[gcc r12-9193] libstdc++: Fix std::filesystem errors with -fkeep-inline-functions [PR108636]

[Jonathan Wakely]

https://gcc.gnu.org/g:0a2597477e482df4d67db6696431286df1ff4428

commit r12-9193-g0a2597477e482df4d67db6696431286df1ff4428
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.
    
    libstdc++-v3/ChangeLog:
    
            PR libstdc++/108636
            * 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.
    
    (cherry picked from commit db8d6fc572ec316ccfcf70b1dffe3be0b1b37212)

Diff:
---
 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 ++++++++
 3 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/libstdc++-v3/include/bits/fs_path.h b/libstdc++-v3/include/bits/fs_path.h
index 7a3d0513134..1f87414c145 100644
--- a/libstdc++-v3/include/bits/fs_path.h
+++ b/libstdc++-v3/include/bits/fs_path.h
@@ -599,12 +599,7 @@ 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 };
 
@@ -859,8 +854,7 @@ 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 047082350ec..830df884915 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
+}