768 lines
26 KiB
Rust
768 lines
26 KiB
Rust
use if_chain::if_chain;
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use rustc_ast::ast::LitKind;
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use rustc_errors::Applicability;
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use rustc_hir::intravisit::FnKind;
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use rustc_hir::{
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self as hir, def, BinOpKind, BindingAnnotation, Body, Expr, ExprKind, FnDecl, HirId, Mutability, PatKind, Stmt,
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StmtKind, TyKind, UnOp,
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};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_middle::lint::in_external_macro;
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use rustc_middle::ty::{self, Ty};
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::hygiene::DesugaringKind;
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use rustc_span::source_map::{ExpnKind, Span};
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use crate::consts::{constant, Constant};
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use crate::utils::sugg::Sugg;
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use crate::utils::{
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get_item_name, get_parent_expr, higher, implements_trait, in_constant, is_integer_const, iter_input_pats,
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last_path_segment, match_qpath, match_trait_method, paths, snippet, snippet_opt, span_lint, span_lint_and_sugg,
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span_lint_and_then, span_lint_hir_and_then, unsext, SpanlessEq,
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};
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declare_clippy_lint! {
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/// **What it does:** Checks for function arguments and let bindings denoted as
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/// `ref`.
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///
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/// **Why is this bad?** The `ref` declaration makes the function take an owned
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/// value, but turns the argument into a reference (which means that the value
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/// is destroyed when exiting the function). This adds not much value: either
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/// take a reference type, or take an owned value and create references in the
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/// body.
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///
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/// For let bindings, `let x = &foo;` is preferred over `let ref x = foo`. The
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/// type of `x` is more obvious with the former.
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///
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/// **Known problems:** If the argument is dereferenced within the function,
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/// removing the `ref` will lead to errors. This can be fixed by removing the
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/// dereferences, e.g., changing `*x` to `x` within the function.
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///
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/// **Example:**
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/// ```rust,ignore
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/// // Bad
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/// fn foo(ref x: u8) -> bool {
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/// true
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/// }
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///
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/// // Good
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/// fn foo(x: &u8) -> bool {
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/// true
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/// }
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/// ```
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pub TOPLEVEL_REF_ARG,
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style,
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"an entire binding declared as `ref`, in a function argument or a `let` statement"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for comparisons to NaN.
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///
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/// **Why is this bad?** NaN does not compare meaningfully to anything – not
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/// even itself – so those comparisons are simply wrong.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// # let x = 1.0;
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///
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/// // Bad
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/// if x == f32::NAN { }
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///
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/// // Good
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/// if x.is_nan() { }
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/// ```
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pub CMP_NAN,
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correctness,
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"comparisons to `NAN`, which will always return false, probably not intended"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for (in-)equality comparisons on floating-point
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/// values (apart from zero), except in functions called `*eq*` (which probably
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/// implement equality for a type involving floats).
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///
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/// **Why is this bad?** Floating point calculations are usually imprecise, so
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/// asking if two values are *exactly* equal is asking for trouble. For a good
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/// guide on what to do, see [the floating point
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/// guide](http://www.floating-point-gui.de/errors/comparison).
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// let x = 1.2331f64;
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/// let y = 1.2332f64;
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///
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/// // Bad
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/// if y == 1.23f64 { }
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/// if y != x {} // where both are floats
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///
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/// // Good
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/// let error_margin = f64::EPSILON; // Use an epsilon for comparison
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/// // Or, if Rust <= 1.42, use `std::f64::EPSILON` constant instead.
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/// // let error_margin = std::f64::EPSILON;
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/// if (y - 1.23f64).abs() < error_margin { }
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/// if (y - x).abs() > error_margin { }
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/// ```
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pub FLOAT_CMP,
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correctness,
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"using `==` or `!=` on float values instead of comparing difference with an epsilon"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for conversions to owned values just for the sake
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/// of a comparison.
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///
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/// **Why is this bad?** The comparison can operate on a reference, so creating
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/// an owned value effectively throws it away directly afterwards, which is
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/// needlessly consuming code and heap space.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// # let x = "foo";
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/// # let y = String::from("foo");
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/// if x.to_owned() == y {}
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/// ```
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/// Could be written as
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/// ```rust
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/// # let x = "foo";
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/// # let y = String::from("foo");
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/// if x == y {}
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/// ```
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pub CMP_OWNED,
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perf,
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"creating owned instances for comparing with others, e.g., `x == \"foo\".to_string()`"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for getting the remainder of a division by one or minus
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/// one.
