[flang-commits] [flang] [flang] Fix corner case of defined component assignment (PR #142201)

[Peter Klausler via flang-commits]

https://github.com/klausler updated https://github.com/llvm/llvm-project/pull/142201

>From 714ace59cd36d7ff513d351e0c01d5b39908d058 Mon Sep 17 00:00:00 2001
From: Peter Klausler <pklausler at nvidia.com>
Date: Fri, 30 May 2025 11:59:44 -0700
Subject: [PATCH] [flang] Fix corner case of defined component assignment

For componentwise assignment in derived type intrinsic assignment,
the runtime type information's special binding table is currently
populated only with type-bound ASSIGNMENT(=) procedures that have
the same derived type for both arguments.  This restriction
excludes all defined assignments for cases that cannot arise in
this context, like defined assignments from intrinsic types or
incompatible derived types.

However, this restriction also excludes defined assignments from
distinct but compatible derived types, i.e. ancestors.  Loosen it
a little to allow them.

Fixes https://github.com/llvm/llvm-project/issues/142151.
---
 flang/lib/Semantics/runtime-type-info.cpp | 12 ++++++---
 flang/test/Semantics/typeinfo01.f90       | 33 +++++++++++++++++++++--
 2 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/flang/lib/Semantics/runtime-type-info.cpp b/flang/lib/Semantics/runtime-type-info.cpp
index 98295f3705a71..378697237ba9b 100644
--- a/flang/lib/Semantics/runtime-type-info.cpp
+++ b/flang/lib/Semantics/runtime-type-info.cpp
@@ -1121,10 +1121,10 @@ void RuntimeTableBuilder::DescribeSpecialProc(
     int argThatMightBeDescriptor{0};
     MaybeExpr which;
     if (isAssignment) {
-      // Only type-bound asst's with the same type on both dummy arguments
+      // Only type-bound asst's with compatible types on both dummy arguments
       // are germane to the runtime, which needs only these to implement
       // component assignment as part of intrinsic assignment.
-      // Non-type-bound generic INTERFACEs and assignments from distinct
+      // Non-type-bound generic INTERFACEs and assignments from incompatible
       // types must not be used for component intrinsic assignment.
       CHECK(proc->dummyArguments.size() == 2);
       const auto t1{
@@ -1137,8 +1137,12 @@ void RuntimeTableBuilder::DescribeSpecialProc(
               .type.type()};
       if (!binding || t1.category() != TypeCategory::Derived ||
           t2.category() != TypeCategory::Derived ||
-          t1.IsUnlimitedPolymorphic() || t2.IsUnlimitedPolymorphic() ||
-          t1.GetDerivedTypeSpec() != t2.GetDerivedTypeSpec()) {
+          t1.IsUnlimitedPolymorphic() || t2.IsUnlimitedPolymorphic()) {
+        return;
+      }
+      if (!derivedTypeSpec ||
+          !derivedTypeSpec->MatchesOrExtends(t1.GetDerivedTypeSpec()) ||
+          !derivedTypeSpec->MatchesOrExtends(t2.GetDerivedTypeSpec())) {
         return;
       }
       which = proc->IsElemental() ? elementalAssignmentEnum_
diff --git a/flang/test/Semantics/typeinfo01.f90 b/flang/test/Semantics/typeinfo01.f90
index c1427f28753cf..d228cd2a84ca4 100644
--- a/flang/test/Semantics/typeinfo01.f90
+++ b/flang/test/Semantics/typeinfo01.f90
@@ -73,7 +73,7 @@ module m06
   end type
   type, extends(t) :: t2
    contains
-    procedure :: s1 => s2 ! override
+    procedure :: s1 => s2
   end type
  contains
   subroutine s1(x, y)
@@ -86,8 +86,37 @@ subroutine s2(x, y)
   end subroutine
 !CHECK: .c.t2, SAVE, TARGET (CompilerCreated, ReadOnly): ObjectEntity type: TYPE(component) shape: 0_8:0_8 init:[component::component(name=.n.t,genre=1_1,category=6_1,kind=0_1,rank=0_1,offset=0_8,characterlen=value(genre=1_1,value=0_8),derived=.dt.t,lenvalue=NULL(),bounds=NULL(),initialization=NULL())]
 !CHECK: .dt.t, SAVE, TARGET (CompilerCreated, ReadOnly): ObjectEntity type: TYPE(derivedtype) init:derivedtype(binding=.v.t,name=.n.t,sizeinbytes=0_8,uninstantiated=NULL(),kindparameter=NULL(),lenparameterkind=NULL(),component=NULL(),procptr=NULL(),special=.s.t,specialbitset=2_4,hasparent=0_1,noinitializationneeded=1_1,nodestructionneeded=1_1,nofinalizationneeded=1_1)
