After completion of test in normal and versioned namespace mode I
committed the attached patch.
Note that there are still failures in versioned namespace mode do to
missing symbol exports for which I'll propose an other patch.
On 30/10/20 7:48 pm, Jonathan Wakely wrote:
On 30/10/20 18:51 +0100, François Dumont wrote:
On 30/10/20 2:37 pm, Jonathan Wakely wrote:
On 30/10/20 13:23 +0000, Jonathan Wakely wrote:
On 30/10/20 13:59 +0100, François Dumont via Libstdc++ wrote:
The gnu-versioned-namespace build is broken.
The fix in charconv/floating_from_chars.cc is quite trivial. I am
not so sure about the fix in sstream-inst.cc.
The change for src/c++20/sstream-inst.cc is OK to commit. It would
probably be better to not build that file at all if the cxx11 ABI is
not supported at all, but then the src/c++20 directory would be empty
and I'm not sure if that would work. So just making the file empty is
fine.
The change for from_chars is not OK. With your change the <charconv>
header doesn't declare those functions if included by a file using the
old ABI. That's wrong, they should be declared unconditionally.
I see two ways to fix it. Either make the declarations in the header
depend on ! _GLIBCXX_INLINE_VERSION (so they're disabled for
gnu-versioned namespace) or fix the code in floating_from_chars to not
use a pmr::memory_resource for allocation in the versioned namespace
build.
Here's a patch for the second way.
A third way to fix it would be to make basic_string work with C++
allocators, so that pmr::string is usable for the gnu-versioned
namespace.
And the fourth would be to switch the versioned namespace to use the
new ABI unconditionally, instead of using the old ABI unconditionally.
Can I commit this one once tested then ?
Yes please.
I'll try to put the fourth way in place however.
N.B. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83077 tracks that.
diff --git a/libstdc++-v3/src/c++17/floating_from_chars.cc b/libstdc++-v3/src/c++17/floating_from_chars.cc
index d52c0a937b9..c279809cf35 100644
--- a/libstdc++-v3/src/c++17/floating_from_chars.cc
+++ b/libstdc++-v3/src/c++17/floating_from_chars.cc
@@ -27,6 +27,9 @@
// 23.2.9 Primitive numeric input conversion [utility.from.chars]
//
+// Prefer to use std::pmr::string if possible, which requires the cxx11 ABI.
+#define _GLIBCXX_USE_CXX11_ABI 1
+
#include <charconv>
#include <string>
#include <memory_resource>
@@ -87,6 +90,12 @@ namespace
void* m_ptr = nullptr;
};
+#if _GLIBCXX_USE_CXX11_ABI
+ using buffered_string = std::pmr::string;
+#else
+ using buffered_string = std::string;
+#endif
+
inline bool valid_fmt(chars_format fmt)
{
return fmt != chars_format{}
@@ -130,7 +139,7 @@ namespace
// Returns a nullptr if a valid pattern is not present.
const char*
pattern(const char* const first, const char* last,
- chars_format& fmt, pmr::string& buf)
+ chars_format& fmt, buffered_string& buf)
{
// fmt has the value of one of the enumerators of chars_format.
__glibcxx_assert(valid_fmt(fmt));
@@ -359,6 +368,22 @@ namespace
return result;
}
+#if ! _GLIBCXX_USE_CXX11_ABI
+ inline bool
+ reserve_string(std::string& s) noexcept
+ {
+ __try
+ {
+ s.reserve(buffer_resource::guaranteed_capacity());
+ }
+ __catch (const std::bad_alloc&)
+ {
+ return false;
+ }
+ return true;
+ }
+#endif
+
} // namespace
// FIXME: This should be reimplemented so it doesn't use strtod and newlocale.
@@ -369,10 +394,16 @@ from_chars_result
from_chars(const char* first, const char* last, float& value,
chars_format fmt) noexcept
{
+ errc ec = errc::invalid_argument;
+#if _GLIBCXX_USE_CXX11_ABI
buffer_resource mr;
pmr::string buf(&mr);
+#else
+ string buf;
+ if (!reserve_string(buf))
+ return make_result(first, 0, {}, ec);
+#endif
size_t len = 0;
- errc ec = errc::invalid_argument;
__try
{
if (const char* pat = pattern(first, last, fmt, buf)) [[likely]]
@@ -389,10 +420,16 @@ from_chars_result
from_chars(const char* first, const char* last, double& value,
chars_format fmt) noexcept
{
+ errc ec = errc::invalid_argument;
+#if _GLIBCXX_USE_CXX11_ABI
buffer_resource mr;
pmr::string buf(&mr);
+#else
+ string buf;
+ if (!reserve_string(buf))
+ return make_result(first, 0, {}, ec);
+#endif
size_t len = 0;
- errc ec = errc::invalid_argument;
__try
{
if (const char* pat = pattern(first, last, fmt, buf)) [[likely]]
@@ -409,10 +446,16 @@ from_chars_result
from_chars(const char* first, const char* last, long double& value,
chars_format fmt) noexcept
{
+ errc ec = errc::invalid_argument;
+#if _GLIBCXX_USE_CXX11_ABI
buffer_resource mr;
pmr::string buf(&mr);
+#else
+ string buf;
+ if (!reserve_string(buf))
+ return make_result(first, 0, {}, ec);
+#endif
size_t len = 0;
- errc ec = errc::invalid_argument;
__try
{
if (const char* pat = pattern(first, last, fmt, buf)) [[likely]]
diff --git a/libstdc++-v3/src/c++20/sstream-inst.cc b/libstdc++-v3/src/c++20/sstream-inst.cc
index e04560d28c8..8c6840115c5 100644
--- a/libstdc++-v3/src/c++20/sstream-inst.cc
+++ b/libstdc++-v3/src/c++20/sstream-inst.cc
@@ -29,6 +29,7 @@
// Instantiations in this file are only for the new SSO std::string ABI
#include <sstream>
+#if _GLIBCXX_USE_CXX11_ABI
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
@@ -106,3 +107,5 @@ basic_stringstream<wchar_t>::view() const noexcept;
_GLIBCXX_END_NAMESPACE_VERSION
}
+
+#endif //_GLIBCXX_USE_CXX11_ABI
