rustc_metadata: Remove some extra diagnostics for legacy plugins

They are deprecated so doing extra work for error recovery doesn't make sense

Author: petrochenkov

src/librustc_error_codes/error_codes.rs

@@ -554,7 +554,7 @@ E0770: include_str!("./error_codes/E0770.md"),
 //  E0420, merged into 532
 //  E0421, merged into 531
 //  E0427, merged into 530
-    E0456, // plugin `..` is not available for triple `..`
+//  E0456, // plugin `..` is not available for triple `..`
     E0457, // plugin `..` only found in rlib format, but must be available...
     E0460, // found possibly newer version of crate `..`
     E0461, // couldn't find crate `..` with expected target triple ..

src/librustc_metadata/locator.rs

@@ -1014,10 +1014,6 @@ pub fn find_plugin_registrar(
     name: Symbol,
 ) -> Option<(PathBuf, CrateDisambiguator)> {
     info!("find plugin registrar `{}`", name);
-    let target_triple = sess.opts.target_triple.clone();
-    let host_triple = TargetTriple::from_triple(config::host_triple());
-    let is_cross = target_triple != host_triple;
-    let mut target_only = false;
     let mut locator = CrateLocator::new(
         sess,
         metadata_loader,
@@ -1032,36 +1028,11 @@ pub fn find_plugin_registrar(
         None, // is_proc_macro
     );
 
-    let library = locator.maybe_load_library_crate().or_else(|| {
-        if !is_cross {
-            return None;
-        }
-        // Try loading from target crates. This will abort later if we
-        // try to load a plugin registrar function,
-        target_only = true;
-
-        locator.target = &sess.target.target;
-        locator.triple = target_triple;
-        locator.filesearch = sess.target_filesearch(PathKind::Crate);
-
-        locator.maybe_load_library_crate()
-    });
-    let library = match library {
-        Some(l) => l,
+    let library = match locator.maybe_load_library_crate() {
+        Some(library) => library,
         None => locator.report_errs(),
     };
 
-    if target_only {
-        let message = format!(
-            "plugin `{}` is not available for triple `{}` (only found {})",
-            name,
-            config::host_triple(),
-            sess.opts.target_triple
-        );
-        struct_span_err!(sess, span, E0456, "{}", &message).emit();
-        return None;
-    }
-
     match library.source.dylib {
         Some(dylib) => Some((dylib.0, library.metadata.get_root().disambiguator())),
         None => {

src/tools/tidy/src/error_codes_check.rs

@@ -8,11 +8,11 @@ use std::path::Path;
 
 // A few of those error codes can't be tested but all the others can and *should* be tested!
 const EXEMPTED_FROM_TEST: &[&str] = &[
-    "E0183", "E0227", "E0279", "E0280", "E0311", "E0313", "E0314", "E0315", "E0377", "E0456",
-    "E0461", "E0462", "E0464", "E0465", "E0472", "E0473", "E0474", "E0475", "E0476", "E0479",
-    "E0480", "E0481", "E0482", "E0483", "E0484", "E0485", "E0486", "E0487", "E0488", "E0489",
-    "E0514", "E0519", "E0523", "E0553", "E0554", "E0570", "E0629", "E0630", "E0640", "E0717",
-    "E0727", "E0729",
+    "E0183", "E0227", "E0279", "E0280", "E0311", "E0313", "E0314", "E0315", "E0377", "E0461",
+    "E0462", "E0464", "E0465", "E0472", "E0473", "E0474", "E0475", "E0476", "E0479", "E0480",
+    "E0481", "E0482", "E0483", "E0484", "E0485", "E0486", "E0487", "E0488", "E0489", "E0514",
+    "E0519", "E0523", "E0553", "E0554", "E0570", "E0629", "E0630", "E0640", "E0717", "E0727",
+    "E0729",
 ];
 
 // Some error codes don't have any tests apparently...