Re: Emacs (today's cvs) aborts under X [PATCH].

[Lute Kamstra]

Richard Stallman <address@hidden> writes:

>     FWIW, we tested Emacs for this bug in some more environments.  Here is
>     a summary of the results.
>
> Thanks, but that sort of investigation is not really useful in a
> situation like this one (or in most situations).  The Bugs chapter
> gives more explanation.
>
> Once you have isolated a specific construct that doesn't produce
> correct results, trying other combinations and cases is basically not
> a useful activity.  It is better to spend your time studying the code
> and figuring out why that construct gives the wrong results you see.

We were quite stubborn and tested yet another combination.  :-)

We tried to compile Emacs 21.3.50 on a Redhat 8.0 system with only
LessTif (so without Open Motif).  This resulted in compile errors in
the lwlib/ directory.  It turns out that the lwlib library cannot find
the LessTif header files.  Is does find Open Motif files when
installed however.  As a result, the following happens on my Redhat
8.0 system:

Open Motif + LessTif installed: lwlib is built with Open Motif, the
rest of emacs is built with LessTif.  This mess is most likely the
cause of the abort call.

Only Open Motif installed: everything is built with Open Motif and
Emacs works fine.

Only LessTif installed: lwlib failed to compile.

It is easy to change lwlib/Makefile.in so that it finds the LessTif
headers on a LessTif only system.  I tried this and got Emacs to
compile and run fine.  This change also lets emacs compile and run
fine when I have only Open Motif installed.

However, I ran into some difficulties when trying to make things
function properly in case both LessTif and Open Motif are installed.
Let me try to explain the problem.

On a Redhat system, the Open Motif libraries and headers are located
in /usr/X11R6/lib/ and /usr/X11R6/include/Xm/.  The LessTif libraries
and headers can be found in /usr/X11R6/LessTif/Motif1.2/lib/ and
/usr/X11R6/LessTif/Motif1.2/include/Xm/.  So if we want to use LessTif
and not Open Motif on a system with both installed, we must make sure
that "-L/usr/X11R6/LessTif/Motif1.2/lib" precedes "/usr/X11R6/lib/"
and that "-I/usr/X11R6/LessTif/Motif1.2/include" precedes
"-I/usr/X11R6/include" when linking and compiling motif things.

In September 2002 we changed the configure.in script to try and
accomplish this.  The lines marked by + were added:

,----[ configure.in; lines 1959 -- 2002 ]
| if test "${USE_X_TOOLKIT}" = "MOTIF"; then
+   AC_CACHE_CHECK(for LessTif where some systems put it, emacs_cv_lesstif,
+   # We put this in CFLAGS temporarily to precede other -I options
+   # that might be in CFLAGS temporarily.
+   # We put this in CPPFLAGS where it precedes the other -I options.
+   OLD_CPPFLAGS=$CPPFLAGS
+   OLD_CFLAGS=$CFLAGS
+   CPPFLAGS="-I/usr/X11R6/LessTif/Motif1.2/include $CPPFLAGS"
+   CFLAGS="-I/usr/X11R6/LessTif/Motif1.2/include $CFLAGS"
+   [AC_TRY_COMPILE([#include </usr/X11R6/LessTif/Motif1.2/include/Xm/Xm.h>],
+     [int x = 5;],
+     emacs_cv_lesstif=yes, emacs_cv_lesstif=no)])
+   if test $emacs_cv_lesstif = yes; then
+     # Make sure this -I option remains in CPPFLAGS after it is set
+     # back to REAL_CPPFLAGS.
+     # There is no need to change REAL_CFLAGS, because REAL_CFLAGS does not
+     # have those other -I options anyway.  Ultimately, having this
+     # directory ultimately in CPPFLAGS will be enough.
+     REAL_CPPFLAGS="-I/usr/X11R6/LessTif/Motif1.2/include $REAL_CPPFLAGS"
+     LDFLAGS="-L/usr/X11R6/LessTif/Motif1.2/lib $LDFLAGS"
+   else
+     CFLAGS=$OLD_CFLAGS
+     CPPFLAGS=$OLD_CPPFLAGS
+   fi
|   AC_CACHE_CHECK(for Motif version 2.1, emacs_cv_motif_version_2_1,
|   [AC_TRY_COMPILE([#include <Xm/Xm.h>],
|     [#if XmVERSION > 2 || (XmVERSION == 2 && XmREVISION >= 1)
| int x = 5;
| #else
| Motif version prior to 2.1.
| #endif],
|     emacs_cv_motif_version_2_1=yes, emacs_cv_motif_version_2_1=no)])
|   HAVE_MOTIF_2_1=$emacs_cv_motif_version_2_1
|   if test $emacs_cv_motif_version_2_1 = yes; then
|     HAVE_LIBXP=no
|     AC_DEFINE(HAVE_MOTIF_2_1, 1,
|             [Define to 1 if you have Motif 2.1 or newer.])
|     AC_CHECK_LIB(Xp, XpCreateContext, HAVE_LIBXP=yes)
|     if test ${HAVE_LIBXP} = yes; then
|       AC_DEFINE(HAVE_LIBXP, 1,
|               [Define to 1 if you have the Xp library (-lXp).])
|     fi
|   fi
| fi
`----

So we basically add "-L/usr/X11R6/LessTif/Motif1.2/lib" to the front
of LDFLAGS and "-I/usr/X11R6/LessTif/Motif1.2/include" to the front of
CPPFLAGS if LessTif is installed there.

