Fix rebase and move suggestion to its own method

Author: estebank

src/librustc/traits/error_reporting.rs

@@ -648,28 +648,6 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                                          trait_ref.to_predicate(), post_message)
                             ));
 
-                        let parent_node = self.tcx.hir().get_parent_node(obligation.cause.body_id);
-                        let node = self.tcx.hir().find(parent_node);
-                        if let Some(hir::Node::Item(hir::Item {
-                            node: hir::ItemKind::Fn(decl, _, _, body_id),
-                            ..
-                        })) = node {
-                            let body = self.tcx.hir().body(*body_id);
-                            if let hir::ExprKind::Block(blk, _) = &body.value.node {
-                                if decl.output.span().overlaps(span) && blk.expr.is_none() &&
-                                    "()" == &trait_ref.self_ty().to_string()
-                                {
-                                    // FIXME(estebank): When encountering a method with a trait
-                                    // bound not satisfied in the return type with a body that has
-                                    // no return, suggest removal of semicolon on last statement.
-                                    // Once that is added, close #54771.
-                                    if let Some(ref stmt) = blk.stmts.last() {
-                                        let sp = self.tcx.sess.source_map().end_point(stmt.span);
-                                        err.span_label(sp, "consider removing this semicolon");
-                                    }
-                                }
-                            }
-                        }
                         let explanation =
                             if obligation.cause.code == ObligationCauseCode::MainFunctionType {
                                 "consider using `()`, or a `Result`".to_owned()
@@ -695,6 +673,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
 
                         self.suggest_borrow_on_unsized_slice(&obligation.cause.code, &mut err);
                         self.suggest_remove_reference(&obligation, &mut err, &trait_ref);
+                        self.suggest_semicolon_removal(&obligation, &mut err, span, &trait_ref);
 
                         // Try to report a help message
                         if !trait_ref.has_infer_types() &&
@@ -923,9 +902,11 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
 
     /// When encountering an assignment of an unsized trait, like `let x = ""[..];`, provide a
     /// suggestion to borrow the initializer in order to use have a slice instead.
-    fn suggest_borrow_on_unsized_slice(&self,
-                                       code: &ObligationCauseCode<'tcx>,
-                                       err: &mut DiagnosticBuilder<'tcx>) {
+    fn suggest_borrow_on_unsized_slice(
+        &self,
+        code: &ObligationCauseCode<'tcx>,
+        err: &mut DiagnosticBuilder<'tcx>,
+    ) {
         if let &ObligationCauseCode::VariableType(node_id) = code {
             let parent_node = self.tcx.hir().get_parent_node(node_id);
             if let Some(Node::Local(ref local)) = self.tcx.hir().find(parent_node) {
@@ -947,10 +928,12 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
 
     /// Whenever references are used by mistake, like `for (i, e) in &vec.iter().enumerate()`,
     /// suggest removing these references until we reach a type that implements the trait.
-    fn suggest_remove_reference(&self,
-                                obligation: &PredicateObligation<'tcx>,
-                                err: &mut DiagnosticBuilder<'tcx>,
-                                trait_ref: &ty::Binder<ty::TraitRef<'tcx>>) {
+    fn suggest_remove_reference(
+        &self,
+        obligation: &PredicateObligation<'tcx>,
+        err: &mut DiagnosticBuilder<'tcx>,
+        trait_ref: &ty::Binder<ty::TraitRef<'tcx>>,
+    ) {
         let trait_ref = trait_ref.skip_binder();
         let span = obligation.cause.span;
 
@@ -992,6 +975,40 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
         }
     }
 
+    fn suggest_semicolon_removal(
+        &self,
+        obligation: &PredicateObligation<'tcx>,
+        err: &mut DiagnosticBuilder<'tcx>,
+        span: Span,
+        trait_ref: &ty::Binder<ty::TraitRef<'tcx>>,
+    ) {
+        let hir = self.tcx.hir();
+        let parent_node = hir.get_parent_node(
+            hir.hir_to_node_id(obligation.cause.body_id),
+        );
+        let node = hir.find(parent_node);
+        if let Some(hir::Node::Item(hir::Item {
+            node: hir::ItemKind::Fn(decl, _, _, body_id),
+            ..
+        })) = node {
+            let body = hir.body(*body_id);
+            if let hir::ExprKind::Block(blk, _) = &body.value.node {
+                if decl.output.span().overlaps(span) && blk.expr.is_none() &&
+                    "()" == &trait_ref.self_ty().to_string()
+                {
+                    // FIXME(estebank): When encountering a method with a trait
+                    // bound not satisfied in the return type with a body that has
+                    // no return, suggest removal of semicolon on last statement.
+                    // Once that is added, close #54771.
+                    if let Some(ref stmt) = blk.stmts.last() {
+                        let sp = self.tcx.sess.source_map().end_point(stmt.span);
+                        err.span_label(sp, "consider removing this semicolon");
+                    }
+                }
+            }
+        }
+    }
+
     /// Given some node representing a fn-like thing in the HIR map,
     /// returns a span and `ArgKind` information that describes the
     /// arguments it expects. This can be supplied to