From 0a2597477e482df4d67db6696431286df1ff4428 Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
Date: Thu, 2 Feb 2023 14:06:40 +0000
Subject: [PATCH] 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)
---
 libstdc++-v3/include/bits/fs_path.h                 | 10 ++--------
 libstdc++-v3/src/c++17/fs_path.cc                   | 13 +++++++++++++
 .../testsuite/27_io/filesystem/path/108636.cc       |  8 ++++++++
 3 files changed, 23 insertions(+), 8 deletions(-)
 create mode 100644 libstdc++-v3/testsuite/27_io/filesystem/path/108636.cc

diff --git a/libstdc++-v3/include/bits/fs_path.h b/libstdc++-v3/include/bits/fs_path.h
index 7a3d05131347..1f87414c1451 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 047082350ec6..830df8849151 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 000000000000..d58de461090d
--- /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
+}
-- 
2.47.2