On 1/10/22 4:38 PM, Jonathan Wakely wrote:
On Mon, 10 Jan 2022 at 21:24, Tom Honermann via Libstdc++
<libstd...@gcc.gnu.org> wrote:
On 1/10/22 8:23 AM, Jonathan Wakely wrote:
On Sat, 8 Jan 2022 at 00:42, Tom Honermann via Libstdc++
<libstd...@gcc.gnu.org <mailto:libstdc%2b...@gcc.gnu.org>> wrote:
This patch completes implementation of the C++20 proposal P0482R6
[1] by
adding declarations of std::c8rtomb() and std::mbrtoc8() in
<cuchar> if
provided by the C library in <uchar.h>.
This patch addresses feedback provided in response to a previous
patch
submission [2].
Autoconf changes determine if the C library declares c8rtomb and
mbrtoc8
at global scope when uchar.h is included and compiled with either
-fchar8_t or -std=c++20. New
_GLIBCXX_USE_UCHAR_C8RTOMB_MBRTOC8_FCHAR8_T
and _GLIBCXX_USE_UCHAR_C8RTOMB_MBRTOC8_CXX20 configuration macros
reflect the probe results. The <cuchar> header declares these
functions
in the std namespace only if available and the _GLIBCXX_USE_CHAR8_T
configuration macro is defined (by default it is defined if the C++20
__cpp_char8_t feature test macro is defined)
Patches to glibc to implement c8rtomb and mbrtoc8 have been
submitted [3].
New tests validate the presence of these declarations. The tests pass
trivially if the C library does not provide these functions.
Otherwise
they ensure that the functions are declared when <cuchar> is included
and either -fchar8_t or -std=c++20 is enabled.
Tested on Linux x86_64.
libstdc++-v3/ChangeLog:
2022-01-07 Tom Honermann <t...@honermann.net
<mailto:t...@honermann.net>>
* acinclude.m4 Define config macros if uchar.h provides
c8rtomb() and mbrtoc8().
* config.h.in <http://config.h.in>: Re-generate.
* configure: Re-generate.
* include/c_compatibility/uchar.h: Declare ::c8rtomb and
::mbrtoc8.
* include/c_global/cuchar: Declare std::c8rtomb and
std::mbrtoc8.
* include/c_std/cuchar: Declare std::c8rtomb and std::mbrtoc8.
* testsuite/21_strings/headers/cuchar/functions_std_cxx20.cc:
New test.
*
testsuite/21_strings/headers/cuchar/functions_std_fchar8_t.cc:
New test.
Thanks, Tom, this looks good and I'll get it committed for GCC 12.
Thank you!
My only concern is that the new tests depend on an internal macro:
+#if _GLIBCXX_USE_UCHAR_C8RTOMB_MBRTOC8_CXX20
+ using std::mbrtoc8;
+ using std::c8rtomb;
I prefer if tests are written as "user code" when possible, and not
using our internal macros. That isn't always possible, and in this
case would require adding new effective-target keyword to
testsuite/lib/libstdc++.exp just for use in these two tests. I don't
think we should bother with that.
I went with this approach solely due to my unfamiliarity with the test
system. I knew there should be a way to conditionally make the test
"pass" as unsupported or as an expected failure, but didn't know how to
go about implementing that. I don't mind following up with an additional
patch if such a change is desirable. I took a look at
testsuite/lib/libstdc++.exp and it looks like it may be pretty straight
forward to add effective-target support. It would probably be a good
learning experience for me. I'll prototype and report back.
Yes, it's very easy to do. Take a look at the
check_effective_target_blah procs in that file, especially the later
ones that use v3_check_preprocessor_condition. You can use that to
define an effective target keyword for any preprocessor condition
(such as the new macros you're adding).
Then the test can do:
// { dg-do compile { target blah } }
which will make it UNSUPPORTED if the effective target proc doesn't return true.
See https://gcc.gnu.org/onlinedocs/gccint/Selectors.html#Selectors for
the docs on target selectors.
I'm just not sure it's worth adding a new keyword for just two tests.
Thank you for the implementation direction; this was quite easy!
Patch attached (to be applied after the original one).
libstdc++-v3/ChangeLog:
2022-01-11 Tom Honermann <t...@honermann.net>
* testsuite/21_strings/headers/cuchar/functions_std_cxx20.cc:
Modify to use new c8rtomb_mbrtoc8_cxx20 effective target.
