| use crate::reexport::*; |
| use crate::utils::{contains_name, higher, iter_input_pats, snippet, span_lint_and_then}; |
| use rustc::hir::intravisit::FnKind; |
| use rustc::hir::*; |
| use rustc::lint::{in_external_macro, LateContext, LateLintPass, LintArray, LintContext, LintPass}; |
| use rustc::ty; |
| use rustc::{declare_lint_pass, declare_tool_lint}; |
| use syntax::source_map::Span; |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for bindings that shadow other bindings already in |
| /// scope, while just changing reference level or mutability. |
| /// |
| /// **Why is this bad?** Not much, in fact it's a very common pattern in Rust |
| /// code. Still, some may opt to avoid it in their code base, they can set this |
| /// lint to `Warn`. |
| /// |
| /// **Known problems:** This lint, as the other shadowing related lints, |
| /// currently only catches very simple patterns. |
| /// |
| /// **Example:** |
| /// ```rust |
| /// let x = &x; |
| /// ``` |
| pub SHADOW_SAME, |
| restriction, |
| "rebinding a name to itself, e.g., `let mut x = &mut x`" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for bindings that shadow other bindings already in |
| /// scope, while reusing the original value. |
| /// |
| /// **Why is this bad?** Not too much, in fact it's a common pattern in Rust |
| /// code. Still, some argue that name shadowing like this hurts readability, |
| /// because a value may be bound to different things depending on position in |
| /// the code. |
| /// |
| /// **Known problems:** This lint, as the other shadowing related lints, |
| /// currently only catches very simple patterns. |
| /// |
| /// **Example:** |
| /// ```rust |
| /// let x = x + 1; |
| /// ``` |
| /// use different variable name: |
| /// ```rust |
| /// let y = x + 1; |
| /// ``` |
| pub SHADOW_REUSE, |
| restriction, |
| "rebinding a name to an expression that re-uses the original value, e.g., `let x = x + 1`" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for bindings that shadow other bindings already in |
| /// scope, either without a initialization or with one that does not even use |
| /// the original value. |
| /// |
| /// **Why is this bad?** Name shadowing can hurt readability, especially in |
| /// large code bases, because it is easy to lose track of the active binding at |
| /// any place in the code. This can be alleviated by either giving more specific |
| /// names to bindings or introducing more scopes to contain the bindings. |
| /// |
| /// **Known problems:** This lint, as the other shadowing related lints, |
| /// currently only catches very simple patterns. |
| /// |
| /// **Example:** |
| /// ```rust |
| /// let x = y; |
| /// let x = z; // shadows the earlier binding |
| /// ``` |
| pub SHADOW_UNRELATED, |
| pedantic, |
| "rebinding a name without even using the original value" |
| } |
| |
| declare_lint_pass!(Shadow => [SHADOW_SAME, SHADOW_REUSE, SHADOW_UNRELATED]); |
| |
| impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Shadow { |
| fn check_fn( |
| &mut self, |
| cx: &LateContext<'a, 'tcx>, |
| _: FnKind<'tcx>, |
| decl: &'tcx FnDecl, |
| body: &'tcx Body, |
| _: Span, |
| _: HirId, |
| ) { |
| if in_external_macro(cx.sess(), body.value.span) { |
| return; |
| } |
| check_fn(cx, decl, body); |
| } |
| } |
| |
| fn check_fn<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, decl: &'tcx FnDecl, body: &'tcx Body) { |
| let mut bindings = Vec::new(); |
| for arg in iter_input_pats(decl, body) { |
| if let PatKind::Binding(.., ident, _) = arg.pat.node { |
| bindings.push((ident.name, ident.span)) |
| } |
| } |
| check_expr(cx, &body.value, &mut bindings); |
| } |
| |
| fn check_block<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, block: &'tcx Block, bindings: &mut Vec<(Name, Span)>) { |
| let len = bindings.len(); |
