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* [Bug libstdc++/99832] New: std::chrono::system_clock::to_time_t needs ABI tag for 32-bit time_t
@ 2021-03-30 16:01 redi at gcc dot gnu.org
2023-06-10 9:33 ` [Bug libstdc++/99832] " redi at gcc dot gnu.org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: redi at gcc dot gnu.org @ 2021-03-30 16:01 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99832
Bug ID: 99832
Summary: std::chrono::system_clock::to_time_t needs ABI tag for
32-bit time_t
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Keywords: ABI
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: redi at gcc dot gnu.org
Target Milestone: ---
chrono::system_clock defines:
static std::time_t
to_time_t(const time_point& __t) noexcept
This is a non-template function and its mangled name does not depend on the
return type. The mangled name is:
_ZNSt6chrono3_V212system_clock9to_time_tERKNS_10time_pointIS1_NS_8durationIlSt5ratioILl1ELl1000000000EEEEEE
For a target that allows time_t to be either 32-bit or 64-bit, we need this
mangled name to reflect the type of time_t.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/99832] std::chrono::system_clock::to_time_t needs ABI tag for 32-bit time_t
2021-03-30 16:01 [Bug libstdc++/99832] New: std::chrono::system_clock::to_time_t needs ABI tag for 32-bit time_t redi at gcc dot gnu.org
@ 2023-06-10 9:33 ` redi at gcc dot gnu.org
2023-07-19 18:24 ` redi at gcc dot gnu.org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: redi at gcc dot gnu.org @ 2023-06-10 9:33 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99832
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2023-06-10
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/99832] std::chrono::system_clock::to_time_t needs ABI tag for 32-bit time_t
2021-03-30 16:01 [Bug libstdc++/99832] New: std::chrono::system_clock::to_time_t needs ABI tag for 32-bit time_t redi at gcc dot gnu.org
2023-06-10 9:33 ` [Bug libstdc++/99832] " redi at gcc dot gnu.org
@ 2023-07-19 18:24 ` redi at gcc dot gnu.org
2024-01-31 11:49 ` redi at gcc dot gnu.org
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: redi at gcc dot gnu.org @ 2023-07-19 18:24 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99832
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |14.0
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/99832] std::chrono::system_clock::to_time_t needs ABI tag for 32-bit time_t
2021-03-30 16:01 [Bug libstdc++/99832] New: std::chrono::system_clock::to_time_t needs ABI tag for 32-bit time_t redi at gcc dot gnu.org
2023-06-10 9:33 ` [Bug libstdc++/99832] " redi at gcc dot gnu.org
2023-07-19 18:24 ` redi at gcc dot gnu.org
@ 2024-01-31 11:49 ` redi at gcc dot gnu.org
2024-01-31 12:05 ` redi at gcc dot gnu.org
2024-05-07 7:39 ` rguenth at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: redi at gcc dot gnu.org @ 2024-01-31 11:49 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99832
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Maybe something like this:
diff --git a/libstdc++-v3/config/os/gnu-linux/os_defines.h
b/libstdc++-v3/config/os/gnu-linux/os_defines.h
index 0af29325388..f7c73560831 100644
--- a/libstdc++-v3/config/os/gnu-linux/os_defines.h
+++ b/libstdc++-v3/config/os/gnu-linux/os_defines.h
@@ -84,7 +84,13 @@
// Since glibc 2.34 all pthreads functions are usable without linking to
// libpthread.
# define _GLIBCXX_GTHREAD_USE_WEAK 0
-# endif
+// Since glibc 2.34 using -D_TIME_BITS=64 will enable 64-bit time_t
+// for "legacy ABIs", i.e. ones that historically used 32-bit time_t.
+// This internal glibc macro will be defined iff new 64-bit time_t is in use.
