Only compute specializes query if specialization is enabled in the crate of the specialized impl

compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs

@@ -314,6 +314,7 @@ provide! { tcx, def_id, other, cdata,
     extern_crate => { cdata.extern_crate.map(|c| &*tcx.arena.alloc(c)) }
     is_no_builtins => { cdata.root.no_builtins }
     symbol_mangling_version => { cdata.root.symbol_mangling_version }
+    specialization_enabled_in => { cdata.root.specialization_enabled_in }
     reachable_non_generics => {
         let reachable_non_generics = tcx
             .exported_symbols(cdata.cnum)

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -741,6 +741,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 expn_data,
                 expn_hashes,
                 def_path_hash_map,
+                specialization_enabled_in: tcx.specialization_enabled_in(LOCAL_CRATE),
             })
         });
 

compiler/rustc_metadata/src/rmeta/mod.rs

@@ -290,6 +290,8 @@ pub(crate) struct CrateRoot {
     panic_runtime: bool,
     profiler_runtime: bool,
     symbol_mangling_version: SymbolManglingVersion,
+
+    specialization_enabled_in: bool,
 }
 
 /// On-disk representation of `DefId`.