[libcxx-commits] [libcxx] 1c1edd1 - [libc++] Fixes thread::id's operator<<.
Mark de Wever via libcxx-commits
libcxx-commits at lists.llvm.org
Sat Jul 15 02:52:25 PDT 2023
Author: Mark de Wever
Date: 2023-07-15T11:52:19+02:00
New Revision: 1c1edd1b5d00daae2efdfbc5754a9fae77597dd4
URL: https://github.com/llvm/llvm-project/commit/1c1edd1b5d00daae2efdfbc5754a9fae77597dd4
DIFF: https://github.com/llvm/llvm-project/commit/1c1edd1b5d00daae2efdfbc5754a9fae77597dd4.diff
LOG: [libc++] Fixes thread::id's operator<<.
The output of
template<class charT, class traits>
basic_ostream<charT, traits>&
operator<<(basic_ostream<charT, traits>& out, thread::id id);
is affected by the state of out. The wording states
[thread.thread.id]/2
The text representation for the character type charT of an object of
type thread::id is an unspecified sequence of charT such that, for two
objects of type thread::id x and y, if x == y is true, the thread::id
objects have the same text representation, and if x != y is true, the
thread::id objects have distinct text representations.
[thread.thread.id]/9
template<class charT, class traits>
basic_ostream<charT, traits>&
operator<< (basic_ostream<charT, traits>& out, thread::id id);
Effects: Inserts the text representation for charT of id into out.
This wording changed in C++23 due to adding a formatter specialization for
thread::id. However the requirement was the same in older versions of C++.
This issue is that thread::id is an integral or pointer and affected by the
formatting manipulators for them. Thus the text representation can differ if
x == y which violates the requirements.
The fix has to hard-code some formatting style for the text
representation. It uses the Standard specified default values
Table 124: basic_ios::init() effectsâ[tab:basic.ios.cons] flags()
flags() skipws | dec
Fixes PR: https://llvm.org/PR62073
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D153336
Added:
Modified:
libcxx/include/__thread/thread.h
libcxx/test/std/thread/thread.threads/thread.thread.class/thread.thread.id/stream.pass.cpp
Removed:
################################################################################
diff --git a/libcxx/include/__thread/thread.h b/libcxx/include/__thread/thread.h
index 3d52d87f702689..dec40c7dc1f04c 100644
--- a/libcxx/include/__thread/thread.h
+++ b/libcxx/include/__thread/thread.h
@@ -24,6 +24,10 @@
#include <iosfwd>
#include <tuple>
+#ifndef _LIBCPP_HAS_NO_LOCALIZATION
+# include <locale>
+#endif
+
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
@@ -126,11 +130,32 @@ struct _LIBCPP_TEMPLATE_VIS hash<__thread_id>
}
};
-template<class _CharT, class _Traits>
-_LIBCPP_INLINE_VISIBILITY
-basic_ostream<_CharT, _Traits>&
-operator<<(basic_ostream<_CharT, _Traits>& __os, __thread_id __id)
-{return __os << __id.__id_;}
+#ifndef _LIBCPP_HAS_NO_LOCALIZATION
+template <class _CharT, class _Traits>
+_LIBCPP_INLINE_VISIBILITY basic_ostream<_CharT, _Traits>&
+operator<<(basic_ostream<_CharT, _Traits>& __os, __thread_id __id) {
+ // [thread.thread.id]/9
+ // Effects: Inserts the text representation for charT of id into out.
+ //
+ // [thread.thread.id]/2
+ // The text representation for the character type charT of an
+ // object of type thread::id is an unspecified sequence of charT
+ // such that, for two objects of type thread::id x and y, if
+ // x == y is true, the thread::id objects have the same text
+ // representation, and if x != y is true, the thread::id objects
+ // have distinct text representations.
+ //
+ // Since various flags in the output stream can affect how the
+ // thread id is represented (e.g. numpunct or showbase), we
+ // use a temporary stream instead and just output the thread
+ // id representation as a string.
