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* [Bug c/50347] New: unexpected -Wconversion error from gcc builtin @ 2011-09-10 8:45 gcc.hall at gmail dot com 2011-09-10 10:19 ` [Bug c/50347] " gcc.hall at gmail dot com ` (5 more replies) 0 siblings, 6 replies; 7+ messages in thread From: gcc.hall at gmail dot com @ 2011-09-10 8:45 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50347 Bug #: 50347 Summary: unexpected -Wconversion error from gcc builtin Classification: Unclassified Product: gcc Version: 4.6.1 Status: UNCONFIRMED Severity: minor Priority: P3 Component: c AssignedTo: unassigned@gcc.gnu.org ReportedBy: gcc.hall@gmail.com This message is produced from the code example below. bug.c: In function 'main': bug.c:17:2: warning: conversion to 'long long int' from 'long long unsigned int' may change the sign of the result [-Wsign-conversion] builtin_ffsll is documented as:- Built-in Function: int __builtin_ffsll (unsigned long long) Similar to __builtin_ffs, except the argument type is unsigned long long. Note this does not happen with the other similar builtin's (__ctzll for example) ----------------------------------------------------------------- #include <stdio.h> #include <stdlib.h> int main( int argc, char *argv[] ) { if( argc > 1 ) { char *tail; unsigned long long n = strtoull( argv[1], &tail, 0 ); if( tail == argv[1] ) return 1; int lsb = __builtin_ffsll( n ); printf("lsb = %d\n", lsb ); } return 0; } ------------------------------------------------------------------- * gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/i686-pc-linux-gnu/4.6.1/lto-wrapper Target: i686-pc-linux-gnu Configured with: ../gcc-4.6.1/configure Thread model: posix gcc version 4.6.1 (GCC) ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/50347] unexpected -Wconversion error from gcc builtin 2011-09-10 8:45 [Bug c/50347] New: unexpected -Wconversion error from gcc builtin gcc.hall at gmail dot com @ 2011-09-10 10:19 ` gcc.hall at gmail dot com 2011-09-11 0:38 ` gcc.hall at gmail dot com ` (4 subsequent siblings) 5 siblings, 0 replies; 7+ messages in thread From: gcc.hall at gmail dot com @ 2011-09-10 10:19 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50347 --- Comment #1 from Jeremy <gcc.hall at gmail dot com> 2011-09-10 10:15:15 UTC --- I see this builtin is presumably intended to implement the library function ffsll() which takes a signed argument. In which case this is just a documentation issue. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/50347] unexpected -Wconversion error from gcc builtin 2011-09-10 8:45 [Bug c/50347] New: unexpected -Wconversion error from gcc builtin gcc.hall at gmail dot com 2011-09-10 10:19 ` [Bug c/50347] " gcc.hall at gmail dot com @ 2011-09-11 0:38 ` gcc.hall at gmail dot com 2012-06-07 14:02 ` manu at gcc dot gnu.org ` (3 subsequent siblings) 5 siblings, 0 replies; 7+ messages in thread From: gcc.hall at gmail dot com @ 2011-09-11 0:38 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50347 --- Comment #2 from Jeremy <gcc.hall at gmail dot com> 2011-09-10 21:57:59 UTC --- I think also the doc needs changing for __builtin_bswap64/32 as it looks like they accept and return unsigned integers. uint64_t instead of int64_t. