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* [Bug c++/47999] New: [C++0x] auto type deduction works incorrectly in a function template @ 2011-03-05 17:28 mimomorin at gmail dot com 2011-03-05 23:39 ` [Bug c++/47999] " paolo.carlini at oracle dot com ` (5 more replies) 0 siblings, 6 replies; 7+ messages in thread From: mimomorin at gmail dot com @ 2011-03-05 17:28 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47999 Summary: [C++0x] auto type deduction works incorrectly in a function template Product: gcc Version: 4.6.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassigned@gcc.gnu.org ReportedBy: mimomorin@gmail.com Created attachment 23554 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23554 Test case When `auto&&` is initialized with a function return value that is an lvalue reference, the deduced type should be an lvalue reference. int& identity(int& i) { return i; } void f() { int i = 0; auto&& x = identity(i); // x has type `int&` } But, in a function template, auto type deduction incorrectly deduces the type as an rvalue reference. template <typename T> void f() { int i = 0; auto&& x = identity(i); // BUG: x has type `int&&` } This bug leads to compilation error in gcc 4.5 and 4.6, because lvalues cannot bind to rvalue references. In gcc 4.4, the code compiles fine because lvalues are allowed to bind to rvalue references. Tested compilers: gcc-4.4.5, 4.5.2, 4.6-20110219. (This problem was found by Nathan Ridge.) ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/47999] [C++0x] auto type deduction works incorrectly in a function template 2011-03-05 17:28 [Bug c++/47999] New: [C++0x] auto type deduction works incorrectly in a function template mimomorin at gmail dot com @ 2011-03-05 23:39 ` paolo.carlini at oracle dot com 2011-03-08 13:47 ` jason at gcc dot gnu.org ` (4 subsequent siblings) 5 siblings, 0 replies; 7+ messages in thread From: paolo.carlini at oracle dot com @ 2011-03-05 23:39 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47999 Paolo Carlini <paolo.carlini at oracle dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jason at gcc dot gnu.org --- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-03-05 23:39:18 UTC --- Let's CC Jason, ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/47999] [C++0x] auto type deduction works incorrectly in a function template 2011-03-05 17:28 [Bug c++/47999] New: [C++0x] auto type deduction works incorrectly in a function template mimomorin at gmail dot com 2011-03-05 23:39 ` [Bug c++/47999] " paolo.carlini at oracle dot com @ 2011-03-08 13:47 ` jason at gcc dot gnu.org 2011-03-08 15:14 ` jason at gcc dot gnu.org ` (3 subsequent siblings) 5 siblings, 0 replies; 7+ messages in thread From: jason at gcc dot gnu.org @ 2011-03-08 13:47 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47999 Jason Merrill <jason at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |ASSIGNED Last reconfirmed| |2011.03.08 13:47:09 AssignedTo|unassigned at gcc dot |jason at gcc dot gnu.org |gnu.org | Ever Confirmed|0 |1 ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/47999] [C++0x] auto type deduction works incorrectly in a function template 2011-03-05 17:28 [Bug c++/47999] New: [C++0x] auto type deduction works incorrectly in a function template mimomorin at gmail dot com 2011-03-05 23:39 ` [Bug c++/47999] " paolo.carlini at oracle dot com 2011-03-08 13:47 ` jason at gcc dot gnu.org @ 2011-03-08 15:14 ` jason at gcc dot gnu.org 2011-03-16 17:22 ` jason at gcc dot gnu.org ` (2 subsequent siblings) 5 siblings, 0 replies; 7+ messages in thread From: jason at gcc dot gnu.org @ 2011-03-08 15:14 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47999 --- Comment #2 from Jason Merrill <jason at gcc dot gnu.org> 2011-03-08 15:14:02 UTC --- Created attachment 23583 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23583 Fix Here's a patch that fixes the bug and passes regression testing. I don't plan to put it in for 4.6.0 as I'm concerned about possible side-effects; I seem to remember trying to do exactly this once before and it causing problems. I'll put it in for 4.7 once 4.6 branches, and then perhaps into 4.6.1. