use rustc::lint::*;
use rustc::middle::const_val::ConstVal;
use rustc::ty;
-use rustc_const_eval::EvalHint::ExprTypeChecked;
-use rustc_const_eval::eval_const_expr_partial;
+use rustc_const_eval::ConstContext;
use rustc_const_math::ConstFloat;
-use syntax::codemap::{Span, Spanned, ExpnFormat};
-use syntax::ptr::P;
-use utils::{
- get_item_name, get_parent_expr, implements_trait, in_macro, is_integer_literal, match_path,
- snippet, span_lint, span_lint_and_then, walk_ptrs_ty
-};
+use syntax::codemap::{Span, ExpnFormat};
+use utils::{get_item_name, get_parent_expr, implements_trait, in_macro, is_integer_literal, match_path, snippet,
+ span_lint, span_lint_and_then, walk_ptrs_ty, last_path_segment, iter_input_pats, in_constant,
+ match_trait_method, paths};
use utils::sugg::Sugg;
+use syntax::ast::{LitKind, CRATE_NODE_ID};
-/// **What it does:** This lint checks for function arguments and let bindings denoted as `ref`.
+/// **What it does:** Checks for function arguments and let bindings denoted as `ref`.
///
-/// **Why is this bad?** The `ref` declaration makes the function take an owned value, but turns the argument into a reference (which means that the value is destroyed when exiting the function). This adds not much value: either take a reference type, or take an owned value and create references in the body.
+/// **Why is this bad?** The `ref` declaration makes the function take an owned
+/// value, but turns the argument into a reference (which means that the value
+/// is destroyed when exiting the function). This adds not much value: either
+/// take a reference type, or take an owned value and create references in the
+/// body.
///
-/// For let bindings, `let x = &foo;` is preferred over `let ref x = foo`. The type of `x` is more obvious with the former.
+/// For let bindings, `let x = &foo;` is preferred over `let ref x = foo`. The
+/// type of `x` is more obvious with the former.
///
-/// **Known problems:** If the argument is dereferenced within the function, removing the `ref` will lead to errors. This can be fixed by removing the dereferences, e.g. changing `*x` to `x` within the function.
+/// **Known problems:** If the argument is dereferenced within the function,
+/// removing the `ref` will lead to errors. This can be fixed by removing the
+/// dereferences, e.g. changing `*x` to `x` within the function.
///
-/// **Example:** `fn foo(ref x: u8) -> bool { .. }`
+/// **Example:**
+/// ```rust
+/// fn foo(ref x: u8) -> bool { .. }
+/// ```
+declare_lint! {
+ pub TOPLEVEL_REF_ARG,
+ Warn,
+ "an entire binding declared as `ref`, in a function argument or a `let` statement"
+}
+
+/// **What it does:** Checks for comparisons to NaN.
+///
+/// **Why is this bad?** NaN does not compare meaningfully to anything – not
+/// even itself – so those comparisons are simply wrong.
+///
+/// **Known problems:** None.
+///
+/// **Example:**
+/// ```rust
+/// x == NAN
+/// ```
+declare_lint! {
+ pub CMP_NAN,
+ Deny,
+ "comparisons to NAN, which will always return false, probably not intended"
+}
+
+/// **What it does:** Checks for (in-)equality comparisons on floating-point
+/// values (apart from zero), except in functions called `*eq*` (which probably
+/// implement equality for a type involving floats).
+///
+/// **Why is this bad?** Floating point calculations are usually imprecise, so
+/// asking if two values are *exactly* equal is asking for trouble. For a good
+/// guide on what to do, see [the floating point
+/// guide](http://www.floating-point-gui.de/errors/comparison).
+///
+/// **Known problems:** None.
