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On Fri, 2010-12-03 at 15:52 -0500, Matt Turner wrote:
<BLOCKQUOTE TYPE=CITE>
<PRE>
From: Matthieu Herrb <<A HREF="mailto:matthieu.herrb@laas.fr">matthieu.herrb@laas.fr</A>>
GNU cpp is predefining a number of symbols, depending on the host and target
architecture. This can produce some unexpected results: for example, the
expansion of CLIENTHOST if the host name is i386.my.domain.
The attached patch creates a new -undef option to xrdb that is passed to
cpp.
---
Should it be on by default?
Matthieu, please give your Signed-off-by.
xrdb.c | 12 +++++++++++-
xrdb.man | 4 ++++
2 files changed, 15 insertions(+), 1 deletions(-)
diff --git a/xrdb.c b/xrdb.c
index 21005c0..68accf8 100644
--- a/xrdb.c
+++ b/xrdb.c
@@ -479,8 +479,11 @@ DoCmdDefines(String *buff)
*val = '=';
} else
AddSimpleDef(buff, arg + 2);
- } else
+ } else if (arg[1] == 'U') {
AddUndef(buff, arg + 2);
+ } else if (!strcmp(arg, "-undef") && oper != OPSYMBOLS) {
+ addstring(buff, " -undef");
+ }
}
}
@@ -867,6 +870,13 @@ main(int argc, char *argv[])
fatal("%s: Too many -U/-D arguments\n", ProgramName);
}
continue;
+ } else if (!strcmp ("-undef", arg)) {
+ if (num_cmd_defines < MAX_CMD_DEFINES) {
+ cmd_defines[num_cmd_defines++] = "-undef";
+ } else {
+ fatal("%s: Too many cpp arguments\n", ProgramName);
+ }
+ continue;
}
Syntax ();
} else if (arg[0] == '=')
diff --git a/xrdb.man b/xrdb.man
index d0d45ad..ddf1a73 100644
--- a/xrdb.man
+++ b/xrdb.man
@@ -223,6 +223,10 @@ This option indicates that
should not run the input file through a preprocessor before loading it
into properties.
.TP 8
+.B -undef
+This option is passed to the C preprocessor if used. It prevents it from
+predefining any system specific macros.
+.TP 8
.B \-symbols
This option indicates that the symbols that are defined for the preprocessor
should be printed onto the standard output.
</PRE>
</BLOCKQUOTE>
<BR>
If I understand, strings like CLIENTHOST were not meant to be substituted.<BR>
<BR>
What if the pre-processor is not a GNU cpp? Solaris or something else.<BR>
<BR>
You might want to look at this link, it looks like -undef does not work properly on CYGWIN gcc 2.95.<BR>
<A HREF="http://www.cygwin.com/ml/cygwin/2002-05/msg01613.html">http://www.cygwin.com/ml/cygwin/2002-05/msg01613.html</A><BR>
<BR>
The gcc doc is pretty vague as to what will not be substituted. It would be nice to have a list of such symbols in the commit to help investigation if something is not expected.<BR>
<BR>
Acked-by: <TT><FONT COLOR="#1a1a1a">Gaetan Nadon <<A HREF="mailto:memsize@videotron.ca">memsize@videotron.ca</A>></FONT></TT><BR>
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