Latest GCC can't compile keymap.c correctly.

Latest GCC can't compile keymap.c correctly.

[Kenichi Handa]

I've got this bug report.

When the latest Emacs is compiled with the following
environment,

% gcc --version
gcc (GCC) 4.2.0 20060903 (experimental)
% uname -a
SunOS mars 5.10 Generic_118833-20 sun4u sparc
% emacs --version
GNU Emacs 22.0.50.1

Meta key stops working.  For instance, we get this error:

M-f is undefined

When we compile only keymap.c with gcc-4.0.3 and link it,
the problem disappears.

---
Kenichi Handa
handa@m17n.org

Re: Latest GCC can't compile keymap.c correctly.

[Stefan Monnier]

> I've got this bug report.
> When the latest Emacs is compiled with the following
> environment,

> % gcc --version
> gcc (GCC) 4.2.0 20060903 (experimental)
> % uname -a
> SunOS mars 5.10 Generic_118833-20 sun4u sparc
> % emacs --version
> GNU Emacs 22.0.50.1

> Meta key stops working.  For instance, we get this error:

> M-f is undefined

> When we compile only keymap.c with gcc-4.0.3 and link it,
> the problem disappears.

If it's compiled with gcc-4.2 but with -Wall, what warnings do you get?


        Stefan

Re: Latest GCC can't compile keymap.c correctly.

[塩野＠システム構築部]

Hi, Stefan

>>>>> In <jwv64fz1v1z.fsf-monnier+emacs@gnu.org> 
>>>>>	Stefan Monnier <monnier@iro.umontreal.ca> wrote:
> > % gcc --version
> > gcc (GCC) 4.2.0 20060903 (experimental)
> > % uname -a
> > SunOS mars 5.10 Generic_118833-20 sun4u sparc
> > % emacs --version
> > GNU Emacs 22.0.50.1

> If it's compiled with gcc-4.2 but with -Wall, what warnings do you get?

>         Stefan

gcc -c  -Demacs -DHAVE_CONFIG_H -DUSE_LUCID  -I. -I/opt/local/src/emacs/src -I/opt/X11R6.6/include -I/usr/dt/include  -g -O2 -Wno-pointer-sign -Wall /opt/local/src/emacs/src/keymap.c
/opt/local/src/emacs/src/keymap.c: In function 'Fkey_description':
/opt/local/src/emacs/src/keymap.c:2016: Warn: implicit declaration of function 'alloca'
/opt/local/src/emacs/src/keymap.c:2016: Warn: incompatible implicit declaration of built-in function 'alloca'
/opt/local/src/emacs/src/keymap.c: In function 'Fsingle_key_description':
/opt/local/src/emacs/src/keymap.c:2292: Warn: incompatible implicit declaration of built-in function 'alloca'
/opt/local/src/emacs/src/keymap.c: In function 'Fwhere_is_internal':
/opt/local/src/emacs/src/keymap.c:2712: Warn: incompatible implicit declaration of built-in function 'alloca'
/opt/local/src/emacs/src/keymap.c: In function 'Fdescribe_buffer_bindings':
/opt/local/src/emacs/src/keymap.c:2941: Warn: incompatible implicit declaration of built-in function 'alloca'
/opt/local/src/emacs/src/keymap.c: In function 'describe_map':
/opt/local/src/emacs/src/keymap.c:3265: Warn: incompatible implicit declaration of built-in function 'alloca'
/opt/local/src/emacs/src/keymap.c: In function 'describe_vector':
/opt/local/src/emacs/src/keymap.c:3502: Warn: incompatible implicit declaration of built-in function 'alloca'

I replaced messages from '警告' to 'Warn'. caz, it's Japanese.
-- 
Jun

Re: Latest GCC can't compile keymap.c correctly.

[Stefan Monnier]

>> If it's compiled with gcc-4.2 but with -Wall, what warnings do you get?

> gcc -c  -Demacs -DHAVE_CONFIG_H -DUSE_LUCID  -I. -I/opt/local/src/emacs/src -I/opt/X11R6.6/include -I/usr/dt/include  -g -O2 -Wno-pointer-sign -Wall /opt/local/src/emacs/src/keymap.c
> /opt/local/src/emacs/src/keymap.c: In function 'Fkey_description':
> /opt/local/src/emacs/src/keymap.c:2016: Warn: implicit declaration of function 'alloca'
> /opt/local/src/emacs/src/keymap.c:2016: Warn: incompatible implicit declaration of built-in function 'alloca'
[...]

Thanks.  Does the patch below fix the problem?


        Stefan


--- keymap.c	20 aoû 2006 01:24:17 -0400	1.330
+++ keymap.c	08 sep 2006 01:05:09 -0400	
@@ -23,6 +23,7 @@
 
 #include <config.h>
 #include <stdio.h>
+#include <alloca.h>
 #include "lisp.h"
 #include "commands.h"
 #include "buffer.h"

Re: Latest GCC can't compile keymap.c correctly.

[塩野＠システム構築部]

Hi,

>>>>> In <jwvejunaqy8.fsf-monnier+emacs@gnu.org> 
>>>>>	Stefan Monnier <monnier@iro.umontreal.ca> wrote:
> Thanks.  Does the patch below fix the problem?

gcc -c  -Demacs -DHAVE_CONFIG_H -DUSE_LUCID  -I. -I/opt/local/src/emacs/src -I/op
t/X11R6.6/include -I/usr/dt/include  -g -O2 -Wno-pointer-sign -Wall /opt/local/sr
c/emacs/src/keymap.c

Warning Messages was gone, but I can not use META key.

I notice that I use emacs -nw mode from Windows machine vie
TeraTerm then I can use META key on that emacs.
--
                             ∧_∧
                            ミ^.^ミ E-Mail: j.s@jp.fujitsu.com

Re: Latest GCC can't compile keymap.c correctly.

[Richard Stallman]

    When we compile only keymap.c with gcc-4.0.3 and link it,
    the problem disappears.

Either keymap.c has a bug or the latest GCC has a bug.
We need to find out which function the problem is in.

I suggest you split keymap.c into two files, and try compiling one
with each GCC version.  By moving functions between the two files you
can determine where the problem is.  (If you are using a high
optimization level that does interprocedural optimization, you may
need more subtle techniques to determine which function.)

Once you know which function it is, make a .s file with each GCC
version, and compare the two with each other and with the source code.
This way you will find where the GCC 4.2 assenbly code is wrong.  Then
you can see whether there is something in the source code that has
unspecified or undefined behavior.  If so, we should fix that.  If
not, then it is a GCC bug, and you will have all the info needed to
report it properly.

I know this is a substantial amount of work, but it is the only way
to solve the problem.  And if this is a GCC bug, it is very important
to fix it.