+///
+/// **Example:**
+/// ```rust
+/// y == 1.23f64
+/// y != x // where both are floats
+/// ```
+declare_lint! {
+ pub FLOAT_CMP,
+ Warn,
+ "using `==` or `!=` on float values instead of comparing difference with an epsilon"
+}
+
+/// **What it does:** Checks for conversions to owned values just for the sake
+/// of a comparison.
+///
+/// **Why is this bad?** The comparison can operate on a reference, so creating
+/// an owned value effectively throws it away directly afterwards, which is
+/// needlessly consuming code and heap space.
+///
+/// **Known problems:** None.
+///
+/// **Example:**
+/// ```rust
+/// x.to_owned() == y
+/// ```
+declare_lint! {
+ pub CMP_OWNED,
+ Warn,
+ "creating owned instances for comparing with others, e.g. `x == \"foo\".to_string()`"
+}
+
+/// **What it does:** Checks for getting the remainder of a division by one.
+///
+/// **Why is this bad?** The result can only ever be zero. No one will write
+/// such code deliberately, unless trying to win an Underhanded Rust
+/// Contest. Even for that contest, it's probably a bad idea. Use something more
+/// underhanded.
+///
+/// **Known problems:** None.
+///
+/// **Example:**
+/// ```rust
+/// x % 1
+/// ```
+declare_lint! {
+ pub MODULO_ONE,
+ Warn,
+ "taking a number modulo 1, which always returns 0"
+}
+
+/// **What it does:** Checks for patterns in the form `name @ _`.
+///
+/// **Why is this bad?** It's almost always more readable to just use direct bindings.
+///
+/// **Known problems:** None.
+///
+/// **Example:**
+/// ```rust
+/// match v {
+/// Some(x) => (),
+/// y @ _ => (), // easier written as `y`,
+/// }
+/// ```
declare_lint! {
- pub TOPLEVEL_REF_ARG, Warn,
- "An entire binding was declared as `ref`, in a function argument (`fn foo(ref x: Bar)`), \
- or a `let` statement (`let ref x = foo()`). In such cases, it is preferred to take \
- references with `&`."
+ pub REDUNDANT_PATTERN,
+ Warn,
+ "using `name @ _` in a pattern"
}
-#[allow(missing_copy_implementations)]
-pub struct TopLevelRefPass;
+/// **What it does:** Checks for the use of bindings with a single leading underscore.
+///
+/// **Why is this bad?** A single leading underscore is usually used to indicate
+/// that a binding will not be used. Using such a binding breaks this
+/// expectation.
+///
+/// **Known problems:** The lint does not work properly with desugaring and
+/// macro, it has been allowed in the mean time.
+///
+/// **Example:**
+/// ```rust
+/// let _x = 0;
+/// let y = _x + 1; // Here we are using `_x`, even though it has a leading underscore.
+/// // We should rename `_x` to `x`
+/// ```
+declare_lint! {
+ pub USED_UNDERSCORE_BINDING,
+ Allow,
+ "using a binding which is prefixed with an underscore"
+}
-impl LintPass for TopLevelRefPass {
+/// **What it does:** Checks for the use of short circuit boolean conditions as a
+/// statement.
+///
+/// **Why is this bad?** Using a short circuit boolean condition as a statement may
+/// hide the fact that the second part is executed or not depending on the outcome of
+/// the first part.
+///
+/// **Known problems:** None.
+///
+/// **Example:**
+/// ```rust
+/// f() && g(); // We should write `if f() { g(); }`.
+/// ```
+declare_lint! {
+ pub SHORT_CIRCUIT_STATEMENT,
+ Warn,
+ "using a short circuit boolean condition as a statement"
+}
+
+/// **What it does:** Catch casts from `0` to some pointer type
+///
+/// **Why is this bad?** This generally means `null` and is better expressed as
+/// {`std`, `core`}`::ptr::`{`null`, `null_mut`}.
+///
+/// **Known problems:** None.
