3 use syntax::codemap::Span;
4 use syntax::visit::FnKind;
6 use rustc::lint::{Context, LintArray, LintPass};
7 use rustc::middle::def::Def::{DefVariant, DefStruct};
9 use utils::{in_external_macro, snippet, span_lint};
11 declare_lint!(pub SHADOW_SAME, Allow,
12 "rebinding a name to itself, e.g. `let mut x = &mut x`");
13 declare_lint!(pub SHADOW_REUSE, Allow,
14 "rebinding a name to an expression that re-uses the original value, e.g. \
16 declare_lint!(pub SHADOW_UNRELATED, Warn,
17 "The name is re-bound without even using the original value");
19 #[derive(Copy, Clone)]
20 pub struct ShadowPass;
22 impl LintPass for ShadowPass {
23 fn get_lints(&self) -> LintArray {
24 lint_array!(SHADOW_SAME, SHADOW_REUSE, SHADOW_UNRELATED)
27 fn check_fn(&mut self, cx: &Context, _: FnKind, decl: &FnDecl,
28 block: &Block, _: Span, _: NodeId) {
29 if in_external_macro(cx, block.span) { return; }
30 check_fn(cx, decl, block);
34 fn check_fn(cx: &Context, decl: &FnDecl, block: &Block) {
35 let mut bindings = Vec::new();
36 for arg in &decl.inputs {
37 if let PatIdent(_, ident, _) = arg.pat.node {
38 bindings.push(ident.node.name)
41 check_block(cx, block, &mut bindings);
44 fn check_block(cx: &Context, block: &Block, bindings: &mut Vec<Name>) {
45 let len = bindings.len();
46 for stmt in &block.stmts {
48 StmtDecl(ref decl, _) => check_decl(cx, decl, bindings),
49 StmtExpr(ref e, _) | StmtSemi(ref e, _) =>
50 check_expr(cx, e, bindings),
54 if let Some(ref o) = block.expr { check_expr(cx, o, bindings); }
55 bindings.truncate(len);
58 fn check_decl(cx: &Context, decl: &Decl, bindings: &mut Vec<Name>) {
59 if in_external_macro(cx, decl.span) { return; }
60 if let DeclLocal(ref local) = decl.node {
61 let Local{ ref pat, ref ty, ref init, id: _, span } = **local;
62 if let &Some(ref t) = ty { check_ty(cx, t, bindings) }
63 if let &Some(ref o) = init { check_expr(cx, o, bindings) }
64 check_pat(cx, pat, init, span, bindings);
68 fn is_binding(cx: &Context, pat: &Pat) -> bool {
69 match cx.tcx.def_map.borrow().get(&pat.id).map(|d| d.full_def()) {
70 Some(DefVariant(..)) | Some(DefStruct(..)) => false,
75 fn check_pat<T>(cx: &Context, pat: &Pat, init: &Option<T>, span: Span,
76 bindings: &mut Vec<Name>) where T: Deref<Target=Expr> {
77 //TODO: match more stuff / destructuring
79 PatIdent(_, ref ident, ref inner) => {
80 let name = ident.node.name;
81 if is_binding(cx, pat) {
82 if bindings.contains(&name) {
83 lint_shadow(cx, name, span, pat.span, init);
88 if let Some(ref p) = *inner { check_pat(cx, p, init, span, bindings); }
90 //PatEnum(Path, Option<Vec<P<Pat>>>),
91 //PatQPath(QSelf, Path),
92 //PatStruct(Path, Vec<Spanned<FieldPat>>, bool),
93 //PatTup(Vec<P<Pat>>),
94 PatBox(ref inner) => {
95 if let Some(ref initp) = *init {
97 ExprBox(_, ref inner_init) =>