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///
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/// **Why is this bad?** The result for a divisor of one can only ever be zero; for
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/// minus one it can cause panic/overflow (if the left operand is the minimal value of
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/// the respective integer type) or results in zero. No one will write such code
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/// deliberately, unless trying to win an Underhanded Rust Contest. Even for that
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/// contest, it's probably a bad idea. Use something more underhanded.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// # let x = 1;
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/// let a = x % 1;
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/// let a = x % -1;
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/// ```
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pub MODULO_ONE,
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correctness,
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"taking a number modulo +/-1, which can either panic/overflow or always returns 0"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for the use of bindings with a single leading
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/// underscore.
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///
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/// **Why is this bad?** A single leading underscore is usually used to indicate
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/// that a binding will not be used. Using such a binding breaks this
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/// expectation.
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///
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/// **Known problems:** The lint does not work properly with desugaring and
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/// macro, it has been allowed in the mean time.
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///
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/// **Example:**
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/// ```rust
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/// let _x = 0;
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/// let y = _x + 1; // Here we are using `_x`, even though it has a leading
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/// // underscore. We should rename `_x` to `x`
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/// ```
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pub USED_UNDERSCORE_BINDING,
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pedantic,
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"using a binding which is prefixed with an underscore"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for the use of short circuit boolean conditions as
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/// a
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/// statement.
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///
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/// **Why is this bad?** Using a short circuit boolean condition as a statement
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/// may hide the fact that the second part is executed or not depending on the
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/// outcome of the first part.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust,ignore
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/// f() && g(); // We should write `if f() { g(); }`.
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/// ```
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pub SHORT_CIRCUIT_STATEMENT,
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complexity,
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"using a short circuit boolean condition as a statement"
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}
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declare_clippy_lint! {
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/// **What it does:** Catch casts from `0` to some pointer type
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///
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/// **Why is this bad?** This generally means `null` and is better expressed as
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/// {`std`, `core`}`::ptr::`{`null`, `null_mut`}.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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///
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/// ```rust
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/// // Bad
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/// let a = 0 as *const u32;
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///
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/// // Good
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/// let a = std::ptr::null::<u32>();
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/// ```
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pub ZERO_PTR,
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style,
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"using `0 as *{const, mut} T`"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for (in-)equality comparisons on floating-point
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/// value and constant, except in functions called `*eq*` (which probably
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/// implement equality for a type involving floats).
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///
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/// **Why is this bad?** Floating point calculations are usually imprecise, so
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/// asking if two values are *exactly* equal is asking for trouble. For a good
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/// guide on what to do, see [the floating point
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/// guide](http://www.floating-point-gui.de/errors/comparison).
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// let x: f64 = 1.0;
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/// const ONE: f64 = 1.00;
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///
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/// // Bad
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/// if x == ONE { } // where both are floats
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///
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/// // Good
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/// let error_margin = f64::EPSILON; // Use an epsilon for comparison
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/// // Or, if Rust <= 1.42, use `std::f64::EPSILON` constant instead.
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/// // let error_margin = std::f64::EPSILON;
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/// if (x - ONE).abs() < error_margin { }
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/// ```
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pub FLOAT_CMP_CONST,
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restriction,
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"using `==` or `!=` on float constants instead of comparing difference with an epsilon"
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}
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declare_lint_pass!(MiscLints => [
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TOPLEVEL_REF_ARG,
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CMP_NAN,
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FLOAT_CMP,
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CMP_OWNED,
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MODULO_ONE,
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USED_UNDERSCORE_BINDING,
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SHORT_CIRCUIT_STATEMENT,
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ZERO_PTR,
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FLOAT_CMP_CONST
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]);
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impl<'tcx> LateLintPass<'tcx> for MiscLints {
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fn check_fn(
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&mut self,
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cx: &LateContext<'tcx>,
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k: FnKind<'tcx>,
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decl: &'tcx FnDecl<'_>,
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body: &'tcx Body<'_>,
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span: Span,
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_: HirId,
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) {
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if let FnKind::Closure(_) = k {
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// Does not apply to closures
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return;
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}
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if in_external_macro(cx.tcx.sess, span) {
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return;
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}
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for arg in iter_input_pats(decl, body) {
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if let PatKind::Binding(BindingAnnotation::Ref | BindingAnnotation::RefMut, ..) = arg.pat.kind {
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span_lint(
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cx,
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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. \
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Consider 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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fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &'tcx Stmt<'_>) {
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if_chain! {
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if !in_external_macro(cx.tcx.sess, stmt.span);
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if let StmtKind::Local(ref local) = stmt.kind;
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if let PatKind::Binding(an, .., name, None) = local.pat.kind;
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if let Some(ref init) = local.init;
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if !higher::is_from_for_desugar(local);
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then {
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if an == BindingAnnotation::Ref || an == BindingAnnotation::RefMut {
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// use the macro callsite when the init span (but not the whole local span)
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// comes from an expansion like `vec![1, 2, 3]` in `let ref _ = vec![1, 2, 3];`
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let sugg_init = if init.span.from_expansion() && !local.span.from_expansion() {
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Sugg::hir_with_macro_callsite(cx, init, "..")
