Wasm registration fn names now based on crate name + index

godot-macros/Cargo.toml

@@ -14,7 +14,7 @@ homepage = "https://godot-rust.github.io"
 api-custom = ["godot-bindings/api-custom"]
 api-custom-json = ["godot-bindings/api-custom-json"]
 codegen-full = ["godot/__codegen-full"]
-experimental-wasm = ["dep:libc"]
+experimental-wasm = []
 register-docs = ["dep:markdown", "dep:litrs"]
 
 [lib]
@@ -28,10 +28,6 @@ markdown = { workspace = true, optional = true }
 litrs = { workspace = true, optional = true }
 venial = { workspace = true }
 
-# Cannot use [target.'cfg(target_family = "wasm")'.dependencies], as proc-macro crates are always compiled for host platform, not target.
-# Thus solved via feature.
-libc = { workspace = true, optional = true }
-
 [build-dependencies]
 godot-bindings = { path = "../godot-bindings", version = "=0.3.1" } # emit_godot_version_cfg
 

godot-macros/src/ffi_macros.rs

@@ -13,22 +13,34 @@ use crate::util::bail;
 use crate::ParseResult;
 use proc_macro2::TokenStream;
 use quote::{format_ident, quote};
+use std::env;
+use std::sync::atomic::{AtomicU32, Ordering};
+
+// Note: global state in proc-macros may become problematic in the future, see:
+// https://users.rust-lang.org/t/simple-state-in-procedural-macro/68204/2
+static FUNCTION_COUNTER: AtomicU32 = AtomicU32::new(0);
 
 pub(super) fn wasm_declare_init_fn(input: TokenStream) -> ParseResult<TokenStream> {
     if !input.is_empty() {
         return bail!(input, "macro expects no arguments");
     }
 
-    // Create sufficiently unique identifier without entire `uuid` (let alone `rand`) crate dependency.
-    let a = unsafe { libc::rand() };
-    let b = unsafe { libc::rand() };
+    let crate_name = env::var("CARGO_CRATE_NAME")
+        .expect("CARGO_CRATE_NAME env var not found. This macro must be run by Cargo.");
+
+    let crate_version = env::var("CARGO_PKG_VERSION")
+        .expect("CARGO_PKG_VERSION env var not found. This macro must be run by Cargo.")
+        .replace(['.', '+', '-'], "_"); // version must follow semver, which allows digits, dots, hyphens, and plus signs, and alphanumeric characters.
+
+    let index = FUNCTION_COUNTER.fetch_add(1, Ordering::Relaxed);
 
     // Rust presently requires that statics with a custom `#[link_section]` must be a simple
     // list of bytes on the Wasm target (with no extra levels of indirection such as references).
     //
-    // As such, instead we export a function with a random name of known prefix to be used by the embedder.
+    // As such, instead we export a function with a known prefix to be used by the embedder.
     // This prefix is queried at load time, see godot-macros/src/gdextension.rs.
-    let function_name = format_ident!("__godot_rust_registrant_{a}_{b}");
+    let function_name =
+        format_ident!("__godot_rust_registrant__{crate_name}__v{crate_version}__i{index}");
 
     let code = quote! {
         #[cfg(target_family = "wasm")] // Strictly speaking not necessary, as this macro is only invoked for Wasm.