+///
+/// **Example:**
+///
+/// ```rust
+/// 0 as *const u32
+/// ```
+declare_lint! {
+ pub ZERO_PTR,
+ Warn,
+ "using 0 as *{const, mut} T"
+}
+
+#[derive(Copy, Clone)]
+pub struct Pass;
+
+impl LintPass for Pass {
fn get_lints(&self) -> LintArray {
- lint_array!(TOPLEVEL_REF_ARG)
+ lint_array!(TOPLEVEL_REF_ARG,
+ CMP_NAN,
+ FLOAT_CMP,
+ CMP_OWNED,
+ MODULO_ONE,
+ REDUNDANT_PATTERN,
+ USED_UNDERSCORE_BINDING,
+ SHORT_CIRCUIT_STATEMENT,
+ ZERO_PTR)
}
}
-impl LateLintPass for TopLevelRefPass {
- fn check_fn(&mut self, cx: &LateContext, k: FnKind, decl: &FnDecl, _: &Block, _: Span, _: NodeId) {
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
+ fn check_fn(
+ &mut self,
+ cx: &LateContext<'a, 'tcx>,
+ k: FnKind<'tcx>,
+ decl: &'tcx FnDecl,
+ body: &'tcx Body,
+ _: Span,
+ _: NodeId
+ ) {
if let FnKind::Closure(_) = k {
// Does not apply to closures
return;
}
- for ref arg in &decl.inputs {
- if let PatKind::Binding(BindByRef(_), _, _) = arg.pat.node {
+ for arg in iter_input_pats(decl, body) {
+ if let PatKind::Binding(BindByRef(_), _, _, _) = arg.pat.node {
span_lint(cx,
TOPLEVEL_REF_ARG,
arg.pat.span,
}
}
}
- fn check_stmt(&mut self, cx: &LateContext, s: &Stmt) {
+
+ fn check_stmt(&mut self, cx: &LateContext<'a, 'tcx>, s: &'tcx Stmt) {
if_let_chain! {[
let StmtDecl(ref d, _) = s.node,
let DeclLocal(ref l) = d.node,
- let PatKind::Binding(BindByRef(_), i, None) = l.pat.node,
+ let PatKind::Binding(BindByRef(mt), _, i, None) = l.pat.node,
let Some(ref init) = l.init
], {
+ let init = Sugg::hir(cx, init, "..");
+ let (mutopt,initref) = if mt == Mutability::MutMutable {
+ ("mut ", init.mut_addr())
+ } else {
+ ("", init.addr())
+ };
let tyopt = if let Some(ref ty) = l.ty {
- format!(": {}", snippet(cx, ty.span, "_"))
+ format!(": &{mutopt}{ty}", mutopt=mutopt, ty=snippet(cx, ty.span, "_"))
} else {
"".to_owned()
};
span_lint_and_then(cx,
TOPLEVEL_REF_ARG,
l.pat.span,
- "`ref` on an entire `let` pattern is discouraged, take a reference with & instead",
+ "`ref` on an entire `let` pattern is discouraged, take a reference with `&` instead",
|db| {
db.span_suggestion(s.span,
"try",
- format!("let {}{} = &{};",
- snippet(cx, i.span, "_"),
- tyopt,
- snippet(cx, init.span, "_")));
+ format!("let {name}{tyopt} = {initref};",
+ name=snippet(cx, i.span, "_"),
+ tyopt=tyopt,
+ initref=initref));
}
);
- }}
- }
-}
-
-/// **What it does:** This lint checks for comparisons to NAN.
-///
-/// **Why is this bad?** NAN does not compare meaningfully to anything – not even itself – so those comparisons are simply wrong.
