Remove an unused error count check

compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs

@@ -45,14 +45,6 @@ pub struct FnCtxt<'a, 'tcx> {
     /// eventually).
     pub(super) param_env: ty::ParamEnv<'tcx>,
 
-    /// Number of errors that had been reported when we started
-    /// checking this function. On exit, if we find that *more* errors
-    /// have been reported, we will skip regionck and other work that
-    /// expects the types within the function to be consistent.
-    // FIXME(matthewjasper) This should not exist, and it's not correct
-    // if type checking is run in parallel.
-    err_count_on_creation: usize,
-
     /// If `Some`, this stores coercion information for returned
     /// expressions. If `None`, this is in a context where return is
     /// inappropriate, such as a const expression.
@@ -126,7 +118,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         FnCtxt {
             body_id,
             param_env,
-            err_count_on_creation: inh.tcx.dcx().err_count(),
             ret_coercion: None,
             ret_coercion_span: Cell::new(None),
             coroutine_types: None,
@@ -195,10 +186,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }),
         }
     }
-
-    pub fn errors_reported_since_creation(&self) -> bool {
-        self.dcx().err_count() > self.err_count_on_creation
-    }
 }
 
 impl<'a, 'tcx> Deref for FnCtxt<'a, 'tcx> {

src/tools/clippy/clippy_lints/src/transmute/utils.rs

@@ -37,12 +37,6 @@ pub(super) fn check_cast<'tcx>(
     let inherited = Inherited::new(cx.tcx, local_def_id);
     let fn_ctxt = FnCtxt::new(&inherited, cx.param_env, local_def_id);
 
-    // If we already have errors, we can't be sure we can pointer cast.
-    assert!(
-        !fn_ctxt.errors_reported_since_creation(),
-        "Newly created FnCtxt contained errors"
-    );
-
     if let Ok(check) = cast::CastCheck::new(
         &fn_ctxt,
         e,
@@ -53,17 +47,7 @@ pub(super) fn check_cast<'tcx>(
         DUMMY_SP,
         hir::Constness::NotConst,
     ) {
-        let res = check.do_check(&fn_ctxt);
+        check.do_check(&fn_ctxt).ok()
-
-        // do_check's documentation says that it might return Ok and create
-        // errors in the fcx instead of returning Err in some cases. Those cases
-        // should be filtered out before getting here.
-        assert!(
-            !fn_ctxt.errors_reported_since_creation(),
-            "`fn_ctxt` contained errors after cast check!"
-        );
-
-        res.ok()
     } else {
         None
     }