| for stmt in &block.stmts { |
| match stmt.node { |
| StmtKind::Local(ref local) => check_local(cx, local, bindings), |
| StmtKind::Expr(ref e) | StmtKind::Semi(ref e) => check_expr(cx, e, bindings), |
| StmtKind::Item(..) => {}, |
| } |
| } |
| if let Some(ref o) = block.expr { |
| check_expr(cx, o, bindings); |
| } |
| bindings.truncate(len); |
| } |
| |
| fn check_local<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, local: &'tcx Local, bindings: &mut Vec<(Name, Span)>) { |
| if in_external_macro(cx.sess(), local.span) { |
| return; |
| } |
| if higher::is_from_for_desugar(local) { |
| return; |
| } |
| let Local { |
| ref pat, |
| ref ty, |
| ref init, |
| span, |
| .. |
| } = *local; |
| if let Some(ref t) = *ty { |
| check_ty(cx, t, bindings) |
| } |
| if let Some(ref o) = *init { |
| check_expr(cx, o, bindings); |
| check_pat(cx, pat, Some(o), span, bindings); |
| } else { |
| check_pat(cx, pat, None, span, bindings); |
| } |
| } |
| |
| fn is_binding(cx: &LateContext<'_, '_>, pat_id: HirId) -> bool { |
| let var_ty = cx.tables.node_type(pat_id); |
| match var_ty.sty { |
| ty::Adt(..) => false, |
| _ => true, |
| } |
| } |
| |
| fn check_pat<'a, 'tcx>( |
| cx: &LateContext<'a, 'tcx>, |
| pat: &'tcx Pat, |
| init: Option<&'tcx Expr>, |
| span: Span, |
| bindings: &mut Vec<(Name, Span)>, |
| ) { |
| // TODO: match more stuff / destructuring |
| match pat.node { |
| PatKind::Binding(.., ident, ref inner) => { |
| let name = ident.name; |
| if is_binding(cx, pat.hir_id) { |
| let mut new_binding = true; |
| for tup in bindings.iter_mut() { |
| if tup.0 == name { |
| lint_shadow(cx, name, span, pat.span, init, tup.1); |
| tup.1 = ident.span; |
| new_binding = false; |
| break; |
| } |
| } |
| if new_binding { |
| bindings.push((name, ident.span)); |
| } |
| } |
| if let Some(ref p) = *inner { |
| check_pat(cx, p, init, span, bindings); |
| } |
| }, |
| PatKind::Struct(_, ref pfields, _) => { |
| if let Some(init_struct) = init { |
| if let ExprKind::Struct(_, ref efields, _) = init_struct.node { |
| for field in pfields { |
| let name = field.node.ident.name; |
| let efield = efields |
| .iter() |
| .find_map(|f| if f.ident.name == name { Some(&*f.expr) } else { None }); |
| check_pat(cx, &field.node.pat, efield, span, bindings); |
| } |
| } else { |
| for field in pfields { |
| check_pat(cx, &field.node.pat, init, span, bindings); |
| } |
| } |
| } else { |
| for field in pfields { |
| check_pat(cx, &field.node.pat, None, span, bindings); |
| } |
| } |
| }, |
| PatKind::Tuple(ref inner, _) => { |
| if let Some(init_tup) = init { |
| if let ExprKind::Tup(ref tup) = init_tup.node { |
| for (i, p) in inner.iter().enumerate() { |
| check_pat(cx, p, Some(&tup[i]), p.span, bindings); |
| } |
| } else { |
| for p in inner { |
| check_pat(cx, p, init, span, bindings); |
| } |
| } |
| } else { |
| for p in inner { |
| check_pat(cx, p, None, span, bindings); |
| } |
| } |
| }, |
| PatKind::Box(ref inner) => { |
| if let Some(initp) = init { |
| if let ExprKind::Box(ref inner_init) = initp.node { |
| check_pat(cx, inner, Some(&**inner_init), span, bindings); |
| } else { |
| check_pat(cx, inner, init, span, bindings); |
| } |
| } else { |
| check_pat(cx, inner, init, span, bindings); |
| } |
| }, |
| PatKind::Ref(ref inner, _) => check_pat(cx, inner, init, span, bindings), |
| // PatVec(Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>), |
| _ => (), |
| } |
| } |
| |
| fn lint_shadow<'a, 'tcx>( |
| cx: &LateContext<'a, 'tcx>, |
| name: Name, |
| span: Span, |
| pattern_span: Span, |
| init: Option<&'tcx Expr>, |
| prev_span: Span, |
| ) { |
| if let Some(expr) = init { |
| if is_self_shadow(name, expr) { |
| span_lint_and_then( |
| cx, |
| SHADOW_SAME, |
| span, |
| &format!( |
| "`{}` is shadowed by itself in `{}`", |
| snippet(cx, pattern_span, "_"), |
