[gcc r13-5662] libstdc++: Fix std::filesystem errors with -fkeep-inline-functions [PR108636]

[Jonathan Wakely]

https://gcc.gnu.org/g:db8d6fc572ec316ccfcf70b1dffe3be0b1b37212

commit r13-5662-gdb8d6fc572ec316ccfcf70b1dffe3be0b1b37212
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Feb 2 14:06:40 2023 +0000

    libstdc++: Fix std::filesystem errors with -fkeep-inline-functions [PR108636]
    
    With -fkeep-inline-functions there are linker errors when including
    <filesystem>. This happens because there are some filesystem::path
    constructors defined inline which call non-exported functions defined in
    the library. That's usually not a problem, because those constructors
    are only called by code that's also inside the library. But when the
    header is compiled with -fkeep-inline-functions those inline functions
    are emitted even though they aren't called. That then creates an
    undefined reference to the other library internsl. The fix is to just
    move the private constructors into the library where they are called.
    That way they are never even seen by users, and so not compiled even if
    -fkeep-inline-functions is used.
    
    On trunk there is a second problem, which is that the new equality
    operators for comparing directory iterators with default_sentinel use
    the shared_ptr::operator bool() conversion operator. The shared_ptr
    specializations used by directory iterators are explicitly instantiated
    in the library, but the bool conversion operators are not exported. This
    causes linker errors at -O0 or with -fkeep-inline-functions. That just
    requires the conversion operators to be exported.
    
    libstdc++-v3/ChangeLog:
    
            PR libstdc++/108636
            * config/abi/pre/gnu.ver (GLIBCXX_3.4.31): Export shared_ptr
            conversion operators for directory iterator comparisons with
            std::default_sentinel_t.
            * include/bits/fs_path.h (path::path(string_view, _Type))
            (path::_Cmpt::_Cmpt(string_view, _Type, size_t)): Move inline
            definitions to ...
            * src/c++17/fs_path.cc: ... here.
            * testsuite/27_io/filesystem/path/108636.cc: New test.

Diff:
---
 libstdc++-v3/config/abi/pre/gnu.ver                    |  7 +++++++
 libstdc++-v3/include/bits/fs_path.h                    | 10 ++--------
 libstdc++-v3/src/c++17/fs_path.cc                      | 13 +++++++++++++
 libstdc++-v3/testsuite/27_io/filesystem/path/108636.cc |  8 ++++++++
 4 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/libstdc++-v3/config/abi/pre/gnu.ver b/libstdc++-v3/config/abi/pre/gnu.ver
index 72716414ccb..34f23bcbce0 100644
--- a/libstdc++-v3/config/abi/pre/gnu.ver
+++ b/libstdc++-v3/config/abi/pre/gnu.ver
@@ -2504,6 +2504,13 @@ GLIBCXX_3.4.31 {
     _ZNSt6chrono9tzdb_list14const_iteratorppEi;
     _ZN9__gnu_cxx21zoneinfo_dir_overrideEv;
 
+    # __shared_ptr<directory_iterator::_Dir>::operator bool()
+    _ZNKSt12__shared_ptrINSt10filesystem4_DirELN9__gnu_cxx12_Lock_policyE[012]EEcvbEv;
+    _ZNKSt12__shared_ptrINSt10filesystem7__cxx114_DirELN9__gnu_cxx12_Lock_policyE[012]EEcvbEv;
+    # __shared_ptr<recursive_directory_iterator::_Dir_stack>::operator bool()
+    _ZNKSt12__shared_ptrINSt10filesystem28recursive_directory_iterator10_Dir_stackELN9__gnu_cxx12_Lock_policyE[012]EEcvbEv;
+    _ZNKSt12__shared_ptrINSt10filesystem7__cxx1128recursive_directory_iterator10_Dir_stackELN9__gnu_cxx12_Lock_policyE[012]EEcvbEv;
+
 } GLIBCXX_3.4.30;
 
 # Symbols in the support library (libsupc++) have their own tag.
diff --git a/libstdc++-v3/include/bits/fs_path.h b/libstdc++-v3/include/bits/fs_path.h
index 1cbfaaa5427..0d7bb10c1a0 100644
--- a/libstdc++-v3/include/bits/fs_path.h
+++ b/libstdc++-v3/include/bits/fs_path.h
@@ -596,12 +596,7 @@ namespace __detail
       _Multi = 0, _Root_name, _Root_dir, _Filename
     };
 
-    path(basic_string_view<value_type> __str, _Type __type)
-    : _M_pathname(__str)
-    {
-      __glibcxx_assert(__type != _Type::_Multi);
-      _M_cmpts.type(__type);
-    }
+    path(basic_string_view<value_type> __str, _Type __type);
 
     enum class _Split { _Stem, _Extension };
 
@@ -851,8 +846,7 @@ namespace __detail
 
   struct path::_Cmpt : path
   {
-    _Cmpt(basic_string_view<value_type> __s, _Type __t, size_t __pos)
-      : path(__s, __t), _M_pos(__pos) { }
+    _Cmpt(basic_string_view<value_type> __s, _Type __t, size_t __pos);
 
     _Cmpt() : _M_pos(-1) { }
 
diff --git a/libstdc++-v3/src/c++17/fs_path.cc b/libstdc++-v3/src/c++17/fs_path.cc
index 93149c4b415..aaea7d2725d 100644
--- a/libstdc++-v3/src/c++17/fs_path.cc
+++ b/libstdc++-v3/src/c++17/fs_path.cc
@@ -187,6 +187,19 @@ struct path::_Parser
   { return origin + c.str.data() - input.data(); }
 };
 
+inline
+path::path(basic_string_view<value_type> __str, _Type __type)
+: _M_pathname(__str)
+{
+  __glibcxx_assert(__type != _Type::_Multi);
+  _M_cmpts.type(__type);
+}
+
+inline
+path::_Cmpt::_Cmpt(basic_string_view<value_type> __s, _Type __t, size_t __pos)
+: path(__s, __t), _M_pos(__pos)
+{ }
+
 struct path::_List::_Impl
 {
   using value_type = _Cmpt;
diff --git a/libstdc++-v3/testsuite/27_io/filesystem/path/108636.cc b/libstdc++-v3/testsuite/27_io/filesystem/path/108636.cc
new file mode 100644
index 00000000000..d58de461090
--- /dev/null
+++ b/libstdc++-v3/testsuite/27_io/filesystem/path/108636.cc
@@ -0,0 +1,8 @@
+// { dg-do link { target c++17 } }
+// { dg-options "-fkeep-inline-functions" }
+
+#include <filesystem>
+int main()
+{
+  // PR libstdc++/108636 - link failure with -fkeep-inline-functions
+}