98 check_pat(cx, inner, &Some(&**inner_init), span, bindings),
99 //TODO: ExprCall on Box::new
100 _ => check_pat(cx, inner, init, span, bindings),
103 check_pat(cx, inner, init, span, bindings);
106 //PatRegion(P<Pat>, Mutability),
107 //PatRange(P<Expr>, P<Expr>),
108 //PatVec(Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>),
113 fn lint_shadow<T>(cx: &Context, name: Name, span: Span, lspan: Span, init:
114 &Option<T>) where T: Deref<Target=Expr> {
115 if let &Some(ref expr) = init {
116 if is_self_shadow(name, expr) {
117 span_lint(cx, SHADOW_SAME, span, &format!(
118 "{} is shadowed by itself in {}",
119 snippet(cx, lspan, "_"),
120 snippet(cx, expr.span, "..")));
122 if contains_self(name, expr) {
123 span_lint(cx, SHADOW_REUSE, span, &format!(
124 "{} is shadowed by {} which reuses the original value",
125 snippet(cx, lspan, "_"),
126 snippet(cx, expr.span, "..")));
128 span_lint(cx, SHADOW_UNRELATED, span, &format!(
129 "{} is shadowed by {} in this declaration",
130 snippet(cx, lspan, "_"),
131 snippet(cx, expr.span, "..")));
135 span_lint(cx, SHADOW_UNRELATED, span, &format!(
136 "{} is shadowed in this declaration", snippet(cx, lspan, "_")));
140 fn check_expr(cx: &Context, expr: &Expr, bindings: &mut Vec<Name>) {
141 if in_external_macro(cx, expr.span) { return; }
143 ExprUnary(_, ref e) | ExprParen(ref e) | ExprField(ref e, _) |
144 ExprTupField(ref e, _) | ExprAddrOf(_, ref e) | ExprBox(None, ref e)
145 => { check_expr(cx, e, bindings) },
146 ExprBox(Some(ref place), ref e) => {
147 check_expr(cx, place, bindings); check_expr(cx, e, bindings) }
148 ExprBlock(ref block) | ExprLoop(ref block, _) =>
149 { check_block(cx, block, bindings) },
152 ExprVec(ref v) | ExprTup(ref v) =>
153 for ref e in v { check_expr(cx, e, bindings) },
154 ExprIf(ref cond, ref then, ref otherwise) => {
155 check_expr(cx, cond, bindings);
156 check_block(cx, then, bindings);
157 if let &Some(ref o) = otherwise { check_expr(cx, o, bindings); }
159 ExprWhile(ref cond, ref block, _) => {
160 check_expr(cx, cond, bindings);
161 check_block(cx, block, bindings);
163 ExprMatch(ref init, ref arms, _) => {
164 check_expr(cx, init, bindings);
165 let len = bindings.len();
166 for ref arm in arms {
167 for ref pat in &arm.pats {
168 check_pat(cx, &pat, &Some(&**init), pat.span, bindings);
169 //TODO: This is ugly, but needed to get the right type
171 if let Some(ref guard) = arm.guard {
172 check_expr(cx, guard, bindings);
174 check_expr(cx, &arm.body, bindings);
175 bindings.truncate(len);
182 fn check_ty(cx: &Context, ty: &Ty, bindings: &mut Vec<Name>) {
184 TyParen(ref sty) | TyObjectSum(ref sty, _) |
185 TyVec(ref sty) => check_ty(cx, sty, bindings),
186 TyFixedLengthVec(ref fty, ref expr) => {
187 check_ty(cx, fty, bindings);
188 check_expr(cx, expr, bindings);