| snippet(cx, expr.span, "..") |
| ), |
| |db| { |
| db.span_note(prev_span, "previous binding is here"); |
| }, |
| ); |
| } else if contains_name(name, expr) { |
| span_lint_and_then( |
| cx, |
| SHADOW_REUSE, |
| pattern_span, |
| &format!( |
| "`{}` is shadowed by `{}` which reuses the original value", |
| snippet(cx, pattern_span, "_"), |
| snippet(cx, expr.span, "..") |
| ), |
| |db| { |
| db.span_note(expr.span, "initialization happens here"); |
| db.span_note(prev_span, "previous binding is here"); |
| }, |
| ); |
| } else { |
| span_lint_and_then( |
| cx, |
| SHADOW_UNRELATED, |
| pattern_span, |
| &format!( |
| "`{}` is shadowed by `{}`", |
| snippet(cx, pattern_span, "_"), |
| snippet(cx, expr.span, "..") |
| ), |
| |db| { |
| db.span_note(expr.span, "initialization happens here"); |
| db.span_note(prev_span, "previous binding is here"); |
| }, |
| ); |
| } |
| } else { |
| span_lint_and_then( |
| cx, |
| SHADOW_UNRELATED, |
| span, |
| &format!("`{}` shadows a previous declaration", snippet(cx, pattern_span, "_")), |
| |db| { |
| db.span_note(prev_span, "previous binding is here"); |
| }, |
| ); |
| } |
| } |
| |
| fn check_expr<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr, bindings: &mut Vec<(Name, Span)>) { |
| if in_external_macro(cx.sess(), expr.span) { |
| return; |
| } |
| match expr.node { |
| ExprKind::Unary(_, ref e) | ExprKind::Field(ref e, _) | ExprKind::AddrOf(_, ref e) | ExprKind::Box(ref e) => { |
| check_expr(cx, e, bindings) |
| }, |
| ExprKind::Block(ref block, _) | ExprKind::Loop(ref block, _, _) => check_block(cx, block, bindings), |
| // ExprKind::Call |
| // ExprKind::MethodCall |
| ExprKind::Array(ref v) | ExprKind::Tup(ref v) => { |
| for e in v { |
| check_expr(cx, e, bindings) |
| } |
| }, |
| ExprKind::While(ref cond, ref block, _) => { |
| check_expr(cx, cond, bindings); |
| check_block(cx, block, bindings); |
| }, |
| ExprKind::Match(ref init, ref arms, _) => { |
| check_expr(cx, init, bindings); |
| let len = bindings.len(); |
| for arm in arms { |
| for pat in &arm.pats { |
| check_pat(cx, pat, Some(&**init), pat.span, bindings); |
| // This is ugly, but needed to get the right type |
| if let Some(ref guard) = arm.guard { |
| match guard { |
| Guard::If(if_expr) => check_expr(cx, if_expr, bindings), |
| } |
| } |
| check_expr(cx, &arm.body, bindings); |
| bindings.truncate(len); |
| } |
| } |
| }, |
| _ => (), |
| } |
| } |
| |
| fn check_ty<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, ty: &'tcx Ty, bindings: &mut Vec<(Name, Span)>) { |
| match ty.node { |
| TyKind::Slice(ref sty) => check_ty(cx, sty, bindings), |
| TyKind::Array(ref fty, ref anon_const) => { |
| check_ty(cx, fty, bindings); |
| check_expr(cx, &cx.tcx.hir().body(anon_const.body).value, bindings); |
| }, |
| TyKind::Ptr(MutTy { ty: ref mty, .. }) | TyKind::Rptr(_, MutTy { ty: ref mty, .. }) => { |
| check_ty(cx, mty, bindings) |
| }, |
| TyKind::Tup(ref tup) => { |
| for t in tup { |
| check_ty(cx, t, bindings) |
| } |
| }, |
| TyKind::Typeof(ref anon_const) => check_expr(cx, &cx.tcx.hir().body(anon_const.body).value, bindings), |
| _ => (), |
| } |
| } |
| |
| fn is_self_shadow(name: Name, expr: &Expr) -> bool { |
| match expr.node { |
| ExprKind::Box(ref inner) | ExprKind::AddrOf(_, ref inner) => is_self_shadow(name, inner), |
| ExprKind::Block(ref block, _) => { |
| block.stmts.is_empty() && block.expr.as_ref().map_or(false, |e| is_self_shadow(name, e)) |
| }, |
| ExprKind::Unary(op, ref inner) => (UnDeref == op) && is_self_shadow(name, inner), |
| ExprKind::Path(QPath::Resolved(_, ref path)) => path_eq_name(name, path), |
| _ => false, |
| } |
| } |
| |
| fn path_eq_name(name: Name, path: &Path) -> bool { |
| !path.is_global() && path.segments.len() == 1 && path.segments[0].ident.as_str() == name.as_str() |
| } |