-///
-/// **Known problems:** None
-///
-/// **Example:** `x == NAN`
-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)
+ }};
+ if_let_chain! {[
+ let StmtSemi(ref expr, _) = s.node,
+ let Expr_::ExprBinary(ref binop, ref a, ref b) = expr.node,
+ binop.node == BiAnd || binop.node == BiOr,
+ let Some(sugg) = Sugg::hir_opt(cx, a),
+ ], {
+ span_lint_and_then(cx,
+ SHORT_CIRCUIT_STATEMENT,
+ s.span,
+ "boolean short circuit operator in statement may be clearer using an explicit test",
+ |db| {
+ let sugg = if binop.node == BiOr { !sugg } else { sugg };
+ db.span_suggestion(s.span, "replace it with",
+ format!("if {} {{ {}; }}", sugg, &snippet(cx, b.span, "..")));
+ });
+ }};
}
-}
-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 cmp.node.is_comparison() {
- if let ExprPath(_, ref path) = left.node {
- check_nan(cx, path, expr.span);
+ fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
+ match expr.node {
+ ExprCast(ref e, ref ty) => {
+ check_cast(cx, expr.span, e, ty);
+ return;
+ },
+ ExprBinary(ref cmp, ref left, ref right) => {
+ let op = cmp.node;
+ if op.is_comparison() {
+ if let ExprPath(QPath::Resolved(_, ref path)) = left.node {
+ check_nan(cx, path, expr);
+ }
+ if let ExprPath(QPath::Resolved(_, ref path)) = right.node {
+ check_nan(cx, path, expr);
+ }
+ check_to_owned(cx, left, right);
+ check_to_owned(cx, right, left);
}
- if let ExprPath(_, ref path) = right.node {
- check_nan(cx, path, expr.span);
+ if (op == BiEq || op == BiNe) && (is_float(cx, left) || is_float(cx, right)) {
+ if is_allowed(cx, left) || is_allowed(cx, right) {
+ return;
+ }
+ if let Some(name) = get_item_name(cx, expr) {
+ let name = name.as_str();
+ if name == "eq" || name == "ne" || name == "is_nan" || name.starts_with("eq_") ||
+ name.ends_with("_eq") {
+ return;
+ }
+ }
+ span_lint_and_then(cx, FLOAT_CMP, expr.span, "strict comparison of f32 or f64", |db| {
+ let lhs = Sugg::hir(cx, left, "..");
+ let rhs = Sugg::hir(cx, right, "..");
+
+ db.span_suggestion(expr.span,
+ "consider comparing them within some error",
+ format!("({}).abs() < error", lhs - rhs));
+ db.span_note(expr.span, "std::f32::EPSILON and std::f64::EPSILON are available.");
+ });
+ } else if op == BiRem && is_integer_literal(right, 1) {
+ span_lint(cx, MODULO_ONE, expr.span, "any number modulo 1 will be 0");
}
+ },
+ _ => {},
+ }
+ if in_attributes_expansion(expr) {
+ // Don't lint things expanded by #[derive(...)], etc
+ return;
+ }
+ let binding = match expr.node {
+ ExprPath(ref qpath) => {
+ let binding = last_path_segment(qpath).name.as_str();
+ if binding.starts_with('_') &&
+ !binding.starts_with("__") &&
+ binding != "_result" && // FIXME: #944
+ is_used(cx, expr) &&
+ // don't lint if the declaration is in a macro
+ non_macro_local(cx, &cx.tables.qpath_def(qpath, expr.id)) {
+ Some(binding)
+ } else {
+ None
+ }
+ },
+ ExprField(_, spanned) => {
+ let name = spanned.node.as_str();
+ if name.starts_with('_') && !name.starts_with("__") {
+ Some(name)
+ } else {
+ None
+ }
+ },
+ _ => None,
+ };
+ if let Some(binding) = binding {
+ span_lint(cx,
+ USED_UNDERSCORE_BINDING,
+ expr.span,
+ &format!("used binding `{}` which is prefixed with an underscore. A leading \
+ underscore signals that a binding will not be used.",
+ binding));
+ }
+ }
+
+ fn check_pat(&mut self, cx: &LateContext<'a, 'tcx>, pat: &'tcx Pat) {
+ if let PatKind::Binding(_, _, ref ident, Some(ref right)) = pat.node {
+ if right.node == PatKind::Wild {
+ span_lint(cx,
+ REDUNDANT_PATTERN,
+ pat.span,
+ &format!("the `{} @ _` pattern can be written as just `{}`", ident.node, ident.node));
}
}
}
}
-fn check_nan(cx: &LateContext, path: &Path, span: Span) {
- path.segments.last().map(|seg| {
- if seg.name.as_str() == "NAN" {
+fn check_nan(cx: &LateContext, path: &Path, expr: &Expr) {
+ if !in_constant(cx, expr.id) {
+ path.segments.last().map(|seg| if seg.name == "NAN" {
span_lint(cx,
CMP_NAN,
- span,
+ expr.span,
"doomed comparison with NAN, use `std::{f32,f64}::is_nan()` instead");
- }
- });
-}
-
-/// **What it does:** This lint checks for (in-)equality comparisons on floating-point values (apart from zero), except in functions called `*eq*` (which probably implement equality for a type involving floats).
