X-Git-Url: https://gcc.gnu.org/git/?a=blobdiff_plain;f=include%2Fsymcat.h;h=ed4c00e10d355b2501dc3fda4fb9ba49d02f2d1f;hb=f1aa7a521a31b60380cf5c2e6913823c8bd18ce5;hp=01efada2618929c6405265137023a4d63e35b474;hpb=64f62168ef931afaa0a57fadf9b4410cadcbe249;p=gcc.git

diff --git a/include/symcat.h b/include/symcat.h
index 01efada26189..ed4c00e10d35 100644
--- a/include/symcat.h
+++ b/include/symcat.h
@@ -1,6 +1,6 @@
 /* Symbol concatenation utilities.
 
-   Copyright (C) 1998, Free Software Foundation, Inc.
+   Copyright (C) 1998, 2000 Free Software Foundation, Inc.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -19,22 +19,31 @@
 #ifndef SYM_CAT_H
 #define SYM_CAT_H
 
-#if defined (__STDC__) || defined (ALMOST_STDC)
+#if defined (__STDC__) || defined (ALMOST_STDC) || defined (HAVE_STRINGIZE)
 #define CONCAT2(a,b)	 a##b
 #define CONCAT3(a,b,c)	 a##b##c
 #define CONCAT4(a,b,c,d) a##b##c##d
 #define STRINGX(s) #s
 #else
+/* Note one should never pass extra whitespace to the CONCATn macros,
+   e.g. CONCAT2(foo, bar) because traditonal C will keep the space between
+   the two labels instead of concatenating them.  Instead, make sure to
+   write CONCAT2(foo,bar).  */
 #define CONCAT2(a,b)	 a/**/b
 #define CONCAT3(a,b,c)	 a/**/b/**/c
 #define CONCAT4(a,b,c,d) a/**/b/**/c/**/d
-#define STRINGX(s) "?"
+#define STRINGX(s) "s"
 #endif
 
 #define XCONCAT2(a,b)     CONCAT2(a,b)
 #define XCONCAT3(a,b,c)   CONCAT3(a,b,c)
 #define XCONCAT4(a,b,c,d) CONCAT4(a,b,c,d)
 
+/* Note the layer of indirection here is typically used to allow
+   stringification of the expansion of macros.  I.e. "#define foo
+   bar", "XSTRING(foo)", to yield "bar".  Be aware that this only
+   works for __STDC__, not for traditional C which will still resolve
+   to "foo".  */
 #define XSTRING(s) STRINGX(s) 
 
-#endif SYM_CAT_H
+#endif