improve clang runtimes

xmake/modules/core/tools/clang.lua

@@ -196,6 +196,7 @@ end
 -- @see https://github.com/xmake-io/xmake/issues/3546
 function nf_runtime(self, runtime, opt)
     opt = opt or {}
+    local maps
     local kind = self:kind()
     if self:is_plat("windows") and runtime then
         if not _has_ms_runtime_lib(self) then
@@ -204,69 +205,43 @@ function nf_runtime(self, runtime, opt)
             end
             return
         end
-        local maps
         if language.sourcekinds()[kind] then
             maps = {
                 MT  = "-fms-runtime-lib=static",
                 MTd = "-fms-runtime-lib=static_dbg",
                 MD  = "-fms-runtime-lib=dll",
                 MDd = "-fms-runtime-lib=dll_dbg"
             }
-            if kind == "cxx" then
-                table.join2(maps, {
-                    ["c++_static"]    = "-stdlib=libc++",
-                    ["c++_shared"]    = "-stdlib=libc++",
-                    ["stdc++_static"] = "-stdlib=libstdc++",
-                    ["stdc++_shared"] = "-stdlib=libstdc++",
-                })
-            end
         elseif kind == "ld" or kind == "sh" then
             maps = {
                 MT  = "-nostdlib",
                 MTd = "-nostdlib",
                 MD  = "-nostdlib",
                 MDd = "-nostdlib"
             }
-            local target = opt.target
-            if target and target.sourcekinds and table.contains(table.wrap(target:sourcekinds()), "cxx") then
-                table.join2(maps, {
-                    ["c++_static"]    = "-stdlib=libc++",
-                    ["c++_shared"]    = "-stdlib=libc++",
-                    ["stdc++_static"] = "-stdlib=libstdc++",
-                    ["stdc++_shared"] = "-stdlib=libstdc++",
-                })
-                if runtime:endswith("_static") and _has_static_libstdcxx(self) then
-                    maps["c++_static"] = table.join(maps["c++_static"], "-static-libstdc++")
-                    maps["stdc++_static"] = table.join(maps["stdc++_static"], "-static-libstdc++")
-                end
-            end
         end
-        return maps and maps[runtime]
-    elseif not self:is_plat("android") then -- we will set runtimes in android ndk toolchain
-        local maps
+    end
+    if not self:is_plat("android") then -- we will set runtimes in android ndk toolchain
+        maps = maps or {}
         if kind == "cxx" then
-            maps = {
-                ["c++_static"]    = "-stdlib=libc++",
-                ["c++_shared"]    = "-stdlib=libc++",
-                ["stdc++_static"] = "-stdlib=libstdc++",
-                ["stdc++_shared"] = "-stdlib=libstdc++",
-            }
+            maps["c++_static"]    = "-stdlib=libc++"
+            maps["c++_shared"]    = "-stdlib=libc++"
+            maps["stdc++_static"] = "-stdlib=libstdc++"
+            maps["stdc++_shared"] = "-stdlib=libstdc++"
         elseif kind == "ld" or kind == "sh" then
             local target = opt.target
             if target and target.sourcekinds and table.contains(table.wrap(target:sourcekinds()), "cxx") then
-                maps = {
-                    ["c++_static"]    = "-stdlib=libc++",
-                    ["c++_shared"]    = "-stdlib=libc++",
-                    ["stdc++_static"] = "-stdlib=libstdc++",
-                    ["stdc++_shared"] = "-stdlib=libstdc++",
-                }
+                maps["c++_static"]    = "-stdlib=libc++"
+                maps["c++_shared"]    = "-stdlib=libc++"
+                maps["stdc++_static"] = "-stdlib=libstdc++"
+                maps["stdc++_shared"] = "-stdlib=libstdc++"
                 if runtime:endswith("_static") and _has_static_libstdcxx(self) then
                     maps["c++_static"] = table.join(maps["c++_static"], "-static-libstdc++")
                     maps["stdc++_static"] = table.join(maps["stdc++_static"], "-static-libstdc++")
                 end
             end
         end
-        return maps and maps[runtime]
     end
+    return maps and maps[runtime]
 end