388 lines
11 KiB
Rust
388 lines
11 KiB
Rust
mod builtin_type_shadow;
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mod double_neg;
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mod literal_suffix;
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mod mixed_case_hex_literals;
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mod redundant_pattern;
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mod unneeded_field_pattern;
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mod unneeded_wildcard_pattern;
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mod zero_prefixed_literal;
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use clippy_utils::diagnostics::span_lint;
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use clippy_utils::source::snippet_opt;
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use rustc_ast::ast::{Expr, ExprKind, Generics, Lit, LitFloatType, LitIntType, LitKind, NodeId, Pat, PatKind};
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use rustc_ast::visit::FnKind;
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use rustc_data_structures::fx::FxHashMap;
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use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
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use rustc_middle::lint::in_external_macro;
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::source_map::Span;
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for structure field patterns bound to wildcards.
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///
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/// ### Why is this bad?
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/// Using `..` instead is shorter and leaves the focus on
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/// the fields that are actually bound.
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///
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/// ### Example
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/// ```rust
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/// # struct Foo {
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/// # a: i32,
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/// # b: i32,
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/// # c: i32,
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/// # }
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/// let f = Foo { a: 0, b: 0, c: 0 };
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///
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/// // Bad
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/// match f {
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/// Foo { a: _, b: 0, .. } => {},
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/// Foo { a: _, b: _, c: _ } => {},
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/// }
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///
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/// // Good
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/// match f {
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/// Foo { b: 0, .. } => {},
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/// Foo { .. } => {},
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/// }
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub UNNEEDED_FIELD_PATTERN,
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restriction,
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"struct fields bound to a wildcard instead of using `..`"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for function arguments having the similar names
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/// differing by an underscore.
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///
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/// ### Why is this bad?
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/// It affects code readability.
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///
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/// ### Example
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/// ```rust
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/// // Bad
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/// fn foo(a: i32, _a: i32) {}
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///
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/// // Good
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/// fn bar(a: i32, _b: i32) {}
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub DUPLICATE_UNDERSCORE_ARGUMENT,
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style,
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"function arguments having names which only differ by an underscore"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Detects expressions of the form `--x`.
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///
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/// ### Why is this bad?
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/// It can mislead C/C++ programmers to think `x` was
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/// decremented.
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///
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/// ### Example
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/// ```rust
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/// let mut x = 3;
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/// --x;
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub DOUBLE_NEG,
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style,
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"`--x`, which is a double negation of `x` and not a pre-decrement as in C/C++"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Warns on hexadecimal literals with mixed-case letter
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/// digits.
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///
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/// ### Why is this bad?
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/// It looks confusing.
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///
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/// ### Example
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/// ```rust
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/// // Bad
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/// let y = 0x1a9BAcD;
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///
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/// // Good
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/// let y = 0x1A9BACD;
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub MIXED_CASE_HEX_LITERALS,
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style,
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"hex literals whose letter digits are not consistently upper- or lowercased"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Warns if literal suffixes are not separated by an
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/// underscore.
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/// To enforce unseparated literal suffix style,
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/// see the `separated_literal_suffix` lint.
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///
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/// ### Why is this bad?
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/// Suffix style should be consistent.
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///
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/// ### Example
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/// ```rust
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/// // Bad
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/// let y = 123832i32;
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///
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/// // Good
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/// let y = 123832_i32;
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub UNSEPARATED_LITERAL_SUFFIX,
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restriction,
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"literals whose suffix is not separated by an underscore"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Warns if literal suffixes are separated by an underscore.
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/// To enforce separated literal suffix style,
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/// see the `unseparated_literal_suffix` lint.
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///
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/// ### Why is this bad?
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/// Suffix style should be consistent.
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///
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/// ### Example
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/// ```rust
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/// // Bad
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/// let y = 123832_i32;
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///
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/// // Good
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/// let y = 123832i32;
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/// ```
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#[clippy::version = "1.58.0"]
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pub SEPARATED_LITERAL_SUFFIX,
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restriction,
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"literals whose suffix is separated by an underscore"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Warns if an integral constant literal starts with `0`.
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///
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/// ### Why is this bad?
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/// In some languages (including the infamous C language
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/// and most of its
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/// family), this marks an octal constant. In Rust however, this is a decimal
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/// constant. This could
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/// be confusing for both the writer and a reader of the constant.
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///
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/// ### Example
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///
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/// In Rust:
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/// ```rust
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/// fn main() {
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/// let a = 0123;
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/// println!("{}", a);
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/// }
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/// ```
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///
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/// prints `123`, while in C:
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///
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/// ```c
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/// #include <stdio.h>
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///
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/// int main() {
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/// int a = 0123;
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/// printf("%d\n", a);
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/// }
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/// ```
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///
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/// prints `83` (as `83 == 0o123` while `123 == 0o173`).
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#[clippy::version = "pre 1.29.0"]
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pub ZERO_PREFIXED_LITERAL,
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complexity,
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"integer literals starting with `0`"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Warns if a generic shadows a built-in type.
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///
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/// ### Why is this bad?
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/// This gives surprising type errors.
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///
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/// ### Example
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///
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/// ```ignore
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/// impl<u32> Foo<u32> {
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/// fn impl_func(&self) -> u32 {
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/// 42
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/// }
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/// }
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub BUILTIN_TYPE_SHADOW,
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style,
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"shadowing a builtin type"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for patterns in the form `name @ _`.
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///
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/// ### Why is this bad?
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/// It's almost always more readable to just use direct
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/// bindings.
