[patch, fortran] ICE in attr_decl1, at fortran/decl.c:8691

[Jerry DeLisle via Fortran]

The attached patch was provided by Steve Kargl.  After exploring for
possible other checks I settled on leaving the patch intact.

Two existing test cases updated as different but sensible error messages
resulted.

Regression tested on main line.

OK to commit?

Regards,

Jerry

Author: Steve Kargl <ka...@gcc.gnu.org>
Date:   Mon Dec 26 14:07:04 2022 -0800

     Modify checks to avoid referencing NULL pointer.
     Update test cases with error messages that changed as a result.

     gcc/fortran/ChangeLog:

             * decl.cc (attr_decl1): Guard against NULL pointer.
             * parse.cc (match_deferred_characteristics): Include
BT_CLASS in check for
               derived being undefined.

     gcc/testsuite/ChangeLog:

             * gfortran.dg/class_result_4.f90: Update error message check.
             * gfortran.dg/pr85779_3.f90: Update error message check.
diff --git a/gcc/fortran/decl.cc b/gcc/fortran/decl.cc
index e593518a77e..bac7b6568b0 100644
--- a/gcc/fortran/decl.cc
+++ b/gcc/fortran/decl.cc
@@ -8743,7 +8743,9 @@ attr_decl1 (void)
   /* Update symbol table.  DIMENSION attribute is set in
      gfc_set_array_spec().  For CLASS variables, this must be applied
      to the first component, or '_data' field.  */
-  if (sym->ts.type == BT_CLASS && sym->ts.u.derived->attr.is_class)
+  if (sym->ts.type == BT_CLASS
+      && sym->ts.u.derived
+      && sym->ts.u.derived->attr.is_class)
     {
       /* gfc_set_array_spec sets sym->attr not CLASS_DATA(sym)->attr.  Check
 	 for duplicate attribute here.  */
diff --git a/gcc/fortran/parse.cc b/gcc/fortran/parse.cc
index bc2b2188eea..6186c48aee2 100644
--- a/gcc/fortran/parse.cc
+++ b/gcc/fortran/parse.cc
@@ -3934,7 +3934,7 @@ match_deferred_characteristics (gfc_typespec * ts)
   m = gfc_match_prefix (ts);
   gfc_buffer_error (false);
 
-  if (ts->type == BT_DERIVED)
+  if (ts->type == BT_DERIVED || ts->type == BT_CLASS)
     {
       ts->kind = 0;
 
@@ -4215,7 +4215,7 @@ declSt:
   if (bad_characteristic)
     {
       ts = &gfc_current_block ()->result->ts;
-      if (ts->type != BT_DERIVED)
+      if (ts->type != BT_DERIVED && ts->type != BT_CLASS)
 	gfc_error ("Bad kind expression for function %qs at %L",
 		   gfc_current_block ()->name,
 		   &gfc_current_block ()->declared_at);
diff --git a/gcc/testsuite/gfortran.dg/class_result_4.f90 b/gcc/testsuite/gfortran.dg/class_result_4.f90
index 4b22a3c30ee..5497ac652ec 100644
--- a/gcc/testsuite/gfortran.dg/class_result_4.f90
+++ b/gcc/testsuite/gfortran.dg/class_result_4.f90
@@ -1,6 +1,6 @@
 ! { dg-do compile }
 ! PR fortran/78500
-class(t) function f() ! { dg-error "must be dummy, allocatable or pointer" }
+class(t) function f() ! { dg-error "is not accessible" }
    f = 1              ! { dg-error "variable must not be polymorphic" }
 end
 
diff --git a/gcc/testsuite/gfortran.dg/pr85779_3.f90 b/gcc/testsuite/gfortran.dg/pr85779_3.f90
index fba1133b3ea..a81a9faf88e 100644
--- a/gcc/testsuite/gfortran.dg/pr85779_3.f90
+++ b/gcc/testsuite/gfortran.dg/pr85779_3.f90
@@ -1,6 +1,6 @@
 ! { dg-do compile }
 ! PR fortran/85779
-class(t) function f()   ! { dg-error "must be dummy, allocatable or pointer" }
+class(t) function f()   ! { dg-error "is not accessible" }
    type f               ! { dg-error "already has a basic type" }
    end type             ! { dg-error "END FUNCTION statement" }
 end