[flang] Fixed comparison for derived types constants.

The two constants should be equal only if their derived types
are the same. This fixes regression caused by D150380.

Differential Revision: https://reviews.llvm.org/D150634

3 files changed, 15 insertions, 0 deletions

diff --git a/flang/include/flang/Evaluate/constant.h b/flang/include/flang/Evaluate/constant.h
index 611ee7772d2a..73e4271cc28a 100644
--- a/flang/include/flang/Evaluate/constant.h
+++ b/flang/include/flang/Evaluate/constant.h
@@ -225,6 +225,7 @@ public:
   std::optional<StructureConstructor> GetScalarValue() const;
   StructureConstructor At(const ConstantSubscripts &) const;
 
+  bool operator==(const Constant &) const;
   Constant Reshape(ConstantSubscripts &&) const;
   std::size_t CopyFrom(const Constant &source, std::size_t count,
       ConstantSubscripts &resultSubscripts, const std::vector<int> *dimOrder);
diff --git a/flang/lib/Evaluate/constant.cpp b/flang/lib/Evaluate/constant.cpp
index 1a4d30cf9d14..c94b198fdaf2 100644
--- a/flang/lib/Evaluate/constant.cpp
+++ b/flang/lib/Evaluate/constant.cpp
@@ -346,6 +346,12 @@ StructureConstructor Constant<SomeDerived>::At(
   return {result().derivedTypeSpec(), values_.at(SubscriptsToOffset(index))};
 }
 
+bool Constant<SomeDerived>::operator==(
+    const Constant<SomeDerived> &that) const {
+  return result().derivedTypeSpec() == that.result().derivedTypeSpec() &&
+      shape() == that.shape() && values_ == that.values_;
+}
+
 auto Constant<SomeDerived>::Reshape(ConstantSubscripts &&dims) const
     -> Constant {
   return {result().derivedTypeSpec(), Base::Reshape(dims), std::move(dims)};
diff --git a/flang/test/Lower/constant-literal-mangling.f90 b/flang/test/Lower/constant-literal-mangling.f90
index ef33ffe450b0..33a658fb61cd 100644
--- a/flang/test/Lower/constant-literal-mangling.f90
+++ b/flang/test/Lower/constant-literal-mangling.f90
@@ -9,6 +9,12 @@ type otherType
   integer :: i
 end type
 
+type emptyType1
+end type emptyType1
+
+type emptyType2
+end type emptyType2
+
   print *, [42, 42]
 ! CHECK: fir.address_of(@_QQro.2xi4.0)
 
@@ -68,6 +74,8 @@ end type
   print *, [otherType(42)]
 ! CHECK: fir.address_of(@_QQro.1x_QFTothertype.14)
 
+  print *, [emptyType1()]
+  print *, [emptyType2()]
 end
 
 ! CHECK: fir.global internal @_QQro.1x_QFTsometype.10 constant : !fir.array<1x!fir.type<_QFTsometype{i:i32}>> {