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* [Bug libstdc++/104875] New: libstdc++-v3/src/c++11/codecvt.cc:312:24: warning: left shift count >= width of type
@ 2022-03-10 23:51 redi at gcc dot gnu.org
2022-03-11 0:22 ` [Bug libstdc++/104875] " redi at gcc dot gnu.org
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: redi at gcc dot gnu.org @ 2022-03-10 23:51 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104875
Bug ID: 104875
Summary: libstdc++-v3/src/c++11/codecvt.cc:312:24: warning:
left shift count >= width of type
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: redi at gcc dot gnu.org
Target Milestone: ---
Target: avr, msp430-elf
/home/jwakely/src/gcc/gcc/libstdc++-v3/src/c++11/codecvt.cc:312:24: warning:
left shift count >= width of type [-Wshift-count-overflow]
312 | char32_t c = (c1 << 18) + (c2 << 12) + (c3 << 6) + c4 -
0x3C82080;
| ~~~~^~~~~~
c1 is an unsigned char, so c1 << 18 promotes to int, but for 16-bit int that
doesn't work as intended.
It needs to be converted to a 32-bit type first, e.g. (char32_t)c1 << 18
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug libstdc++/104875] libstdc++-v3/src/c++11/codecvt.cc:312:24: warning: left shift count >= width of type
2022-03-10 23:51 [Bug libstdc++/104875] New: libstdc++-v3/src/c++11/codecvt.cc:312:24: warning: left shift count >= width of type redi at gcc dot gnu.org
@ 2022-03-11 0:22 ` redi at gcc dot gnu.org
2022-03-14 13:09 ` cvs-commit at gcc dot gnu.org
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: redi at gcc dot gnu.org @ 2022-03-11 0:22 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104875
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2022-03-11
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(c1 << 12) is wrong too, because it loses the high bits.
We should just declare all those variables as char32_t in the first place.
--- a/libstdc++-v3/src/c++11/codecvt.cc
+++ b/libstdc++-v3/src/c++11/codecvt.cc
@@ -254,7 +254,7 @@ namespace
const size_t avail = from.size();
if (avail == 0)
return incomplete_mb_character;
- unsigned char c1 = from[0];
+ char32_t c1 = (unsigned char) from[0];
// https://en.wikipedia.org/wiki/UTF-8#Sample_code
if (c1 < 0x80)
{
@@ -267,7 +267,7 @@ namespace
{
if (avail < 2)
return incomplete_mb_character;
- unsigned char c2 = from[1];
+ char32_t c2 = (unsigned char) from[1];
if ((c2 & 0xC0) != 0x80)
return invalid_mb_sequence;
char32_t c = (c1 << 6) + c2 - 0x3080;
@@ -279,12 +279,12 @@ namespace
{
if (avail < 3)
return incomplete_mb_character;
- unsigned char c2 = from[1];
+ char32_t c2 = (unsigned char) from[1];
if ((c2 & 0xC0) != 0x80)
return invalid_mb_sequence;
if (c1 == 0xE0 && c2 < 0xA0) // overlong
return invalid_mb_sequence;
- unsigned char c3 = from[2];
+ char32_t c3 = (unsigned char) from[2];
if ((c3 & 0xC0) != 0x80)
return invalid_mb_sequence;
char32_t c = (c1 << 12) + (c2 << 6) + c3 - 0xE2080;
@@ -296,17 +296,17 @@ namespace
{
if (avail < 4)
return incomplete_mb_character;
- unsigned char c2 = from[1];
+ char32_t c2 = (unsigned char) from[1];
if ((c2 & 0xC0) != 0x80)
return invalid_mb_sequence;
if (c1 == 0xF0 && c2 < 0x90) // overlong
return invalid_mb_sequence;
if (c1 == 0xF4 && c2 >= 0x90) // > U+10FFFF
return invalid_mb_sequence;
- unsigned char c3 = from[2];
+ char32_t c3 = (unsigned char) from[2];
if ((c3 & 0xC0) != 0x80)
return invalid_mb_sequence;
- unsigned char c4 = from[3];
+ char32_t c4 = (unsigned char) from[3];
if ((c4 & 0xC0) != 0x80)
return invalid_mb_sequence;
char32_t c = (c1 << 18) + (c2 << 12) + (c3 << 6) + c4 - 0x3C82080;
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug libstdc++/104875] libstdc++-v3/src/c++11/codecvt.cc:312:24: warning: left shift count >= width of type
2022-03-10 23:51 [Bug libstdc++/104875] New: libstdc++-v3/src/c++11/codecvt.cc:312:24: warning: left shift count >= width of type redi at gcc dot gnu.org
2022-03-11 0:22 ` [Bug libstdc++/104875] " redi at gcc dot gnu.org
@ 2022-03-14 13:09 ` cvs-commit at gcc dot gnu.org
2022-11-23 17:58 ` gjl at gcc dot gnu.org
` (3 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-03-14 13:09 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104875
--- 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:8f7b7c1495f92c72da154d32317943a2cc276ca8
commit r12-7643-g8f7b7c1495f92c72da154d32317943a2cc276ca8
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Fri Mar 11 14:52:38 2022 +0000
libstdc++: Fix reading UTF-8 characters for 16-bit targets [PR104875]
The current code in read_utf8_code_point assumes that integer promotion
will create a 32-bit int, but that's not true for 16-bit targets like
msp430 and avr. This changes the intermediate variables used for each
octet from unsigned char to char32_t, so that (c << N) works correctly
when N > 8.
