Merge pull request #4681 from Arthapz/fix-libcppruntime-windows

fix libc++ support on windows

xmake/modules/core/tools/clang.lua

@@ -191,6 +191,21 @@ function _has_static_libstdcxx(self)
     return has_static_libstdcxx
 end
 
+-- get llvm sdk root directory
+function _get_llvm_rootdir(self)
+    local llvm_rootdir = _g._LLVM_ROOTDIR
+    if llvm_rootdir == nil then
+        local outdata = try { function() return os.iorun(self:program() .. " -print-resource-dir") end }
+        if outdata then
+            llvm_rootdir = path.normalize(path.join(outdata:trim(), "..", "..", ".."))
+            if not os.isdir(llvm_rootdir) then
+                llvm_rootdir = nil
+            end
+        end
+        _g._LLVM_ROOTDIR = llvm_rootdir or false
+    end
+    return llvm_rootdir or nil
+end
 
 -- make the runtime flag
 -- @see https://github.com/xmake-io/xmake/issues/3546
@@ -228,13 +243,31 @@ function nf_runtime(self, runtime, opt)
             maps["c++_shared"]    = "-stdlib=libc++"
             maps["stdc++_static"] = "-stdlib=libstdc++"
             maps["stdc++_shared"] = "-stdlib=libstdc++"
+            -- clang on windows fail to add libc++ includepath when using -stdlib=libc++ so we manually add it
+            -- @see https://github.com/llvm/llvm-project/issues/79647
+            if self:is_plat("windows") then
+                local llvm_rootdir = _get_llvm_rootdir(self)
+                if llvm_rootdir then
+                    maps["c++_static"] = table.join(maps["c++_static"], "-cxx-isystem" .. path.join(llvm_rootdir, "include", "c++", "v1"))
+                    maps["c++_shared"] = table.join(maps["c++_shared"], "-cxx-isystem" .. path.join(llvm_rootdir, "include", "c++", "v1"))
+                end
+            end
         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++"
                 maps["c++_shared"]    = "-stdlib=libc++"
                 maps["stdc++_static"] = "-stdlib=libstdc++"
                 maps["stdc++_shared"] = "-stdlib=libstdc++"
+                -- clang on windows fail to add libc++ librarypath when using -stdlib=libc++ so we manually add it
+                -- @see https://github.com/llvm/llvm-project/issues/79647
+                if self:is_plat("windows") then
+                    local llvm_rootdir = _get_llvm_rootdir(self)
+                    if llvm_rootdir then
+                        maps["c++_static"] = table.join(maps["c++_static"], "-L" .. path.join(llvm_rootdir, "lib"))
+                        maps["c++_shared"] = table.join(maps["c++_shared"], "-L" .. path.join(llvm_rootdir, "lib"))
+                    end
+                end
                 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++")
@@ -244,4 +277,3 @@ function nf_runtime(self, runtime, opt)
     end
     return maps and maps[runtime]
 end
-