[Bug preprocessor/37549] New: gcc -E -dD prints predefined macros, contrary to docs

[Bug preprocessor/37549] New: gcc -E -dD prints predefined macros, contrary to docs

[martinrb at google dot com]

The docs for preprocessor -dD flag states

    `D'
          Like `M' except in two respects: it does _not_ include the
          predefined macros

So one would expect -dD and -dM to differ substantially.
But....

(martinrb@spraggett) ~ $ gcc -E -dM -x c /dev/null | sort >/tmp/t1
(martinrb@spraggett) ~ $ gcc -E -dD -x c /dev/null | sort >/tmp/t2
(martinrb@spraggett) ~ $ diff /tmp/t[12]
0a1,4
> # 1 "<built-in>"
> # 1 "<command-line>"
> # 1 "/dev/null"
> # 1 "/dev/null"
(martinrb@spraggett) ~ $ wc /tmp/t[12]
 111  340 3482 /tmp/t1
 115  352 3552 /tmp/t2
 226  692 7034 total
(martinrb@spraggett) ~ $ gcc --version
gcc (GCC) 4.2.3 (Ubuntu 4.2.3-2ubuntu7)


-- 
           Summary: gcc -E -dD prints predefined macros, contrary to docs
           Product: gcc
           Version: 4.2.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: preprocessor
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: martinrb at google dot com
  GCC host triplet: x86_64-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37549

Re: [Bug preprocessor/37549] New: gcc -E -dD prints predefined macros, contrary to docs

[Andrew Thomas Pinski]

Sent from my iPhone

On Sep 16, 2008, at 7:25 PM, "martinrb at google dot com" <gcc-bugzilla@gcc.gnu.org 
 > wrote:

> The docs for preprocessor -dD flag states
>
>    `D'
>          Like `M' except in two respects: it does _not_ include the
>          predefined macros

I think what it means by predefines are the ones included on the  
command line that are defined by the user via -D.

>
>
> So one would expect -dD and -dM to differ substantially.
> But....
>
> (martinrb@spraggett) ~ $ gcc -E -dM -x c /dev/null | sort >/tmp/t1
> (martinrb@spraggett) ~ $ gcc -E -dD -x c /dev/null | sort >/tmp/t2
> (martinrb@spraggett) ~ $ diff /tmp/t[12]
> 0a1,4
>> # 1 "<built-in>"
>> # 1 "<command-line>"
>> # 1 "/dev/null"
>> # 1 "/dev/null"
> (martinrb@spraggett) ~ $ wc /tmp/t[12]
> 111  340 3482 /tmp/t1
> 115  352 3552 /tmp/t2
> 226  692 7034 total
> (martinrb@spraggett) ~ $ gcc --version
> gcc (GCC) 4.2.3 (Ubuntu 4.2.3-2ubuntu7)
>
>
> -- 
>           Summary: gcc -E -dD prints predefined macros, contrary to  
> docs
>           Product: gcc
>           Version: 4.2.3
>            Status: UNCONFIRMED
>          Severity: normal
>          Priority: P3
>         Component: preprocessor
>        AssignedTo: unassigned at gcc dot gnu dot org
>        ReportedBy: martinrb at google dot com
>  GCC host triplet: x86_64-linux-gnu
>
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37549
>

[Bug preprocessor/37549] gcc -E -dD prints predefined macros, contrary to docs

[pinskia at gmail dot com]

------- Comment #1 from pinskia at gmail dot com  2008-09-17 03:13 -------
Subject: Re:   New: gcc -E -dD prints predefined macros, contrary to docs



Sent from my iPhone

On Sep 16, 2008, at 7:25 PM, "martinrb at google dot com"
<gcc-bugzilla@gcc.gnu.org 
 > wrote:

> The docs for preprocessor -dD flag states
>
>    `D'
>          Like `M' except in two respects: it does _not_ include the
>          predefined macros

I think what it means by predefines are the ones included on the  
command line that are defined by the user via -D.

