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* [Bug c/35069] New: Casting from a volatile type to a non-volatile type should cause a warning
@ 2008-02-04 1:33 gcc-david at tulloh dot id dot au
2008-02-04 5:19 ` [Bug c/35069] " gcc-david at tulloh dot id dot au
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: gcc-david at tulloh dot id dot au @ 2008-02-04 1:33 UTC (permalink / raw)
To: gcc-bugs
Given the following code:
volatile int16_t foo;
x = (int32_t)foo;
The above cast should almost certainly have been (volatile int32_t), I see no
obvious case where someone would want to cast away the volatile attribute.
I suggest that a cast that drops a volatile attribute from a variable should
cause a warning.
(Epiphany occurred at the end of a frustrating day, was using gcc 4.2.2
targeting an AVR)
--
Summary: Casting from a volatile type to a non-volatile type
should cause a warning
Product: gcc
Version: 4.2.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: gcc-david at tulloh dot id dot au
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35069
^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug c/35069] Casting from a volatile type to a non-volatile type should cause a warning 2008-02-04 1:33 [Bug c/35069] New: Casting from a volatile type to a non-volatile type should cause a warning gcc-david at tulloh dot id dot au @ 2008-02-04 5:19 ` gcc-david at tulloh dot id dot au 2008-02-04 9:11 ` pinskia at gcc dot gnu dot org ` (3 subsequent siblings) 4 siblings, 0 replies; 6+ messages in thread From: gcc-david at tulloh dot id dot au @ 2008-02-04 5:19 UTC (permalink / raw) To: gcc-bugs -- gcc-david at tulloh dot id dot au changed: What |Removed |Added ---------------------------------------------------------------------------- Severity|normal |enhancement http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35069 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c/35069] Casting from a volatile type to a non-volatile type should cause a warning 2008-02-04 1:33 [Bug c/35069] New: Casting from a volatile type to a non-volatile type should cause a warning gcc-david at tulloh dot id dot au 2008-02-04 5:19 ` [Bug c/35069] " gcc-david at tulloh dot id dot au @ 2008-02-04 9:11 ` pinskia at gcc dot gnu dot org 2008-02-04 22:14 ` gcc-david at tulloh dot id dot au ` (2 subsequent siblings) 4 siblings, 0 replies; 6+ messages in thread From: pinskia at gcc dot gnu dot org @ 2008-02-04 9:11 UTC (permalink / raw) To: gcc-bugs ------- Comment #1 from pinskia at gcc dot gnu dot org 2008-02-04 09:11 ------- > The above cast should almost certainly have been (volatile int32_t) The volatile here does not mean anything really so there is no lost info as it is on a scalar type. So I am going to close this as invalid. -- pinskia at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution| |INVALID http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35069 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c/35069] Casting from a volatile type to a non-volatile type should cause a warning 2008-02-04 1:33 [Bug c/35069] New: Casting from a volatile type to a non-volatile type should cause a warning gcc-david at tulloh dot id dot au 2008-02-04 5:19 ` [Bug c/35069] " gcc-david at tulloh dot id dot au 2008-02-04 9:11 ` pinskia at gcc dot gnu dot org @ 2008-02-04 22:14 ` gcc-david at tulloh dot id dot au 2008-02-04 22:17 ` pinskia at gcc dot gnu dot org 2008-11-14 23:56 ` pinskia at gcc dot gnu dot org 4 siblings, 0 replies; 6+ messages in thread From: gcc-david at tulloh dot id dot au @ 2008-02-04 22:14 UTC (permalink / raw) To: gcc-bugs ------- Comment #2 from gcc-david at tulloh dot id dot au 2008-02-04 22:14 ------- Yes, I didn't provide any context. I believe that this warning should apply any time you are working with volatile variables. A truncated real world example (kind of, real world debugging). volatile static uint8_t OutputBuffer[4]; int16_t main(void) { while(1) { *(uint16_t *)(OutputBuffer)++; } } ISR(PCINT0_vect) { implement software SPI interface, transmit OutputBuffer in reverse byte order. } -- gcc-david at tulloh dot id dot au changed: What |Removed |Added ---------------------------------------------------------------------------- Status|RESOLVED |UNCONFIRMED Resolution|INVALID | http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35069 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c/35069] Casting from a volatile type to a non-volatile type should cause a warning 2008-02-04 1:33 [Bug c/35069] New: Casting from a volatile type to a non-volatile type should cause a warning gcc-david at tulloh dot id dot au ` (2 preceding siblings ...) 2008-02-04 22:14 ` gcc-david at tulloh dot id dot au @ 2008-02-04 22:17 ` pinskia at gcc dot gnu dot org 2008-11-14 23:56 ` pinskia at gcc dot gnu dot org 4 siblings, 0 replies; 6+ messages in thread From: pinskia at gcc dot gnu dot org @ 2008-02-04 22:17 UTC (permalink / raw) To: gcc-bugs ------- Comment #3 from pinskia at gcc dot gnu dot org 2008-02-04 22:16 ------- Anyways you are violating C aliasing rules here. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35069 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c/35069] Casting from a volatile type to a non-volatile type should cause a warning 2008-02-04 1:33 [Bug c/35069] New: Casting from a volatile type to a non-volatile type should cause a warning gcc-david at tulloh dot id dot au ` (3 preceding siblings ...) 2008-02-04 22:17 ` pinskia at gcc dot gnu dot org @ 2008-11-14 23:56 ` pinskia at gcc dot gnu dot org 4 siblings, 0 replies; 6+ messages in thread From: pinskia at gcc dot gnu dot org @ 2008-11-14 23:56 UTC (permalink / raw) To: gcc-bugs ------- Comment #4 from pinskia at gcc dot gnu dot org 2008-11-14 23:55 ------- -Wcast-qual exist already and works like what you want it to work. -- pinskia at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution| |INVALID http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35069 ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2008-11-14 23:56 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2008-02-04 1:33 [Bug c/35069] New: Casting from a volatile type to a non-volatile type should cause a warning gcc-david at tulloh dot id dot au 2008-02-04 5:19 ` [Bug c/35069] " gcc-david at tulloh dot id dot au 2008-02-04 9:11 ` pinskia at gcc dot gnu dot org 2008-02-04 22:14 ` gcc-david at tulloh dot id dot au 2008-02-04 22:17 ` pinskia at gcc dot gnu dot org 2008-11-14 23:56 ` pinskia at gcc dot gnu dot org
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