Rollup merge of #117918 - daxpedda:wasm-c-abi-warning, r=workingjubilee

Add `wasm_c_abi` `future-incompat` lint

This is a warning that will tell users to update to `wasm-bindgen` v0.2.88, which supports spec-compliant C ABI.

The idea is to prepare for a future where Rust will switch to the spec-compliant C ABI by default; so not to break everyone's world, this warning is introduced.

Addresses #71871.

2 files changed, 43 insertions, 1 deletions

diff --git a/compiler/rustc_metadata/messages.ftl b/compiler/rustc_metadata/messages.ftl
index a1c6fba4d43..f456dd09dea 100644
--- a/compiler/rustc_metadata/messages.ftl
+++ b/compiler/rustc_metadata/messages.ftl
@@ -281,6 +281,8 @@ metadata_unsupported_abi =
 metadata_unsupported_abi_i686 =
     ABI not supported by `#[link(kind = "raw-dylib")]` on i686
 
+metadata_wasm_c_abi =
+    older versions of the `wasm-bindgen` crate will be incompatible with future versions of Rust; please update to `wasm-bindgen` v0.2.88
 metadata_wasm_import_form =
     wasm import module must be of the form `wasm_import_module = "string"`
 
diff --git a/compiler/rustc_metadata/src/creader.rs b/compiler/rustc_metadata/src/creader.rs
index 72757d90e42..faa3bb7caec 100644
--- a/compiler/rustc_metadata/src/creader.rs
+++ b/compiler/rustc_metadata/src/creader.rs
@@ -31,8 +31,9 @@ use proc_macro::bridge::client::ProcMacro;
 use std::error::Error;
 use std::ops::Fn;
 use std::path::Path;
+use std::str::FromStr;
 use std::time::Duration;
-use std::{cmp, iter};
+use std::{cmp, env, iter};
 
 /// The backend's way to give the crate store access to the metadata in a library.
 /// Note that it returns the raw metadata bytes stored in the library file, whether
@@ -985,6 +986,44 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
         }
     }
 
+    fn report_future_incompatible_deps(&self, krate: &ast::Crate) {
+        let name = self.tcx.crate_name(LOCAL_CRATE);
+
+        if name.as_str() == "wasm_bindgen" {
+            let major = env::var("CARGO_PKG_VERSION_MAJOR")
+                .ok()
+                .and_then(|major| u64::from_str(&major).ok());
+            let minor = env::var("CARGO_PKG_VERSION_MINOR")
+                .ok()
+                .and_then(|minor| u64::from_str(&minor).ok());
+            let patch = env::var("CARGO_PKG_VERSION_PATCH")
+                .ok()
+                .and_then(|patch| u64::from_str(&patch).ok());
+
+            match (major, minor, patch) {
+                // v1 or bigger is valid.
+                (Some(1..), _, _) => return,
+                // v0.3 or bigger is valid.
+                (Some(0), Some(3..), _) => return,
+                // v0.2.88 or bigger is valid.
+                (Some(0), Some(2), Some(88..)) => return,
+                // Not using Cargo.
+                (None, None, None) => return,
+                _ => (),
+            }
+
+            // Make a point span rather than covering the whole file
+            let span = krate.spans.inner_span.shrink_to_lo();
+
+            self.sess.psess.buffer_lint(
+                lint::builtin::WASM_C_ABI,
+                span,
+                ast::CRATE_NODE_ID,
+                crate::fluent_generated::metadata_wasm_c_abi,
+            );
+        }
+    }
+
     pub fn postprocess(&mut self, krate: &ast::Crate) {
         self.inject_forced_externs();
         self.inject_profiler_runtime(krate);
@@ -992,6 +1031,7 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
         self.inject_panic_runtime(krate);
 
         self.report_unused_deps(krate);
+        self.report_future_incompatible_deps(krate);
 
         info!("{:?}", CrateDump(self.cstore));
     }