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} else {
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Sugg::hir(cx, init, "..")
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};
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let (mutopt, initref) = if an == BindingAnnotation::RefMut {
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("mut ", sugg_init.mut_addr())
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} else {
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("", sugg_init.addr())
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};
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let tyopt = if let Some(ref ty) = local.ty {
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format!(": &{mutopt}{ty}", mutopt=mutopt, ty=snippet(cx, ty.span, ".."))
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} else {
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String::new()
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};
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span_lint_hir_and_then(
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cx,
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TOPLEVEL_REF_ARG,
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init.hir_id,
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local.pat.span,
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"`ref` on an entire `let` pattern is discouraged, take a reference with `&` instead",
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|diag| {
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diag.span_suggestion(
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stmt.span,
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"try",
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format!(
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"let {name}{tyopt} = {initref};",
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name=snippet(cx, name.span, ".."),
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tyopt=tyopt,
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initref=initref,
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),
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Applicability::MachineApplicable,
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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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if_chain! {
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if let StmtKind::Semi(ref expr) = stmt.kind;
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if let ExprKind::Binary(ref binop, ref a, ref b) = expr.kind;
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if binop.node == BinOpKind::And || binop.node == BinOpKind::Or;
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if let Some(sugg) = Sugg::hir_opt(cx, a);
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then {
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span_lint_and_then(cx,
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SHORT_CIRCUIT_STATEMENT,
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stmt.span,
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"boolean short circuit operator in statement may be clearer using an explicit test",
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|diag| {
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let sugg = if binop.node == BinOpKind::Or { !sugg } else { sugg };
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diag.span_suggestion(
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stmt.span,
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"replace it with",
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format!(
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"if {} {{ {}; }}",
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sugg,
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&snippet(cx, b.span, ".."),
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),
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Applicability::MachineApplicable, // snippet
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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_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
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match expr.kind {
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ExprKind::Cast(ref e, ref ty) => {
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check_cast(cx, expr.span, e, ty);
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return;
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},
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ExprKind::Binary(ref cmp, ref left, ref right) => {
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check_binary(cx, expr, cmp, left, right);
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return;
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},
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_ => {},
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}
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if in_attributes_expansion(expr) || expr.span.is_desugaring(DesugaringKind::Await) {
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// Don't lint things expanded by #[derive(...)], etc or `await` desugaring
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return;
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}
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let binding = match expr.kind {
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ExprKind::Path(ref qpath) if !matches!(qpath, hir::QPath::LangItem(..)) => {
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let binding = last_path_segment(qpath).ident.as_str();
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if binding.starts_with('_') &&
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!binding.starts_with("__") &&
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binding != "_result" && // FIXME: #944
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is_used(cx, expr) &&
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// don't lint if the declaration is in a macro
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non_macro_local(cx, cx.qpath_res(qpath, expr.hir_id))
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{
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Some(binding)
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} else {
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None
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}
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},
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ExprKind::Field(_, ident) => {
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let name = ident.as_str();
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if name.starts_with('_') && !name.starts_with("__") {
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Some(name)
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} else {
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None
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}
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},
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_ => None,
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};
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if let Some(binding) = binding {
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span_lint(
