365 lines
14 KiB
Rust
365 lines
14 KiB
Rust
use std::ops::Deref;
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use rustc_front::hir::*;
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use reexport::*;
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use syntax::codemap::Span;
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use rustc_front::visit::FnKind;
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use rustc::lint::*;
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use rustc::middle::def::Def::{DefVariant, DefStruct};
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use utils::{in_external_macro, snippet, span_lint, span_note_and_lint};
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declare_lint!(pub SHADOW_SAME, Allow,
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"rebinding a name to itself, e.g. `let mut x = &mut x`");
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declare_lint!(pub SHADOW_REUSE, Allow,
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"rebinding a name to an expression that re-uses the original value, e.g. \
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`let x = x + 1`");
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declare_lint!(pub SHADOW_UNRELATED, Allow,
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"The name is re-bound without even using the original value");
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#[derive(Copy, Clone)]
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pub struct ShadowPass;
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impl LintPass for ShadowPass {
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fn get_lints(&self) -> LintArray {
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lint_array!(SHADOW_SAME, SHADOW_REUSE, SHADOW_UNRELATED)
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}
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}
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impl LateLintPass for ShadowPass {
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fn check_fn(&mut self, cx: &LateContext, _: FnKind, decl: &FnDecl,
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block: &Block, _: Span, _: NodeId) {
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if in_external_macro(cx, block.span) { return; }
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check_fn(cx, decl, block);
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}
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}
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fn check_fn(cx: &LateContext, decl: &FnDecl, block: &Block) {
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let mut bindings = Vec::new();
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for arg in &decl.inputs {
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if let PatIdent(_, ident, _) = arg.pat.node {
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bindings.push((ident.node.name, ident.span))
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}
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}
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check_block(cx, block, &mut bindings);
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}
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fn check_block(cx: &LateContext, block: &Block, bindings: &mut Vec<(Name, Span)>) {
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let len = bindings.len();
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for stmt in &block.stmts {
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match stmt.node {
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StmtDecl(ref decl, _) => check_decl(cx, decl, bindings),
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StmtExpr(ref e, _) | StmtSemi(ref e, _) =>
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check_expr(cx, e, bindings)
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}
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}
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if let Some(ref o) = block.expr { check_expr(cx, o, bindings); }
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bindings.truncate(len);
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}
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fn check_decl(cx: &LateContext, decl: &Decl, bindings: &mut Vec<(Name, Span)>) {
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if in_external_macro(cx, decl.span) { return; }
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if let DeclLocal(ref local) = decl.node {
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let Local{ ref pat, ref ty, ref init, id: _, span } = **local;
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if let &Some(ref t) = ty { check_ty(cx, t, bindings) }
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if let &Some(ref o) = init {
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check_expr(cx, o, bindings);
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check_pat(cx, pat, &Some(o), span, bindings);
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} else {
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check_pat(cx, pat, &None, span, bindings);
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}
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}
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}
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fn is_binding(cx: &LateContext, pat: &Pat) -> bool {
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match cx.tcx.def_map.borrow().get(&pat.id).map(|d| d.full_def()) {
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Some(DefVariant(..)) | Some(DefStruct(..)) => false,
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_ => true
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}
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}
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fn check_pat(cx: &LateContext, pat: &Pat, init: &Option<&Expr>, span: Span,
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bindings: &mut Vec<(Name, Span)>) {
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//TODO: match more stuff / destructuring
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match pat.node {
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PatIdent(_, ref ident, ref inner) => {
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let name = ident.node.name;
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if is_binding(cx, pat) {
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let mut new_binding = true;
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for tup in bindings.iter_mut() {
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if tup.0 == name {
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lint_shadow(cx, name, span, pat.span, init, tup.1);
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tup.1 = ident.span;
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new_binding = false;
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break;
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}
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}
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if new_binding {
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bindings.push((name, ident.span));
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}
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}
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if let Some(ref p) = *inner { check_pat(cx, p, init, span, bindings); }
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},
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//PatEnum(Path, Option<Vec<P<Pat>>>),
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PatStruct(_, ref pfields, _) =>
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if let Some(ref init_struct) = *init {
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if let ExprStruct(_, ref efields, _) = init_struct.node {
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for field in pfields {
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let name = field.node.name;
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let efield = efields.iter()
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.find(|ref f| f.name.node == name)
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.map(|f| &*f.expr);
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check_pat(cx, &field.node.pat, &efield, span, bindings);
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}
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} else {
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for field in pfields {
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check_pat(cx, &field.node.pat, init, span, bindings);
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}
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}
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} else {
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for field in pfields {
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check_pat(cx, &field.node.pat, &None, span, bindings);
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}
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},
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PatTup(ref inner) =>
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if let Some(ref init_tup) = *init {
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if let ExprTup(ref tup) = init_tup.node {
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for (i, p) in inner.iter().enumerate() {
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check_pat(cx, p, &Some(&tup[i]), p.span, bindings);
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}
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} else {
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for p in inner {
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check_pat(cx, p, init, span, bindings);
