Added _LIBCPP_HAS_NO_THREADS for single_threaded binaries linked with libcxx.

Fixed single-threaded mode for Windows.

1 files changed, 13 insertions, 0 deletions

diff --git a/src/Compilation.zig b/src/Compilation.zig
index 9126289804..3eb527b612 100644
--- a/src/Compilation.zig
+++ b/src/Compilation.zig
@@ -1180,6 +1180,15 @@ pub fn create(gpa: Allocator, options: InitOptions) !*Compilation {
         if (must_single_thread and !single_threaded) {
             return error.TargetRequiresSingleThreaded;
         }
+        if (!single_threaded and options.link_libcpp) {
+            if (options.target.cpu.arch.isARM()) {
+                log.warn(
+                    \\libc++ does not work on multi-threaded ARM yet.
+                    \\For more details: https://github.com/ziglang/zig/issues/6573
+                , .{});
+                return error.TargetRequiresSingleThreaded;
+            }
+        }
 
         const llvm_cpu_features: ?[*:0]const u8 = if (build_options.have_llvm and use_llvm) blk: {
             var buf = std.ArrayList(u8).init(arena);
@@ -3803,6 +3812,10 @@ pub fn addCCArgs(
         try argv.append("-D_LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS");
         try argv.append("-D_LIBCXXABI_DISABLE_VISIBILITY_ANNOTATIONS");
         try argv.append("-D_LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS");
+
+        if (comp.bin_file.options.single_threaded) {
+            try argv.append("-D_LIBCPP_HAS_NO_THREADS");
+        } else {}
     }
 
     if (comp.bin_file.options.link_libunwind) {