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/47999] [C++0x] auto type deduction works incorrectly in a function template 2011-03-05 17:28 [Bug c++/47999] New: [C++0x] auto type deduction works incorrectly in a function template mimomorin at gmail dot com ` (2 preceding siblings ...) 2011-03-08 15:14 ` jason at gcc dot gnu.org @ 2011-03-16 17:22 ` jason at gcc dot gnu.org 2011-03-29 14:30 ` jason at gcc dot gnu.org 2011-03-29 14:56 ` jason at gcc dot gnu.org 5 siblings, 0 replies; 7+ messages in thread From: jason at gcc dot gnu.org @ 2011-03-16 17:22 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47999 --- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> 2011-03-16 17:04:35 UTC --- Author: jason Date: Wed Mar 16 17:04:30 2011 New Revision: 171053 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=171053 Log: PR c++/47999 * semantics.c (finish_call_expr): Preserve reference semantics in templates. Added: trunk/gcc/testsuite/g++.dg/cpp0x/auto22.C Modified: trunk/gcc/cp/ChangeLog trunk/gcc/cp/semantics.c trunk/gcc/testsuite/ChangeLog ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/47999] [C++0x] auto type deduction works incorrectly in a function template 2011-03-05 17:28 [Bug c++/47999] New: [C++0x] auto type deduction works incorrectly in a function template mimomorin at gmail dot com ` (3 preceding siblings ...) 2011-03-16 17:22 ` jason at gcc dot gnu.org @ 2011-03-29 14:30 ` jason at gcc dot gnu.org 2011-03-29 14:56 ` jason at gcc dot gnu.org 5 siblings, 0 replies; 7+ messages in thread From: jason at gcc dot gnu.org @ 2011-03-29 14:30 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47999 --- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> 2011-03-29 14:25:49 UTC --- Author: jason Date: Tue Mar 29 14:25:37 2011 New Revision: 171670 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=171670 Log: PR c++/47999 * semantics.c (finish_call_expr): Preserve reference semantics in templates. Added: branches/gcc-4_6-branch/gcc/testsuite/g++.dg/cpp0x/auto22.C Modified: branches/gcc-4_6-branch/gcc/cp/ChangeLog branches/gcc-4_6-branch/gcc/cp/semantics.c branches/gcc-4_6-branch/gcc/testsuite/ChangeLog ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/47999] [C++0x] auto type deduction works incorrectly in a function template 2011-03-05 17:28 [Bug c++/47999] New: [C++0x] auto type deduction works incorrectly in a function template mimomorin at gmail dot com ` (4 preceding siblings ...) 2011-03-29 14:30 ` jason at gcc dot gnu.org @ 2011-03-29 14:56 ` jason at gcc dot gnu.org 5 siblings, 0 replies; 7+ messages in thread From: jason at gcc dot gnu.org @ 2011-03-29 14:56 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47999 Jason Merrill <jason at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|ASSIGNED |RESOLVED Resolution| |FIXED Target Milestone|--- |4.6.1 --- Comment #5 from Jason Merrill <jason at gcc dot gnu.org> 2011-03-29 14:38:30 UTC --- Fixed for 4.6.1. ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2011-03-29 14:38 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2011-03-05 17:28 [Bug c++/47999] New: [C++0x] auto type deduction works incorrectly in a function template mimomorin at gmail dot com 2011-03-05 23:39 ` [Bug c++/47999] " paolo.carlini at oracle dot com 2011-03-08 13:47 ` jason at gcc dot gnu.org 2011-03-08 15:14 ` jason at gcc dot gnu.org 2011-03-16 17:22 ` jason at gcc dot gnu.org 2011-03-29 14:30 ` jason at gcc dot gnu.org 2011-03-29 14:56 ` jason at gcc dot gnu.org
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