-///
-/// **Why is this bad?** Floating point calculations are usually imprecise, so asking if two values are *exactly* equal is asking for trouble. For a good guide on what to do, see [the floating point guide](http://www.floating-point-gui.de/errors/comparison).
-///
-/// **Known problems:** None
-///
-/// **Example:** `y == 1.23f64`
-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 is_allowed(cx, left) || is_allowed(cx, right) {
- return;
- }
- if let Some(name) = get_item_name(cx, expr) {
- let name = name.as_str();
- if name == "eq" || name == "ne" || name == "is_nan" || name.starts_with("eq_") ||
- name.ends_with("_eq") {
- return;
- }
- }
- span_lint_and_then(cx,
- FLOAT_CMP,
- expr.span,
- "strict comparison of f32 or f64",
- |db| {
- let lhs = &Sugg::hir(cx, left, "..");
- let rhs = &Sugg::hir(cx, right, "..");
-
- db.span_suggestion(expr.span,
- "consider comparing them within some error",
- format!("({}).abs() < error", lhs - rhs));
- db.span_note(expr.span, "std::f32::EPSILON and std::f64::EPSILON are available.");
- });
- }
- }
+ });
}
}
fn is_allowed(cx: &LateContext, expr: &Expr) -> bool {
- let res = eval_const_expr_partial(cx.tcx, expr, ExprTypeChecked, None);
+ let res = ConstContext::with_tables(cx.tcx, cx.tables).eval(expr);
if let Ok(ConstVal::Float(val)) = res {
use std::cmp::Ordering;
+ match val {
+ val @ ConstFloat::F32(_) => {
+ let zero = ConstFloat::F32(0.0);
- let zero = ConstFloat::FInfer {
- f32: 0.0,
- f64: 0.0,
- };
+ let infinity = ConstFloat::F32(::std::f32::INFINITY);
- let infinity = ConstFloat::FInfer {
- f32: ::std::f32::INFINITY,
- f64: ::std::f64::INFINITY,
- };
+ let neg_infinity = ConstFloat::F32(::std::f32::NEG_INFINITY);
- let neg_infinity = ConstFloat::FInfer {
- f32: ::std::f32::NEG_INFINITY,
- f64: ::std::f64::NEG_INFINITY,
- };
+ val.try_cmp(zero) == Ok(Ordering::Equal) || val.try_cmp(infinity) == Ok(Ordering::Equal) ||
+ val.try_cmp(neg_infinity) == Ok(Ordering::Equal)
+ },
+ val @ ConstFloat::F64(_) => {
+ let zero = ConstFloat::F64(0.0);
- val.try_cmp(zero) == Ok(Ordering::Equal)
- || val.try_cmp(infinity) == Ok(Ordering::Equal)
- || val.try_cmp(neg_infinity) == Ok(Ordering::Equal)
+ let infinity = ConstFloat::F64(::std::f64::INFINITY);
+
+ let neg_infinity = ConstFloat::F64(::std::f64::NEG_INFINITY);
+
+ val.try_cmp(zero) == Ok(Ordering::Equal) || val.try_cmp(infinity) == Ok(Ordering::Equal) ||
+ val.try_cmp(neg_infinity) == Ok(Ordering::Equal)
+ },
+ }
} else {
false
}
}
fn is_float(cx: &LateContext, expr: &Expr) -> bool {
- matches!(walk_ptrs_ty(cx.tcx.expr_ty(expr)).sty, ty::TyFloat(_))
-}
-
-/// **What it does:** This lint checks for conversions to owned values just for the sake of a comparison.
