[gcc r12-1540] Fortran - ICE in gfc_check_do_variable, at fortran/parse.c:4446

[gcc r12-1540] Fortran - ICE in gfc_check_do_variable, at fortran/parse.c:4446

[Harald Anlauf]

https://gcc.gnu.org/g:72e3d92178b44a3722519ec68e72e307443bda70

commit r12-1540-g72e3d92178b44a3722519ec68e72e307443bda70
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Wed Jun 16 21:54:16 2021 +0200

    Fortran - ICE in gfc_check_do_variable, at fortran/parse.c:4446
    
    Avoid NULL pointer dereferences during error recovery.
    
    gcc/fortran/ChangeLog:
    
            PR fortran/95501
            PR fortran/95502
            * expr.c (gfc_check_pointer_assign): Avoid NULL pointer
            dereference.
            * match.c (gfc_match_pointer_assignment): Likewise.
            * parse.c (gfc_check_do_variable): Avoid comparison with NULL
            symtree.
    
    gcc/testsuite/ChangeLog:
    
            PR fortran/95501
            PR fortran/95502
            * gfortran.dg/pr95502.f90: New test.

Diff:
---
 gcc/fortran/expr.c                    | 15 +++++++++++++++
 gcc/fortran/match.c                   |  2 +-
 gcc/fortran/parse.c                   |  3 +++
 gcc/testsuite/gfortran.dg/pr95502.f90 |  8 ++++++++
 4 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/gcc/fortran/expr.c b/gcc/fortran/expr.c
index 956003ec605..6e663b4b828 100644
--- a/gcc/fortran/expr.c
+++ b/gcc/fortran/expr.c
@@ -1683,10 +1683,21 @@ find_array_section (gfc_expr *expr, gfc_ref *ref)
 	  return false;
 	}
 
+#if 1
       cons = gfc_constructor_lookup (base, limit);
       gcc_assert (cons);
       gfc_constructor_append_expr (&expr->value.constructor,
 				   gfc_copy_expr (cons->expr), NULL);
+#else
+      cons = gfc_constructor_lookup (base, limit);
+      if (cons)
+	gfc_constructor_append_expr (&expr->value.constructor,
+				     gfc_copy_expr (cons->expr), NULL);
+      else
+	{
+	  t = false;
+	}
+#endif
     }
 
   mpz_clear (ptr);
@@ -3476,6 +3487,7 @@ gfc_specification_expr (gfc_expr *e)
     {
       gfc_error ("Expression at %L must be of INTEGER type, found %s",
 		 &e->where, gfc_basic_typename (e->ts.type));
+      gfc_clear_ts (&e->ts);
       return false;
     }
 
@@ -3815,6 +3827,9 @@ gfc_check_pointer_assign (gfc_expr *lvalue, gfc_expr *rvalue,
   int proc_pointer;
   bool same_rank;
 
+  if (!lvalue->symtree)
+    return false;
+
   lhs_attr = gfc_expr_attr (lvalue);
   if (lvalue->ts.type == BT_UNKNOWN && !lhs_attr.proc_pointer)
     {
diff --git a/gcc/fortran/match.c b/gcc/fortran/match.c
index 29462013038..d148de3e3b5 100644
--- a/gcc/fortran/match.c
+++ b/gcc/fortran/match.c
@@ -1409,7 +1409,7 @@ gfc_match_pointer_assignment (void)
   gfc_matching_procptr_assignment = 0;
 
   m = gfc_match (" %v =>", &lvalue);
-  if (m != MATCH_YES)
+  if (m != MATCH_YES || !lvalue->symtree)
     {
       m = MATCH_NO;
       goto cleanup;
diff --git a/gcc/fortran/parse.c b/gcc/fortran/parse.c
index 0522b391393..6d7845e8517 100644
--- a/gcc/fortran/parse.c
+++ b/gcc/fortran/parse.c
@@ -4588,6 +4588,9 @@ gfc_check_do_variable (gfc_symtree *st)
 {
   gfc_state_data *s;
 
+  if (!st)
+    return 0;
+
   for (s=gfc_state_stack; s; s = s->previous)
     if (s->do_variable == st)
       {
diff --git a/gcc/testsuite/gfortran.dg/pr95502.f90 b/gcc/testsuite/gfortran.dg/pr95502.f90
new file mode 100644
index 00000000000..d40fd9a5508
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr95502.f90
@@ -0,0 +1,8 @@
+! { dg-do compile }
+! PR fortran/95502 - ICE in gfc_check_do_variable, at fortran/parse.c:4446
+
+program p
+  integer, pointer :: z
+  nullify (z%kind)  ! { dg-error "in variable definition context" }
+  z%kind => NULL()  ! { dg-error "constant expression" }
+end