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* [Bug libstdc++/103549] New: [12 regression] Uninitialized member warning from regex header
@ 2021-12-03 23:46 sss@li-snyder.org
2021-12-04 1:00 ` [Bug libstdc++/103549] " redi at gcc dot gnu.org
` (8 more replies)
0 siblings, 9 replies; 10+ messages in thread
From: sss@li-snyder.org @ 2021-12-03 23:46 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103549
Bug ID: 103549
Summary: [12 regression] Uninitialized member warning from
regex header
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: sss@li-snyder.org
Target Milestone: ---
hi -
With a recent checkout of gcc12 (20211201) on a x86_64-pc-linux-gnu host,
compiling the following source with -O2 -Wall gives a warning
about an uninitialized member in the regex header:
-- x.cc ---------------------------------------------------
#include <string>
#include <regex>
std::string plover(char *s)
{
return std::regex_replace (s, std::regex{"xyzzy"}, "plugh");
}
-----------------------------------------------------------
$ g++ -c -O2 -Wall x.cc
In file included from /usr/local/gcc/include/c++/12.0.0/regex:66,
from x.cc:2:
In member function ‘std::__cxx11::match_results< <template-parameter-1-1>,
<template-parameter-1-2> >& std::__cxx11::match_results<
<template-parameter-1-1>, <template-parameter-1-2> >::operator=(const
std::__cxx11::match_results< <template-parameter-1-1>, <template-parameter-1-2>
>&) [with _Bi_iter = const char*; _Alloc =
std::allocator<std::__cxx11::sub_match<const char*> >]’,
inlined from ‘std::__cxx11::regex_iterator<_Bi_iter, _Ch_type, _Rx_traits>&
std::__cxx11::regex_iterator<_Bi_iter, _Ch_type, _Rx_traits>::operator=(const
std::__cxx11::regex_iterator<_Bi_iter, _Ch_type, _Rx_traits>&) [with _Bi_iter =
const char*; _Ch_type = char; _Rx_traits = std::__cxx11::regex_traits<char>]’
at /usr/local/gcc/include/c++/12.0.0/bits/regex.h:2699:7,
inlined from ‘std::__cxx11::regex_iterator<_Bi_iter, _Ch_type,
_Rx_traits>::regex_iterator(_Bi_iter, _Bi_iter, const
std::__cxx11::regex_iterator<_Bi_iter, _Ch_type, _Rx_traits>::regex_type&,
std::regex_constants::match_flag_type) [with _Bi_iter = const char*; _Ch_type =
char; _Rx_traits = std::__cxx11::regex_traits<char>]’ at
/usr/local/gcc/include/c++/12.0.0/bits/regex.h:2685:10,
inlined from ‘_Out_iter std::regex_replace(_Out_iter, _Bi_iter, _Bi_iter,
const std::__cxx11::basic_regex<_Ch_type, _Rx_traits>&, const _Ch_type*,
std::regex_constants::match_flag_type) [with _Out_iter =
std::back_insert_iterator<std::__cxx11::basic_string<char> >; _Bi_iter = const
char*; _Rx_traits = std::__cxx11::regex_traits<char>; _Ch_type = char]’ at
/usr/local/gcc/include/c++/12.0.0/bits/regex.tcc:470:14,
inlined from ‘std::__cxx11::basic_string<_Ch_type> std::regex_replace(const
_Ch_type*, const std::__cxx11::basic_regex<_Ch_type, _Rx_traits>&, const
_Ch_type*, std::regex_constants::match_flag_type) [with _Rx_traits =
std::__cxx11::regex_traits<char>; _Ch_type = char]’ at
/usr/local/gcc/include/c++/12.0.0/bits/regex.h:2638:20,
inlined from ‘std::string plover(char*)’ at x.cc:6:61:
/usr/local/gcc/include/c++/12.0.0/bits/regex.h:1784:7: warning:
‘<unnamed>.std::__cxx11::regex_iterator<const char*, char,
std::__cxx11::regex_traits<char> >::_M_match.std::__cxx11::match_results<const
char*>::_M_begin’ may be used uninitialized [-Wmaybe-uninitialized]
1784 | operator=(const match_results&) = default;
| ^~~~~~~~
/usr/local/gcc/include/c++/12.0.0/bits/regex.h: In function ‘std::string
plover(char*)’:
/usr/local/gcc/include/c++/12.0.0/bits/regex.h:2685:19: note: ‘<anonymous>’
declared here
2685 | *this = regex_iterator();
| ^~~~~~~~~~~~~~~~
$
This warning seems to be correct. The match_results class in regex.h
is default-constructed here, and it has a member
_Bi_iter _M_begin;
In this example, _Bi_iter is const char*, so it is indeed not initialized
if the class is default-constructed.
