Re: Help with create_pipe_bidi

[Joel E. Denny]

Hi Eric and Akim.

On Thu, 20 Aug 2009, Eric Blake wrote:

> According to Akim Demaille on 8/12/2009 9:08 AM:
> >> * submodules/autoconf: Update.
> >> * configure.ac (M4_GNU_OPTION): New define.
> >> * src/output.c (output_skeleton): Use it to resolve FIXME.
> > 
> > This is good, please install.  In addition, please install an assert like
> > 
> > @@ -622,7 +624,9 @@ output_skeleton (void)
> >      argv[i++] = full_m4bison;
> >      argv[i++] = full_skeleton;
> >      argv[i++] = NULL;
> > +    assert(i <= sizeof argv / sizeof *argv);
> >    }
>
> Now done on all three active branches, but with the macro
> ARRAY_CARDINALITY (in use elsewhere).

That assert is now the only use of assert or assert.h in src/.  In Bison's 
src/system.h, we have this:

  /* <assert.h>'s assertions are too heavyweight, and can be disabled
     too easily, so use aver rather than assert.  */
  static inline void
  aver (bool assertion)
  {
    if (! assertion)
      abort ();
  }

This was introduced by Paul Eggert.  His reason for not using assert from 
assert.h is here:

  http://lists.gnu.org/archive/html/bison-patches/2006-01/msg00080.html

And his reason for using the name aver is here:

  http://lists.gnu.org/archive/html/bison-patches/2006-09/msg00111.html

I don't have a strong opinion on this issue, but we ought to consider it.  
Any reason not to continue with his approach?

If not, I'll push this to master, branch-2.5, and branch-2.4.2.

>From b23a6c046dd37e73b3b7069f92071e90990ca293 Mon Sep 17 00:00:00 2001
From: Joel E. Denny <address@hidden>
Date: Thu, 3 Sep 2009 13:59:07 -0400
Subject: [PATCH] Use aver not assert.

* src/output.c: Don't include assert.h.
(output_skeleton): Use aver not assert.
* src/system.h (aver): In documentation of why, add links to
Paul Eggert's explanations in the mailing lists.
---
 ChangeLog    |    8 ++++++++
 src/output.c |    3 +--
 src/system.h |    5 ++++-
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index d4cdc6d..f30d1ff 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2009-09-03  Joel E. Denny  <address@hidden>
+
+       Use aver not assert.
+       * src/output.c: Don't include assert.h.
+       (output_skeleton): Use aver not assert.
+       * src/system.h (aver): In documentation of why, add links to
+       Paul Eggert's explanations in the mailing lists.
+
 2009-09-03  Akim Demaille  <address@hidden>
 
        * NEWS (2.4.2): Add "Internationalization" item.
diff --git a/src/output.c b/src/output.c
index 23cd8ff..562918c 100644
--- a/src/output.c
+++ b/src/output.c
@@ -21,7 +21,6 @@
 #include <config.h>
 #include "system.h"
 
-#include <assert.h>
 #include <configmake.h>
 #include <error.h>
 #include <get-errno.h>
@@ -637,7 +636,7 @@ output_skeleton (void)
     argv[i++] = full_m4bison;
     argv[i++] = full_skeleton;
     argv[i++] = NULL;
-    assert (i <= ARRAY_CARDINALITY (argv));
+    aver (i <= ARRAY_CARDINALITY (argv));
   }
 
   init_subpipe ();
diff --git a/src/system.h b/src/system.h
index cc2b09b..8ea5653 100644
--- a/src/system.h
+++ b/src/system.h
@@ -124,7 +124,10 @@ typedef size_t uintptr_t;
 `-------------*/
 
 /* <assert.h>'s assertions are too heavyweight, and can be disabled
-   too easily, so use aver rather than assert.  */
+   too easily, so use aver rather than assert.  See discussions at
+   <http://lists.gnu.org/archive/html/bison-patches/2006-01/msg00080.html>
+   <http://lists.gnu.org/archive/html/bison-patches/2006-09/msg00111.html>.
+*/
 static inline void
 aver (bool assertion)
 {
-- 
1.5.4.3