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

[Pete Steinfeld via Phabricator via llvm-commits]

PeteSteinfeld created this revision.
PeteSteinfeld added reviewers: klausler, tskeith.
Herald added a reviewer: DavidTruby.
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PeteSteinfeld requested review of this revision.

A type name in an IMPLICIT declaration that was later used in a PARAMETER
statement caused problems because the default symbol scope had not yet been
initialized.  I avoided dereferencing in the situation where the default scope
was uninitialized and added a test that triggers the problem.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D87535

Files:
  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 +70,13 @@
   type, extends(undef) :: t
   end type
 end subroutine
+
+subroutine s8
+  !ERROR: Derived type 't2' was used but never defined
+  !ERROR: The derived type 't2' was forward-referenced but not defined
+  implicit type(t2)(x)
+  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 +541,12 @@
 
 const Symbol *Symbol::GetParentComponent(const Scope *scope) const {
   if (const auto *dtDetails{detailsIf<DerivedTypeDetails>()}) {
-    if (!scope) {
-      scope = scope_;
+    const Scope *localScope = scope ? scope : scope_;
+    if (localScope) {
+      return dtDetails->GetParentComponent(DEREF(localScope));
     }
-    return dtDetails->GetParentComponent(DEREF(scope));
-  } else {
-    return nullptr;
   }
+  return nullptr;
 }
 
 void DerivedTypeDetails::add_component(const Symbol &symbol) {


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