-///
-/// **Why is this bad?** The comparison can operate on a reference, so creating an owned value effectively throws it away directly afterwards, which is needlessly consuming code and heap space.
-///
-/// **Known problems:** None
-///
-/// **Example:** `x.to_owned() == y`
-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 cmp.node.is_comparison() {
- check_to_owned(cx, left, right, true, cmp.span);
- check_to_owned(cx, right, left, false, cmp.span)
- }
- }
- }
+ matches!(walk_ptrs_ty(cx.tables.expr_ty(expr)).sty, ty::TyFloat(_))
}
-fn check_to_owned(cx: &LateContext, expr: &Expr, other: &Expr, left: bool, op: Span) {
+fn check_to_owned(cx: &LateContext, expr: &Expr, other: &Expr) {
let (arg_ty, snip) = match expr.node {
- ExprMethodCall(Spanned { node: ref name, .. }, _, ref args) if args.len() == 1 => {
- if name.as_str() == "to_string" || name.as_str() == "to_owned" && is_str_arg(cx, args) {
- (cx.tcx.expr_ty(&args[0]), snippet(cx, args[0].span, ".."))
+ ExprMethodCall(.., ref args) if args.len() == 1 => {
+ if match_trait_method(cx, expr, &paths::TO_STRING) || match_trait_method(cx, expr, &paths::TO_OWNED) {
+ (cx.tables.expr_ty_adjusted(&args[0]), snippet(cx, args[0].span, ".."))
} else {
return;
}
- }
+ },
ExprCall(ref path, ref v) if v.len() == 1 => {
- if let ExprPath(None, ref path) = path.node {
+ if let ExprPath(ref path) = path.node {
if match_path(path, &["String", "from_str"]) || match_path(path, &["String", "from"]) {
- (cx.tcx.expr_ty(&v[0]), snippet(cx, v[0].span, ".."))
+ (cx.tables.expr_ty_adjusted(&v[0]), snippet(cx, v[0].span, ".."))
} else {
return;
}
} else {
return;
}
- }
+ },
_ => return,
};
- let other_ty = cx.tcx.expr_ty(other);
+ let other_ty = cx.tables.expr_ty_adjusted(other);
let partial_eq_trait_id = match cx.tcx.lang_items.eq_trait() {
Some(id) => id,
None => return,
};
- if !implements_trait(cx, arg_ty, partial_eq_trait_id, vec![other_ty]) {
+ // *arg impls PartialEq<other>
+ if !arg_ty
+ .builtin_deref(true, ty::LvaluePreference::NoPreference)
+ .map_or(false, |tam| implements_trait(cx, tam.ty, partial_eq_trait_id, &[other_ty]))
+ // arg impls PartialEq<*other>
+ && !other_ty
+ .builtin_deref(true, ty::LvaluePreference::NoPreference)
+ .map_or(false, |tam| implements_trait(cx, arg_ty, partial_eq_trait_id, &[tam.ty]))
+ // arg impls PartialEq<other>
+ && !implements_trait(cx, arg_ty, partial_eq_trait_id, &[other_ty]) {
return;
}
- if left {
- span_lint(cx,
- CMP_OWNED,
- expr.span,
- &format!("this creates an owned instance just for comparison. Consider using `{} {} {}` to \
- compare without allocation",
- snip,
- snippet(cx, op, "=="),
- snippet(cx, other.span, "..")));
- } else {
- span_lint(cx,
- CMP_OWNED,
- expr.span,
- &format!("this creates an owned instance just for comparison. Consider using `{} {} {}` to \
- compare without allocation",
- snippet(cx, other.span, ".."),
- snippet(cx, op, "=="),
- snip));
- }
-
-}
-
-fn is_str_arg(cx: &LateContext, args: &[P<Expr>]) -> bool {
- args.len() == 1 &&
- matches!(walk_ptrs_ty(cx.tcx.expr_ty(&args[0])).sty, ty::TyStr)
-}
-
-/// **What it does:** This lint checks for getting the remainder of a division by one.