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cx,
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USED_UNDERSCORE_BINDING,
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expr.span,
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&format!(
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"used binding `{}` which is prefixed with an underscore. A leading \
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underscore signals that a binding will not be used.",
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binding
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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 get_lint_and_message(
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is_comparing_constants: bool,
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is_comparing_arrays: bool,
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) -> (&'static rustc_lint::Lint, &'static str) {
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if is_comparing_constants {
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(
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FLOAT_CMP_CONST,
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if is_comparing_arrays {
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"strict comparison of `f32` or `f64` constant arrays"
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} else {
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"strict comparison of `f32` or `f64` constant"
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},
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)
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} else {
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(
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FLOAT_CMP,
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if is_comparing_arrays {
|
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"strict comparison of `f32` or `f64` arrays"
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} else {
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"strict comparison of `f32` or `f64`"
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},
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)
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}
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}
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fn check_nan(cx: &LateContext<'_>, expr: &Expr<'_>, cmp_expr: &Expr<'_>) {
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if_chain! {
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if !in_constant(cx, cmp_expr.hir_id);
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if let Some((value, _)) = constant(cx, cx.typeck_results(), expr);
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then {
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let needs_lint = match value {
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Constant::F32(num) => num.is_nan(),
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Constant::F64(num) => num.is_nan(),
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_ => false,
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};
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if needs_lint {
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span_lint(
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cx,
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CMP_NAN,
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cmp_expr.span,
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"doomed comparison with `NAN`, use `{f32,f64}::is_nan()` 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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fn is_named_constant<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> bool {
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if let Some((_, res)) = constant(cx, cx.typeck_results(), expr) {
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res
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} else {
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false
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}
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}
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fn is_allowed<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> bool {
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match constant(cx, cx.typeck_results(), expr) {
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Some((Constant::F32(f), _)) => f == 0.0 || f.is_infinite(),
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Some((Constant::F64(f), _)) => f == 0.0 || f.is_infinite(),
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Some((Constant::Vec(vec), _)) => vec.iter().all(|f| match f {
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Constant::F32(f) => *f == 0.0 || (*f).is_infinite(),
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Constant::F64(f) => *f == 0.0 || (*f).is_infinite(),
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_ => false,
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}),
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_ => false,
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}
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}
|
||
|
||
// Return true if `expr` is the result of `signum()` invoked on a float value.
|
||
fn is_signum(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
|
||
// The negation of a signum is still a signum
|
||
if let ExprKind::Unary(UnOp::UnNeg, ref child_expr) = expr.kind {
|
||
return is_signum(cx, &child_expr);
|
||
}
|
||
|
||
if_chain! {
|
||
if let ExprKind::MethodCall(ref method_name, _, ref expressions, _) = expr.kind;
|
||
if sym!(signum) == method_name.ident.name;
|
||
// Check that the receiver of the signum() is a float (expressions[0] is the receiver of
|
||
// the method call)
|
||
then {
|
||
return is_float(cx, &expressions[0]);
|
||
}
|
||
}
|
||
false
|
||
}
|
||
|
||
fn is_float(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
|
||
let value = &cx.typeck_results().expr_ty(expr).peel_refs().kind();
|
||
|
||
if let ty::Array(arr_ty, _) = value {
|
||
return matches!(arr_ty.kind(), ty::Float(_));
|
||
};
|
||
|
||
matches!(value, ty::Float(_))
|
||
}
|
||
|
||
fn is_array(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
|
||
matches!(&cx.typeck_results().expr_ty(expr).peel_refs().kind(), ty::Array(_, _))
|
||
}
|
||
|
||
fn check_to_owned(cx: &LateContext<'_>, expr: &Expr<'_>, other: &Expr<'_>, left: bool) {
|
||
#[derive(Default)]
|
||
struct EqImpl {
|
||
ty_eq_other: bool,
|
||
other_eq_ty: bool,
|
||
}
|
||
|
||
impl EqImpl {
|
||
fn is_implemented(&self) -> bool {
|
||
self.ty_eq_other || self.other_eq_ty
|
||
}
|
||
}
|
||
|
||
fn symmetric_partial_eq<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, other: Ty<'tcx>) -> Option<EqImpl> {
|
||
cx.tcx.lang_items().eq_trait().map(|def_id| EqImpl {
|
||
ty_eq_other: implements_trait(cx, ty, def_id, &[other.into()]),
|
||
other_eq_ty: implements_trait(cx, other, def_id, &[ty.into()]),
|
||
})
|
||
}
|
||
|
||
let (arg_ty, snip) = match expr.kind {
|
||
ExprKind::MethodCall(.., ref args, _) if args.len() == 1 => {
|
||
if match_trait_method(cx, expr, &paths::TO_STRING) || match_trait_method(cx, expr, &paths::TO_OWNED) {
|
||
(cx.typeck_results().expr_ty(&args[0]), snippet(cx, args[0].span, ".."))
