Updated library version selection to avoid ODR violations.

The previous strategy of force-inlining methods that are dependent
on the library version is not effective with MSVC in debug mode,
when linking the static library. The compiler does not inline
methods despite the markup, and during linking the static library
with the user's module the linker may or may not pick up user's
definitions of these methods.

When building the library, do not define path methods that depend
on the library version. Instead, explicitly call v4 internal methods
throughout the implementation. This way the compiled library does not
contain v4 versions of these methods, and therefore does not conflict
with user's definitions of these methods.

Fixes #279.

.github/workflows/ci.yml

@@ -264,7 +264,7 @@ jobs:
             compiler: clang++-14
             cxxstd: "03-gnu,11-gnu,14-gnu,17-gnu,20-gnu,2b-gnu"
             cxxflags: -stdlib=libc++
-            linkflags: -stdlib=libc++
+            linkflags: "-stdlib=libc++ -lubsan"
             ubsan: 1
             build_variant: debug
             os: ubuntu-22.04

CMakeLists.txt

@@ -73,6 +73,31 @@ endif()
 add_library(boost_filesystem ${BOOST_FILESYSTEM_SOURCES})
 add_library(Boost::filesystem ALIAS boost_filesystem)
 
+get_target_property(BOOST_FILESYSTEM_TARGET_TYPE boost_filesystem TYPE)
+if(BOOST_FILESYSTEM_TARGET_TYPE STREQUAL "SHARED_LIBRARY")
+    set(CMAKE_REQUIRED_LIBRARIES "-Wl,--no-undefined")
+    check_cxx_source_compiles("#include <${CMAKE_CURRENT_SOURCE_DIR}/config/has_linkflag_no_undefined.cpp>" BOOST_FILESYSTEM_HAS_LINKFLAG_NO_UNDEFINED)
+    unset(CMAKE_REQUIRED_LIBRARIES)
+    if(NOT BOOST_FILESYSTEM_HAS_LINKFLAG_NO_UNDEFINED)
+        set(CMAKE_REQUIRED_LIBRARIES "-Wl,-undefined,error")
+        check_cxx_source_compiles("#include <${CMAKE_CURRENT_SOURCE_DIR}/config/has_linkflag_no_undefined.cpp>" BOOST_FILESYSTEM_HAS_LINKFLAG_UNDEFINED_ERROR)
+        unset(CMAKE_REQUIRED_LIBRARIES)
+    endif()
+    if(BOOST_FILESYSTEM_HAS_LINKFLAG_NO_UNDEFINED)
+        if(NOT CMAKE_VERSION VERSION_LESS 3.13)
+            target_link_options(boost_filesystem PRIVATE "-Wl,--no-undefined")
+        else()
+            target_link_libraries(boost_filesystem PRIVATE "-Wl,--no-undefined")
+        endif()
+    elseif(BOOST_FILESYSTEM_HAS_LINKFLAG_UNDEFINED_ERROR)
+        if(NOT CMAKE_VERSION VERSION_LESS 3.13)
+            target_link_options(boost_filesystem PRIVATE "-Wl,-undefined,error")
+        else()
+            target_link_libraries(boost_filesystem PRIVATE "-Wl,-undefined,error")
+        endif()
+    endif()
+endif()
+
 target_include_directories(boost_filesystem PUBLIC include)
 target_include_directories(boost_filesystem PRIVATE src)
 

build/Jamfile.v2

@@ -101,6 +101,27 @@ rule check-cxx20-atomic-ref ( properties * )
     return $(result) ;
 }
 
+# The rule checks if the linker supports requiring no unresolved symbols
+rule check-linkflag-no-undefined ( properties * )
+{
+    local result ;
+
+    if <link>shared in $(properties)
+    {
+        if [ configure.builds ../config//has_linkflag_no_undefined : $(properties) : "has -Wl,--no-undefined" ]
+        {
+            result = <linkflags>"-Wl,--no-undefined" ;
+        }
+        else if [ configure.builds ../config//has_linkflag_undefined_error : $(properties) : "has -Wl,-undefined,error" ]
+        {
+            result = <linkflags>"-Wl,-undefined,error" ;
+        }
+    }
+
+    #ECHO Result: $(result) ;
+    return $(result) ;
+}
+
 project boost/filesystem
     : requirements
       <host-os>hpux,<toolset>gcc:<define>_INCLUDE_STDC__SOURCE_199901
@@ -117,6 +138,8 @@ project boost/filesystem
       <conditional>@check-statx
       <conditional>@select-windows-crypto-api
       <conditional>@check-cxx20-atomic-ref
+      # Make sure no undefined references are left from the library
+      <conditional>@check-linkflag-no-undefined
       <target-os>windows:<define>_SCL_SECURE_NO_WARNINGS
       <target-os>windows:<define>_SCL_SECURE_NO_DEPRECATE
       <target-os>windows:<define>_CRT_SECURE_NO_WARNINGS
@@ -131,6 +154,7 @@ project boost/filesystem
       # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105329
       # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105651
       <toolset>gcc-12:<cxxflags>"-Wno-restrict"
+
     : source-location ../src
     : usage-requirements # pass these requirement to dependents (i.e. users)
       <link>shared:<define>BOOST_FILESYSTEM_DYN_LINK=1

config/Jamfile.v2

@@ -39,3 +39,8 @@ exe has_bcrypt : has_bcrypt.cpp : <include>../src <library>bcrypt ;
 explicit has_bcrypt ;
 obj is_windows_ce : is_windows_ce.cpp ;
 explicit is_windows_ce ;
+
+lib has_linkflag_no_undefined : has_linkflag_no_undefined.cpp : <link>shared <linkflags>"-Wl,--no-undefined" ;
+explicit has_linkflag_no_undefined ;
+lib has_linkflag_undefined_error : has_linkflag_no_undefined.cpp : <link>shared <linkflags>"-Wl,-undefined,error" ;
+explicit has_linkflag_undefined_error ;

config/has_linkflag_no_undefined.cpp

@@ -0,0 +1,18 @@
+//  Copyright 2023 Andrey Semashev
+
+//  Distributed under the Boost Software License, Version 1.0.
+//  See http://www.boost.org/LICENSE_1_0.txt
+
+//  See library home page at http://www.boost.org/libs/filesystem
+
+#if defined(_MSC_VER)
+// MSVC's link.exe does not support -Wl,... flags, but doesn't fail the linking.
+// The linker may be used by different compilers, not only MSVC.
+// Luckily, those compilers all pretend to be MSVC.
+#error "MSVC and compatible compilers don't support -Wl,... flags"
+#endif
+
+int main()
+{
+    return 0;
+}

doc/release_history.html

@@ -45,6 +45,7 @@ <h2>1.82.0</h2>
   <li><b>v4:</b> <code>path::remove_filename</code> now presesrves the trailing directory separator. (<a href="https://github.com/boostorg/filesystem/issues/271">#271</a>)</li>
   <li>Added <code>path::remove_filename_and_trailing_separators</li>, which removes the filename and directory separators preceding it from the path. This behavior is similar to <code>path::remove_filename</code> in Filesystem <b>v3</b>, but is also usable in <b>v4</b>.
   <li>Added <code>path::replace_filename</code>, which replaces filename in a path.</li>
+  <li>Updated implementation of the library version selection to avoid ODR violations. (<a href="https://github.com/boostorg/filesystem/issues/279">#279</a>)</li>
 </ul>
 
 <h2>1.81.0</h2>