-!CHECK: .dt.t2, SAVE, TARGET (CompilerCreated, ReadOnly): ObjectEntity type: TYPE(derivedtype) init:derivedtype(binding=.v.t2,name=.n.t2,sizeinbytes=0_8,uninstantiated=NULL(),kindparameter=NULL(),lenparameterkind=NULL(),component=.c.t2,procptr=NULL(),special=NULL(),specialbitset=0_4,hasparent=1_1,noinitializationneeded=1_1,nodestructionneeded=1_1,nofinalizationneeded=1_1)
+!CHECK: .dt.t2, SAVE, TARGET (CompilerCreated, ReadOnly): ObjectEntity type: TYPE(derivedtype) init:derivedtype(binding=.v.t2,name=.n.t2,sizeinbytes=0_8,uninstantiated=NULL(),kindparameter=NULL(),lenparameterkind=NULL(),component=.c.t2,procptr=NULL(),special=.s.t2,specialbitset=2_4,hasparent=1_1,noinitializationneeded=1_1,nodestructionneeded=1_1,nofinalizationneeded=1_1)
 !CHECK: .s.t, SAVE, TARGET (CompilerCreated, ReadOnly): ObjectEntity type: TYPE(specialbinding) shape: 0_8:0_8 init:[specialbinding::specialbinding(which=1_1,isargdescriptorset=3_1,istypebound=1_1,isargcontiguousset=0_1,proc=s1)]
+!CHECK: .s.t2, SAVE, TARGET (CompilerCreated, ReadOnly): ObjectEntity type: TYPE(specialbinding) shape: 0_8:0_8 init:[specialbinding::specialbinding(which=1_1,isargdescriptorset=3_1,istypebound=1_1,isargcontiguousset=0_1,proc=s2)]
+!CHECK: .v.t, SAVE, TARGET (CompilerCreated, ReadOnly): ObjectEntity type: TYPE(binding) shape: 0_8:0_8 init:[binding::binding(proc=s1,name=.n.s1)]
+!CHECK: .v.t2, SAVE, TARGET (CompilerCreated, ReadOnly): ObjectEntity type: TYPE(binding) shape: 0_8:0_8 init:[binding::binding(proc=s2,name=.n.s1)]
+end module
+
+module m06a
+  type :: t
+   contains
+    procedure, pass(y) :: s1
+    generic :: assignment(=) => s1
+  end type
+  type, extends(t) :: t2
+   contains
+    procedure, pass(y) :: s1 => s2
+  end type
+ contains
+  subroutine s1(x, y)
+    class(t), intent(out) :: x
+    class(t), intent(in) :: y
+  end subroutine
+  subroutine s2(x, y)
+    class(t), intent(out) :: x
+    class(t2), intent(in) :: y
+  end subroutine
+!CHECK: .c.t2, SAVE, TARGET (CompilerCreated, ReadOnly): ObjectEntity type: TYPE(component) shape: 0_8:0_8 init:[component::component(name=.n.t,genre=1_1,category=6_1,kind=0_1,rank=0_1,offset=0_8,characterlen=value(genre=1_1,value=0_8),derived=.dt.t,lenvalue=NULL(),bounds=NULL(),initialization=NULL())]
+!CHECK: .dt.t, SAVE, TARGET (CompilerCreated, ReadOnly): ObjectEntity type: TYPE(derivedtype) init:derivedtype(binding=.v.t,name=.n.t,sizeinbytes=0_8,uninstantiated=NULL(),kindparameter=NULL(),lenparameterkind=NULL(),component=NULL(),procptr=NULL(),special=.s.t,specialbitset=2_4,hasparent=0_1,noinitializationneeded=1_1,nodestructionneeded=1_1,nofinalizationneeded=1_1)
+!CHECK: .dt.t2, SAVE, TARGET (CompilerCreated, ReadOnly): ObjectEntity type: TYPE(derivedtype) init:derivedtype(binding=.v.t2,name=.n.t2,sizeinbytes=0_8,uninstantiated=NULL(),kindparameter=NULL(),lenparameterkind=NULL(),component=.c.t2,procptr=NULL(),special=.s.t2,specialbitset=2_4,hasparent=1_1,noinitializationneeded=1_1,nodestructionneeded=1_1,nofinalizationneeded=1_1)
+!CHECK: .s.t, SAVE, TARGET (CompilerCreated, ReadOnly): ObjectEntity type: TYPE(specialbinding) shape: 0_8:0_8 init:[specialbinding::specialbinding(which=1_1,isargdescriptorset=3_1,istypebound=1_1,isargcontiguousset=0_1,proc=s1)]
+!CHECK: .s.t2, SAVE, TARGET (CompilerCreated, ReadOnly): ObjectEntity type: TYPE(specialbinding) shape: 0_8:0_8 init:[specialbinding::specialbinding(which=1_1,isargdescriptorset=3_1,istypebound=1_1,isargcontiguousset=0_1,proc=s2)]
 !CHECK: .v.t, SAVE, TARGET (CompilerCreated, ReadOnly): ObjectEntity type: TYPE(binding) shape: 0_8:0_8 init:[binding::binding(proc=s1,name=.n.s1)]
 !CHECK: .v.t2, SAVE, TARGET (CompilerCreated, ReadOnly): ObjectEntity type: TYPE(binding) shape: 0_8:0_8 init:[binding::binding(proc=s2,name=.n.s1)]
 end module