Experiment: call ZigString__freeGlobal when calling deref on an external string

src/bun.js/bindings/headers-handwritten.h

@@ -79,6 +79,8 @@ typedef struct BunString {
     // This one usually will clone the raw bytes.
     WTF::String toWTFString() const;
 
+    WTF::String toWTFString();
+
 } BunString;
 
 typedef struct ZigErrorType {
@@ -456,6 +458,46 @@ class ScriptArguments;
 
 using ScriptArguments = Inspector::ScriptArguments;
 
+namespace Zig {
+
+// 8 bit byte
+// we tag the final two bits
+// so 56 bits are copied over
+// rest we zero out for consistentcy
+static const unsigned char* untag(const unsigned char* ptr)
+{
+    return reinterpret_cast<const unsigned char*>(
+        (((reinterpret_cast<uintptr_t>(ptr) & ~(static_cast<uint64_t>(1) << 63) & ~(static_cast<uint64_t>(1) << 62)) & ~(static_cast<uint64_t>(1) << 61)) & ~(static_cast<uint64_t>(1) << 60)));
+}
+
+static void* untagVoid(const unsigned char* ptr)
+{
+    return const_cast<void*>(reinterpret_cast<const void*>(untag(ptr)));
+}
+
+static void* untagVoid(const char16_t* ptr)
+{
+    return untagVoid(reinterpret_cast<const unsigned char*>(ptr));
+}
+
+static bool isTaggedUTF16Ptr(const unsigned char* ptr)
+{
+    return (reinterpret_cast<uintptr_t>(ptr) & (static_cast<uint64_t>(1) << 63)) != 0;
+}
+
+// Do we need to convert the string from UTF-8 to UTF-16?
+static bool isTaggedUTF8Ptr(const unsigned char* ptr)
+{
+    return (reinterpret_cast<uintptr_t>(ptr) & (static_cast<uint64_t>(1) << 61)) != 0;
+}
+
+static bool isTaggedExternalPtr(const unsigned char* ptr)
+{
+    return (reinterpret_cast<uintptr_t>(ptr) & (static_cast<uint64_t>(1) << 62)) != 0;
+}
+
+}
+
 ALWAYS_INLINE void BunString::ref()
 {
     if (this->tag == BunStringTag::WTFStringImpl) {
@@ -466,8 +508,12 @@ ALWAYS_INLINE void BunString::deref()
 {
     if (this->tag == BunStringTag::WTFStringImpl) {
         this->impl.wtf->deref();
+    } else if (UNLIKELY(this->tag == BunStringTag::ZigString && this->impl.zig.len > 0 && Zig::isTaggedExternalPtr(this->impl.zig.ptr))) {
+        ZigString__freeGlobal(Zig::untag(this->impl.zig.ptr), this->impl.zig.len);
+        this->tag = BunStringTag::Dead;
     }
 }
 
 #endif // __cplusplus
+
 #endif // HEADERS_HANDWRITTEN

src/bun.js/bindings/helpers.h

@@ -26,42 +26,6 @@ extern "C" const char* Bun__errnoName(int);
 
 namespace Zig {
 
-// 8 bit byte
-// we tag the final two bits
-// so 56 bits are copied over
-// rest we zero out for consistentcy
-static const unsigned char* untag(const unsigned char* ptr)
-{
-    return reinterpret_cast<const unsigned char*>(
-        (((reinterpret_cast<uintptr_t>(ptr) & ~(static_cast<uint64_t>(1) << 63) & ~(static_cast<uint64_t>(1) << 62)) & ~(static_cast<uint64_t>(1) << 61)) & ~(static_cast<uint64_t>(1) << 60)));
-}
-
-static void* untagVoid(const unsigned char* ptr)
-{
-    return const_cast<void*>(reinterpret_cast<const void*>(untag(ptr)));
-}
-
-static void* untagVoid(const char16_t* ptr)
-{
-    return untagVoid(reinterpret_cast<const unsigned char*>(ptr));
-}
-
-static bool isTaggedUTF16Ptr(const unsigned char* ptr)
-{
-    return (reinterpret_cast<uintptr_t>(ptr) & (static_cast<uint64_t>(1) << 63)) != 0;
-}
-
-// Do we need to convert the string from UTF-8 to UTF-16?
-static bool isTaggedUTF8Ptr(const unsigned char* ptr)
-{
-    return (reinterpret_cast<uintptr_t>(ptr) & (static_cast<uint64_t>(1) << 61)) != 0;
-}
-
-static bool isTaggedExternalPtr(const unsigned char* ptr)
-{
-    return (reinterpret_cast<uintptr_t>(ptr) & (static_cast<uint64_t>(1) << 62)) != 0;
-}
-
 static void free_global_string(void* str, void* ptr, unsigned len)
 {
     // i don't understand why this happens