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Merge pull request #730 from mcarton/unused-labels
Lint unused labels and types with `fn new() -> Self` and no `Default` impl
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,65 @@ | ||
| use rustc::lint::*; | ||
| use rustc_front::hir; | ||
| use rustc_front::intravisit::FnKind; | ||
| use syntax::ast; | ||
| use syntax::codemap::Span; | ||
| use utils::{get_trait_def_id, implements_trait, in_external_macro, return_ty, same_tys, span_lint, | ||
| DEFAULT_TRAIT_PATH}; | ||
|
|
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| /// **What it does:** This lints about type with a `fn new() -> Self` method and no `Default` | ||
| /// implementation. | ||
| /// | ||
| /// **Why is this bad?** User might expect to be able to use `Default` is the type can be | ||
| /// constructed without arguments. | ||
| /// | ||
| /// **Known problems:** Hopefully none. | ||
| /// | ||
| /// **Example:** | ||
| /// | ||
| /// ```rust,ignore | ||
| /// struct Foo; | ||
| /// | ||
| /// impl Foo { | ||
| /// fn new() -> Self { | ||
| /// Foo | ||
| /// } | ||
| /// } | ||
| /// ``` | ||
| declare_lint! { | ||
| pub NEW_WITHOUT_DEFAULT, | ||
| Warn, | ||
| "`fn new() -> Self` method without `Default` implementation" | ||
| } | ||
|
|
||
| #[derive(Copy,Clone)] | ||
| pub struct NewWithoutDefault; | ||
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|
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| impl LintPass for NewWithoutDefault { | ||
| fn get_lints(&self) -> LintArray { | ||
| lint_array!(NEW_WITHOUT_DEFAULT) | ||
| } | ||
| } | ||
|
|
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| impl LateLintPass for NewWithoutDefault { | ||
| fn check_fn(&mut self, cx: &LateContext, kind: FnKind, decl: &hir::FnDecl, _: &hir::Block, span: Span, id: ast::NodeId) { | ||
| if in_external_macro(cx, span) { | ||
| return; | ||
| } | ||
|
|
||
| if let FnKind::Method(name, _, _) = kind { | ||
| if decl.inputs.is_empty() && name.as_str() == "new" { | ||
| let self_ty = cx.tcx.lookup_item_type(cx.tcx.map.local_def_id(cx.tcx.map.get_parent(id))).ty; | ||
|
|
||
| if_let_chain!{[ | ||
| let Some(ret_ty) = return_ty(cx.tcx.node_id_to_type(id)), | ||
| same_tys(cx, self_ty, ret_ty), | ||
| let Some(default_trait_id) = get_trait_def_id(cx, &DEFAULT_TRAIT_PATH), | ||
| !implements_trait(cx, self_ty, default_trait_id, Vec::new()) | ||
| ], { | ||
| span_lint(cx, NEW_WITHOUT_DEFAULT, span, | ||
| &format!("you should consider adding a `Default` implementation for `{}`", self_ty)); | ||
| }} | ||
| } | ||
| } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,78 @@ | ||
| use rustc::lint::*; | ||
| use rustc_front::hir; | ||
| use rustc_front::intravisit::{FnKind, Visitor, walk_expr, walk_fn}; | ||
| use std::collections::HashMap; | ||
| use syntax::ast; | ||
| use syntax::codemap::Span; | ||
| use syntax::parse::token::InternedString; | ||
| use utils::{in_macro, span_lint}; | ||
|
|
||
| /// **What it does:** This lint checks for unused labels. | ||
| /// | ||
| /// **Why is this bad?** Maybe the label should be used in which case there is an error in the | ||
| /// code or it should be removed. | ||
| /// | ||
| /// **Known problems:** Hopefully none. | ||
| /// | ||
| /// **Example:** | ||
| /// ```rust,ignore | ||
| /// fn unused_label() { | ||
| /// 'label: for i in 1..2 { | ||
| /// if i > 4 { continue } | ||
| /// } | ||
| /// ``` | ||
| declare_lint! { | ||
| pub UNUSED_LABEL, | ||
| Warn, | ||
| "unused label" | ||
| } | ||
|
|
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| pub struct UnusedLabel; | ||
|
|
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| #[derive(Default)] | ||
| struct UnusedLabelVisitor { | ||
| labels: HashMap<InternedString, Span>, | ||
| } | ||
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| impl UnusedLabelVisitor { | ||
| pub fn new() -> UnusedLabelVisitor { | ||
| ::std::default::Default::default() | ||
| } | ||
| } | ||
|
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| impl LintPass for UnusedLabel { | ||
| fn get_lints(&self) -> LintArray { | ||
| lint_array!(UNUSED_LABEL) | ||
| } | ||
| } | ||
|
|
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| impl LateLintPass for UnusedLabel { | ||
| fn check_fn(&mut self, cx: &LateContext, kind: FnKind, decl: &hir::FnDecl, body: &hir::Block, span: Span, _: ast::NodeId) { | ||
| if in_macro(cx, span) { | ||
| return; | ||
| } | ||
|
|
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| let mut v = UnusedLabelVisitor::new(); | ||
| walk_fn(&mut v, kind, decl, body, span); | ||
|
|
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| for (label, span) in v.labels { | ||
| span_lint(cx, UNUSED_LABEL, span, &format!("unused label `{}`", label)); | ||
| } | ||
| } | ||
| } | ||
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| impl<'v> Visitor<'v> for UnusedLabelVisitor { | ||
| fn visit_expr(&mut self, expr: &hir::Expr) { | ||
| match expr.node { | ||
| hir::ExprBreak(Some(label)) | hir::ExprAgain(Some(label)) => { | ||
| self.labels.remove(&label.node.name.as_str()); | ||
| } | ||
| hir::ExprLoop(_, Some(label)) | hir::ExprWhile(_, _, Some(label)) => { | ||
| self.labels.insert(label.name.as_str(), expr.span); | ||
| } | ||
| _ => (), | ||
| } | ||
|
|
||
| walk_expr(self, expr); | ||
| } | ||
| } |
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