[Bug fortran/87764] gfortran crashes with illegal code

["anlauf at gmx dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87764

Harald Anlauf <anlauf at gmx dot de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |anlauf at gmx dot de

--- Comment #2 from Harald Anlauf <anlauf at gmx dot de> ---
(In reply to Dominique d'Humieres from comment #1)
> Confirmed from 4.8 up to trunk (9.0). An instrumented compiler gives
> 
> f951: Warning: No location in statement
> ../../work/gcc/fortran/trans.c:1768:39: runtime error: member access within
> null pointer of type 'struct gfc_linebuf'
> f951: internal compiler error: Segmentation fault: 11

The warning in comment#0 would be restored by the patch:

Index: gcc/fortran/trans.c
===================================================================
--- gcc/fortran/trans.c (revision 267065)
+++ gcc/fortran/trans.c (working copy)
@@ -1765,8 +1765,11 @@
 void
 gfc_set_backend_locus (locus * loc)
 {
-  gfc_current_backend_file = loc->lb->file;
-  input_location = loc->lb->location;
+  if (loc->lb)
+    {
+      gfc_current_backend_file = loc->lb->file;
+      input_location = loc->lb->location;
+    }
 }

However, this papers over the issue that the locus is not properly set.