|
||
} else {
|
||
return;
|
||
}
|
||
},
|
||
ExprKind::Call(ref path, ref v) if v.len() == 1 => {
|
||
if let ExprKind::Path(ref path) = path.kind {
|
||
if match_qpath(path, &["String", "from_str"]) || match_qpath(path, &["String", "from"]) {
|
||
(cx.typeck_results().expr_ty(&v[0]), snippet(cx, v[0].span, ".."))
|
||
} else {
|
||
return;
|
||
}
|
||
} else {
|
||
return;
|
||
}
|
||
},
|
||
_ => return,
|
||
};
|
||
|
||
let other_ty = cx.typeck_results().expr_ty(other);
|
||
|
||
let without_deref = symmetric_partial_eq(cx, arg_ty, other_ty).unwrap_or_default();
|
||
let with_deref = arg_ty
|
||
.builtin_deref(true)
|
||
.and_then(|tam| symmetric_partial_eq(cx, tam.ty, other_ty))
|
||
.unwrap_or_default();
|
||
|
||
if !with_deref.is_implemented() && !without_deref.is_implemented() {
|
||
return;
|
||
}
|
||
|
||
let other_gets_derefed = matches!(other.kind, ExprKind::Unary(UnOp::UnDeref, _));
|
||
|
||
let lint_span = if other_gets_derefed {
|
||
expr.span.to(other.span)
|
||
} else {
|
||
expr.span
|
||
};
|
||
|
||
span_lint_and_then(
|
||
cx,
|
||
CMP_OWNED,
|
||
lint_span,
|
||
"this creates an owned instance just for comparison",
|
||
|diag| {
|
||
// This also catches `PartialEq` implementations that call `to_owned`.
|
||
if other_gets_derefed {
|
||
diag.span_label(lint_span, "try implementing the comparison without allocating");
|
||
return;
|
||
}
|
||
|
||
let expr_snip;
|
||
let eq_impl;
|
||
if with_deref.is_implemented() {
|
||
expr_snip = format!("*{}", snip);
|
||
eq_impl = with_deref;
|
||
} else {
|
||
expr_snip = snip.to_string();
|
||
eq_impl = without_deref;
|
||
};
|
||
|
||
let span;
|
||
let hint;
|
||
if (eq_impl.ty_eq_other && left) || (eq_impl.other_eq_ty && !left) {
|
||
span = expr.span;
|
||
hint = expr_snip;
|
||
} else {
|
||
span = expr.span.to(other.span);
|
||
if eq_impl.ty_eq_other {
|
||
hint = format!("{} == {}", expr_snip, snippet(cx, other.span, ".."));
|
||
} else {
|
||
hint = format!("{} == {}", snippet(cx, other.span, ".."), expr_snip);
|
||
}
|
||
}
|
||
|
||
diag.span_suggestion(
|
||
span,
|
||
"try",
|
||
hint,
|
||
Applicability::MachineApplicable, // snippet
|
||
);
|
||
},
|
||
);
|
||
}
|
||
|
||
/// 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 {
|
||
get_parent_expr(cx, expr).map_or(true, |parent| match parent.kind {
|
||
ExprKind::Assign(_, ref rhs, _) | ExprKind::AssignOp(_, _, ref rhs) => SpanlessEq::new(cx).eq_expr(rhs, expr),
|
||
_ => is_used(cx, parent),
|
||
})
|
||
}
|
||
|
||
/// Tests whether an expression is in a macro expansion (e.g., something
|
||
/// generated by `#[derive(...)]` or the like).
|
||
fn in_attributes_expansion(expr: &Expr<'_>) -> bool {
|
||
use rustc_span::hygiene::MacroKind;
|
||
if expr.span.from_expansion() {
|
||
let data = expr.span.ctxt().outer_expn_data();
|
||
matches!(data.kind, ExpnKind::Macro(MacroKind::Attr, _))
|
||
} else {
|
||
false
|
||
}
|
||
}
|
||
|
||
/// Tests whether `res` is a variable defined outside a macro.
