On FreeBSD 11, I see this warning:
../src/fmt.c:501:50: warning: data argument not used by format string
[-Wformat-extra-args]
The code there implements this logic:
- If an error number is known, present an error message with a file name,
but without telling the user in which context the error occurred.
- If an error number is not known, tell the user about the context,
but not about the file name.
This logic makes no sense.
Here's a patch to change that. Its effects are:
When a file name is known, e.g. "foobar.txt":
If there was an error before fclose():
Before: read error
After: error reading 'foobar.txt'
If there was no error before fclose():
Before: 'foobar.txt': I/O error
After: error reading 'foobar.txt': I/O error
When reading from standard input (in this case no error number is known):
Before: read error
After: read error
>From e41b9e372f1f17378091654fc78ba76913ba61c6 Mon Sep 17 00:00:00 2001
From: Bruno Haible <[email protected]>
Date: Thu, 18 Sep 2025 23:05:06 +0200
Subject: [PATCH] fmt: Eliminate a clang -Wformat-extra-args warning
* src/fmt.c (fmt): When not reading from stdin, always mention the
file name in the error message.
---
src/fmt.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/src/fmt.c b/src/fmt.c
index b44bbde5c..4591e266d 100644
--- a/src/fmt.c
+++ b/src/fmt.c
@@ -493,12 +493,18 @@ fmt (FILE *f, char const *file)
}
int err = ferror (f) ? 0 : -1;
+ /* err < 0 means success. */
if (f == stdin)
clearerr (f);
else if (fclose (f) != 0 && err < 0)
err = errno;
if (0 <= err)
- error (0, err, err ? "%s" : _("read error"), quotef (file));
+ {
+ if (f == stdin)
+ error (0, err, _("read error"));
+ else
+ error (0, err, _("error reading %s"), quotef (file));
+ }
return err < 0;
}
--
2.51.0
