fix link objectfiles conflicts

Author: waruqi

xmake/core/project/target.lua

@@ -2375,11 +2375,16 @@ function _instance:sourcebatches()
                 sourcebatch.sourcekind = sourcekind
 
                 -- insert object files to source batches
-                sourcebatch.objectfiles = sourcebatch.objectfiles or {}
-                sourcebatch.dependfiles = sourcebatch.dependfiles or {}
-                local objectfile = self:objectfile(sourcefile, sourcekind)
-                table.insert(sourcebatch.objectfiles, objectfile)
-                table.insert(sourcebatch.dependfiles, self:dependfile(objectfile))
+                -- and we need to avoid duplication with object files, which may cause some conflicts.
+                -- e.g. c++.build, c++ module and unity_build rules
+                -- @see https://github.com/xmake-io/xmake/issues/6420
+                if filerule:extraconf("sourcekinds", sourcekind, "objectfiles") ~= false then
+                    sourcebatch.objectfiles = sourcebatch.objectfiles or {}
+                    sourcebatch.dependfiles = sourcebatch.dependfiles or {}
+                    local objectfile = self:objectfile(sourcefile, sourcekind)
+                    table.insert(sourcebatch.objectfiles, objectfile)
+                    table.insert(sourcebatch.dependfiles, self:dependfile(objectfile))
+                end
             end
         end
     end

xmake/rules/c++/modules/support.lua

@@ -158,7 +158,7 @@ function has_module_extension(sourcefile, opt)
     opt = opt or {}
     local modulexts = _g.modulexts
     if modulexts == nil then
-        modulexts = hashset.of(".mpp", ".mxx", ".cppm", ".ixx")
+        modulexts = hashset.of(".cppm", ".ccm", ".cxxm", ".c++m", ".mpp", ".mxx", ".ixx")
         _g.modulexts = modulexts
     end
     local extension = opt.extension or path.extension(sourcefile)

xmake/rules/c++/modules/xmake.lua

@@ -20,7 +20,6 @@
 
 -- define rule: c++.build.modules
 rule("c++.build.modules")
-
     -- @note support.contains_modules() need it
     set_extensions(".cppm", ".ccm", ".cxxm", ".c++m", ".mpp", ".mxx", ".ixx")
 
@@ -35,38 +34,30 @@ rule("c++.build.modules")
 
 -- scan modules
 rule("c++.build.modules.scanner")
-    set_sourcekinds("cxx")
-    set_extensions(".mpp", ".mxx", ".cppm", ".ixx")
-
-    -- generate module dependencies
+    set_sourcekinds("cxx", {objectfiles = false})
+    set_extensions(".cppm", ".ccm", ".cxxm", ".c++m", ".mpp", ".mxx", ".ixx")
     on_prepare_files("scanner", {jobgraph = true})
-
-    -- insert objectfiles
     after_prepare_files("scanner.after_scan")
 
 -- build modules
 rule("c++.build.modules.builder")
-    set_sourcekinds("cxx")
-    set_extensions(".mpp", ".mxx", ".cppm", ".ixx")
-
+    set_sourcekinds("cxx", {objectfiles = false})
+    set_extensions(".cppm", ".ccm", ".cxxm", ".c++m", ".mpp", ".mxx", ".ixx")
     add_orders("c++.build.modules.scanner", "c++.build.modules.builder")
 
     -- parallel build support to accelerate `xmake build` to build modules
     before_build_files("builder.build_bmis", {jobgraph = true, batch = true})
-
     on_build_files("builder.build_objectfiles", {jobgraph = true, batch = true})
 
     -- serial compilation only, usually used to support project generator
     before_buildcmd_files("builder.build_bmis")
-
     on_buildcmd_files("builder.build_objectfiles")
 
     after_clean("builder.clean")
 
 -- install modules
 rule("c++.build.modules.install")
-    set_extensions(".mpp", ".mxx", ".cppm", ".ixx")
+    set_extensions(".cppm", ".ccm", ".cxxm", ".c++m", ".mpp", ".mxx", ".ixx")
 
     before_install("install.install")
-
     before_uninstall("install.uninstall")