[NetBSD-PR lib/46163] netbsd-6 build broken at tests/lib/libobjc

[Takehiko NOZAKI]

see detail: http://gnats.netbsd.org/cgi-bin/query-pr-single.pl?number=46163

if libobjc is built with -g(=debug) option + -stdc={c99,gnu99} some inline function(objc_read_* etc) become missing undefined symbol.

1. gcc always erase inline function body.
2. but gcc don't expand inline function into caller.
3. so inline function become undefined symbol

[Takehiko NOZAKI]

minimal case is:

$ cat>test.c
#include <stdio.h>

extern void bar(void);

inline int
foo()
{
        printf("foo\n");
}

int
bar()
{
        foo();
        printf("bar\n");
}
^D

compile and check symbol:

$ gcc -shared -fPIC -std=c99 -O2 a.c -o a.o
nm a.o | grep foo

if -O2 is specified, foo() is expaned as inline.

$ gcc -shared -fPIC -std=c99 -g a.c -o a.o
$ nm a.o | grep foo
                 U foo

but if -g is specified, foo() is not expaned so it become undefined symbol.

[Takehiko NOZAKI]

$ gcc --version
gcc (NetBSD nb2 20110806) 4.5.3
Copyright (C) 2010 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[Takehiko NOZAKI]

i confirmed gcc 4.8.2(CentOS7) still have same problem.

[Takehiko NOZAKI]

ISO/IEC9899:1999 says that if you want export the symbol and exand inline same time, decrate following prototype:

extern void foo(void);

inline void
foo()
{
    ...
}

or if you want only expand inline function, use static inline:

static inline void
foo()
{
    ...
}

but libobjc's code don't have extern prototype or static inline decls. it is bad behavior.

[Takehiko NOZAKI]

i believe following function in archive.c is not public API because these were not defined in objc.h.

__objc_read_nbyte_uint
__objc_read_nbyte_ulong
__objc_write_class
__objc_write_object
__objc_write_selector
objc_read_char
objc_read_int
objc_read_long
objc_read_selector
objc_read_short
objc_read_string
objc_read_unsigned_char
objc_read_unsigned_int
objc_read_unsigned_long
objc_read_unsigned_short
objc_write_char
objc_write_int
objc_write_long
objc_write_selector
objc_write_short
objc_write_string
objc_write_string_atomic
objc_write_unsigned_char
objc_write_unsigned_int
objc_write_unsigned_long
objc_write_unsigned_short

so that simply change inline -> static inline.

following function in sendmsg.c too.

__objc_get_forward_imp

be aware, recent gcc applied following patch:

https://patchwork.ozlabs.org/patch/433574/

they revive __objc_get_forward_imp symbol. but i don't think it is not nessesary expect get_imp() ABI.

[Takehiko NOZAKI]

BUGFIX: Issue #102 - [NetBSD-PR lib/46163] netbsd-6 build broken at tests/lib/libobjc.

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