[PATCH 3/3] vcs-svn: suppress a -Wtype-limits warning

From: Jonathan Nieder <jrnieder@gmail.com>
Date: Feb 2, 2012, 11:06 UTC
Message-ID: <20120202110601.GL3823@burratino>
In-Reply-To: <20120202104128.GG3823@burratino>

On 32-bit architectures with 64-bit file offsets, gcc 4.3 and earlier produce the following warning:

	    CC vcs-svn/sliding_window.o
	vcs-svn/sliding_window.c: In function `check_overflow':
	vcs-svn/sliding_window.c:36: warning: comparison is always false \
	    due to limited range of data type

The warning appears even when gcc is run without any warning flags (this is gcc bug 12963). In later versions the same warning can be reproduced with -Wtype-limits, which is implied by -Wextra.

On 64-bit architectures it really is possible for a size_t not to be representable as an off_t so the check this is warning about is not actually redundant. But even false positives are distracting. Avoid the warning by making the "len" argument to check_overflow a uintmax_t; no functional change intended.

Reported-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
That's the end of the series.  I hope it was entertaining.

Thoughts of all kinds welcome, as usual.

Jonathan

 vcs-svn/sliding_window.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/vcs-svn/sliding_window.c b/vcs-svn/sliding_window.c
index fafa4a63..2f4ae60f 100644
--- a/vcs-svn/sliding_window.c
+++ b/vcs-svn/sliding_window.c
@@ -31,15 +31,15 @@ static int read_to_fill_or_whine(struct line_buffer *file,
 	return 0;
 }
 
-static int check_overflow(off_t offset, size_t len)
+static int check_overflow(off_t offset, uintmax_t len)
 {
 	if (len > maximum_signed_value_of_type(off_t))
 		return error("unrepresentable length in delta: "
-				"%"PRIuMAX" > OFF_MAX", (uintmax_t) len);
+				"%"PRIuMAX" > OFF_MAX", len);
 	if (signed_add_overflows(offset, (off_t) len))
 		return error("unrepresentable offset in delta: "
 				"%"PRIuMAX" + %"PRIuMAX" > OFF_MAX",
-				(uintmax_t) offset, (uintmax_t) len);
+				(uintmax_t) offset, len);
 	return 0;
 }

-- 
1.7.9