GNU bug report logs - #40780
guile 3.0.2: Prevent warning using libguile with -Wpedantic (redefinition)

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Hannes Müller <h.c.f.mueller <at> gmail.com>
To: bug-guile <at> gnu.org
Subject: guile 3.0.2: Prevent warning using libguile with -Wpedantic
 (redefinition)
Date: Wed, 22 Apr 2020 21:30:52 +0200

Dear Maintainer,

2 warnings as shown below for libguile 3.0.2 (i.e. usage of libguile in
external C code) with gcc 9.3.0 and option -Wpedantic are indicated. In
contrast I get no warnings for libguile 2.2.7 with the same compiler
options. Therefore, please fix this easy to circumvent warning. 

Best regards
Hannes

In file included from /usr/include/guile/3.0/libguile/numbers.h:29,
                 from /usr/include/guile/3.0/libguile/array-
handle.h:27,
                 from /usr/include/guile/3.0/libguile.h:35,
                 from read_cfg.c:7:
/usr/include/guile/3.0/libguile/print.h:79:3: warning: redefinition of
typedef 'scm_print_state' [-Wpedantic]
   79 | } scm_print_state;
      |   ^~~~~~~~~~~~~~~
In file included from /usr/include/guile/3.0/libguile.h:33,
                 from read_cfg.c:7:
/usr/include/guile/3.0/libguile/scm.h:824:32: note: previous
declaration of 'scm_print_state' was here
  824 | typedef struct scm_print_state scm_print_state;
      |                                ^~~~~~~~~~~~~~~


In file included from /usr/include/guile/3.0/libguile/threads.h:27,
                 from /usr/include/guile/3.0/libguile/async.h:25,
                 from /usr/include/guile/3.0/libguile.h:38,
                 from read_cfg.c:7:
/usr/include/guile/3.0/libguile/dynstack.h:37:3: warning: redefinition
of typedef 'scm_t_dynstack' [-Wpedantic]
   37 | } scm_t_dynstack;
      |   ^~~~~~~~~~~~~~
In file included from /usr/include/guile/3.0/libguile.h:33,
                 from read_cfg.c:7:
/usr/include/guile/3.0/libguile/scm.h:825:29: note: previous
declaration of 'scm_t_dynstack' was here
  825 | typedef struct scm_dynstack scm_t_dynstack;
      |                             ^~~~~~~~~~~~~~

Message #8 received at 40780 <at> debbugs.gnu.org (full text, mbox):

From: Hannes Müller <h.c.f.mueller <at> gmail.com>
To: 40780 <at> debbugs.gnu.org
Subject: guile 3.0.4: #40780 can be closed (typedef redefinition allowed in
 c11)
Date: Sat, 05 Dec 2020 12:25:25 +0100

Dear Maintainer,

I consider this bug report can be closed.

The 2011 C standard allows redeclaration of typedef names. 6.7 3 says:
… a typedef name may be redefined to denote the same type as it
currently does, provided that type is not a variably modified type;…

I compiled my application with -std=c11 and -Wpedantic using libguile
3.0.4: no warning is shown any more. 

Thanks!
Hannes

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