[RFA jit] initialize input_location

[Tom Tromey]

>>>>> "Dave" == David Malcolm <dmalcolm-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> writes:

Dave> Given this declaration in input.c:
Dave>   location_t input_location;
Dave> then assigning 0 is a faithful way of resetting it to its initial state.

Dave> That said, "0" feels like a magic number.  Would it better to assign
Dave> UNKNOWN_LOCATION to it? which is 0, c.f. input.h:

Dave>   #define UNKNOWN_LOCATION ((source_location) 0)

Dave> If so, perhaps the declaration in input.c should gain an initializer to
Dave> the same value?  (shouldn't affect the code, since it's 0 either way,
Dave> but perhaps it's more readable?)

Sounds reasonable to me.
How about the appended?

Tom

commit 79ce51eaf41ce7b0e90407245b7cad33ada6887b
Author: Tom Tromey <tromey@redhat.com>
Date:   Thu Mar 20 08:51:25 2014 -0600

    initialize input_location
    
    This patch initializes input_location at the same spot where the line
    table is initialized.  Without this, it's possible to crash when
    emitting a diagnostic in a reinvocation of the compiler, because
    input_location refers to a location that is no longer valid.

diff --git a/gcc/ChangeLog.jit b/gcc/ChangeLog.jit
index ee1df88..5145cf9 100644
--- a/gcc/ChangeLog.jit
+++ b/gcc/ChangeLog.jit
@@ -1,3 +1,8 @@
+2014-03-24  Tom Tromey  <tromey@redhat.com>
+
+	* toplev.c (general_init): Initialize input_location.
+	* input.c (input_location): Initialize to UNKNOWN_LOCATION.
+
 2014-03-19  Tom Tromey  <tromey@redhat.com>
 
 	* timevar.h (auto_timevar): New class.
diff --git a/gcc/input.c b/gcc/input.c
index a141a92..90a708c 100644
--- a/gcc/input.c
+++ b/gcc/input.c
@@ -1,5 +1,5 @@
 /* Data and functions related to line maps and input files.
-   Copyright (C) 2004-2013 Free Software Foundation, Inc.
+   Copyright (C) 2004-2014 Free Software Foundation, Inc.
 
 This file is part of GCC.
 
@@ -25,7 +25,7 @@ along with GCC; see the file COPYING3.  If not see
 
 /* Current position in real source file.  */
 
-location_t input_location;
+location_t input_location = UNKNOWN_LOCATION;
 
 struct line_maps *line_table;
 
diff --git a/gcc/toplev.c b/gcc/toplev.c
index b257ab2..54a884e 100644
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -1161,6 +1161,7 @@ general_init (const char *argv0)
      table.  */
   init_ggc ();
   init_stringpool ();
+  input_location = UNKNOWN_LOCATION;
   line_table = ggc_alloc_line_maps ();
   linemap_init (line_table);
   line_table->reallocator = realloc_for_line_map;