use rustc::lint::*;
use syntax::ptr::P;
use rustc_front::hir::*;
use reexport::*;
use rustc_front::util::{is_comparison_binop, binop_to_string};
use syntax::codemap::{Span, Spanned};
use rustc_front::visit::FnKind;
use rustc::middle::ty;
use utils::{get_item_name, match_path, snippet, span_lint, walk_ptrs_ty, is_integer_literal};
use consts::constant;
declare_lint!(pub TOPLEVEL_REF_ARG, Warn,
"a function argument is declared `ref` (i.e. `fn foo(ref x: u8)`, but not \
`fn foo((ref x, ref y): (u8, u8))`)");
#[allow(missing_copy_implementations)]
pub struct TopLevelRefPass;
impl LintPass for TopLevelRefPass {
fn get_lints(&self) -> LintArray {
lint_array!(TOPLEVEL_REF_ARG)
}
}
impl LateLintPass for TopLevelRefPass {
fn check_fn(&mut self, cx: &LateContext, k: FnKind, decl: &FnDecl, _: &Block, _: Span, _: NodeId) {
if let FnKind::Closure = k {
return
}
for ref arg in &decl.inputs {
if let PatIdent(BindByRef(_), _, _) = arg.pat.node {
span_lint(cx,
TOPLEVEL_REF_ARG,
arg.pat.span,
"`ref` directly on a function argument is ignored. Consider using a reference type instead."
);
}
}
}
}
declare_lint!(pub CMP_NAN, Deny,
"comparisons to NAN (which will always return false, which is probably not intended)");
#[derive(Copy,Clone)]
pub struct CmpNan;
impl LintPass for CmpNan {
fn get_lints(&self) -> LintArray {
lint_array!(CMP_NAN)
}
}
impl LateLintPass for CmpNan {
fn check_expr(&mut self, cx: &LateContext, 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: &LateContext, path: &Path, span: Span) {
path.segments.last().map(|seg| if seg.identifier.name == "NAN" {
span_lint(cx, CMP_NAN, span,
"doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead");
});
}
declare_lint!(pub FLOAT_CMP, Warn,
"using `==` or `!=` on float values (as floating-point operations \
usually involve rounding errors, it is always better to check for approximate \
equality within small bounds)");
#[derive(Copy,Clone)]
pub struct FloatCmp;
impl LintPass for FloatCmp {
fn get_lints(&self) -> LintArray {
lint_array!(FLOAT_CMP)
}
}
impl LateLintPass for FloatCmp {
fn check_expr(&mut self, cx: &LateContext, 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)) {
if constant(cx, left).or_else(|| constant(cx, right)).map_or(
false, |c| c.0.as_float().map_or(false, |f| f == 0.0)) {
return;
}
if let Some(name) = get_item_name(cx, expr) {
if name == "eq" || name == "ne" || name == "is_nan" ||
name.as_str().starts_with("eq_") ||
name.as_str().ends_with("_eq") {
return;
}
}
span_lint(cx, FLOAT_CMP, expr.span, &format!(
"{}-comparison of f32 or f64 detected. Consider changing 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: &LateContext, expr: &Expr) -> bool {
if let ty::TyFloat(_) = walk_ptrs_ty(cx.tcx.expr_ty(expr)).sty {
true
} else {
false
}
}
declare_lint!(pub CMP_OWNED, Warn,
"creating owned instances for comparing with others, e.g. `x == \"foo\".to_string()`");
#[derive(Copy,Clone)]
pub struct CmpOwned;
impl LintPass for CmpOwned {
fn get_lints(&self) -> LintArray {
lint_array!(CMP_OWNED)
}
}
impl LateLintPass for CmpOwned {
fn check_expr(&mut self, cx: &LateContext, 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: &LateContext, expr: &Expr, other_span: Span) {
match expr.node {
ExprMethodCall(Spanned{node: ref ident, ..}, _, ref args) => {
let name = ident.name;
if name == "to_string" ||
name == "to_owned" && is_str_arg(cx, args) {
span_lint(cx, 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"]) {
span_lint(cx, 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: &LateContext, args: &[P<Expr>]) -> bool {
args.len() == 1 && if let ty::TyStr =
walk_ptrs_ty(cx.tcx.expr_ty(&args[0])).sty { true } else { false }
}
declare_lint!(pub MODULO_ONE, Warn, "taking a number modulo 1, which always returns 0");
#[derive(Copy,Clone)]
pub struct ModuloOne;
impl LintPass for ModuloOne {
fn get_lints(&self) -> LintArray {
lint_array!(MODULO_ONE)
}
}
impl LateLintPass for ModuloOne {
fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
if let ExprBinary(ref cmp, _, ref right) = expr.node {
if let &Spanned {node: BinOp_::BiRem, ..} = cmp {
if is_integer_literal(right, 1) {
cx.span_lint(MODULO_ONE, expr.span, "any number modulo 1 will be 0");
}
}
}
}
}
declare_lint!(pub REDUNDANT_PATTERN, Warn, "using `name @ _` in a pattern");
#[derive(Copy,Clone)]
pub struct PatternPass;
impl LintPass for PatternPass {
fn get_lints(&self) -> LintArray {
lint_array!(REDUNDANT_PATTERN)
}
}
impl LateLintPass for PatternPass {
fn check_pat(&mut self, cx: &LateContext, pat: &Pat) {
if let PatIdent(_, ref ident, Some(ref right)) = pat.node {
if right.node == PatWild(PatWildSingle) {
cx.span_lint(REDUNDANT_PATTERN, pat.span, &format!(
"the `{} @ _` pattern can be written as just `{}`",
ident.node.name, ident.node.name));
}
}
}
}