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/50347] unexpected -Wconversion error from gcc builtin 2011-09-10 8:45 [Bug c/50347] New: unexpected -Wconversion error from gcc builtin gcc.hall at gmail dot com 2011-09-10 10:19 ` [Bug c/50347] " gcc.hall at gmail dot com 2011-09-11 0:38 ` gcc.hall at gmail dot com @ 2012-06-07 14:02 ` manu at gcc dot gnu.org 2014-03-25 20:53 ` mpolacek at gcc dot gnu.org ` (2 subsequent siblings) 5 siblings, 0 replies; 7+ messages in thread From: manu at gcc dot gnu.org @ 2012-06-07 14:02 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50347 Manuel López-Ibáñez <manu at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |manu at gcc dot gnu.org --- Comment #3 from Manuel López-Ibáñez <manu at gcc dot gnu.org> 2012-06-07 14:02:12 UTC --- Could you send a doc patch to gcc-patches@ ? Thanks! ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/50347] unexpected -Wconversion error from gcc builtin 2011-09-10 8:45 [Bug c/50347] New: unexpected -Wconversion error from gcc builtin gcc.hall at gmail dot com ` (2 preceding siblings ...) 2012-06-07 14:02 ` manu at gcc dot gnu.org @ 2014-03-25 20:53 ` mpolacek at gcc dot gnu.org 2014-03-27 15:59 ` mpolacek at gcc dot gnu.org 2014-03-27 15:59 ` mpolacek at gcc dot gnu.org 5 siblings, 0 replies; 7+ messages in thread From: mpolacek at gcc dot gnu.org @ 2014-03-25 20:53 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50347 Marek Polacek <mpolacek at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |documentation Status|UNCONFIRMED |ASSIGNED Last reconfirmed| |2014-03-25 CC| |mpolacek at gcc dot gnu.org Assignee|unassigned at gcc dot gnu.org |mpolacek at gcc dot gnu.org Ever confirmed|0 |1 --- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> --- __builtin_bswap* were fixed in r191774. I have a patch for ffs* builtins. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/50347] unexpected -Wconversion error from gcc builtin 2011-09-10 8:45 [Bug c/50347] New: unexpected -Wconversion error from gcc builtin gcc.hall at gmail dot com ` (3 preceding siblings ...) 2014-03-25 20:53 ` mpolacek at gcc dot gnu.org @ 2014-03-27 15:59 ` mpolacek at gcc dot gnu.org 2014-03-27 15:59 ` mpolacek at gcc dot gnu.org 5 siblings, 0 replies; 7+ messages in thread From: mpolacek at gcc dot gnu.org @ 2014-03-27 15:59 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50347 --- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> --- Author: mpolacek Date: Thu Mar 27 15:59:07 2014 New Revision: 208870 URL: http://gcc.gnu.org/viewcvs?rev=208870&root=gcc&view=rev Log: PR c/50347 * doc/extend.texi (ffs Builtins): Change unsigned types to signed types. Modified: trunk/gcc/ChangeLog trunk/gcc/doc/extend.texi ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/50347] unexpected -Wconversion error from gcc builtin 2011-09-10 8:45 [Bug c/50347] New: unexpected -Wconversion error from gcc builtin gcc.hall at gmail dot com ` (4 preceding siblings ...) 2014-03-27 15:59 ` mpolacek at gcc dot gnu.org @ 2014-03-27 15:59 ` mpolacek at gcc dot gnu.org 5 siblings, 0 replies; 7+ messages in thread From: mpolacek at gcc dot gnu.org @ 2014-03-27 15:59 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50347 Marek Polacek <mpolacek at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|ASSIGNED |RESOLVED Resolution|--- |FIXED --- Comment #6 from Marek Polacek <mpolacek at gcc dot gnu.org> --- Fixed. ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2014-03-27 15:59 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2011-09-10 8:45 [Bug c/50347] New: unexpected -Wconversion error from gcc builtin gcc.hall at gmail dot com 2011-09-10 10:19 ` [Bug c/50347] " gcc.hall at gmail dot com 2011-09-11 0:38 ` gcc.hall at gmail dot com 2012-06-07 14:02 ` manu at gcc dot gnu.org 2014-03-25 20:53 ` mpolacek at gcc dot gnu.org 2014-03-27 15:59 ` mpolacek at gcc dot gnu.org 2014-03-27 15:59 ` mpolacek at gcc dot gnu.org
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