[flang] Fix searches for polymorphic components (llvm#102212)

FindPolymorphicAllocatableUltimateComponent needs to be
FindPolymorphicAllocatablePotentialComponent. The current search is
missing cases where a derived type has an allocatable component whose
type has a polymorphic allocatable component.

flang/include/flang/Semantics/tools.h

@@ -442,6 +442,18 @@ std::list<std::list<SymbolRef>> GetStorageAssociations(const Scope &);
 //     closure of its components (including POINTERs) and the
 //     PotentialAndPointer subobject components of its non-POINTER derived type
 //     components.
+//
+// type t1                     ultimate components:  x, a, p
+//  real x                     direct components:    x, a, p
+//  real, allocatable :: a     potential components: x, a
+//  real, pointer :: p         potential & pointers: x, a, p
+// end type
+// type t2                     ultimate components:  y, c%x, c%a, c%p, b
+//  real y                     direct components:    y, c, c%x, c%a, c%p, b
+//  type(t1) :: c              potential components: y, c, c%x, c%a, b, b%x, b%a
+//  type(t1), allocatable :: b potential & pointers: potentials + c%p + b%p
+// end type
+//
 // Parent and procedure components are considered against these definitions.
 // For this kind of iterator, the component tree is recursively visited in the
 // following order:
@@ -620,8 +632,8 @@ UltimateComponentIterator::const_iterator FindAllocatableUltimateComponent(
     const DerivedTypeSpec &);
 DirectComponentIterator::const_iterator FindAllocatableOrPointerDirectComponent(
     const DerivedTypeSpec &);
-UltimateComponentIterator::const_iterator
-FindPolymorphicAllocatableUltimateComponent(const DerivedTypeSpec &);
+PotentialComponentIterator::const_iterator
+FindPolymorphicAllocatablePotentialComponent(const DerivedTypeSpec &);
 
 // The LabelEnforce class (given a set of labels) provides an error message if
 // there is a branch to a label which is not in the given set.

flang/lib/Semantics/check-declarations.cpp

@@ -405,9 +405,10 @@ void CheckHelper::Check(const Symbol &symbol) {
             messages_.Say(
                 "Result of pure function may not have an impure FINAL subroutine"_err_en_US);
           }
-          if (auto bad{FindPolymorphicAllocatableUltimateComponent(*derived)}) {
+          if (auto bad{
+                  FindPolymorphicAllocatablePotentialComponent(*derived)}) {
             SayWithDeclaration(*bad,
-                "Result of pure function may not have polymorphic ALLOCATABLE ultimate component '%s'"_err_en_US,
+                "Result of pure function may not have polymorphic ALLOCATABLE potential component '%s'"_err_en_US,
                 bad.BuildResultDesignatorName());
           }
         }

flang/lib/Semantics/definable.cpp

@@ -223,7 +223,8 @@ static std::optional<parser::Message> WhyNotDefinableLast(parser::CharBlock at,
       }
       if (const DerivedTypeSpec * derived{GetDerivedTypeSpec(dyType)}) {
         if (!flags.test(DefinabilityFlag::PolymorphicOkInPure)) {
-          if (auto bad{FindPolymorphicAllocatableUltimateComponent(*derived)}) {
+          if (auto bad{
+                  FindPolymorphicAllocatablePotentialComponent(*derived)}) {
             return BlameSymbol(at,
                 "'%s' has polymorphic component '%s' in a pure subprogram"_en_US,
                 original, bad.BuildResultDesignatorName());

flang/lib/Semantics/tools.cpp

@@ -866,7 +866,7 @@ const Symbol *HasImpureFinal(const Symbol &original, std::optional<int> rank) {
 
 bool MayRequireFinalization(const DerivedTypeSpec &derived) {
   return IsFinalizable(derived) ||
-      FindPolymorphicAllocatableUltimateComponent(derived);
+      FindPolymorphicAllocatablePotentialComponent(derived);
 }
 
 bool HasAllocatableDirectComponent(const DerivedTypeSpec &derived) {
@@ -1404,11 +1404,11 @@ DirectComponentIterator::const_iterator FindAllocatableOrPointerDirectComponent(
   return std::find_if(directs.begin(), directs.end(), IsAllocatableOrPointer);
 }
 
-UltimateComponentIterator::const_iterator
-FindPolymorphicAllocatableUltimateComponent(const DerivedTypeSpec &derived) {
-  UltimateComponentIterator ultimates{derived};
+PotentialComponentIterator::const_iterator
+FindPolymorphicAllocatablePotentialComponent(const DerivedTypeSpec &derived) {
+  PotentialComponentIterator potentials{derived};
   return std::find_if(
-      ultimates.begin(), ultimates.end(), IsPolymorphicAllocatable);
+      potentials.begin(), potentials.end(), IsPolymorphicAllocatable);
 }
 
 const Symbol *FindUltimateComponent(const DerivedTypeSpec &derived,

flang/test/Semantics/call10.f90

@@ -78,7 +78,7 @@ pure function f07() ! C1585
     class(t), allocatable :: f07
   end function
   pure function f08() ! C1585
-    !ERROR: Result of pure function may not have polymorphic ALLOCATABLE ultimate component '%a'
+    !ERROR: Result of pure function may not have polymorphic ALLOCATABLE potential component '%a'
     type(polyAlloc) :: f08
   end function
 

flang/test/Semantics/typeinfo11.f90

@@ -0,0 +1,17 @@
+!RUN: bbc --dump-symbols %s | FileCheck %s
+!RUN: %flang_fc1 -fdebug-dump-symbols %s | FileCheck %s
+
+!Tests that derived types with polymorphic potential subobject
+!components do not have their noFinalizationNeeded flags set, even
+!when those components are packaged within another allocatable.
+
+type t1
+  class(*), allocatable :: a
+end type
+type t2
+  type(t1), allocatable :: b
+end type
+type(t2) x
+end
+
+!CHECK: .dt.t2, SAVE, TARGET (CompilerCreated, ReadOnly): ObjectEntity type: TYPE(derivedtype) init:derivedtype(binding=NULL(),name=.n.t2,sizeinbytes=40_8,uninstantiated=NULL(),kindparameter=NULL(),lenparameterkind=NULL(),component=.c.t2,procptr=NULL(),special=NULL(),specialbitset=0_4,hasparent=0_1,noinitializationneeded=0_1,nodestructionneeded=0_1,nofinalizationneeded=0_1)