300 lines
9.1 KiB
Rust
300 lines
9.1 KiB
Rust
use syntax::ptr::P;
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use syntax::ast;
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use syntax::ast::*;
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use syntax::ast_util::{is_comparison_binop, binop_to_string};
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use syntax::visit::{FnKind};
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use rustc::lint::{Context, LintPass, LintArray, Lint, Level};
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use rustc::middle::ty::{self, expr_ty, ty_str, ty_ptr, ty_rptr, ty_float};
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use syntax::codemap::{Span, Spanned};
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use types::span_note_and_lint;
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fn walk_ty<'t>(ty: ty::Ty<'t>) -> ty::Ty<'t> {
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match ty.sty {
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ty_ptr(ref tm) | ty_rptr(_, ref tm) => walk_ty(tm.ty),
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_ => ty
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}
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}
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/// Handles uncategorized lints
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/// Currently handles linting of if-let-able matches
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#[allow(missing_copy_implementations)]
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pub struct MiscPass;
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declare_lint!(pub SINGLE_MATCH, Warn,
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"Warn on usage of matches with a single nontrivial arm");
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impl LintPass for MiscPass {
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fn get_lints(&self) -> LintArray {
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lint_array!(SINGLE_MATCH)
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}
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fn check_expr(&mut self, cx: &Context, expr: &Expr) {
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if let ExprMatch(ref ex, ref arms, ast::MatchSource::Normal) = expr.node {
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if arms.len() == 2 {
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if arms[0].guard.is_none() && arms[1].pats.len() == 1 {
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match arms[1].body.node {
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ExprTup(ref v) if v.len() == 0 && arms[1].guard.is_none() => (),
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ExprBlock(ref b) if b.stmts.len() == 0 && arms[1].guard.is_none() => (),
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_ => return
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}
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// In some cases, an exhaustive match is preferred to catch situations when
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// an enum is extended. So we only consider cases where a `_` wildcard is used
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if arms[1].pats[0].node == PatWild(PatWildSingle) && arms[0].pats.len() == 1 {
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let map = cx.sess().codemap();
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span_note_and_lint(cx, SINGLE_MATCH, expr.span,
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"You seem to be trying to use match for destructuring a single type. Did you mean to use `if let`?",
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&*format!("Try if let {} = {} {{ ... }}",
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&*map.span_to_snippet(arms[0].pats[0].span).unwrap_or("..".to_string()),
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&*map.span_to_snippet(ex.span).unwrap_or("..".to_string()))
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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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}
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declare_lint!(pub STR_TO_STRING, Warn, "Warn when a String could use to_owned() instead of to_string()");
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#[allow(missing_copy_implementations)]
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pub struct StrToStringPass;
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impl LintPass for StrToStringPass {
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fn get_lints(&self) -> LintArray {
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lint_array!(STR_TO_STRING)
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}
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fn check_expr(&mut self, cx: &Context, expr: &ast::Expr) {
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match expr.node {
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ast::ExprMethodCall(ref method, _, ref args)
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if method.node.as_str() == "to_string"
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&& is_str(cx, &*args[0]) => {
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cx.span_lint(STR_TO_STRING, expr.span, "str.to_owned() is faster");
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},
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_ => ()
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}
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fn is_str(cx: &Context, expr: &ast::Expr) -> bool {
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match walk_ty(expr_ty(cx.tcx, expr)).sty {
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ty_str => true,
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_ => false
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}
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}
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}
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}
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declare_lint!(pub TOPLEVEL_REF_ARG, Warn, "Warn about pattern matches with top-level `ref` bindings");
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#[allow(missing_copy_implementations)]
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pub struct TopLevelRefPass;
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impl LintPass for TopLevelRefPass {
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fn get_lints(&self) -> LintArray {
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lint_array!(TOPLEVEL_REF_ARG)
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}
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fn check_fn(&mut self, cx: &Context, _: FnKind, decl: &FnDecl, _: &Block, _: Span, _: NodeId) {
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for ref arg in decl.inputs.iter() {
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if let PatIdent(BindByRef(_), _, _) = arg.pat.node {
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cx.span_lint(
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TOPLEVEL_REF_ARG,
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arg.pat.span,
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"`ref` directly on a function argument is ignored. Have you considered using a reference type instead?"