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}
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}
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} else {
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for p in inner {
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check_pat(cx, p, &None, span, bindings);
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}
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},
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PatBox(ref inner) => {
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if let Some(ref initp) = *init {
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if let ExprBox(ref inner_init) = initp.node {
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check_pat(cx, inner, &Some(&**inner_init), span, bindings);
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} else {
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check_pat(cx, inner, init, span, bindings);
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}
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} else {
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check_pat(cx, inner, init, span, bindings);
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}
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},
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PatRegion(ref inner, _) =>
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check_pat(cx, inner, init, span, bindings),
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//PatVec(Vec<P<Pat>>, Option<P<Pat>>, Vec<P<Pat>>),
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_ => (),
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}
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}
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fn lint_shadow<T>(cx: &LateContext, name: Name, span: Span, lspan: Span, init:
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&Option<T>, prev_span: Span) where T: Deref<Target=Expr> {
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fn note_orig(cx: &LateContext, lint: &'static Lint, span: Span) {
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if cx.current_level(lint) != Level::Allow {
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cx.sess().span_note(span, "previous binding is here");
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}
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}
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if let Some(ref expr) = *init {
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if is_self_shadow(name, expr) {
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span_lint(cx, SHADOW_SAME, span, &format!(
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"{} is shadowed by itself in {}",
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snippet(cx, lspan, "_"),
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snippet(cx, expr.span, "..")));
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note_orig(cx, SHADOW_SAME, prev_span);
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} else {
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if contains_self(name, expr) {
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span_note_and_lint(cx, SHADOW_REUSE, lspan, &format!(
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"{} is shadowed by {} which reuses the original value",
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snippet(cx, lspan, "_"),
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snippet(cx, expr.span, "..")),
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expr.span, "initialization happens here");
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note_orig(cx, SHADOW_REUSE, prev_span);
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} else {
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span_note_and_lint(cx, SHADOW_UNRELATED, lspan, &format!(
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"{} is shadowed by {}",
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snippet(cx, lspan, "_"),
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snippet(cx, expr.span, "..")),
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expr.span, "initialization happens here");
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note_orig(cx, SHADOW_UNRELATED, prev_span);
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}
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}
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} else {
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span_lint(cx, SHADOW_UNRELATED, span, &format!(
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"{} shadows a previous declaration", snippet(cx, lspan, "_")));
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note_orig(cx, SHADOW_UNRELATED, prev_span);
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}
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}
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fn check_expr(cx: &LateContext, expr: &Expr, bindings: &mut Vec<(Name, Span)>) {
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if in_external_macro(cx, expr.span) { return; }
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match expr.node {
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ExprUnary(_, ref e) | ExprField(ref e, _) |
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ExprTupField(ref e, _) | ExprAddrOf(_, ref e) | ExprBox(ref e)
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=> { check_expr(cx, e, bindings) },
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ExprBlock(ref block) | ExprLoop(ref block, _) =>
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{ check_block(cx, block, bindings) },
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//ExprCall
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//ExprMethodCall
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ExprVec(ref v) | ExprTup(ref v) =>
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for ref e in v { check_expr(cx, e, bindings) },
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ExprIf(ref cond, ref then, ref otherwise) => {
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check_expr(cx, cond, bindings);
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check_block(cx, then, bindings);
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if let &Some(ref o) = otherwise { check_expr(cx, o, bindings); }
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},
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ExprWhile(ref cond, ref block, _) => {
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check_expr(cx, cond, bindings);
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check_block(cx, block, bindings);
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},
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ExprMatch(ref init, ref arms, _) => {
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check_expr(cx, init, bindings);
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let len = bindings.len();
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for ref arm in arms {
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for ref pat in &arm.pats {
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check_pat(cx, &pat, &Some(&**init), pat.span, bindings);
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//This is ugly, but needed to get the right type
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if let Some(ref guard) = arm.guard {
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check_expr(cx, guard, bindings);
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}
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check_expr(cx, &arm.body, bindings);
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bindings.truncate(len);
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}
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}
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},
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_ => ()
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}
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}
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fn check_ty(cx: &LateContext, ty: &Ty, bindings: &mut Vec<(Name, Span)>) {
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match ty.node {
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TyParen(ref sty) | TyObjectSum(ref sty, _) |
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TyVec(ref sty) => check_ty(cx, sty, bindings),
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TyFixedLengthVec(ref fty, ref expr) => {
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check_ty(cx, fty, bindings);
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check_expr(cx, expr, bindings);
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},
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TyPtr(MutTy{ ty: ref mty, .. }) |
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TyRptr(_, MutTy{ ty: ref mty, .. }) => check_ty(cx, mty, bindings),
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TyTup(ref tup) => { for ref t in tup { check_ty(cx, t, bindings) } },
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TyTypeof(ref expr) => check_expr(cx, expr, bindings),
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_ => (),
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}
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}
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fn is_self_shadow(name: Name, expr: &Expr) -> bool {
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match expr.node {
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ExprBox(ref inner) |
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ExprAddrOf(_, ref inner) => is_self_shadow(name, inner),
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ExprBlock(ref block) => block.stmts.is_empty() && block.expr.as_ref().