* testsuite/21_strings/headers/cuchar/functions_std_fchar8_t.cc:
Modify to use new c8rtomb_mbrtoc8_fchar8_t effective target.
* testsuite/lib/libstdc++.exp: Add new effective targets.
If you decide that the new keywords aren't worth adding, no worries; my
feelings won't be hurt :)
Tom.
commit 0542361fe8cb5da146097f86ca8ea8bca86421e0
Author: Tom Honermann <t...@honermann.net>
Date: Tue Jan 11 14:57:51 2022 -0500
Add effective target support for tests of C++20 c8rtomb and mbrtoc8.
diff --git a/libstdc++-v3/testsuite/21_strings/headers/cuchar/functions_std_cxx20.cc b/libstdc++-v3/testsuite/21_strings/headers/cuchar/functions_std_cxx20.cc
index 7c152ed42b5..681c12127db 100644
--- a/libstdc++-v3/testsuite/21_strings/headers/cuchar/functions_std_cxx20.cc
+++ b/libstdc++-v3/testsuite/21_strings/headers/cuchar/functions_std_cxx20.cc
@@ -1,12 +1,10 @@
-// { dg-do compile }
+// { dg-do compile { target c8rtomb_mbrtoc8_cxx20 } }
// { dg-options "-std=c++20" }
#include <cuchar>
namespace gnu
{
-#if _GLIBCXX_USE_UCHAR_C8RTOMB_MBRTOC8_CXX20
using std::mbrtoc8;
using std::c8rtomb;
-#endif // _GLIBCXX_USE_UCHAR_C8RTOMB_MBRTOC8_CXX20
}
diff --git a/libstdc++-v3/testsuite/21_strings/headers/cuchar/functions_std_fchar8_t.cc b/libstdc++-v3/testsuite/21_strings/headers/cuchar/functions_std_fchar8_t.cc
index 1cfaf7427e5..836690f0349 100644
--- a/libstdc++-v3/testsuite/21_strings/headers/cuchar/functions_std_fchar8_t.cc
+++ b/libstdc++-v3/testsuite/21_strings/headers/cuchar/functions_std_fchar8_t.cc
@@ -1,12 +1,10 @@
-// { dg-do compile }
+// { dg-do compile { target c8rtomb_mbrtoc8_fchar8_t } }
// { dg-options "-fchar8_t" }
#include <cuchar>
namespace gnu
{
-#if _GLIBCXX_USE_UCHAR_C8RTOMB_MBRTOC8_FCHAR8_T
using std::mbrtoc8;
using std::c8rtomb;
-#endif // _GLIBCXX_USE_UCHAR_C8RTOMB_MBRTOC8_FCHAR8_T
}
diff --git a/libstdc++-v3/testsuite/lib/libstdc++.exp b/libstdc++-v3/testsuite/lib/libstdc++.exp
index 1a43dd05ba7..7a2379c9982 100644
--- a/libstdc++-v3/testsuite/lib/libstdc++.exp
+++ b/libstdc++-v3/testsuite/lib/libstdc++.exp
@@ -1346,6 +1346,22 @@ proc check_effective_target_std_allocator_new { } {
}]
}
+# Return 1 if mbrtoc8 and c8rtomb are available for C++20, 0 otherwise.
+proc check_effective_target_c8rtomb_mbrtoc8_cxx20 { } {
+ return [check_v3_target_prop_cached et_c8rtomb_mbrtoc8_cxx20 {
+ set cond "_GLIBCXX_USE_UCHAR_C8RTOMB_MBRTOC8_CXX20"
+ return [v3_check_preprocessor_condition c8rtomb_mbrtoc8_cxx20 $cond]
+ }]
+}
+
+# Return 1 if mbrtoc8 and c8rtomb are available for -fchar8_t, 0 otherwise.
+proc check_effective_target_c8rtomb_mbrtoc8_fchar8_t { } {
+ return [check_v3_target_prop_cached et_c8rtomb_mbrtoc8_fchar8_t {
+ set cond "_GLIBCXX_USE_UCHAR_C8RTOMB_MBRTOC8_FCHAR8_T"
+ return [v3_check_preprocessor_condition c8rtomb_mbrtoc8_fchar8_t $cond]
+ }]
+}
+
set additional_prunes ""
if { [info exists env(GCC_RUNTEST_PARALLELIZE_DIR)] \
