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