Fixed potential mistakes with nesting. Added tests.

Author: daxpedda

clippy_lints/src/use_self.rs

@@ -7,7 +7,7 @@ use rustc::lint::{in_external_macro, LateContext, LateLintPass, LintArray, LintC
 use rustc::ty;
 use rustc::{declare_tool_lint, lint_array};
 use rustc_errors::Applicability;
-use syntax_pos::{symbol::keywords::SelfUpper, Span};
+use syntax_pos::symbol::keywords::SelfUpper;
 
 /// **What it does:** Checks for unnecessary repetition of structure name when a
 /// replacement with `Self` is applicable.
@@ -55,7 +55,13 @@ impl LintPass for UseSelf {
 
 const SEGMENTS_MSG: &str = "segments should be composed of at least 1 element";
 
-fn span_use_self_lint(cx: &LateContext<'_, '_>, span: Span) {
+fn span_use_self_lint(cx: &LateContext<'_, '_>, path: &Path) {
+    // path segments only include actual path, no methods or fields
+    let last_path_span = path.segments.last().expect(SEGMENTS_MSG).ident.span;
+    // `to()` doesn't shorten span, so we shorten it with `until(..)`
+    // and then include it with `to(..)`
+    let span = path.span.until(last_path_span).to(last_path_span);
+
     span_lint_and_sugg(
         cx,
         USE_SELF,
@@ -92,7 +98,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TraitImplTyVisitor<'a, 'tcx> {
                         };
 
                         if !is_self_ty {
-                            span_use_self_lint(self.cx, path.span);
+                            span_use_self_lint(self.cx, path);
                         }
                     }
                 }
@@ -221,10 +227,10 @@ impl<'a, 'tcx> Visitor<'tcx> for UseSelfVisitor<'a, 'tcx> {
     fn visit_path(&mut self, path: &'tcx Path, _id: HirId) {
         if path.segments.last().expect(SEGMENTS_MSG).ident.name != SelfUpper.name() {
             if self.item_path.def == path.def {
-                span_use_self_lint(self.cx, path.segments.first().expect(SEGMENTS_MSG).ident.span);
+                span_use_self_lint(self.cx, path);
             } else if let Def::StructCtor(ctor_did, CtorKind::Fn) = path.def {
                 if self.item_path.def.opt_def_id() == self.cx.tcx.parent_def_id(ctor_did) {
-                    span_use_self_lint(self.cx, path.span);
+                    span_use_self_lint(self.cx, path);
                 }
             }
         }

tests/ui/use_self.rs

@@ -274,3 +274,23 @@ mod issue3410 {
         fn a(_: Vec<A>) {}
     }
 }
+
+#[allow(clippy::no_effect)]
+mod rustfix {
+    mod nested {
+        pub struct A {}
+    }
+
+    impl nested::A {
+        const A: bool = true;
+
+        fn fun_1() {}
+
+        fn fun_2() {
+            nested::A::fun_1();
+            nested::A::A;
+
+            nested::A {};
+        }
+    }
+}

tests/ui/use_self.stderr

@@ -162,5 +162,23 @@ error: unnecessary structure name repetition
 LL |                     Bar { foo: Foo {} }
    |                     ^^^ help: use the applicable keyword: `Self`
 
-error: aborting due to 26 previous errors
+error: unnecessary structure name repetition
+  --> $DIR/use_self.rs:290:13
+   |
+LL |             nested::A::fun_1();
+   |             ^^^^^^^^^ help: use the applicable keyword: `Self`
+
+error: unnecessary structure name repetition
+  --> $DIR/use_self.rs:291:13
+   |
+LL |             nested::A::A;
+   |             ^^^^^^^^^ help: use the applicable keyword: `Self`
+
+error: unnecessary structure name repetition
+  --> $DIR/use_self.rs:293:13
+   |
+LL |             nested::A {};
+   |             ^^^^^^^^^ help: use the applicable keyword: `Self`
+
+error: aborting due to 29 previous errors