use -fkeep-system-includes only if supported by underlying clang

2 files changed, 16 insertions, 1 deletions

diff --git a/xmake/rules/c++/modules/modules_support/clang/compiler_support.lua b/xmake/rules/c++/modules/modules_support/clang/compiler_support.lua
index 6e4b36645..6cd5270dc 100644
--- a/xmake/rules/c++/modules/modules_support/clang/compiler_support.lua
+++ b/xmake/rules/c++/modules/modules_support/clang/compiler_support.lua
@@ -372,6 +372,20 @@ function has_clangscandepssupport(target)
     return support_clangscandeps or nil
 end
 
+function get_keepsystemincludesflag(target)
+    local keepsystemincludesflag = _g.keepsystemincludesflag
+    if keepsystemincludesflag == nil then
+        local compinst = target:compiler("cxx")
+        local clang_version = get_clang_version(target)
+        if compinst:has_flags("-fkeep-system-includes", "cxxflags", {flagskey = "clang_keep_system_includes", tryrun = true}) and
+            semver.compare(clang_version, "18.0") >= 0 then
+            keepsystemincludesflag = "-fkeep-system-includes"
+        end
+        _g.keepsystemincludesflag = keepsystemincludesflag or false
+    end
+    return keepsystemincludesflag or nil
+end
+
 function get_moduleoutputflag(target)
     local moduleoutputflag = _g.moduleoutputflag
     if moduleoutputflag == nil then
diff --git a/xmake/rules/c++/modules/modules_support/clang/dependency_scanner.lua b/xmake/rules/c++/modules/modules_support/clang/dependency_scanner.lua
index 71ccabb72..6f78b3a41 100644
--- a/xmake/rules/c++/modules/modules_support/clang/dependency_scanner.lua
+++ b/xmake/rules/c++/modules/modules_support/clang/dependency_scanner.lua
@@ -57,6 +57,7 @@ function generate_dependencies(target, sourcebatch, opt)
                 io.writefile(jsonfile, outdata)
             else
                 fallback_generate_dependencies(target, jsonfile, sourcefile, function(file)
+                    local keepsystemincludesflag = compiler_support.get_keepsystemincludesflag(target)
                     local compflags = compinst:compflags({sourcefile = file, target = target})
                     -- exclude -fmodule* and -std=c++/gnu++* flags because,
                     -- when they are set clang try to find bmi of imported modules but they don't exists a this point of compilation
@@ -64,7 +65,7 @@ function generate_dependencies(target, sourcebatch, opt)
                         return flag:startswith("-fmodule") or flag:startswith("-std=c++") or flag:startswith("-std=gnu++")
                     end)
                     local ifile = path.translate(path.join(outputdir, path.filename(file) .. ".i"))
-                    local flags = table.join(compflags or {}, {"-E", runtime_flag, "-fkeep-system-includes", "-x", "c++", file, "-o", ifile})
+                    local flags = table.join(compflags or {}, keepsystemincludesflag or {}, {"-E", "-x", "c++", file, "-o", ifile})
                     os.vrunv(compinst:program(), flags)
                     local content = io.readfile(ifile)
                     os.rm(ifile)