[Patch, Fortran] PR 88047: [9 Regression] ICE in gfc_find_vtab, at fortran/class.c:2843

[Janus Weil]

Hi all,

the attached patch is close to obvious and fixes another small
ICE-on-invalid regression. Since there was a bit of discussion in the
PR, I am submitting it for approval instead of just committing as
obvious.

Regtests cleanly on x86_64-linux-gnu. Ok for trunk?

Cheers,
Janus

diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index ba95a26e6ae..4d50f880d38 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,9 @@
+2019-01-08  Janus Weil  <ja...@gcc.gnu.org>
+
+	PR fortran/88047
+	* class.c (gfc_find_vtab): For polymorphic typespecs, the components of
+	the class container may not be available (in case of invalid code).
+
 2019-01-07  Thomas Koenig  <tkoe...@gcc.gnu.org>
 	Harald Anlauf <anl...@gmx.de>
 	Tobias Burnus <bur...@gcc.gnu.org>
diff --git a/gcc/fortran/class.c b/gcc/fortran/class.c
index 77f0fca9385..8809b5b5b6e 100644
--- a/gcc/fortran/class.c
+++ b/gcc/fortran/class.c
@@ -2846,7 +2846,10 @@ gfc_find_vtab (gfc_typespec *ts)
     case BT_DERIVED:
       return gfc_find_derived_vtab (ts->u.derived);
     case BT_CLASS:
-      return gfc_find_derived_vtab (ts->u.derived->components->ts.u.derived);
+      if (ts->u.derived->components && ts->u.derived->components->ts.u.derived)
+	return gfc_find_derived_vtab (ts->u.derived->components->ts.u.derived);
+      else
+	return NULL;
     default:
       return find_intrinsic_vtab (ts);
     }
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 23de2ea6f0b..45279ccae0c 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2019-01-08  Janus Weil  <ja...@gcc.gnu.org>
+
+	PR fortran/88047
+	* gfortran.dg/class_69.f90: New test case.
+
 2019-01-07  David Malcolm  <dmalc...@redhat.com>
 
 	PR jit/88747
diff --git a/gcc/testsuite/gfortran.dg/class_69.f90 b/gcc/testsuite/gfortran.dg/class_69.f90
new file mode 100644
index 00000000000..e45e03528b7
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/class_69.f90
@@ -0,0 +1,21 @@
+! { dg-do compile }
+!
+! PR 88047: [9 Regression] ICE in gfc_find_vtab, at fortran/class.c:2843
+!
+! Contributed by G. Steinmetz <gs...@t-online.de>
+
+subroutine sub_a
+   type t
+   end type
+   class(t) :: x(2)                   ! { dg-error "must be dummy, allocatable or pointer" }
+   class(t), parameter :: a(2) = t()  ! { dg-error "cannot have the PARAMETER attribute" }
+   x = a                              ! { dg-error "Nonallocatable variable must not be polymorphic in intrinsic assignment" }
+end
+
+subroutine sub_b
+   type t
+      integer :: n
+   end type
+   class(t) :: a, x                   ! { dg-error "must be dummy, allocatable or pointer" }
+   x = a                              ! { dg-error "Nonallocatable variable must not be polymorphic in intrinsic assignment" }
+end