    // look in ancestor types for a generic of the same name
     for (const auto &name : GetAllNames(context(), symbolName)) {
-      inheritedSymbol = currScope().FindComponent(SourceName{name});
-      if (inheritedSymbol) {
-        break;
+      if (Symbol * inherited{currScope().FindComponent(SourceName{name})}) {
+        if (inherited->has<GenericDetails>()) {
+          CheckAccessibility(symbolName, isPrivate, *inherited); // C771
+        } else {
+          Say(symbolName,
+              "Type bound generic procedure '%s' may not have the same name as a non-generic symbol inherited from an ancestor type"_err_en_US)
+              .Attach(inherited->name(), "Inherited symbol"_en_US);
         }
+        break;
       }
-    if (inheritedSymbol && inheritedSymbol->has<GenericDetails>()) {
-      CheckAccessibility(symbolName, isPrivate, *inheritedSymbol); // C771
     }
   }
   if (genericSymbol) {
     CheckAccessibility(symbolName, isPrivate, *genericSymbol); // C771
   } else {
     genericSymbol = MakeTypeSymbol(symbolName, GenericDetails{});
     if (!genericSymbol) {
       return false;

flang/test/Semantics/resolve117.f90

+! RUN: %python %S/test_errors.py %s %flang_fc1
+! Test name conflicts with type-bound generics
+module m
+  type base1(k)
+    integer, kind :: k = 4
+    real x
+   contains
+    procedure, nopass :: tbp => sub
+    generic :: gen => tbp
+  end type
+  type, extends(base1) :: ext1
+   contains
+    procedure, nopass :: sub
+    !ERROR: Type parameter, component, or procedure binding 'base1' already defined in this type
+    generic :: base1 => sub
+    !ERROR: Type bound generic procedure 'k' may not have the same name as a non-generic symbol inherited from an ancestor type
+    generic :: k => sub
+    !ERROR: Type bound generic procedure 'x' may not have the same name as a non-generic symbol inherited from an ancestor type
+    generic :: x => sub
+    !ERROR: Type bound generic procedure 'tbp' may not have the same name as a non-generic symbol inherited from an ancestor type
+    generic :: tbp => sub
+    generic :: gen => sub ! ok
+  end type
+ contains
+  subroutine sub
+  end
+end