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* [gcc r12-1397] libstdc++: Fix filesystem::path comparisons for C++23
@ 2021-06-11 18:23 Jonathan Wakely
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From: Jonathan Wakely @ 2021-06-11 18:23 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:1e690757d30775ed340a368b9a9463b2ad68de01
commit r12-1397-g1e690757d30775ed340a368b9a9463b2ad68de01
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Fri Jun 11 19:18:11 2021 +0100
libstdc++: Fix filesystem::path comparisons for C++23
In C++23 there is a basic_string_view(Range&&) constructor, which is
constrained to take a range (specifically, a contiguous_range). When the
filesystem::path comparison operators call lhs.compare(rhs) the overload
taking a string_view is considered, which means checking whether path
satisfies the range concept. That satisfaction result changes depending
whether path::iterator is complete, which is ill-formed; no diagnostic
required. To avoid the problem, this change ensures that the overload
resolution is performed in a context where path::iterator is complete
and the range concept is satisfied. (The result of overload resolution
is always that the compare(const path&) overload is the best match, but
we still have to consider the compare(basic_string_view<value_type>) one
to decide if it even participates in overload resolution).
For std::filesystem::path we can't define the comparison operators later
in the file, because they are hidden friends, so a new helper is
introduced that gets defined when everything else is complete.
For std::experimental::filesystem::path we can just move the definitions
of the comparison operators later in the file.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
* include/bits/fs_path.h (operator==, operator<=>): Use new
_S_compare function.
(path::_S_compare): New function to call path::compare in a
context where path::iterator is complete.
* include/experimental/bits/fs_path.h (operator<, operator==):
Define after path::iterator is complete.
* testsuite/27_io/filesystem/path/native/conv_c++23.cc: New
test.
* testsuite/experimental/filesystem/path/native/conv_c++23.cc:
New test.
Diff:
---
libstdc++-v3/include/bits/fs_path.h | 17 +++++++++++++++--
libstdc++-v3/include/experimental/bits/fs_path.h | 16 ++++++++++++----
.../27_io/filesystem/path/native/conv_c++23.cc | 12 ++++++++++++
.../experimental/filesystem/path/native/conv_c++23.cc | 12 ++++++++++++
4 files changed, 51 insertions(+), 6 deletions(-)
diff --git a/libstdc++-v3/include/bits/fs_path.h b/libstdc++-v3/include/bits/fs_path.h
index ad2518f414c..5e285204527 100644
--- a/libstdc++-v3/include/bits/fs_path.h
+++ b/libstdc++-v3/include/bits/fs_path.h
@@ -513,13 +513,13 @@ namespace __detail
/// Compare paths
friend bool operator==(const path& __lhs, const path& __rhs) noexcept
- { return __lhs.compare(__rhs) == 0; }
+ { return path::_S_compare(__lhs, __rhs) == 0; }
#if __cpp_lib_three_way_comparison
/// Compare paths
friend strong_ordering
operator<=>(const path& __lhs, const path& __rhs) noexcept
- { return __lhs.compare(__rhs) <=> 0; }
+ { return path::_S_compare(__lhs, __rhs) <=> 0; }
#else
/// Compare paths
friend bool operator!=(const path& __lhs, const path& __rhs) noexcept
@@ -627,6 +627,11 @@ namespace __detail
static basic_string<_CharT, _Traits, _Allocator>
_S_str_convert(basic_string_view<value_type>, const _Allocator&);
+ // Returns lhs.compare(rhs), but defined after path::iterator is complete.
+ __attribute__((__always_inline__))
+ static int
+ _S_compare(const path& __lhs, const path& __rhs) noexcept;
+
void _M_split_cmpts();
_Type _M_type() const noexcept { return _M_cmpts.type(); }
@@ -1330,6 +1335,14 @@ namespace __detail
return _M_at_end == __rhs._M_at_end;
}
+ // Define this now that path and path::iterator are complete.
+ // It needs to consider the string_view(Range&&) constructor during
+ // overload resolution, which depends on whether range<path> is satisfied,
+ // which depends on whether path::iterator is complete.
+ inline int
+ path::_S_compare(const path& __lhs, const path& __rhs) noexcept
+ { return __lhs.compare(__rhs); }
+
/// @} group filesystem
_GLIBCXX_END_NAMESPACE_CXX11
} // namespace filesystem
diff --git a/libstdc++-v3/include/experimental/bits/fs_path.h b/libstdc++-v3/include/experimental/bits/fs_path.h
index 1ecf2f3a7bd..1fb84ec1e78 100644
--- a/libstdc++-v3/include/experimental/bits/fs_path.h
+++ b/libstdc++-v3/include/experimental/bits/fs_path.h
@@ -551,8 +551,7 @@ namespace __detail
size_t hash_value(const path& __p) noexcept;
/// Compare paths
- inline bool operator<(const path& __lhs, const path& __rhs) noexcept
- { return __lhs.compare(__rhs) < 0; }
+ inline bool operator<(const path& __lhs, const path& __rhs) noexcept;
/// Compare paths
inline bool operator<=(const path& __lhs, const path& __rhs) noexcept
@@ -567,8 +566,7 @@ namespace __detail
{ return !(__lhs < __rhs); }
/// Compare paths
- inline bool operator==(const path& __lhs, const path& __rhs) noexcept
- { return __lhs.compare(__rhs) == 0; }
+ inline bool operator==(const path& __lhs, const path& __rhs) noexcept;
/// Compare paths
inline bool operator!=(const path& __lhs, const path& __rhs) noexcept
@@ -1275,6 +1273,16 @@ namespace __detail
return _M_at_end == __rhs._M_at_end;
}
+ // Define these now that path and path::iterator are complete.
+ // They needs to consider the string_view(Range&&) constructor during
+ // overload resolution, which depends on whether range<path> is satisfied,
+ // which depends on whether path::iterator is complete.
+ inline bool operator<(const path& __lhs, const path& __rhs) noexcept
+ { return __lhs.compare(__rhs) < 0; }
+
+ inline bool operator==(const path& __lhs, const path& __rhs) noexcept
+ { return __lhs.compare(__rhs) == 0; }
+
/// @} group filesystem-ts
_GLIBCXX_END_NAMESPACE_CXX11
} // namespace v1
diff --git a/libstdc++-v3/testsuite/27_io/filesystem/path/native/conv_c++23.cc b/libstdc++-v3/testsuite/27_io/filesystem/path/native/conv_c++23.cc
new file mode 100644
index 00000000000..b4efed2bd47
--- /dev/null
+++ b/libstdc++-v3/testsuite/27_io/filesystem/path/native/conv_c++23.cc
@@ -0,0 +1,12 @@
+// { dg-options "-std=gnu++23" }
+// { dg-do compile { target c++23 } }
+
+#include <filesystem>
+
+void
+test01()
+{
+ using std::filesystem::path;
+ path p;
+ path::string_type s(p);
+}
diff --git a/libstdc++-v3/testsuite/experimental/filesystem/path/native/conv_c++23.cc b/libstdc++-v3/testsuite/experimental/filesystem/path/native/conv_c++23.cc
new file mode 100644
index 00000000000..f3c3f884965
--- /dev/null
+++ b/libstdc++-v3/testsuite/experimental/filesystem/path/native/conv_c++23.cc
@@ -0,0 +1,12 @@
+// { dg-options "-std=gnu++23" }
+// { dg-do compile { target c++23 } }
+
+#include <experimental/filesystem>
+
+void
+test01()
+{
+ using std::experimental::filesystem::path;
+ path p;
+ path::string_type s(p);
+}
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