+# ifdef __USE_TIME_BITS64
+# define _GLIBCXX_TIME_BITS64 1
+# endif
+# endif // glibc 2.34
#endif // __linux__
#endif
diff --git a/libstdc++-v3/include/bits/chrono.h
b/libstdc++-v3/include/bits/chrono.h
index 579c5a266be..a63782b92ff 100644
--- a/libstdc++-v3/include/bits/chrono.h
+++ b/libstdc++-v3/include/bits/chrono.h
@@ -1242,6 +1242,9 @@ _GLIBCXX_BEGIN_INLINE_ABI_NAMESPACE(_V2)
now() noexcept;
// Map to C API
+#ifdef _GLIBCXX_TIME_BITS64
+ [[__gnu__::__abi_tag__("__time64")]]
+#endif
static std::time_t
to_time_t(const time_point& __t) noexcept
{
@@ -1249,6 +1252,9 @@ _GLIBCXX_BEGIN_INLINE_ABI_NAMESPACE(_V2)
(__t.time_since_epoch()).count());
}
+#ifdef _GLIBCXX_TIME_BITS64
+ [[__gnu__::__abi_tag__("__time64")]]
+#endif
static time_point
from_time_t(std::time_t __t) noexcept
{
Alternatively, in <bits/c++config.h> do:
#define _GLIBCXX_TIME_BITS64_ABI_TAG
and then in config/os/gnu-linux/os_defines.h:
# ifdef __USE_TIME_BITS64
# undef _GLIBCXX_TIME_BITS64_ABI_TAG
# define _GLIBCXX_TIME_BITS64_ABI_TAG [[__gnu__::__abi_tag__("__time64")]]
# endif
Then the chrono code can just use that unconditionally instead of using #ifdef
I think for musl, newer versions use 64-bit time_t unconditionally. I'm not
sure if we can (or need to) use the abi_tag there.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/99832] std::chrono::system_clock::to_time_t needs ABI tag for 32-bit time_t
2021-03-30 16:01 [Bug libstdc++/99832] New: std::chrono::system_clock::to_time_t needs ABI tag for 32-bit time_t redi at gcc dot gnu.org
` (2 preceding siblings ...)
2024-01-31 11:49 ` redi at gcc dot gnu.org
@ 2024-01-31 12:05 ` redi at gcc dot gnu.org
2024-05-07 7:39 ` rguenth at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: redi at gcc dot gnu.org @ 2024-01-31 12:05 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99832
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #1)
> +// Since glibc 2.34 using -D_TIME_BITS=64 will enable 64-bit time_t
> +// for "legacy ABIs", i.e. ones that historically used 32-bit time_t.
> +// This internal glibc macro will be defined iff new 64-bit time_t is in
> use.
This is correct for current glibc releases, but in glibc master
__USE_TIME_BITS64 is defined unconditionally to 0 or 1 and tells you the size
of time_t, not whether it switched to 64-bit counter to the legacy ABI:
https://inbox.sourceware.org/libc-alpha/20240118131801.600373-1-adhemerval.zanella@linaro.org/
Yay.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/99832] std::chrono::system_clock::to_time_t needs ABI tag for 32-bit time_t
2021-03-30 16:01 [Bug libstdc++/99832] New: std::chrono::system_clock::to_time_t needs ABI tag for 32-bit time_t redi at gcc dot gnu.org
` (3 preceding siblings ...)
2024-01-31 12:05 ` redi at gcc dot gnu.org
@ 2024-05-07 7:39 ` rguenth at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2024-05-07 7:39 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99832
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|14.0 |14.2
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 14.1 is being released, retargeting bugs to GCC 14.2.
^ permalink raw reply [flat|nested] 6+ messages in thread
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2021-03-30 16:01 [Bug libstdc++/99832] New: std::chrono::system_clock::to_time_t needs ABI tag for 32-bit time_t redi at gcc dot gnu.org
2023-06-10 9:33 ` [Bug libstdc++/99832] " redi at gcc dot gnu.org
2023-07-19 18:24 ` redi at gcc dot gnu.org
2024-01-31 11:49 ` redi at gcc dot gnu.org
2024-01-31 12:05 ` redi at gcc dot gnu.org
2024-05-07 7:39 ` rguenth at gcc dot gnu.org
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