From: Benjamin Berg <benjamin.berg@intel.com>

There is no errno variable when NOLIBC_IGNORE_ERRNO is defined. As such,
the perror function does not make any sense then and cannot compile.

Fixes: acab7bcdb1bc ("tools/nolibc/stdio: add perror() to report the errno value")
Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
---
 tools/include/nolibc/stdio.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h
index 7630234408c5..c512159b8374 100644
--- a/tools/include/nolibc/stdio.h
+++ b/tools/include/nolibc/stdio.h
@@ -597,11 +597,13 @@ int sscanf(const char *str, const char *format, ...)
 	return ret;
 }
 
+#ifndef NOLIBC_IGNORE_ERRNO
 static __attribute__((unused))
 void perror(const char *msg)
 {
 	fprintf(stderr, "%s%serrno=%d\n", (msg && *msg) ? msg : "", (msg && *msg) ? ": " : "", errno);
 }
+#endif
 
 static __attribute__((unused))
 int setvbuf(FILE *stream __attribute__((unused)),
-- 
2.51.0

On 2025-09-15 09:11:09+0200, Benjamin Berg wrote:
> From: Benjamin Berg <benjamin.berg@intel.com>
> 
> There is no errno variable when NOLIBC_IGNORE_ERRNO is defined. As such,
> the perror function does not make any sense then and cannot compile.
> 
> Fixes: acab7bcdb1bc ("tools/nolibc/stdio: add perror() to report the errno value")
> Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>

Acked-by: Thomas Weißschuh <linux@weissschuh.net>

> ---
>  tools/include/nolibc/stdio.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h
> index 7630234408c5..c512159b8374 100644
> --- a/tools/include/nolibc/stdio.h
> +++ b/tools/include/nolibc/stdio.h
> @@ -597,11 +597,13 @@ int sscanf(const char *str, const char *format, ...)
>  	return ret;
>  }
>  
> +#ifndef NOLIBC_IGNORE_ERRNO
>  static __attribute__((unused))
>  void perror(const char *msg)
>  {
>  	fprintf(stderr, "%s%serrno=%d\n", (msg && *msg) ? msg : "", (msg && *msg) ? ": " : "", errno);
>  }
> +#endif
>  
>  static __attribute__((unused))
>  int setvbuf(FILE *stream __attribute__((unused)),
> -- 
> 2.51.0
>