[PATCH] D87535: [flang] Fix bug for forward referenced type

[Pete Steinfeld via Phabricator via llvm-commits]

PeteSteinfeld updated this revision to Diff 291682.
PeteSteinfeld added a comment.

I added code to detect the actual error and associate it with the correct
source line.  Note that the `git commit` message is changed with a more
detailed explanation.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D87535/new/

https://reviews.llvm.org/D87535

Files:
  flang/lib/Semantics/expression.cpp
  flang/lib/Semantics/symbol.cpp
  flang/test/Semantics/bad-forward-type.f90


Index: flang/test/Semantics/bad-forward-type.f90
===================================================================
--- flang/test/Semantics/bad-forward-type.f90
+++ flang/test/Semantics/bad-forward-type.f90
@@ -70,3 +70,12 @@
   type, extends(undef) :: t
   end type
 end subroutine
+
+subroutine s8
+  implicit type(t2)(x)
+  !ERROR: Cannot construct value for derived type 't2' before it is defined
+  parameter(y=t2(12.3))
+  type t2
+    real :: c
+  end type
+end subroutine
Index: flang/lib/Semantics/symbol.cpp
===================================================================
--- flang/lib/Semantics/symbol.cpp
+++ flang/lib/Semantics/symbol.cpp
@@ -541,13 +541,11 @@
 
 const Symbol *Symbol::GetParentComponent(const Scope *scope) const {
   if (const auto *dtDetails{detailsIf<DerivedTypeDetails>()}) {
-    if (!scope) {
-      scope = scope_;
+    if (const Scope * localScope{scope ? scope : scope_}) {
+      return dtDetails->GetParentComponent(DEREF(localScope));
     }
-    return dtDetails->GetParentComponent(DEREF(scope));
-  } else {
-    return nullptr;
   }
+  return nullptr;
 }
 
 void DerivedTypeDetails::add_component(const Symbol &symbol) {
Index: flang/lib/Semantics/expression.cpp
===================================================================
--- flang/lib/Semantics/expression.cpp
+++ flang/lib/Semantics/expression.cpp
@@ -1997,11 +1997,18 @@
       const auto &designator{std::get<parser::ProcedureDesignator>(call.t)};
       if (const auto *name{std::get_if<parser::Name>(&designator.u)}) {
         semantics::Scope &scope{context_.FindScope(name->source)};
+        semantics::DerivedTypeSpec dtSpec{
+            name->source, derivedType.GetUltimate()};
+        if (dtSpec.IsForwardReferenced()) {
+          Say(call.source,
+              "Cannot construct value for derived type '%s' "
+              "before it is defined"_err_en_US,
+              name->source);
+          return std::nullopt;
+        }
         const semantics::DeclTypeSpec &type{
-            semantics::FindOrInstantiateDerivedType(scope,
-                semantics::DerivedTypeSpec{
-                    name->source, derivedType.GetUltimate()},
-                context_)};
+            semantics::FindOrInstantiateDerivedType(
+                scope, std::move(dtSpec), context_)};
         auto &mutableRef{const_cast<parser::FunctionReference &>(funcRef)};
         *structureConstructor =
             mutableRef.ConvertToStructureConstructor(type.derivedTypeSpec());


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