Re: bison-1.875: build feedback: Apple Mac OS X

[Paul Eggert]

> Date: Thu, 2 Jan 2003 07:29:30 -0700 (MST)
> From: "Nelson H. F. Beebe" <address@hidden>
> 
> The build of bison-1.875 on Apple Mac OS X succeeded, but two members
> of the test suite failed.

> 36. headers.at:76: testing Invalid CPP guards: input/input...
> headers.at:76: bison --defines=input/input.h --output=y.tab.c input/input.y
> headers.at:76: $CC -E -I. y.tab.c
> --- /dev/null Thu Jan  2 07:13:25 2003
> +++ /local/build/bison-1.875/tests/testsuite.dir/at-stderr    Thu Jan  2 
> 07:13:26 2003
> @@ -0,0 +1,2 @@
> +y.tab.c:1077: syntax error, missing `;' after `)'
> +cpp-precomp: warning: errors during smart preprocessing, retrying in basic 
> mode

What is "smart preprocessing"?  I'm not familiar with this notion,
since I don't use MacOS X.  It sounds like they have a preprocessor
that is "smarter", but which sometimes doesn't work correctly, and in
that case they fall back on a "basic mode" preprocessor which _does_
work correctly.  Is this what's happening?

The y.tab.c lines in question look like this:

  1073  yyerrlab1:
  1074  
  1075    /* Suppress GCC warning that yyerrlab1 is unused when no action
  1076       invokes YYERROR.  */
  1077  #if defined (__GNUC_MINOR__) && 2093 <= (__GNUC__ * 1000 + 
__GNUC_MINOR__)
  1078    __attribute__ ((__unused__))
  1079  #endif
  1080  
  1081  
  1082    goto yyerrlab2;

Line 1077 doesn't contain any explicit semicolons.  Perhaps it's
actually complaining about line 1078.

What are __GNUC_MINOR__ and __GNUC__ defined to in your compilation
environment?  

The other test failed for the same reason.

Here's a shot in the dark.  Does the following patch work around your
preprocessor bug?  If so, could you please tell me the exact OS and
compiler version you're using, so that I can make the comment more
precise?  Thanks.

--- bison-1.875/data/yacc.c     2002-12-28 00:36:02.000000000 -0800
+++ bison-macos/data/yacc.c     2003-01-02 10:13:49.000000000 -0800
@@ -1112,9 +1112,10 @@
 yyerrlab1:
 
   /* Suppress GCC warning that yyerrlab1 is unused when no action
-     invokes YYERROR.  */
+     invokes YYERROR.  MacOS X's "smart preprocessor" insists on the
+     trailing semicolon here.  */
 #if defined (__GNUC_MINOR__) && 2093 <= (__GNUC__ * 1000 + __GNUC_MINOR__)
-  __attribute__ ((__unused__))
+  __attribute__ ((__unused__));
 #endif
 
 ]b4_location_if([  yylerrsp = yylsp;