-///
-/// **Why is this bad?** The result can only ever be zero. No one will write such code deliberately, unless trying to win an Underhanded Rust Contest. Even for that contest, it's probably a bad idea. Use something more underhanded.
-///
-/// **Known problems:** None
-///
-/// **Example:** `x % 1`
-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) {
- span_lint(cx, MODULO_ONE, expr.span, "any number modulo 1 will be 0");
- }
- }
- }
- }
-}
-
-/// **What it does:** This lint checks for patterns in the form `name @ _`.
-///
-/// **Why is this bad?** It's almost always more readable to just use direct bindings.
-///
-/// **Known problems:** None
-///
-/// **Example**:
-/// ```
-/// match v {
-/// Some(x) => (),
-/// y @ _ => (), // easier written as `y`,
-/// }
-/// ```
-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 PatKind::Binding(_, ref ident, Some(ref right)) = pat.node {
- if right.node == PatKind::Wild {
- span_lint(cx,
- REDUNDANT_PATTERN,
- pat.span,
- &format!("the `{} @ _` pattern can be written as just `{}`",
- ident.node,
- ident.node));
- }
- }
- }
-}
-
-
-/// **What it does:** This lint checks for the use of bindings with a single leading underscore
-///
-/// **Why is this bad?** A single leading underscore is usually used to indicate that a binding
-/// will not be used. Using such a binding breaks this expectation.
-///
-/// **Known problems:** The lint does not work properly with desugaring and macro, it has been
-/// allowed in the mean time.
-///
-/// **Example**:
-/// ```
-/// let _x = 0;
-/// let y = _x + 1; // Here we are using `_x`, even though it has a leading underscore.
-/// // We should rename `_x` to `x`
-/// ```
-declare_lint!(pub USED_UNDERSCORE_BINDING, Allow,
- "using a binding which is prefixed with an underscore");
-
-#[derive(Copy, Clone)]
-pub struct UsedUnderscoreBinding;
-
-impl LintPass for UsedUnderscoreBinding {
- fn get_lints(&self) -> LintArray {
- lint_array!(USED_UNDERSCORE_BINDING)
- }
-}
-
-impl LateLintPass for UsedUnderscoreBinding {
- #[cfg_attr(rustfmt, rustfmt_skip)]
- fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
- if in_attributes_expansion(cx, expr) {
- // Don't lint things expanded by #[derive(...)], etc
- return;
- }
- let binding = match expr.node {
- ExprPath(_, ref path) => {
- let binding = path.segments
- .last()
- .expect("path should always have at least one segment")
- .name
- .as_str();
- if binding.starts_with('_') &&
- !binding.starts_with("__") &&
- binding != "_result" && // FIXME: #944
- is_used(cx, expr) &&
- // don't lint if the declaration is in a macro
- non_macro_local(cx, &cx.tcx.expect_def(expr.id)) {
- Some(binding)
- } else {
- None
- }
- }
- ExprField(_, spanned) => {
- let name = spanned.node.as_str();
- if name.starts_with('_') && !name.starts_with("__") {
- Some(name)
- } else {
- None
+ span_lint_and_then(cx,
+ CMP_OWNED,
+ expr.span,
+ "this creates an owned instance just for comparison",
+ |db| {
