root6: Add workaround for Xcode 15 linker issue

science/root6/Portfile

@@ -229,6 +229,18 @@ if {${os.platform} eq "darwin" && ${os.major} >= 20} {
     configure.sdk_version
 }
 
+if {${os.platform} eq "darwin" && ${os.major} >= 22} {
+    if { [vercmp ${xcodeversion} >= 15.0] || [vercmp ${xcodecltversion} >= 15.0] } {
+        # On macOS13 and newer ensure the 'legacy' linker is used as GCC currently has problems
+        # with the new default linker in Xcode 15. See e.g.
+        # https://developer.apple.com/documentation/xcode-release-notes/xcode-15-release-notes#Linking
+        # https://discussions.apple.com/thread/255137447
+        # https://developer.apple.com/forums/thread/737707
+        # https://github.com/Homebrew/homebrew-core/issues/145991
+        configure.ldflags-append  -Wl,-ld_classic
+    }
+}
+
 pre-configure {
     # Force use of system python in build scripts
     # Find command finds text files containing the string to be replaced.