Auto merge of #85834 - cjgillot:save-sbi, r=michaelwoerister

Encode CrateNum using the StableCrateId for incr. comp.

compiler/rustc_middle/src/ty/context.rs

@@ -53,6 +53,7 @@ use rustc_serialize::opaque::{FileEncodeResult, FileEncoder};
 use rustc_session::config::{BorrowckMode, CrateType, OutputFilenames};
 use rustc_session::lint::{Level, Lint};
 use rustc_session::Session;
+use rustc_span::def_id::StableCrateId;
 use rustc_span::source_map::MultiSpan;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{Span, DUMMY_SP};
@@ -1264,6 +1265,11 @@ impl<'tcx> TyCtxt<'tcx> {
         }
     }
 
+    #[inline]
+    pub fn stable_crate_id(self, cnum: CrateNum) -> StableCrateId {
+        self.def_path_hash(cnum.as_def_id()).stable_crate_id()
+    }
+
     pub fn def_path_debug_str(self, def_id: DefId) -> String {
         // We are explicitly not going through queries here in order to get
         // crate name and disambiguator since this code is called from debug!()