190 TyPtr(MutTy{ ty: ref mty, .. }) |
191 TyRptr(_, MutTy{ ty: ref mty, .. }) => check_ty(cx, mty, bindings),
192 TyTup(ref tup) => { for ref t in tup { check_ty(cx, t, bindings) } },
193 TyTypeof(ref expr) => check_expr(cx, expr, bindings),
198 fn is_self_shadow(name: Name, expr: &Expr) -> bool {
200 ExprBox(_, ref inner) |
201 ExprParen(ref inner) |
202 ExprAddrOf(_, ref inner) => is_self_shadow(name, inner),
203 ExprBlock(ref block) => block.stmts.is_empty() && block.expr.as_ref().
204 map_or(false, |ref e| is_self_shadow(name, e)),
205 ExprUnary(op, ref inner) => (UnUniq == op || UnDeref == op) &&
206 is_self_shadow(name, inner),
207 ExprPath(_, ref path) => path_eq_name(name, path),
212 fn path_eq_name(name: Name, path: &Path) -> bool {
213 !path.global && path.segments.len() == 1 &&
214 path.segments[0].identifier.name == name
217 fn contains_self(name: Name, expr: &Expr) -> bool {
219 ExprUnary(_, ref e) | ExprParen(ref e) | ExprField(ref e, _) |
220 ExprTupField(ref e, _) | ExprAddrOf(_, ref e) | ExprBox(_, ref e)
221 => contains_self(name, e),
222 ExprBinary(_, ref l, ref r) =>
223 contains_self(name, l) || contains_self(name, r),
224 ExprBlock(ref block) | ExprLoop(ref block, _) =>
225 contains_block_self(name, block),
226 ExprCall(ref fun, ref args) => contains_self(name, fun) ||
227 args.iter().any(|ref a| contains_self(name, a)),
228 ExprMethodCall(_, _, ref args) =>
229 args.iter().any(|ref a| contains_self(name, a)),
230 ExprVec(ref v) | ExprTup(ref v) =>
231 v.iter().any(|ref e| contains_self(name, e)),
232 ExprIf(ref cond, ref then, ref otherwise) =>
233 contains_self(name, cond) || contains_block_self(name, then) ||
234 otherwise.as_ref().map_or(false, |ref e| contains_self(name, e)),
235 ExprWhile(ref e, ref block, _) =>
236 contains_self(name, e) || contains_block_self(name, block),
237 ExprMatch(ref e, ref arms, _) =>
238 arms.iter().any(|ref arm| arm.pats.iter().any(|ref pat|
239 contains_pat_self(name, pat))) || contains_self(name, e),
240 ExprPath(_, ref path) => path_eq_name(name, path),
245 fn contains_block_self(name: Name, block: &Block) -> bool {
246 for stmt in &block.stmts {
248 StmtDecl(ref decl, _) =>
249 if let DeclLocal(ref local) = decl.node {
250 //TODO: We don't currently handle the case where the name
251 //is shadowed wiithin the block; this means code including this
252 //degenerate pattern will get the wrong warning.
253 if let Some(ref init) = local.init {
254 if contains_self(name, init) { return true; }
257 StmtExpr(ref e, _) | StmtSemi(ref e, _) =>
258 if contains_self(name, e) { return true },
262 if let Some(ref e) = block.expr { contains_self(name, e) } else { false }
265 fn contains_pat_self(name: Name, pat: &Pat) -> bool {
267 PatIdent(_, ref ident, ref inner) => name == ident.node.name ||
268 inner.as_ref().map_or(false, |ref p| contains_pat_self(name, p)),
269 PatEnum(_, ref opats) => opats.as_ref().map_or(false,
270 |pats| pats.iter().any(|p| contains_pat_self(name, p))),
271 PatQPath(_, ref path) => path_eq_name(name, path),
272 PatStruct(_, ref fieldpats, _) => fieldpats.iter().any(
273 |ref fp| contains_pat_self(name, &fp.node.pat)),
274 PatTup(ref ps) => ps.iter().any(|ref p| contains_pat_self(name, p)),
276 PatRegion(ref p, _) => contains_pat_self(name, p),
277 PatRange(ref from, ref until) =>
278 contains_self(name, from) || contains_self(name, until),
279 PatVec(ref pre, ref opt, ref post) =>
280 pre.iter().any(|ref p| contains_pat_self(name, p)) ||
281 opt.as_ref().map_or(false, |ref p| contains_pat_self(name, p)) ||
282 post.iter().any(|ref p| contains_pat_self(name, p)),