>
>
> So one would expect -dD and -dM to differ substantially.
> But....
>
> (martinrb@spraggett) ~ $ gcc -E -dM -x c /dev/null | sort >/tmp/t1
> (martinrb@spraggett) ~ $ gcc -E -dD -x c /dev/null | sort >/tmp/t2
> (martinrb@spraggett) ~ $ diff /tmp/t[12]
> 0a1,4
>> # 1 "<built-in>"
>> # 1 "<command-line>"
>> # 1 "/dev/null"
>> # 1 "/dev/null"
> (martinrb@spraggett) ~ $ wc /tmp/t[12]
> 111  340 3482 /tmp/t1
> 115  352 3552 /tmp/t2
> 226  692 7034 total
> (martinrb@spraggett) ~ $ gcc --version
> gcc (GCC) 4.2.3 (Ubuntu 4.2.3-2ubuntu7)
>
>
> -- 
>           Summary: gcc -E -dD prints predefined macros, contrary to  
> docs
>           Product: gcc
>           Version: 4.2.3
>            Status: UNCONFIRMED
>          Severity: normal
>          Priority: P3
>         Component: preprocessor
>        AssignedTo: unassigned at gcc dot gnu dot org
>        ReportedBy: martinrb at google dot com
>  GCC host triplet: x86_64-linux-gnu
>
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37549
>


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37549

[Bug preprocessor/37549] gcc -E -dD prints predefined macros, contrary to docs

[martinrb at google dot com]

------- Comment #2 from martinrb at google dot com  2008-09-17 04:27 -------
I tried to check how -dM and -dD treats macros defined on the command line
and in the source file:

(martinrb@spraggett) ~/src/toy $ cat foo.c
#define FOO 1
(martinrb@spraggett) ~/src/toy $ gcc -E -dM -x c -DBAR=1 foo.c | sort >/tmp/t1
(martinrb@spraggett) ~/src/toy $ gcc -E -dD -x c -DBAR=1 foo.c | sort >/tmp/t2
(martinrb@spraggett) ~/src/toy $ diff /tmp/t[12]                              
0a1,4
> # 1 "<built-in>"
> # 1 "<command-line>"
> # 1 "foo.c"
> # 1 "foo.c"

=> No difference in the treatment of various classes of macros.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37549

[Bug preprocessor/37549] gcc -E -dD prints predefined macros, contrary to docs

[jsm28 at gcc dot gnu dot org]

------- Comment #3 from jsm28 at gcc dot gnu dot org  2009-03-30 00:39 -------
It seems -dD used not to print predefined macros (whether defined by the
compiler or the user) but this changed in 3.0.  Since the documentation did
not change, I will guess the change was not deliberate.


-- 

jsm28 at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2009-03-30 00:39:56
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37549

[Bug preprocessor/37549] gcc -E -dD prints predefined macros, contrary to docs

[tromey at gcc dot gnu dot org]

------- Comment #4 from tromey at gcc dot gnu dot org  2009-03-30 23:22 -------
Try this.
I'll submit it if it regression tests ok.

Index: c-ppoutput.c
===================================================================
--- c-ppoutput.c        (revision 145295)
+++ c-ppoutput.c        (working copy)
@@ -377,6 +380,8 @@
 static void
 cb_define (cpp_reader *pfile, source_location line, cpp_hashnode *node)
 {
+  if (line <= BUILTINS_LOCATION)
+    return;
   maybe_print_line (line);
   fputs ("#define ", print.outf);

@@ -396,6 +401,8 @@
 cb_undef (cpp_reader *pfile ATTRIBUTE_UNUSED, source_location line,
          cpp_hashnode *node)
 {
+  if (line <= BUILTINS_LOCATION)
+    return;
   maybe_print_line (line);
   fprintf (print.outf, "#undef %s\n", NODE_NAME (node));
   print.src_line++;


-- 

tromey at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tromey at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37549