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///
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/// ### Example
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/// ```rust
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/// # let v = Some("abc");
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///
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/// // Bad
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/// match v {
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/// Some(x) => (),
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/// y @ _ => (),
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/// }
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///
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/// // Good
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/// match v {
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/// Some(x) => (),
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/// y => (),
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/// }
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub REDUNDANT_PATTERN,
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style,
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"using `name @ _` in a pattern"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for tuple patterns with a wildcard
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/// pattern (`_`) is next to a rest pattern (`..`).
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///
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/// _NOTE_: While `_, ..` means there is at least one element left, `..`
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/// means there are 0 or more elements left. This can make a difference
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/// when refactoring, but shouldn't result in errors in the refactored code,
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/// since the wildcard pattern isn't used anyway.
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/// ### Why is this bad?
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/// The wildcard pattern is unneeded as the rest pattern
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/// can match that element as well.
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///
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/// ### Example
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/// ```rust
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/// # struct TupleStruct(u32, u32, u32);
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/// # let t = TupleStruct(1, 2, 3);
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/// // Bad
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/// match t {
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/// TupleStruct(0, .., _) => (),
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/// _ => (),
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/// }
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///
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/// // Good
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/// match t {
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/// TupleStruct(0, ..) => (),
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/// _ => (),
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/// }
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/// ```
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#[clippy::version = "1.40.0"]
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pub UNNEEDED_WILDCARD_PATTERN,
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complexity,
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"tuple patterns with a wildcard pattern (`_`) is next to a rest pattern (`..`)"
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}
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declare_lint_pass!(MiscEarlyLints => [
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UNNEEDED_FIELD_PATTERN,
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DUPLICATE_UNDERSCORE_ARGUMENT,
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DOUBLE_NEG,
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MIXED_CASE_HEX_LITERALS,
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UNSEPARATED_LITERAL_SUFFIX,
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SEPARATED_LITERAL_SUFFIX,
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ZERO_PREFIXED_LITERAL,
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BUILTIN_TYPE_SHADOW,
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REDUNDANT_PATTERN,
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UNNEEDED_WILDCARD_PATTERN,
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]);
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impl EarlyLintPass for MiscEarlyLints {
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fn check_generics(&mut self, cx: &EarlyContext<'_>, gen: &Generics) {
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for param in &gen.params {
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builtin_type_shadow::check(cx, param);
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}
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}
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fn check_pat(&mut self, cx: &EarlyContext<'_>, pat: &Pat) {
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unneeded_field_pattern::check(cx, pat);
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redundant_pattern::check(cx, pat);
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unneeded_wildcard_pattern::check(cx, pat);
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}
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fn check_fn(&mut self, cx: &EarlyContext<'_>, fn_kind: FnKind<'_>, _: Span, _: NodeId) {
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let mut registered_names: FxHashMap<String, Span> = FxHashMap::default();
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for arg in &fn_kind.decl().inputs {
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if let PatKind::Ident(_, ident, None) = arg.pat.kind {
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let arg_name = ident.to_string();
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if let Some(arg_name) = arg_name.strip_prefix('_') {
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if let Some(correspondence) = registered_names.get(arg_name) {
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span_lint(
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cx,
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DUPLICATE_UNDERSCORE_ARGUMENT,
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*correspondence,
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&format!(
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"`{}` already exists, having another argument having almost the same \
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name makes code comprehension and documentation more difficult",
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arg_name
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),
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);
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}
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} else {
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registered_names.insert(arg_name, arg.pat.span);
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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: &EarlyContext<'_>, expr: &Expr) {
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if in_external_macro(cx.sess(), expr.span) {
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return;
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}
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if let ExprKind::Lit(ref lit) = expr.kind {
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MiscEarlyLints::check_lit(cx, lit);
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}
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double_neg::check(cx, expr);
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}
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}
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impl MiscEarlyLints {
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fn check_lit(cx: &EarlyContext<'_>, lit: &Lit) {
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// We test if first character in snippet is a number, because the snippet could be an expansion
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// from a built-in macro like `line!()` or a proc-macro like `#[wasm_bindgen]`.
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// Note that this check also covers special case that `line!()` is eagerly expanded by compiler.
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// See <https://github.com/rust-lang/rust-clippy/issues/4507> for a regression.
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// FIXME: Find a better way to detect those cases.
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let lit_snip = match snippet_opt(cx, lit.span) {
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Some(snip) if snip.chars().next().map_or(false, |c| c.is_digit(10)) => snip,
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_ => return,
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};
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if let LitKind::Int(value, lit_int_type) = lit.kind {
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let suffix = match lit_int_type {
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LitIntType::Signed(ty) => ty.name_str(),
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LitIntType::Unsigned(ty) => ty.name_str(),
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LitIntType::Unsuffixed => "",
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};
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literal_suffix::check(cx, lit, &lit_snip, suffix, "integer");
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if lit_snip.starts_with("0x") {
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mixed_case_hex_literals::check(cx, lit, suffix, &lit_snip);
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} else if lit_snip.starts_with("0b") || lit_snip.starts_with("0o") {
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// nothing to do
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} else if value != 0 && lit_snip.starts_with('0') {
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zero_prefixed_literal::check(cx, lit, &lit_snip);
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}
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} else if let LitKind::Float(_, LitFloatType::Suffixed(float_ty)) = lit.kind {
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let suffix = float_ty.name_str();
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literal_suffix::check(cx, lit, &lit_snip, suffix, "float");
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}
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}
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}
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