libstdc++-v3/ChangeLog:
PR libstdc++/104875
* src/c++11/codecvt.cc (read_utf8_code_point): Use char32_t to
hold octets that will be left-shifted.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug libstdc++/104875] libstdc++-v3/src/c++11/codecvt.cc:312:24: warning: left shift count >= width of type
2022-03-10 23:51 [Bug libstdc++/104875] New: libstdc++-v3/src/c++11/codecvt.cc:312:24: warning: left shift count >= width of type redi at gcc dot gnu.org
2022-03-11 0:22 ` [Bug libstdc++/104875] " redi at gcc dot gnu.org
2022-03-14 13:09 ` cvs-commit at gcc dot gnu.org
@ 2022-11-23 17:58 ` gjl at gcc dot gnu.org
2022-11-23 18:06 ` redi at gcc dot gnu.org
` (2 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: gjl at gcc dot gnu.org @ 2022-11-23 17:58 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104875
--- Comment #3 from Georg-Johann Lay <gjl at gcc dot gnu.org> ---
Is this fixed now?
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug libstdc++/104875] libstdc++-v3/src/c++11/codecvt.cc:312:24: warning: left shift count >= width of type
2022-03-10 23:51 [Bug libstdc++/104875] New: libstdc++-v3/src/c++11/codecvt.cc:312:24: warning: left shift count >= width of type redi at gcc dot gnu.org
` (2 preceding siblings ...)
2022-11-23 17:58 ` gjl at gcc dot gnu.org
@ 2022-11-23 18:06 ` redi at gcc dot gnu.org
2023-05-16 12:50 ` cvs-commit at gcc dot gnu.org
2023-05-16 15:03 ` redi at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: redi at gcc dot gnu.org @ 2022-11-23 18:06 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104875
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Only for gcc-12 and trunk.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug libstdc++/104875] libstdc++-v3/src/c++11/codecvt.cc:312:24: warning: left shift count >= width of type
2022-03-10 23:51 [Bug libstdc++/104875] New: libstdc++-v3/src/c++11/codecvt.cc:312:24: warning: left shift count >= width of type redi at gcc dot gnu.org
` (3 preceding siblings ...)
2022-11-23 18:06 ` redi at gcc dot gnu.org
@ 2023-05-16 12:50 ` cvs-commit at gcc dot gnu.org
2023-05-16 15:03 ` redi at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2023-05-16 12:50 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104875
--- Comment #5 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:e4b0d0b84b719ea9cd3d0a7b0668cdd8055a07d2
commit r11-10770-ge4b0d0b84b719ea9cd3d0a7b0668cdd8055a07d2
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Fri Mar 11 14:52:38 2022 +0000
libstdc++: Fix reading UTF-8 characters for 16-bit targets [PR104875]
The current code in read_utf8_code_point assumes that integer promotion
will create a 32-bit int, but that's not true for 16-bit targets like
msp430 and avr. This changes the intermediate variables used for each
octet from unsigned char to char32_t, so that (c << N) works correctly
when N > 8.
libstdc++-v3/ChangeLog:
PR libstdc++/104875
* src/c++11/codecvt.cc (read_utf8_code_point): Use char32_t to
hold octets that will be left-shifted.
(cherry picked from commit 8f7b7c1495f92c72da154d32317943a2cc276ca8)
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug libstdc++/104875] libstdc++-v3/src/c++11/codecvt.cc:312:24: warning: left shift count >= width of type
2022-03-10 23:51 [Bug libstdc++/104875] New: libstdc++-v3/src/c++11/codecvt.cc:312:24: warning: left shift count >= width of type redi at gcc dot gnu.org
` (4 preceding siblings ...)
2023-05-16 12:50 ` cvs-commit at gcc dot gnu.org
@ 2023-05-16 15:03 ` redi at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: redi at gcc dot gnu.org @ 2023-05-16 15:03 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104875
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Target Milestone|--- |11.4
Resolution|--- |FIXED
--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Fixed for 11.4 now as well. I'm not going to bother with gcc-10.
^ permalink raw reply [flat|nested] 7+ messages in thread
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2022-03-11 0:22 ` [Bug libstdc++/104875] " redi at gcc dot gnu.org
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