Re: GNULIB_POSIXCHECK, remove, and gl_oset

[Bruno Haible]

Hi Eric,

> I tried compiling m4 with -DGNULIB_POSIXCHECK, to see if I was missing any 
> useful modules.  To my surprise, gl_oset.h failed to compile:
> 
> In file included from ../../lib/gl_avltree_oset.h:21,
>                  from ../../src/output.c:27:
> ../../lib/gl_oset.h:236:76: macro "remove" passed 2 arguments, but takes just 
> 1
> 
> POSIX states that:
> Any function declared in a header may also be implemented as a macro defined 
> in 
> the header, so a function should not be declared explicitly if its header is 
> included. Any macro definition of a function can be suppressed locally by 
> enclosing the name of the function in parentheses, because the name is then 
> not 
> followed by the <left-parenthesis> that indicates expansion of a macro 
> function 
> name.
> 
> In other words, it is legal for a system to #define remove(x), and so any use 
> of the name remove as a user identifier must be tolerant of the existence of 
> such a function-like macro.

Agreed.

> I see two options - either rewrite gl_oset.h to call 
> vtable->(remove)(set,elt),

This is not an option, because it leads to an error as well:

  gl_oset.h: In function ‘gl_oset_remove_inline’:
  gl_oset.h:236: error: expected identifier before ‘(’ token

> or rewrite gl_oset.h and clients to use a different vtable member function 
> pointer name that does not clash with the standardized name remove.  Which 
> would you prefer?

There is not much choice. I'm applying this:


2009-09-28  Bruno Haible  <address@hidden>

        Avoid identifier clash with POSIX function 'remove' defined as a macro.
        * lib/gl_list.h (struct gl_list_implementation): Rename field 'remove'
        to 'remove_elt'.
        (gl_list_remove): Update.
        * lib/gl_list.c (gl_list_remove): Update.
        * lib/gl_oset.h (struct gl_oset_implementation): Rename field 'remove'
        to 'remove_elt'.
        (gl_oset_remove): Update.
        * lib/gl_list.c (gl_oset_remove): Update.
        Reported by Eric Blake.

--- lib/gl_list.c.orig  2009-09-28 23:24:21.000000000 +0200
+++ lib/gl_list.c       2009-09-28 23:19:47.000000000 +0200
@@ -1,5 +1,5 @@
 /* Abstract sequential list data type.
-   Copyright (C) 2006-2008 Free Software Foundation, Inc.
+   Copyright (C) 2006-2009 Free Software Foundation, Inc.
    Written by Bruno Haible <address@hidden>, 2006.
 
    This program is free software: you can redistribute it and/or modify
@@ -197,7 +197,7 @@
 gl_list_remove (gl_list_t list, const void *elt)
 {
   return ((const struct gl_list_impl_base *) list)->vtable
-        ->remove (list, elt);
+        ->remove_elt (list, elt);
 }
 
 void
--- lib/gl_list.h.orig  2009-09-28 23:24:21.000000000 +0200
+++ lib/gl_list.h       2009-09-28 23:19:47.000000000 +0200
@@ -1,5 +1,5 @@
 /* Abstract sequential list data type.
-   Copyright (C) 2006-2008 Free Software Foundation, Inc.
+   Copyright (C) 2006-2009 Free Software Foundation, Inc.
    Written by Bruno Haible <address@hidden>, 2006.
 
    This program is free software: you can redistribute it and/or modify
@@ -405,7 +405,7 @@
                            const void *elt);
   bool (*remove_node) (gl_list_t list, gl_list_node_t node);
   bool (*remove_at) (gl_list_t list, size_t position);
-  bool (*remove) (gl_list_t list, const void *elt);
+  bool (*remove_elt) (gl_list_t list, const void *elt);
   void (*list_free) (gl_list_t list);
   /* gl_list_iterator_t functions.  */
   gl_list_iterator_t (*iterator) (gl_list_t list);
@@ -650,7 +650,7 @@
 gl_list_remove (gl_list_t list, const void *elt)
 {
   return ((const struct gl_list_impl_base *) list)->vtable
-        ->remove (list, elt);
+        ->remove_elt (list, elt);
 }
 
 # define gl_list_free gl_list_free_inline
--- lib/gl_oset.c.orig  2009-09-28 23:24:21.000000000 +0200
+++ lib/gl_oset.c       2009-09-28 23:21:28.000000000 +0200
@@ -1,5 +1,5 @@
 /* Abstract ordered set data type.
-   Copyright (C) 2006-2007 Free Software Foundation, Inc.
+   Copyright (C) 2006-2007, 2009 Free Software Foundation, Inc.
    Written by Bruno Haible <address@hidden>, 2006.
 
    This program is free software: you can redistribute it and/or modify
@@ -64,7 +64,8 @@
 bool
 gl_oset_remove (gl_oset_t set, const void *elt)
 {
-  return ((const struct gl_oset_impl_base *) set)->vtable->remove (set, elt);
+  return ((const struct gl_oset_impl_base *) set)->vtable
+        ->remove_elt (set, elt);
 }
 
 void
--- lib/gl_oset.h.orig  2009-09-28 23:24:21.000000000 +0200
+++ lib/gl_oset.h       2009-09-28 23:24:19.000000000 +0200
@@ -1,5 +1,5 @@
 /* Abstract ordered set data type.
-   Copyright (C) 2006-2007 Free Software Foundation, Inc.
+   Copyright (C) 2006-2007, 2009 Free Software Foundation, Inc.
    Written by Bruno Haible <address@hidden>, 2006.
 
    This program is free software: you can redistribute it and/or modify
@@ -168,7 +168,7 @@
                          gl_setelement_threshold_fn threshold_fn,
                          const void *threshold, const void **eltp);
   bool (*add) (gl_oset_t set, const void *elt);
-  bool (*remove) (gl_oset_t set, const void *elt);
+  bool (*remove_elt) (gl_oset_t set, const void *elt);
   void (*oset_free) (gl_oset_t set);
   /* gl_oset_iterator_t functions.  */
   gl_oset_iterator_t (*iterator) (gl_oset_t set);
@@ -233,7 +233,8 @@
 static inline bool
 gl_oset_remove (gl_oset_t set, const void *elt)
 {
-  return ((const struct gl_oset_impl_base *) set)->vtable->remove (set, elt);
+  return ((const struct gl_oset_impl_base *) set)->vtable
+        ->remove_elt (set, elt);
 }
 
 # define gl_oset_free gl_oset_free_inline