chore: import upstream snapshot with attribution

native/zero-c/src/llvm_backend_metadata.c

@@ -0,0 +1,48 @@
+#include "zero.h"
+
+static void metadata_append_json_string(ZBuf *buf, const char *value) {
+  zbuf_append_char(buf, '"');
+  for (const char *cursor = value ? value : ""; *cursor; cursor++) {
+    unsigned char ch = (unsigned char)*cursor;
+    if (ch == '"') zbuf_append(buf, "\\\"");
+    else if (ch == '\\') zbuf_append(buf, "\\\\");
+    else if (ch == '\n') zbuf_append(buf, "\\n");
+    else if (ch == '\r') zbuf_append(buf, "\\r");
+    else if (ch == '\t') zbuf_append(buf, "\\t");
+    else if (ch < 0x20) zbuf_appendf(buf, "\\u%04x", (unsigned)ch);
+    else zbuf_append_char(buf, (char)ch);
+  }
+  zbuf_append_char(buf, '"');
+}
+
+const char *z_llvm_backend_lifecycle_json_text(void) {
+  return "{\"stability\":\"experimental\",\"defaultEligible\":false,\"releaseEligible\":false,\"fallbackEligible\":false,\"supportedReleaseFamily\":\"direct\",\"reason\":\"LLVM is explicit experimental build/run/IR only; direct emitters remain the supported release path\"}";
+}
+
+void z_append_llvm_backend_lifecycle_json(ZBuf *buf) {
+  zbuf_append(buf, z_llvm_backend_lifecycle_json_text());
+}
+
+void z_append_llvm_backend_lifecycle_field_json(ZBuf *buf) {
+  zbuf_append(buf, ",\"backendLifecycle\":");
+  z_append_llvm_backend_lifecycle_json(buf);
+}
+
+void z_append_doctor_llvm_toolchain_json(ZBuf *buf, const ZTargetInfo *host_target, const ZLlvmToolchainPlan *plan) {
+  zbuf_append(buf, ",\n  \"llvmToolchain\": {\"status\":");
+  metadata_append_json_string(buf, plan ? plan->status : "unsupported-target");
+  zbuf_append(buf, ",\"target\":");
+  metadata_append_json_string(buf, host_target && host_target->name ? host_target->name : z_host_target());
+  zbuf_append(buf, ",\"driverKind\":\"clang\",\"selectionSource\":");
+  metadata_append_json_string(buf, plan ? plan->selection_source : "path");
+  zbuf_append(buf, ",\"compiler\":");
+  metadata_append_json_string(buf, plan ? plan->compiler : "clang");
+  zbuf_append(buf, ",\"targetTriple\":");
+  metadata_append_json_string(buf, plan ? plan->target_triple : "unknown-unknown-unknown");
+  zbuf_append(buf, ",\"nativeExecutable\":");
+  zbuf_append(buf, plan && plan->native_executable ? "true" : "false");
+  z_append_llvm_backend_lifecycle_field_json(buf);
+  zbuf_append(buf, ",\"reason\":");
+  metadata_append_json_string(buf, plan ? plan->reason : "host target is not supported by native LLVM executable builds");
+  zbuf_append(buf, "}");
+}