|
||
fn non_macro_local(cx: &LateContext<'_>, res: def::Res) -> bool {
|
||
if let def::Res::Local(id) = res {
|
||
!cx.tcx.hir().span(id).from_expansion()
|
||
} else {
|
||
false
|
||
}
|
||
}
|
||
|
||
fn check_cast(cx: &LateContext<'_>, span: Span, e: &Expr<'_>, ty: &hir::Ty<'_>) {
|
||
if_chain! {
|
||
if let TyKind::Ptr(ref mut_ty) = ty.kind;
|
||
if let ExprKind::Lit(ref lit) = e.kind;
|
||
if let LitKind::Int(0, _) = lit.node;
|
||
if !in_constant(cx, e.hir_id);
|
||
then {
|
||
let (msg, sugg_fn) = match mut_ty.mutbl {
|
||
Mutability::Mut => ("`0 as *mut _` detected", "std::ptr::null_mut"),
|
||
Mutability::Not => ("`0 as *const _` detected", "std::ptr::null"),
|
||
};
|
||
|
||
let (sugg, appl) = if let TyKind::Infer = mut_ty.ty.kind {
|
||
(format!("{}()", sugg_fn), Applicability::MachineApplicable)
|
||
} else if let Some(mut_ty_snip) = snippet_opt(cx, mut_ty.ty.span) {
|
||
(format!("{}::<{}>()", sugg_fn, mut_ty_snip), Applicability::MachineApplicable)
|
||
} else {
|
||
// `MaybeIncorrect` as type inference may not work with the suggested code
|
||
(format!("{}()", sugg_fn), Applicability::MaybeIncorrect)
|
||
};
|
||
span_lint_and_sugg(cx, ZERO_PTR, span, msg, "try", sugg, appl);
|
||
}
|
||
}
|
||
}
|
||
|
||
fn check_binary(
|
||
cx: &LateContext<'a>,
|
||
expr: &Expr<'_>,
|
||
cmp: &rustc_span::source_map::Spanned<rustc_hir::BinOpKind>,
|
||
left: &'a Expr<'_>,
|
||
right: &'a Expr<'_>,
|
||
) {
|
||
let op = cmp.node;
|
||
if op.is_comparison() {
|
||
check_nan(cx, left, expr);
|
||
check_nan(cx, right, expr);
|
||
check_to_owned(cx, left, right, true);
|
||
check_to_owned(cx, right, left, false);
|
||
}
|
||
if (op == BinOpKind::Eq || op == BinOpKind::Ne) && (is_float(cx, left) || is_float(cx, right)) {
|
||
if is_allowed(cx, left) || is_allowed(cx, right) {
|
||
return;
|
||
}
|
||
|
||
// Allow comparing the results of signum()
|
||
if is_signum(cx, left) && is_signum(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;
|
||
}
|
||
}
|
||
let is_comparing_arrays = is_array(cx, left) || is_array(cx, right);
|
||
let (lint, msg) = get_lint_and_message(
|
||
is_named_constant(cx, left) || is_named_constant(cx, right),
|
||
is_comparing_arrays,
|
||
);
|
||
span_lint_and_then(cx, lint, expr.span, msg, |diag| {
|
||
let lhs = Sugg::hir(cx, left, "..");
|
||
let rhs = Sugg::hir(cx, right, "..");
|
||
|
||
if !is_comparing_arrays {
|
||
diag.span_suggestion(
|
||
expr.span,
|
||
"consider comparing them within some margin of error",
|
||
format!(
|
||
"({}).abs() {} error_margin",
|
||
lhs - rhs,
|
||
if op == BinOpKind::Eq { '<' } else { '>' }
|
||
),
|
||
Applicability::HasPlaceholders, // snippet
|
||
);
|
||
}
|
||
diag.note("`f32::EPSILON` and `f64::EPSILON` are available for the `error_margin`");
|
||
});
|
||
} else if op == BinOpKind::Rem {
|
||
if is_integer_const(cx, right, 1) {
|
||
span_lint(cx, MODULO_ONE, expr.span, "any number modulo 1 will be 0");
|
||
}
|
||
|
||
if let ty::Int(ity) = cx.typeck_results().expr_ty(right).kind() {
|
||
if is_integer_const(cx, right, unsext(cx.tcx, -1, *ity)) {
|
||
span_lint(
|
||
cx,
|
||
MODULO_ONE,
|
||
expr.span,
|
||
"any number modulo -1 will panic/overflow or result in 0",
|
||
);
|
||
}
|
||
};
|
||
}
|
||
}
|