+
+ basic_ostringstream<_CharT, _Traits> __sstr;
+ __sstr.imbue(locale::classic());
+ __sstr << __id.__id_;
+ return __os << __sstr.str();
+}
+#endif // _LIBCPP_HAS_NO_LOCALIZATION
class _LIBCPP_EXPORTED_FROM_ABI thread
{
diff --git a/libcxx/test/std/thread/thread.threads/thread.thread.class/thread.thread.id/stream.pass.cpp b/libcxx/test/std/thread/thread.threads/thread.thread.class/thread.thread.id/stream.pass.cpp
index b89a1bb55628f4..97e797f9a8fbb9 100644
--- a/libcxx/test/std/thread/thread.threads/thread.thread.class/thread.thread.id/stream.pass.cpp
+++ b/libcxx/test/std/thread/thread.threads/thread.thread.class/thread.thread.id/stream.pass.cpp
@@ -10,6 +10,8 @@
// UNSUPPORTED: no-localization
// UNSUPPORTED: GCC-ALWAYS_INLINE-FIXME
+// REQUIRES: locale.fr_FR.UTF-8
+
// TODO FMT This test should not require std::to_chars(floating-point)
// XFAIL: availability-fp_to_chars-missing
@@ -21,16 +23,18 @@
// basic_ostream<charT, traits>&
// operator<<(basic_ostream<charT, traits>& out, thread::id id);
-#include <thread>
+#include <cassert>
#include <format>
+#include <locale>
#include <sstream>
-#include <cassert>
+#include <thread>
#include "make_string.h"
+#include "platform_support.h" // locale name macros
#include "test_macros.h"
template <class CharT>
-static void test() {
+static void basic() {
std::thread::id id0 = std::this_thread::get_id();
std::basic_ostringstream<CharT> os;
os << id0;
@@ -49,6 +53,91 @@ static void test() {
#endif
}
+template <class CharT>
+static std::basic_string<CharT> format(std::ios_base::fmtflags flags) {
+ std::basic_stringstream<CharT> sstr;
+ sstr.flags(flags);
+ sstr << std::this_thread::get_id();
+ return sstr.str();
+}
+
+template <class CharT>
+static void stream_state() {
+ std::basic_stringstream<CharT> sstr;
+ sstr << std::this_thread::get_id();
+ std::basic_string<CharT> expected = sstr.str();
+
+ // Unaffected by fill, width, and align.
+
+ assert(expected == format<CharT>(std::ios_base::dec | std::ios_base::skipws)); // default flags
+
+ assert(expected == format<CharT>(std::ios_base::oct));
+ assert(expected == format<CharT>(std::ios_base::hex));
+
+ assert(expected == format<CharT>(std::ios_base::scientific));
+ assert(expected == format<CharT>(std::ios_base::fixed));
+
+ assert(expected == format<CharT>(std::ios_base::boolalpha));
+ assert(expected == format<CharT>(std::ios_base::showbase));
+ assert(expected == format<CharT>(std::ios_base::showpoint));
+ assert(expected == format<CharT>(std::ios_base::showpos));
+ assert(expected == format<CharT>(std::ios_base::skipws)); // added for completeness
+ assert(expected == format<CharT>(std::ios_base::unitbuf)); // added for completeness
+ assert(expected == format<CharT>(std::ios_base::uppercase));
+
+ // Test fill, width, and align.
+
+ sstr.str(std::basic_string<CharT>());
+ sstr.fill(CharT('#'));
+ sstr.width(expected.size() + 10); // Make sure fill and align affect the output.
+ sstr.flags(std::ios_base::dec | std::ios_base::skipws | std::ios_base::right);
+ sstr << std::this_thread::get_id();
+ expected = sstr.str();
+
+ sstr.str(std::basic_string<CharT>());
+ sstr.fill(CharT('*'));
+ sstr.width(expected.size());
+ sstr.flags(std::ios_base::dec | std::ios_base::skipws | std::ios_base::right);
+ sstr << std::this_thread::get_id();
+ assert(expected != sstr.str());
+
+ sstr.str(std::basic_string<CharT>());
+ sstr.fill(CharT('#'));
+ sstr.width(expected.size() - 1);
+ sstr.flags(std::ios_base::dec | std::ios_base::skipws | std::ios_base::right);
+ sstr << std::this_thread::get_id();
+ assert(expected != sstr.str());
+
+ sstr.str(std::basic_string<CharT>());
+ sstr.fill(CharT('#'));
+ sstr.width(expected.size());
+ sstr.flags(std::ios_base::dec | std::ios_base::skipws | std::ios_base::left);
+ sstr << std::this_thread::get_id();
+ assert(expected != sstr.str());
+
+ sstr.str(std::basic_string<CharT>());
+ sstr.fill(CharT('#'));
+ sstr.width(expected.size());
+ sstr.flags(std::ios_base::dec | std::ios_base::skipws | std::ios_base::internal);
+ sstr << std::this_thread::get_id();
+ assert(expected == sstr.str()); // internal does *not* affect strings
+
+ // Test the locale's numpunct.
+
+ std::locale::global(std::locale(LOCALE_fr_FR_UTF_8));
+ sstr.str(std::basic_string<CharT>());
+ sstr.fill(CharT('#'));
+ sstr.width(expected.size());
+ sstr << std::this_thread::get_id();
+ assert(expected == sstr.str());
+}
+
+template <class CharT>
+static void test() {
+ basic<CharT>();
+ stream_state<CharT>();
+}
+
int main(int, char**) {
test<char>();
#ifndef TEST_HAS_NO_WIDE_CHARACTERS
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