The following change gets rid of the warning for me:
diff --git a/libstdc++-v3/include/bits/regex.h
b/libstdc++-v3/include/bits/regex.h
index 785edc71800..5318f378ada 100644
--- a/libstdc++-v3/include/bits/regex.h
+++ b/libstdc++-v3/include/bits/regex.h
@@ -2109,7 +2109,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
_M_suffix()
{ return _Unchecked::operator[](_Unchecked::size() - 1); }
- _Bi_iter _M_begin;
+ _Bi_iter _M_begin {};
/// @endcond
};
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug libstdc++/103549] [12 regression] Uninitialized member warning from regex header
2021-12-03 23:46 [Bug libstdc++/103549] New: [12 regression] Uninitialized member warning from regex header sss@li-snyder.org
@ 2021-12-04 1:00 ` redi at gcc dot gnu.org
2021-12-04 15:55 ` cvs-commit at gcc dot gnu.org
` (7 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: redi at gcc dot gnu.org @ 2021-12-04 1:00 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103549
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2021-12-04
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I think this is intentional, or at least not a bug. The match_results type
can't be used for much until it's "ready" and the member will be set then.
But it looks like this would read the indeterminate value:
cmatch m1, m2;
m1.swap(m2);
So we should initialize it as you suggest.
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug libstdc++/103549] [12 regression] Uninitialized member warning from regex header
2021-12-03 23:46 [Bug libstdc++/103549] New: [12 regression] Uninitialized member warning from regex header sss@li-snyder.org
2021-12-04 1:00 ` [Bug libstdc++/103549] " redi at gcc dot gnu.org
@ 2021-12-04 15:55 ` cvs-commit at gcc dot gnu.org
2021-12-06 8:21 ` rguenth at gcc dot gnu.org
` (6 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2021-12-04 15:55 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103549
--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jonathan Wakely <redi@gcc.gnu.org>:
https://gcc.gnu.org/g:87710ec7b213245ecb194b778e97ae3a6790394f
commit r12-5792-g87710ec7b213245ecb194b778e97ae3a6790394f
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Sat Dec 4 11:38:25 2021 +0000
libstdc++: Initialize member in std::match_results [PR103549]
This fixes a -Wuninitialized warning for std::cmatch m1, m2; m1=m2;
Also name the template parameters in the forward declaration, to get rid
of the <template-parameter-1-1> noise in diagnostics.
libstdc++-v3/ChangeLog:
PR libstdc++/103549
* include/bits/regex.h (match_results): Give names to template
parameters in first declaration.
(match_results::_M_begin): Add default member-initializer.
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug libstdc++/103549] [12 regression] Uninitialized member warning from regex header
2021-12-03 23:46 [Bug libstdc++/103549] New: [12 regression] Uninitialized member warning from regex header sss@li-snyder.org
2021-12-04 1:00 ` [Bug libstdc++/103549] " redi at gcc dot gnu.org
2021-12-04 15:55 ` cvs-commit at gcc dot gnu.org
@ 2021-12-06 8:21 ` rguenth at gcc dot gnu.org
2021-12-06 10:39 ` [Bug libstdc++/103549] " redi at gcc dot gnu.org
` (5 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu.org @ 2021-12-06 8:21 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103549
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |12.0
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug libstdc++/103549] Uninitialized member warning from regex header
2021-12-03 23:46 [Bug libstdc++/103549] New: [12 regression] Uninitialized member warning from regex header sss@li-snyder.org
` (2 preceding siblings ...)
2021-12-06 8:21 ` rguenth at gcc dot gnu.org
@ 2021-12-06 10:39 ` redi at gcc dot gnu.org
2022-01-05 22:06 ` cvs-commit at gcc dot gnu.org
` (4 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: redi at gcc dot gnu.org @ 2021-12-06 10:39 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103549
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|[12 regression] |Uninitialized member
|Uninitialized member |warning from regex header
|warning from regex header |
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Fixed on trunk, but I'll backport it too.
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug libstdc++/103549] Uninitialized member warning from regex header
2021-12-03 23:46 [Bug libstdc++/103549] New: [12 regression] Uninitialized member warning from regex header sss@li-snyder.org
` (3 preceding siblings ...)
2021-12-06 10:39 ` [Bug libstdc++/103549] " redi at gcc dot gnu.org
@ 2022-01-05 22:06 ` cvs-commit at gcc dot gnu.org
2022-01-05 22:06 ` cvs-commit at gcc dot gnu.org
` (3 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-01-05 22:06 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103549
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:
https://gcc.gnu.org/g:5e0ef5621b518caa593b77b7c8f202ee018a0900
commit r11-9437-g5e0ef5621b518caa593b77b7c8f202ee018a0900
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Sat Dec 4 11:38:25 2021 +0000
libstdc++: Initialize member in std::match_results [PR103549]
This fixes a -Wuninitialized warning for std::cmatch m1, m2; m1=m2;
Also name the template parameters in the forward declaration, to get rid
of the <template-parameter-1-1> noise in diagnostics.
libstdc++-v3/ChangeLog:
PR libstdc++/103549
* include/bits/regex.h (match_results): Give names to template
parameters in first declaration.
