Bug 13507

For the source below, gives a bogus warning when -Wall is used:

$ ./cc1plus -Wall -quiet x.i
x.i: In function `void foo(unsigned int)':
x.i:8: warning: format argument is not a pointer (arg 2)
$

This problem appears to have been introduced by this change:

2003-12-28  Roger Sayle  <roger@eyesopen.com>

	PR c++/13070
	* decl.c (duplicate_decls): When setting the type of an anticipated
	declaration, merge the existing type attributes.

If i revert that change, then the warning goes away.

Below is the dump of the attrs parameter at the entry
to check_function_format().  It contains _two_ format
attributes, one printf and one scanf.  check_format_info is being
called twice, once for each; the second time (the scanf one)
is when the warnings gets emitted.

 <tree_list 0x400eab40
    purpose <identifier_node 0x40026e40 format
    bindings <(nil)>
    local bindings <(nil)>>
    value <tree_list 0x40030ca8
        value <identifier_node 0x40026fc0 printf public
        bindings <0x4007a460>
        local bindings <(nil)>>
        chain <tree_list 0x40030b04
            value <integer_cst 0x40030a50 constant 1>
            chain <tree_list 0x40030a8c
                value <integer_cst 0x40030a78 constant 2>>>>
    chain <tree_list 0x4007a8fc
        purpose <identifier_node 0x40026f00 nonnull
        bindings <(nil)>
        local bindings <(nil)>>
        value <tree_list 0x40030a64 value <integer_cst 0x40030a50 1>>
        chain <tree_list 0x4007a8e8 purpose <identifier_node 0x40026e40 format>
            value <tree_list 0x40030d98
                value <identifier_node 0x40033140 scanf public
                bindings <0x4007a988>
                local bindings <(nil)>> chain <tree_list 0x40030b04>>>>>

Environment:
System: Linux karma 2.6.0 #9 Sun Dec 28 19:12:01 EST 2003 i686 i686 i386 GNU/Linux
Architecture: i686

	
host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
configured with: ../gcc/configure --prefix=/usr/local/gcc --enable-threads=posix --enable-long-long --enable-languages=c,c++,f77

How-To-Repeat:

Compile with -Wall:

-----------------------------------------------------------
extern "C" {
extern int printf (__const char *__restrict __format, ...) throw ();
extern int scanf (__const char *__restrict __format, ...) throw ();
}

void foo(unsigned int x)
{
  printf ("%d\n", x);
}
-----------------------------------------------------------