This works fine for everything in the src/ directory.  Indeed, in
src/Makefile.in it says:

,----[ src/Makefile.in; lines 30 -- 40 ]
| # Here are the things that we expect ../configure to edit.
| # We use $(srcdir) explicitly in dependencies so as not to depend on VPATH.
| address@hidden@
| address@hidden@
| address@hidden@
| address@hidden@
| address@hidden@
| address@hidden@
| address@hidden@
| address@hidden@
| address@hidden@
`----

and: 

,----[ src/Makefile.in; lines 283 -- 285 ]
| ALL_CFLAGS=-Demacs -DHAVE_CONFIG_H $(TOOLKIT_DEFINES) $(MYCPPFLAGS) -I. 
-I${srcdir} C_SWITCH_MACHINE C_SWITCH_SYSTEM C_SWITCH_SITE C_SWITCH_X_SITE 
C_SWITCH_X_MACHINE C_SWITCH_X_SYSTEM C_SWITCH_SYSTEM_TEMACS ${CFLAGS}
| .c.o:
|       $(CC) -c $(CPPFLAGS) $(ALL_CFLAGS) $<
`----

This results in the following Makefile parts:

,----[ src/Makefile; lines 30 -- 40 ]
| # Here are the things that we expect ../configure to edit.
| # We use $(srcdir) explicitly in dependencies so as not to depend on VPATH.
| srcdir=/export/scratch1/lute/sources/cvs/emacs/src
| VPATH=/export/scratch1/lute/sources/cvs/emacs/src
| CC=gcc
| CPP=gcc -E
| CFLAGS=-g -O2
| CPPFLAGS=-I/usr/X11R6/LessTif/Motif1.2/include -D_BSD_SOURCE  
| LDFLAGS=-L/usr/X11R6/LessTif/Motif1.2/lib  -L/usr/X11R6/lib
| LN_S=ln -s
| EXEEXT=
`----

and

,----[ src/Makefile; lines 69 -- 71 ]
| ALL_CFLAGS=-Demacs -DHAVE_CONFIG_H $(TOOLKIT_DEFINES) $(MYCPPFLAGS) -I. 
-I${srcdir} -D_BSD_SOURCE -I/usr/X11R6/include ${CFLAGS}
| .c.o:
|              $(CC) -c $(CPPFLAGS) $(ALL_CFLAGS) $<
`----

This works for the library paths in a similar fashion.

However, things fail for the lwlib/ directory.  In lwlib/Makefile.in,
there is no "address@hidden@" line.

,----[ lwlib/Makefile.in; lines 5 -- 14 ]
| address@hidden@
| address@hidden@
| address@hidden@
| 
| address@hidden@
| address@hidden@
| address@hidden@
| address@hidden@
| address@hidden@
| address@hidden@
`----

As a result, the LessTif header files are never found.  Adding such a
"address@hidden@" line repairs the situation where only LessTif is
installed.  However, since

,----[ lwlib/Makefile.in; lines 33 -- 39 ]
| # ../src is needed to find config.h.
| ALL_CFLAGS= $(C_SWITCH_SITE) $(C_SWITCH_SYSTEM) $(C_SWITCH_X_SITE) \
|   $(C_SWITCH_X_SYSTEM) $(C_SWITCH_MACHINE) $(CPPFLAGS) $(CFLAGS) \
|   -DHAVE_CONFIG_H -Demacs -I. -I../src -I${srcdir} -I${srcdir}/../src
| 
| .c.o:
|       $(CC) -c ${ALL_CFLAGS} $<
`----

and configure sets C_SWITCH_X_SITE to -I/usr/X11R6/include, the Open
Motif headers are found before the LessTif headers on a system with
both toolkits installed.

I changed lwlib/Makefile.in to make it behave like src/Makefile.in and
this solves all the Open Motif vs LessTif problems (see patch below).
However, I don't know why $(CPPFLAGS) was originally placed after
$(C_SWITCH_SITE), $(C_SWITCH_SYSTEM), $(C_SWITCH_X_SITE),
$(C_SWITCH_X_SYSTEM), and $(C_SWITCH_MACHINE).  So my naive patch may
cause problems for others.  Use with caution.

Regards,

  Lute.



*** Makefile.in.~1.26.~ 2002-04-28 15:33:40.000000000 +0200
--- Makefile.in 2003-04-28 16:54:07.000000000 +0200
***************
*** 9,14 ****
--- 9,15 ----
  address@hidden@
  address@hidden@
  address@hidden@
+ address@hidden@
  address@hidden@
  address@hidden@
  # See address@hidden@ is used below.
***************
*** 31,41 ****
  
  # ../src is needed to find config.h.
  ALL_CFLAGS= $(C_SWITCH_SITE) $(C_SWITCH_SYSTEM) $(C_SWITCH_X_SITE) \
!   $(C_SWITCH_X_SYSTEM) $(C_SWITCH_MACHINE) $(CPPFLAGS) $(CFLAGS) \
    -DHAVE_CONFIG_H -Demacs -I. -I../src -I${srcdir} -I${srcdir}/../src
  
  .c.o:
!       $(CC) -c ${ALL_CFLAGS} $<
  
  all:: liblw.a
  
--- 32,42 ----
  
  # ../src is needed to find config.h.
  ALL_CFLAGS= $(C_SWITCH_SITE) $(C_SWITCH_SYSTEM) $(C_SWITCH_X_SITE) \
!   $(C_SWITCH_X_SYSTEM) $(C_SWITCH_MACHINE) $(CFLAGS) \
    -DHAVE_CONFIG_H -Demacs -I. -I../src -I${srcdir} -I${srcdir}/../src
  
  .c.o:
!       $(CC) -c $(CPPFLAGS) ${ALL_CFLAGS} $<
  
  all:: liblw.a
  


-- 
Lute Kamstra  <address@hidden>
CWI  department PNA4
Room M233  phone (+31) 20 592 4214
[Echelon material: blackjack CDMA Peking]