Add support for compiling with VS clang-cl toolset

2 files changed, 28 insertions, 9 deletions

diff --git a/platform/windows/crash_handler_windows_seh.cpp b/platform/windows/crash_handler_windows_seh.cpp
index 2abe285d31..a6015092e8 100644
--- a/platform/windows/crash_handler_windows_seh.cpp
+++ b/platform/windows/crash_handler_windows_seh.cpp
@@ -118,7 +118,7 @@ DWORD CrashHandlerException(EXCEPTION_POINTERS *ep) {
 	HANDLE process = GetCurrentProcess();
 	HANDLE hThread = GetCurrentThread();
 	DWORD offset_from_symbol = 0;
-	IMAGEHLP_LINE64 line = { 0 };
+	IMAGEHLP_LINE64 line = {};
 	std::vector<module_data> modules;
 	DWORD cbNeeded;
 	std::vector<HMODULE> module_handles(1);
diff --git a/platform/windows/detect.py b/platform/windows/detect.py
index 82a98655c0..d2a9c2315f 100644
--- a/platform/windows/detect.py
+++ b/platform/windows/detect.py
@@ -381,6 +381,15 @@ def configure_msvc(env: "SConsEnvironment", vcvars_msvc_config):
 
     ## Compile/link flags
 
+    if env["use_llvm"]:
+        env["CC"] = "clang-cl"
+        env["CXX"] = "clang-cl"
+        env["LINK"] = "lld-link"
+        env["AR"] = "llvm-lib"
+
+        env.AppendUnique(CPPDEFINES=["R128_STDC_ONLY"])
+        env.extra_suffix = ".llvm" + env.extra_suffix
+
     env["MAXLINELENGTH"] = 8192  # Windows Vista and beyond, so always applicable.
 
     if env["silence_msvc"] and not env.GetOption("clean"):
@@ -465,7 +474,6 @@ def configure_msvc(env: "SConsEnvironment", vcvars_msvc_config):
 
     env.AppendUnique(CCFLAGS=["/Gd", "/GR", "/nologo"])
     env.AppendUnique(CCFLAGS=["/utf-8"])  # Force to use Unicode encoding.
-    env.AppendUnique(CXXFLAGS=["/TP"])  # assume all sources are C++
     # Once it was thought that only debug builds would be too large,
     # but this has recently stopped being true. See the mingw function
     # for notes on why this shouldn't be enabled for gcc
@@ -590,6 +598,9 @@ def configure_msvc(env: "SConsEnvironment", vcvars_msvc_config):
     if env["target"] in ["editor", "template_debug"]:
         LIBS += ["psapi", "dbghelp"]
 
+    if env["use_llvm"]:
+        LIBS += [f"clang_rt.builtins-{env['arch']}"]
+
     env.Append(LINKFLAGS=[p + env["LIBSUFFIX"] for p in LIBS])
 
     if vcvars_msvc_config:
@@ -605,14 +616,22 @@ def configure_msvc(env: "SConsEnvironment", vcvars_msvc_config):
 
     if env["lto"] != "none":
         if env["lto"] == "thin":
-            print_error("ThinLTO is only compatible with LLVM, use `use_llvm=yes` or `lto=full`.")
-            sys.exit(255)
-        env.AppendUnique(CCFLAGS=["/GL"])
-        env.AppendUnique(ARFLAGS=["/LTCG"])
-        if env["progress"]:
-            env.AppendUnique(LINKFLAGS=["/LTCG:STATUS"])
+            if not env["use_llvm"]:
+                print("ThinLTO is only compatible with LLVM, use `use_llvm=yes` or `lto=full`.")
+                sys.exit(255)
+
+            env.Append(CCFLAGS=["-flto=thin"])
+            env.Append(LINKFLAGS=["-flto=thin"])
+        elif env["use_llvm"]:
+            env.Append(CCFLAGS=["-flto"])
+            env.Append(LINKFLAGS=["-flto"])
         else:
-            env.AppendUnique(LINKFLAGS=["/LTCG"])
+            env.AppendUnique(CCFLAGS=["/GL"])
+            env.AppendUnique(ARFLAGS=["/LTCG"])
+            if env["progress"]:
+                env.AppendUnique(LINKFLAGS=["/LTCG:STATUS"])
+            else:
+                env.AppendUnique(LINKFLAGS=["/LTCG"])
 
     if vcvars_msvc_config:
         env.Prepend(CPPPATH=[p for p in str(os.getenv("INCLUDE")).split(";")])