Description: Fix mapping_callback import on Rust 1.96+
 Rust 1.96 stopped passing --allow-undefined to wasm-ld
 (https://github.com/rust-lang/rust/pull/149868). Previously, a bare extern "C"
 block on wasm32-unknown-unknown implicitly imported symbols from the "env"
 module. Now, as stated upstream
 (https://github.com/rust-lang/rust/pull/149868#issuecomment-3730522786),
 the link to env must be manually added.
Author: Max Gilmour <max.gilmour@canonical.com>
Bug: https://github.com/mozilla/source-map/issues/530
Bug-Debian: https://bugs.debian.org/1142614
Forwarded: https://github.com/mozilla/source-map/pull/531
Last-Update: 2026-07-22
---
--- a/wasm-mappings/source-map-mappings-wasm-api/src/lib.rs
+++ b/wasm-mappings/source-map-mappings-wasm-api/src/lib.rs
@@ -251,6 +251,10 @@
     mappings.as_mut().unwrap()
 }
 
+// Since Rust 1.96 (rust-lang/rust#149868), wasm-ld is no longer invoked with
+// `--allow-undefined`. As the PR states, importing from `env` must now be
+// declared with the following line.
+#[link(wasm_import_module = "env")]
 extern "C" {
     fn mapping_callback(
         // These two parameters are always valid.