Always print `aborting due to n previous error(s)` and only print it once for multi-threaded code

src/librustc_driver/lib.rs

@@ -63,6 +63,7 @@
 use rustc_save_analysis as save;
 use rustc_save_analysis::DumpHandler;
 use rustc_data_structures::sync::Lrc;
+use rustc_data_structures::OnDrop;
 use rustc::session::{self, config, Session, build_session, CompileResult};
 use rustc::session::CompileIncomplete;
 use rustc::session::config::{Input, PrintRequest, ErrorOutputType};
@@ -515,30 +516,35 @@ fn run_compiler_impl<'a>(args: &[String],
     target_features::add_configuration(&mut cfg, &sess, &*trans);
     sess.parse_sess.config = cfg;
 
-    let plugins = sess.opts.debugging_opts.extra_plugins.clone();
-
-    let cstore = CStore::new(trans.metadata_loader());
-
-    do_or_return!(callbacks.late_callback(&*trans,
-                                          &matches,
-                                          &sess,
-                                          &cstore,
-                                          &input,
-                                          &odir,
-                                          &ofile), Some(sess));
-
-    let control = callbacks.build_controller(&sess, &matches);
-
-    (driver::compile_input(trans,
-                           &sess,
-                           &cstore,
-                           &input_file_path,
-                           &input,
-                           &odir,
-                           &ofile,
-                           Some(plugins),
-                           &control),
-     Some(sess))
+    let result = {
+        let plugins = sess.opts.debugging_opts.extra_plugins.clone();
+
+        let cstore = CStore::new(trans.metadata_loader());
+
+        do_or_return!(callbacks.late_callback(&*trans,
+                                              &matches,
+                                              &sess,
+                                              &cstore,
+                                              &input,
+                                              &odir,
+                                              &ofile), Some(sess));
+
+        let _sess_abort_error = OnDrop(|| sess.diagnostic().print_error_count());
+
+        let control = callbacks.build_controller(&sess, &matches);
+
+        driver::compile_input(trans,
+                              &sess,
+                              &cstore,
+                              &input_file_path,
+                              &input,
+                              &odir,
+                              &ofile,
+                              Some(plugins),
+                              &control)
+    };
+
+    (result, Some(sess))
 }
 
 // Extract output directory and file from matches.

src/librustc_errors/lib.rs

@@ -555,21 +555,15 @@ pub fn err_count(&self) -> usize {
     pub fn has_errors(&self) -> bool {
         self.err_count() > 0
     }
-    pub fn abort_if_errors(&self) {
-        let s;
-        match self.err_count() {
-            0 => {
-                if let Some(bug) = self.delayed_span_bug.borrow_mut().take() {
-                    DiagnosticBuilder::new_diagnostic(self, bug).emit();
-                }
-                return;
-            }
-            1 => s = "aborting due to previous error".to_string(),
-            _ => {
-                s = format!("aborting due to {} previous errors", self.err_count());
-            }
-        }
-        let err = self.fatal(&s);
+
+    pub fn print_error_count(&self) {
+        let s = match self.err_count() {
+            0 => return,
+            1 => "aborting due to previous error".to_string(),
+            _ => format!("aborting due to {} previous errors", self.err_count())
+        };
+
+        let _ = self.fatal(&s);
 
         let can_show_explain = self.emitter.borrow().should_show_explain();
         let are_there_diagnostics = !self.tracked_diagnostic_codes.borrow().is_empty();
@@ -600,8 +594,16 @@ pub fn abort_if_errors(&self) {
                 }
             }
         }
+    }
 
-        err.raise();
+    pub fn abort_if_errors(&self) {
+        if self.err_count() == 0 {
+            if let Some(bug) = self.delayed_span_bug.borrow_mut().take() {
+                DiagnosticBuilder::new_diagnostic(self, bug).emit();
+            }
+            return;
+        }
+        FatalError.raise();
     }
     pub fn emit(&self, msp: &MultiSpan, msg: &str, lvl: Level) {
         if lvl == Warning && !self.flags.can_emit_warnings {

src/librustc_typeck/astconv.rs

@@ -27,6 +27,7 @@
 use require_c_abi_if_variadic;
 use util::common::ErrorReported;
 use util::nodemap::FxHashSet;
+use errors::FatalError;
 
 use std::iter;
 use syntax::{abi, ast};
@@ -337,7 +338,7 @@ fn trait_def_id(&self, trait_ref: &hir::TraitRef) -> DefId {
             Def::Trait(trait_def_id) => trait_def_id,
             Def::TraitAlias(alias_def_id) => alias_def_id,
             Def::Err => {
-                self.tcx().sess.fatal("cannot continue compilation due to previous error");
+                FatalError.raise();
             }
             _ => unreachable!(),
         }