compiling 64bit webassembly returning an empty string using embind returns a string with "0" in it.

Please include the following in your bug report:

**Version of emscripten/emsdk:**
4.0.2

The code in libembind.js that handles the fromWireType for a std::string does
var a = new Array(length);

In 64 bit builds length is a BigInt so this creates an array with 1 element in it with the value of length not a 0 length string.
This can be fixed by this patch:-

--- libembind.js.orig 2025-03-13 12:49:21.000000000 +0000
+++ libembind.js 2025-03-13 12:50:28.582019800 +0000
@@ -528,7 +528,7 @@
}
}
} else {
- var a = new Array(length);
+ var a = new Array(Number(length));
for (var i = 0; i < length; ++i) {
a[i] = String.fromCharCode(HEAPU8[payload + i]);
}