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map_or(false, |ref e| is_self_shadow(name, e)),
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ExprUnary(op, ref inner) => (UnDeref == op) &&
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is_self_shadow(name, inner),
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ExprPath(_, ref path) => path_eq_name(name, path),
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_ => false,
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}
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}
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fn path_eq_name(name: Name, path: &Path) -> bool {
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!path.global && path.segments.len() == 1 &&
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path.segments[0].identifier.name == name
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}
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fn contains_self(name: Name, expr: &Expr) -> bool {
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match expr.node {
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// the "self" name itself (maybe)
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ExprPath(_, ref path) => path_eq_name(name, path),
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// no subexprs
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ExprLit(_) => false,
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// one subexpr
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ExprUnary(_, ref e) | ExprField(ref e, _) |
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ExprTupField(ref e, _) | ExprAddrOf(_, ref e) | ExprBox(ref e) |
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ExprCast(ref e, _) =>
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contains_self(name, e),
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// two subexprs
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ExprBinary(_, ref l, ref r) | ExprIndex(ref l, ref r) |
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ExprAssign(ref l, ref r) | ExprAssignOp(_, ref l, ref r) |
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ExprRepeat(ref l, ref r) =>
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contains_self(name, l) || contains_self(name, r),
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// one optional subexpr
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ExprRet(ref oe) =>
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oe.as_ref().map_or(false, |ref e| contains_self(name, e)),
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// two optional subexprs
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ExprRange(ref ol, ref or) =>
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ol.as_ref().map_or(false, |ref e| contains_self(name, e)) ||
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or.as_ref().map_or(false, |ref e| contains_self(name, e)),
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// one subblock
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ExprBlock(ref block) | ExprLoop(ref block, _) |
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ExprClosure(_, _, ref block) =>
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contains_block_self(name, block),
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// one vec
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ExprMethodCall(_, _, ref v) | ExprVec(ref v) | ExprTup(ref v) =>
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v.iter().any(|ref a| contains_self(name, a)),
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// one expr, one vec
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ExprCall(ref fun, ref args) =>
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contains_self(name, fun) ||
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args.iter().any(|ref a| contains_self(name, a)),
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// special ones
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ExprIf(ref cond, ref then, ref otherwise) =>
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contains_self(name, cond) || contains_block_self(name, then) ||
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otherwise.as_ref().map_or(false, |ref e| contains_self(name, e)),
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ExprWhile(ref e, ref block, _) =>
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contains_self(name, e) || contains_block_self(name, block),
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ExprMatch(ref e, ref arms, _) =>
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contains_self(name, e) ||
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arms.iter().any(
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|ref arm|
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arm.pats.iter().any(|ref pat| contains_pat_self(name, pat)) ||
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arm.guard.as_ref().map_or(false, |ref g| contains_self(name, g)) ||
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contains_self(name, &arm.body)),
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ExprStruct(_, ref fields, ref other) =>
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fields.iter().any(|ref f| contains_self(name, &f.expr)) ||
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other.as_ref().map_or(false, |ref e| contains_self(name, e)),
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_ => false,
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}
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}
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fn contains_block_self(name: Name, block: &Block) -> bool {
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for stmt in &block.stmts {
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match stmt.node {
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StmtDecl(ref decl, _) =>
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if let DeclLocal(ref local) = decl.node {
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//TODO: We don't currently handle the case where the name
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//is shadowed wiithin the block; this means code including this
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//degenerate pattern will get the wrong warning.
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if let Some(ref init) = local.init {
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if contains_self(name, init) { return true; }
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}
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},
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StmtExpr(ref e, _) | StmtSemi(ref e, _) =>
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if contains_self(name, e) { return true }
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}
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}
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if let Some(ref e) = block.expr { contains_self(name, e) } else { false }
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}
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fn contains_pat_self(name: Name, pat: &Pat) -> bool {
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match pat.node {
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PatIdent(_, ref ident, ref inner) => name == ident.node.name ||
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inner.as_ref().map_or(false, |ref p| contains_pat_self(name, p)),
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PatEnum(_, ref opats) => opats.as_ref().map_or(false,
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|pats| pats.iter().any(|p| contains_pat_self(name, p))),
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PatQPath(_, ref path) => path_eq_name(name, path),
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PatStruct(_, ref fieldpats, _) => fieldpats.iter().any(
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|ref fp| contains_pat_self(name, &fp.node.pat)),
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PatTup(ref ps) => ps.iter().any(|ref p| contains_pat_self(name, p)),
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PatBox(ref p) |
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PatRegion(ref p, _) => contains_pat_self(name, p),
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PatRange(ref from, ref until) =>
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contains_self(name, from) || contains_self(name, until),
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PatVec(ref pre, ref opt, ref post) =>
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pre.iter().any(|ref p| contains_pat_self(name, p)) ||
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opt.as_ref().map_or(false, |ref p| contains_pat_self(name, p)) ||
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post.iter().any(|ref p| contains_pat_self(name, p)),
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_ => false,
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}
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}
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