[binutils-gdb] libctf: use __attribute__((__gnu_printf__)) where appropriate

[Nick Alcock]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f86f9fd85999c7a483855793b3efe85da1d6eb74

commit f86f9fd85999c7a483855793b3efe85da1d6eb74
Author: Nick Alcock <nick.alcock@oracle.com>
Date:   Tue Jun 3 13:39:33 2025 +0100

    libctf: use __attribute__((__gnu_printf__)) where appropriate
    
    We don't use any GNU-specific printf args, but this prevents warnings about
    %z, observed on MinGW even though every libc anyone is likely to use there
    supports %z perfectly well, and we're not stopping using it just because
    MinGW complains.  Doing this means we stand more chance of seeing *actual*
    problems on such platforms without them being drowned in noise.
    
    We turn this off on clang, which doesn't support __gnu_printf__.
    
    Suggested by Eli Zaretskii.
    
    libctf/
            PR libctf/31863
            * ctf-impl.h (_libctf_printflike_): Use __gnu_printf__.

Diff:
---
 libctf/ctf-impl.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libctf/ctf-impl.h b/libctf/ctf-impl.h
index 2691a689d31..3217f921254 100644
--- a/libctf/ctf-impl.h
+++ b/libctf/ctf-impl.h
@@ -66,8 +66,13 @@ extern "C"
    macros glibc may introduce, which have names of the pattern
    __attribute_blah__.  */
 
+#if defined (__clang__)
 #define _libctf_printflike_(string_index,first_to_check) \
     __attribute__ ((__format__ (__printf__, (string_index), (first_to_check))))
+#else
+#define _libctf_printflike_(string_index,first_to_check) \
+    __attribute__ ((__format__ (__gnu_printf__, (string_index), (first_to_check))))
+#endif
 #define _libctf_unlikely_(x) __builtin_expect ((x), 0)
 #define _libctf_unused_ __attribute__ ((__unused__))
 #define _libctf_malloc_ __attribute__((__malloc__))