[Bug c++/55783] Warnings instead of compiler errors for narrowing conversions within list-initializations
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55783 Andrew Pinski changed: What|Removed |Added CC||antoshkka at gmail dot com --- Comment #16 from Andrew Pinski --- *** Bug 96452 has been marked as a duplicate of this bug. ***
[Bug c++/55783] Warnings instead of compiler errors for narrowing conversions within list-initializations
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55783 Marc Mutz changed: What|Removed |Added CC||marc at kdab dot com --- Comment #15 from Marc Mutz --- *** Bug 92856 has been marked as a duplicate of this bug. ***
[Bug c++/55783] Warnings instead of compiler errors for narrowing conversions within list-initializations
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55783 --- Comment #14 from Manuel López-Ibáñez --- *** Bug 71985 has been marked as a duplicate of this bug. ***
[Bug c++/55783] Warnings instead of compiler errors for narrowing conversions within list-initializations
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55783 Markus Trippelsdorf changed: What|Removed |Added CC||nico at josuttis dot de --- Comment #13 from Markus Trippelsdorf --- *** Bug 71985 has been marked as a duplicate of this bug. ***
[Bug c++/55783] Warnings instead of compiler errors for narrowing conversions within list-initializations
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55783 Manuel López-Ibáñez changed: What|Removed |Added CC||manu at gcc dot gnu.org --- Comment #12 from Manuel López-Ibáñez --- Since it seems this has to be explained repeatedly (and I had to read this in detail to understand why this is a pedwarn enabled by -Wall), I created a FAQ: https://gcc.gnu.org/wiki/FAQ#Wnarrowing Jonathan, I used most of your comment #4 verbatim, I hope this is OK. Feel free to edit it for corrections or further clarification.
[Bug c++/55783] Warnings instead of compiler errors for narrowing conversions within list-initializations
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55783 Manuel López-Ibáñez changed: What|Removed |Added CC||mgsergio at yandex dot ru --- Comment #11 from Manuel López-Ibáñez --- *** Bug 69864 has been marked as a duplicate of this bug. ***
[Bug c++/55783] Warnings instead of compiler errors for narrowing conversions within list-initializations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55783 Paolo Carlini paolo.carlini at oracle dot com changed: What|Removed |Added CC||thomas.braun@virtuell-zuhau ||se.de --- Comment #10 from Paolo Carlini paolo.carlini at oracle dot com --- *** Bug 58986 has been marked as a duplicate of this bug. ***
[Bug c++/55783] Warnings instead of compiler errors for narrowing conversions within list-initializations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55783 Jason Merrill jason at gcc dot gnu.org changed: What|Removed |Added Status|UNCONFIRMED |RESOLVED CC||jason at gcc dot gnu.org Resolution||WORKSFORME --- Comment #9 from Jason Merrill jason at gcc dot gnu.org 2013-02-15 17:16:39 UTC --- You can use -pedantic-errors to turn this and various other violations from warnings into errors.
[Bug c++/55783] Warnings instead of compiler errors for narrowing conversions within list-initializations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55783 --- Comment #1 from Andrew Pinski pinskia at gcc dot gnu.org 2012-12-22 00:06:50 UTC --- With -std=c++11, -Wno-narrowing suppresses the diagnostic required by the standard. Note that this does not affect the meaning of well-formed code; narrowing conversions are still considered ill-formed in SFINAE context.
[Bug c++/55783] Warnings instead of compiler errors for narrowing conversions within list-initializations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55783 --- Comment #2 from David Sankel david at stellarscience dot com 2012-12-22 00:13:33 UTC --- From what I understand, the standard requires the compiler to reject the program, not to accept it with a warning.
[Bug c++/55783] Warnings instead of compiler errors for narrowing conversions within list-initializations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55783 --- Comment #3 from Andrew Pinski pinskia at gcc dot gnu.org 2012-12-22 00:15:04 UTC --- use -Werror=Wnarrowing then
[Bug c++/55783] Warnings instead of compiler errors for narrowing conversions within list-initializations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55783
Jonathan Wakely redi at gcc dot gnu.org changed:
What|Removed |Added
Severity|major |normal
--- Comment #4 from Jonathan Wakely redi at gcc dot gnu.org 2012-12-22
00:26:10 UTC ---
The standard only requires that a conforming implementation shall issue at
least one diagnostic message so compiling the program with a warning is
allowed. As Andrew said, -Werror=narrowing allows you to make it an error if
you want.
G++ 4.6 gave an error but it was changed to a warning intentionally for 4.7
because many people (myself included) found that narrowing conversions where
one of the most commonly encountered problems when trying to compile large
C++03 codebases as C++11. Previously well-formed code such as char c[] = { i,
0 }; (where i will only ever be within the range of char) caused errors and had
to be changed to char c[] = { (char)i, 0 }
[Bug c++/55783] Warnings instead of compiler errors for narrowing conversions within list-initializations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55783 --- Comment #5 from Jonathan Wakely redi at gcc dot gnu.org 2012-12-22 00:27:51 UTC --- (In reply to comment #4) The standard only requires that a conforming implementation shall issue at least one diagnostic message (This is from 1.4 [intro.compliance] p2)
[Bug c++/55783] Warnings instead of compiler errors for narrowing conversions within list-initializations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55783 --- Comment #6 from David Sankel david at stellarscience dot com 2012-12-22 00:33:44 UTC --- I suppose which gnu extensions are, by default, enabled in the -std=c++11 mode is up for debate (one which I have no interest in). However, this program still compiles with -pedantic. -pedantic Issue all the warnings demanded by strict ISO C and ISO C++; reject all programs that use forbidden extensions Allowing for these narrowing conversions would qualify as a forbidden extension. Regarding compliance, I think Johnathan's snippet is misleading. Here is the relevant surrounding text: If a program contains a violation of any diagnosable rule or an occurrence of a construct described in this Standard as “conditionally-supported” when the implementation does not support that construct, a conforming implementation shall issue at least one diagnostic message. I didn't see in the standard where it states that breaking this feature is conditionally supported. However, it does say: If a program contains a violation of a rule for which no diagnostic is required, this International Standard places no requirement on implementations with respect to that program. Which pretty much allows gcc to do anything it wants with malformed programs. But as stated above, -pedantic should guarentee rejection.
[Bug c++/55783] Warnings instead of compiler errors for narrowing conversions within list-initializations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55783 --- Comment #7 from David Sankel david at stellarscience dot com 2012-12-22 00:42:35 UTC --- I just realized my above comment doesn't make much sense regarding the standard. Please disregard. On the other hand it seems like -pedantic should reject this program, no?
[Bug c++/55783] Warnings instead of compiler errors for narrowing conversions within list-initializations
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55783 Jonathan Wakely redi at gcc dot gnu.org changed: What|Removed |Added Keywords||diagnostic --- Comment #8 from Jonathan Wakely redi at gcc dot gnu.org 2012-12-22 00:55:31 UTC --- Comment 6 misinterprets the standard in multiple ways :) Narrowing conversions do require a diagnostic, but a warning *is* a diagnostic, so G++ is compliant in this regard, this is not a GNU extension. Whether the diagnostic should default to a warning or an error or a pedwarn (the category of diagnostic enabled by -pedantic and made into errors by -pedantic-errors) is debatable, but the current behaviour is the result of a conscious decision and is not a bug (certainly not Severity=major)