(match_results::_M_begin): Add default member-initializer.
(cherry picked from commit 87710ec7b213245ecb194b778e97ae3a6790394f)
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug libstdc++/103549] Uninitialized member warning from regex header
2021-12-03 23:46 [Bug libstdc++/103549] New: [12 regression] Uninitialized member warning from regex header sss@li-snyder.org
` (4 preceding siblings ...)
2022-01-05 22:06 ` cvs-commit at gcc dot gnu.org
@ 2022-01-05 22:06 ` cvs-commit at gcc dot gnu.org
2022-01-05 22:08 ` redi at gcc dot gnu.org
` (2 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-01-05 22:06 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103549
--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:
https://gcc.gnu.org/g:17af7c1a054c9663e5b353a4fc576522e0cd9a4f
commit r10-10379-g17af7c1a054c9663e5b353a4fc576522e0cd9a4f
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Sat Dec 4 11:38:25 2021 +0000
libstdc++: Initialize member in std::match_results [PR103549]
This fixes a -Wuninitialized warning for std::cmatch m1, m2; m1=m2;
Also name the template parameters in the forward declaration, to get rid
of the <template-parameter-1-1> noise in diagnostics.
libstdc++-v3/ChangeLog:
PR libstdc++/103549
* include/bits/regex.h (match_results): Give names to template
parameters in first declaration.
(match_results::_M_begin): Add default member-initializer.
(cherry picked from commit 87710ec7b213245ecb194b778e97ae3a6790394f)
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug libstdc++/103549] Uninitialized member warning from regex header
2021-12-03 23:46 [Bug libstdc++/103549] New: [12 regression] Uninitialized member warning from regex header sss@li-snyder.org
` (5 preceding siblings ...)
2022-01-05 22:06 ` cvs-commit at gcc dot gnu.org
@ 2022-01-05 22:08 ` redi at gcc dot gnu.org
2022-05-09 16:39 ` cvs-commit at gcc dot gnu.org
2022-05-09 19:44 ` redi at gcc dot gnu.org
8 siblings, 0 replies; 10+ messages in thread
From: redi at gcc dot gnu.org @ 2022-01-05 22:08 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103549
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Target Milestone|12.0 |10.4
Status|NEW |RESOLVED
--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Fixed for 11.3 and 10.4
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug libstdc++/103549] Uninitialized member warning from regex header
2021-12-03 23:46 [Bug libstdc++/103549] New: [12 regression] Uninitialized member warning from regex header sss@li-snyder.org
` (6 preceding siblings ...)
2022-01-05 22:08 ` redi at gcc dot gnu.org
@ 2022-05-09 16:39 ` cvs-commit at gcc dot gnu.org
2022-05-09 19:44 ` redi at gcc dot gnu.org
8 siblings, 0 replies; 10+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-05-09 16:39 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103549
--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:
https://gcc.gnu.org/g:756d1581d11c583d9cbfc2e0b7ce1a095845085e
commit r9-10055-g756d1581d11c583d9cbfc2e0b7ce1a095845085e
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Sat Dec 4 11:38:25 2021 +0000
libstdc++: Initialize member in std::match_results [PR103549]
This fixes a -Wuninitialized warning for std::cmatch m1, m2; m1=m2;
Also name the template parameters in the forward declaration, to get rid
of the <template-parameter-1-1> noise in diagnostics.
libstdc++-v3/ChangeLog:
PR libstdc++/103549
* include/bits/regex.h (match_results): Give names to template
parameters in first declaration.
(match_results::_M_begin): Add default member-initializer.
(cherry picked from commit 87710ec7b213245ecb194b778e97ae3a6790394f)
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug libstdc++/103549] Uninitialized member warning from regex header
2021-12-03 23:46 [Bug libstdc++/103549] New: [12 regression] Uninitialized member warning from regex header sss@li-snyder.org
` (7 preceding siblings ...)
2022-05-09 16:39 ` cvs-commit at gcc dot gnu.org
@ 2022-05-09 19:44 ` redi at gcc dot gnu.org
8 siblings, 0 replies; 10+ messages in thread
From: redi at gcc dot gnu.org @ 2022-05-09 19:44 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103549
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|10.4 |9.5
--- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> ---
And 9.5
^ permalink raw reply [flat|nested] 10+ messages in thread
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