+ // this is as good as our recursion check can get, we can't prove that the current function is
+ // called by
+ // PartialEq::eq, but we can at least ensure that this code is not part of it
+ let parent_fn = cx.tcx.hir.get_parent(expr.id);
+ let parent_impl = cx.tcx.hir.get_parent(parent_fn);
+ if parent_impl != CRATE_NODE_ID {
+ if let map::NodeItem(item) = cx.tcx.hir.get(parent_impl) {
+ if let ItemImpl(.., Some(ref trait_ref), _, _) = item.node {
+ if trait_ref.path.def.def_id() == partial_eq_trait_id {
+ // we are implementing PartialEq, don't suggest not doing `to_owned`, otherwise we go into
+ // recursion
+ db.span_label(expr.span, "try calling implementing the comparison without allocating");
+ return;
+ }
}
}
- _ => None,
- };
- if let Some(binding) = binding {
- span_lint(cx,
- USED_UNDERSCORE_BINDING,
- expr.span,
- &format!("used binding `{}` which is prefixed with an underscore. A leading \
- underscore signals that a binding will not be used.", binding));
}
- }
+ db.span_suggestion(expr.span, "try", snip.to_string());
+ });
}
/// Heuristic to see if an expression is used. Should be compatible with `unused_variables`'s idea
/// of what it means for an expression to be "used".
fn is_used(cx: &LateContext, expr: &Expr) -> bool {
- if let Some(ref parent) = get_parent_expr(cx, expr) {
+ if let Some(parent) = get_parent_expr(cx, expr) {
match parent.node {
ExprAssign(_, ref rhs) |
ExprAssignOp(_, _, ref rhs) => **rhs == *expr,
/// Test whether an expression is in a macro expansion (e.g. something generated by
/// `#[derive(...)`] or the like).
-fn in_attributes_expansion(cx: &LateContext, expr: &Expr) -> bool {
- cx.sess().codemap().with_expn_info(expr.span.expn_id, |info_opt| {
- info_opt.map_or(false, |info| {
- matches!(info.callee.format, ExpnFormat::MacroAttribute(_))
- })
- })
+fn in_attributes_expansion(expr: &Expr) -> bool {
+ expr.span.ctxt.outer().expn_info().map_or(false, |info| matches!(info.callee.format, ExpnFormat::MacroAttribute(_)))
}
/// Test whether `def` is a variable defined outside a macro.
fn non_macro_local(cx: &LateContext, def: &def::Def) -> bool {
match *def {
- def::Def::Local(_, id) | def::Def::Upvar(_, id, _, _) => {
- if let Some(span) = cx.tcx.map.opt_span(id) {
- !in_macro(cx, span)
+ def::Def::Local(id) |
+ def::Def::Upvar(id, _, _) => {
+ if let Some(span) = cx.tcx.hir.span_if_local(id) {
+ !in_macro(span)
} else {
true
}
- }
+ },
_ => false,
}
}
+
+fn check_cast(cx: &LateContext, span: Span, e: &Expr, ty: &Ty) {
+ if_let_chain! {[
+ let TyPtr(MutTy { mutbl, .. }) = ty.node,
+ let ExprLit(ref lit) = e.node,
+ let LitKind::Int(value, ..) = lit.node,
+ value == 0,
+ !in_constant(cx, e.id)
+ ], {
+ let msg = match mutbl {
+ Mutability::MutMutable => "`0 as *mut _` detected. Consider using `ptr::null_mut()`",
+ Mutability::MutImmutable => "`0 as *const _` detected. Consider using `ptr::null()`",
+ };
+ span_lint(cx, ZERO_PTR, span, msg);
+ }}
+}
projects / rust.git / blobdiff