[PATCH] PR fortran/104573 - ICE in resolve_structure_cons, at fortran/resolve.cc:1299

[Harald Anlauf <anlauf@gmx.de>]

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Dear Fortranners,

while we detect invalid uses of type(*), we may run into other issues
later when the declared variable is used, leading to an ICE due to a
NULL pointer dereference.  This is demonstrated by Gerhard's testcase.

Steve and I came to rather similar fixes, see PR.  Mine is attached.

Regtested on x86_64-pc-linux-gnu.  OK for mainline?

Thanks,
Harald


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From 01d629506edca711f02912e2cc124f8894cfa389 Mon Sep 17 00:00:00 2001
From: Harald Anlauf <anlauf@gmx.de>
Date: Wed, 16 Feb 2022 22:13:02 +0100
Subject: [PATCH] Fortran: error recovery after invalid assumed type
 declaration

gcc/fortran/ChangeLog:

	PR fortran/104573
	* resolve.cc (resolve_structure_cons): Avoid NULL pointer
	dereference when there is no valid component.

gcc/testsuite/ChangeLog:

	PR fortran/104573
	* gfortran.dg/assumed_type_14.f90: New test.
---
 gcc/fortran/resolve.cc                        |  8 +++++---
 gcc/testsuite/gfortran.dg/assumed_type_14.f90 | 12 ++++++++++++
 2 files changed, 17 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gfortran.dg/assumed_type_14.f90

diff --git a/gcc/fortran/resolve.cc b/gcc/fortran/resolve.cc
index 266e41e25b1..2fa1acdbd6d 100644
--- a/gcc/fortran/resolve.cc
+++ b/gcc/fortran/resolve.cc
@@ -1288,15 +1288,17 @@ resolve_structure_cons (gfc_expr *expr, int init)
 	}
     }

-  cons = gfc_constructor_first (expr->value.constructor);
-
   /* A constructor may have references if it is the result of substituting a
      parameter variable.  In this case we just pull out the component we
      want.  */
   if (expr->ref)
     comp = expr->ref->u.c.sym->components;
-  else
+  else if (expr->ts.u.derived)
     comp = expr->ts.u.derived->components;
+  else
+    return false;
+
+  cons = gfc_constructor_first (expr->value.constructor);

   for (; comp && cons; comp = comp->next, cons = gfc_constructor_next (cons))
     {
diff --git a/gcc/testsuite/gfortran.dg/assumed_type_14.f90 b/gcc/testsuite/gfortran.dg/assumed_type_14.f90
new file mode 100644
index 00000000000..6cfe2e4fb73
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/assumed_type_14.f90
@@ -0,0 +1,12 @@
+! { dg-do compile }
+! PR fortran/104573 - ICE in resolve_structure_cons
+! Contributed by G.Steinmetz
+
+program p
+  type t
+  end type
+  type(*), parameter :: x = t() ! { dg-error "Assumed type of variable" }
+  print *, x
+end
+
+! { dg-prune-output "Cannot convert" }
--
2.34.1