Run compiler callbacks even when there are errors.

src/librustc/middle/resolve_lifetime.rs

@@ -93,9 +93,12 @@ type Scope<'a> = &'a ScopeChain<'a>;
 
 static ROOT_SCOPE: ScopeChain<'static> = RootScope;
 
-pub fn krate(sess: &Session, krate: &hir::Crate, def_map: &DefMap) -> NamedRegionMap {
+pub fn krate(sess: &Session,
+             krate: &hir::Crate,
+             def_map: &DefMap)
+             -> Result<NamedRegionMap, usize> {
     let mut named_region_map = NodeMap();
-    sess.abort_if_new_errors(|| {
+    try!(sess.track_errors(|| {
         krate.visit_all_items(&mut LifetimeContext {
             sess: sess,
             named_region_map: &mut named_region_map,
@@ -104,8 +107,8 @@ pub fn krate(sess: &Session, krate: &hir::Crate, def_map: &DefMap) -> NamedRegio
             trait_ref_hack: false,
             labels_in_fn: vec![],
         });
-    });
-    named_region_map
+    }));
+    Ok(named_region_map)
 }
 
 impl<'a, 'v> Visitor<'v> for LifetimeContext<'a> {

src/librustc/middle/ty/mod.rs

@@ -1915,6 +1915,16 @@ impl<'tcx> ctxt<'tcx> {
         })
     }
 
+    pub fn expr_ty_adjusted_opt(&self, expr: &hir::Expr) -> Option<Ty<'tcx>> {
+        self.expr_ty_opt(expr).map(|t| t.adjust(self,
+                                                expr.span,
+                                                expr.id,
+                                                self.tables.borrow().adjustments.get(&expr.id),
+                                                |method_call| {
+            self.tables.borrow().method_map.get(&method_call).map(|method| method.ty)
+        }))
+    }
+
     pub fn expr_span(&self, id: NodeId) -> Span {
         match self.map.find(id) {
             Some(ast_map::NodeExpr(e)) => {

src/librustc/session/mod.rs

@@ -179,24 +179,13 @@ impl Session {
     pub fn track_errors<F, T>(&self, f: F) -> Result<T, usize>
         where F: FnOnce() -> T
     {
-        let count = self.err_count();
+        let old_count = self.err_count();
         let result = f();
-        let count = self.err_count() - count;
-        if count == 0 {
+        let errors = self.err_count() - old_count;
+        if errors == 0 {
             Ok(result)
         } else {
-            Err(count)
-        }
-    }
-    pub fn abort_if_new_errors<F, T>(&self, f: F) -> T
-        where F: FnOnce() -> T
-    {
-        match self.track_errors(f) {
-            Ok(result) => result,
-            Err(_) => {
-                self.abort_if_errors();
-                unreachable!();
-            }
+            Err(errors)
         }
     }
     pub fn span_warn<S: Into<MultiSpan>>(&self, sp: S, msg: &str) {
@@ -515,3 +504,15 @@ pub fn early_warn(output: config::ErrorOutputType, msg: &str) {
     };
     emitter.emit(None, msg, None, errors::Level::Warning);
 }
+
+// Err(0) means compilation was stopped, but no errors were found.
+// This would be better as a dedicated enum, but using try! is so convenient.
+pub type CompileResult = Result<(), usize>;
+
+pub fn compile_result_from_err_count(err_count: usize) -> CompileResult {
+    if err_count == 0 {
+        Ok(())
+    } else {
+        Err(err_count)
+    }
+}