Remove EarlyDiagCtxt::abort_if_errors.

Its one use isn't necessary, because it's not possible for errors to
have been emitted at that point.

Author: nnethercote

Diff for: compiler/rustc_driver_impl/src/lib.rs

@@ -349,11 +349,10 @@ fn run_compiler(
         },
     };
 
-    callbacks.config(&mut config);
-
-    default_early_dcx.abort_if_errors();
     drop(default_early_dcx);
 
+    callbacks.config(&mut config);
+
     interface::run_compiler(config, |compiler| {
         let sess = &compiler.sess;
         let codegen_backend = &*compiler.codegen_backend;

Diff for: compiler/rustc_session/src/session.rs

@@ -1410,10 +1410,6 @@ impl EarlyDiagCtxt {
         Self { dcx: DiagCtxt::with_emitter(emitter) }
     }
 
-    pub fn abort_if_errors(&self) {
-        self.dcx.abort_if_errors()
-    }
-
     /// Swap out the underlying dcx once we acquire the user's preference on error emission
     /// format. Any errors prior to that will cause an abort and all stashed diagnostics of the
     /// previous dcx will be emitted.