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);
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}
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}
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}
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}
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declare_lint!(pub CMP_NAN, Deny, "Deny comparisons to std::f32::NAN or std::f64::NAN");
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#[derive(Copy,Clone)]
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pub struct CmpNan;
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impl LintPass for CmpNan {
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fn get_lints(&self) -> LintArray {
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lint_array!(CMP_NAN)
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}
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fn check_expr(&mut self, cx: &Context, expr: &Expr) {
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if let ExprBinary(ref cmp, ref left, ref right) = expr.node {
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if is_comparison_binop(cmp.node) {
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if let &ExprPath(_, ref path) = &left.node {
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check_nan(cx, path, expr.span);
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}
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if let &ExprPath(_, ref path) = &right.node {
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check_nan(cx, path, expr.span);
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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_nan(cx: &Context, path: &Path, span: Span) {
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path.segments.last().map(|seg| if seg.identifier.as_str() == "NAN" {
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cx.span_lint(CMP_NAN, span, "Doomed comparison with NAN, use std::{f32,f64}::is_nan instead");
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});
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}
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declare_lint!(pub FLOAT_CMP, Warn,
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"Warn on ==/!= comparison of floaty values");
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#[derive(Copy,Clone)]
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pub struct FloatCmp;
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impl LintPass for FloatCmp {
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fn get_lints(&self) -> LintArray {
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lint_array!(FLOAT_CMP)
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}
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fn check_expr(&mut self, cx: &Context, expr: &Expr) {
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if let ExprBinary(ref cmp, ref left, ref right) = expr.node {
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let op = cmp.node;
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if (op == BiEq || op == BiNe) && (is_float(cx, left) || is_float(cx, right)) {
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let map = cx.sess().codemap();
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cx.span_lint(FLOAT_CMP, expr.span, &format!(
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"{}-Comparison of f32 or f64 detected. You may want to change this to 'abs({} - {}) < epsilon' for some suitable value of epsilon",
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binop_to_string(op), &*map.span_to_snippet(left.span).unwrap_or("..".to_string()),
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&*map.span_to_snippet(right.span).unwrap_or("..".to_string())));
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}
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}
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}
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}
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fn is_float(cx: &Context, expr: &Expr) -> bool {
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if let ty_float(_) = walk_ty(expr_ty(cx.tcx, expr)).sty { true } else { false }
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}
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declare_lint!(pub PRECEDENCE, Warn,
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"Warn on mixing bit ops with integer arithmetic without parenthesis");
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#[derive(Copy,Clone)]
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pub struct Precedence;
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impl LintPass for Precedence {
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fn get_lints(&self) -> LintArray {
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lint_array!(PRECEDENCE)
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}
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fn check_expr(&mut self, cx: &Context, expr: &Expr) {
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if let ExprBinary(Spanned { node: op, ..}, ref left, ref right) = expr.node {
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if is_bit_op(op) && (is_arith_expr(left) || is_arith_expr(right)) {
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cx.span_lint(PRECEDENCE, expr.span,
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"Operator precedence can trip the unwary. Consider adding parenthesis to the subexpression.");
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}
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}
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}
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}
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fn is_arith_expr(expr : &Expr) -> bool {
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match expr.node {
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ExprBinary(Spanned { node: op, ..}, _, _) => is_arith_op(op),
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_ => false
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}
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}
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fn is_bit_op(op : BinOp_) -> bool {
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match op {
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BiBitXor | BiBitAnd | BiBitOr | BiShl | BiShr => true,
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_ => false
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}
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}
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fn is_arith_op(op : BinOp_) -> bool {
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match op {
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BiAdd | BiSub | BiMul | BiDiv | BiRem => true,
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_ => false
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}
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}
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declare_lint!(pub CMP_OWNED, Warn,
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"Warn on creating an owned string just for comparison");
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#[derive(Copy,Clone)]
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pub struct CmpOwned;
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impl LintPass for CmpOwned {
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fn get_lints(&self) -> LintArray {
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lint_array!(CMP_OWNED)
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}
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fn check_expr(&mut self, cx: &Context, expr: &Expr) {
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if let ExprBinary(ref cmp, ref left, ref right) = expr.node {
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if is_comparison_binop(cmp.node) {
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check_to_owned(cx, left, right.span);
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check_to_owned(cx, right, left.span)
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}
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}
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}
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}
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fn check_to_owned(cx: &Context, expr: &Expr, other_span: Span) {
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match &expr.node {
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&ExprMethodCall(Spanned{node: ref ident, ..}, _, ref args) => {
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let name = ident.as_str();
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if name == "to_string" ||
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name == "to_owned" && is_str_arg(cx, args) {
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cx.span_lint(CMP_OWNED, expr.span, &format!(
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"this creates an owned instance just for comparison. \
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Consider using {}.as_slice() to compare without allocation",
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cx.sess().codemap().span_to_snippet(other_span).unwrap_or(
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"..".to_string())))
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}
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},
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&ExprCall(ref path, _) => {
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if let &ExprPath(None, ref path) = &path.node {
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if path.segments.iter().zip(["String", "from_str"].iter()).all(
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|(seg, name)| &seg.identifier.as_str() == name) {
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cx.span_lint(CMP_OWNED, expr.span, &format!(
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"this creates an owned instance just for comparison. \
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Consider using {}.as_slice() to compare without allocation",
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cx.sess().codemap().span_to_snippet(other_span).unwrap_or(
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"..".to_string())))
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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 is_str_arg(cx: &Context, args: &[P<Expr>]) -> bool {
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args.len() == 1 && if let ty_str =
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walk_ty(expr_ty(cx.tcx, &*args[0])).sty { true } else { false }
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}
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declare_lint!(pub MODULO_ONE, Warn, "Warn on expressions that include % 1, which is always 0");
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#[derive(Copy,Clone)]
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pub struct ModuloOne;
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impl LintPass for ModuloOne {
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fn get_lints(&self) -> LintArray {
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lint_array!(MODULO_ONE)
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}
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fn check_expr(&mut self, cx: &Context, expr: &Expr) {
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if let ExprBinary(ref cmp, _, ref right) = expr.node {
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if let &Spanned {node: BinOp_::BiRem, ..} = cmp {
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if is_lit_one(right) {
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cx.span_lint(MODULO_ONE, expr.span, "Any number modulo 1 will be 0");
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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 is_lit_one(expr: &Expr) -> bool {
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if let ExprLit(ref spanned) = expr.node {
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if let LitInt(1, _) = spanned.node {
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return true;
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}
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}
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false
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}
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