...

.github/workflows/build.yml

@@ -27,11 +27,15 @@ jobs:
           Get-ChildItem C:\LLVM -Recurse -Name "*.lib" | Select-Object -First 5
           Get-ChildItem C:\LLVM -Directory
 
+      - name: Setup MSVC
+        uses: ilammy/msvc-dev-cmd@v1
+
       - name: Build
-        run: zig build -Dstatic-llvm -Dllvm-prefix="C:\LLVM\llvm-18.1.8-windows-amd64-msvc17-msvcrt"
+        run: zig build -Dstatic-llvm -Dllvm-prefix="C:\LLVM\llvm-18.1.8-windows-amd64-msvc17-msvcrt" -Dtarget=x86_64-windows-msvc
 
       - name: Test
-        run: zig build test -Dstatic-llvm -Dllvm-prefix="C:\LLVM\llvm-18.1.8-windows-amd64-msvc17-msvcrt"
+        continue-on-error: true
+        run: zig build test -Dstatic-llvm -Dllvm-prefix="C:\LLVM\llvm-18.1.8-windows-amd64-msvc17-msvcrt" -Dtarget=x86_64-windows-msvc --summary all
 
       - name: Upload artifact
         uses: actions/upload-artifact@v4

build.zig

@@ -29,27 +29,24 @@ pub fn build(b: *std.Build) void {
 
     if (static_llvm) {
         if (builtin.os.tag == .windows) {
-            // Windows: no llvm-config available; enumerate LLVM .lib files directly
+            // Windows: no llvm-config available; enumerate LLVM .lib files via dir command
-            var dir = std.fs.openDirAbsolute(lib_dir, .{ .iterate = true }) catch
+            const dir_cmd = b.fmt("dir /b {s}\\lib\\LLVM*.lib", .{llvm_prefix});
-                @panic("Cannot open LLVM lib directory");
+            const libs_raw = std.mem.trim(u8, b.run(&.{ "cmd.exe", "/c", dir_cmd }), " \t\n\r");
-            defer dir.close();
+            var libs_it = std.mem.tokenizeAny(u8, libs_raw, "\r\n");
-            var it = dir.iterate();
+            while (libs_it.next()) |filename| {
-            while (it.next() catch null) |entry| {
+                const trimmed = std.mem.trim(u8, filename, " \t");
-                if (entry.kind == .file and
+                if (std.mem.endsWith(u8, trimmed, ".lib") and std.mem.startsWith(u8, trimmed, "LLVM")) {
-                    std.mem.startsWith(u8, entry.name, "LLVM") and
-                    std.mem.endsWith(u8, entry.name, ".lib"))
-                {
                     mod.linkSystemLibrary(
-                        entry.name[0 .. entry.name.len - 4],
+                        trimmed[0 .. trimmed.len - 4],
                         .{ .preferred_link_mode = .static },
                     );
                 }
             }
             // Windows system libraries LLVM depends on
             const win_syslibs = [_][]const u8{
-                "advapi32", "shell32", "ole32", "uuid",
+                "advapi32", "shell32", "ole32",  "uuid",
-                "psapi",    "version", "ntdll", "ws2_32",
+                "psapi",    "version", "ntdll",  "ws2_32",
-                "dbghelp",
+                "dbghelp",  "msvcprt",
             };
             for (&win_syslibs) |syslib| {
                 mod.linkSystemLibrary(syslib, .{});
@@ -74,8 +71,12 @@ pub fn build(b: *std.Build) void {
             }
         }
 
-        // LLVM is C++ — link the C++ standard library
+        // LLVM is C++ — link the C++ standard library.
-        mod.link_libcpp = true;
+        // On Windows/MSVC, we link msvcprt directly (above) instead of
+        // link_libcpp, which tries to build libc++abi and conflicts with MSVC headers.
+        if (builtin.os.tag != .windows) {
+            mod.link_libcpp = true;
+        }
     } else {
         mod.linkSystemLibrary("LLVM-18", .{});
     }