src/tools/clippy/clippy_lints/src/misc_early/mod.rs - toolchain/rustc - Git at Google

 mod builtin_type_shadow;
 mod double_neg;
 mod literal_suffix;
 mod mixed_case_hex_literals;
 mod redundant_at_rest_pattern;
 mod redundant_pattern;
 mod unneeded_field_pattern;
 mod unneeded_wildcard_pattern;
 mod zero_prefixed_literal;

 use clippy_utils::diagnostics::span_lint;
 use clippy_utils::source::snippet_opt;
 use rustc_ast::ast::{Expr, ExprKind, Generics, LitFloatType, LitIntType, LitKind, NodeId, Pat, PatKind};
 use rustc_ast::token;
 use rustc_ast::visit::FnKind;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
 use rustc_middle::lint::in_external_macro;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::Span;

 declare_clippy_lint! {
     /// ### What it does
     /// Checks for structure field patterns bound to wildcards.
     ///
     /// ### Why is this bad?
     /// Using `..` instead is shorter and leaves the focus on
     /// the fields that are actually bound.
     ///
     /// ### Example
     /// ```no_run
     /// # struct Foo {
     /// #     a: i32,
     /// #     b: i32,
     /// #     c: i32,
     /// # }
     /// let f = Foo { a: 0, b: 0, c: 0 };
     ///
     /// match f {
     ///     Foo { a: _, b: 0, .. } => {},
     ///     Foo { a: _, b: _, c: _ } => {},
     /// }
     /// ```
     ///
     /// Use instead:
     /// ```no_run
     /// # struct Foo {
     /// #     a: i32,
     /// #     b: i32,
     /// #     c: i32,
     /// # }
     /// let f = Foo { a: 0, b: 0, c: 0 };
     ///
     /// match f {
     ///     Foo { b: 0, .. } => {},
     ///     Foo { .. } => {},
     /// }
     /// ```
     #[clippy::version = "pre 1.29.0"]
     pub UNNEEDED_FIELD_PATTERN,
     restriction,
     "struct fields bound to a wildcard instead of using `..`"
 }

 declare_clippy_lint! {
     /// ### What it does
     /// Checks for function arguments having the similar names
     /// differing by an underscore.
     ///
     /// ### Why is this bad?
     /// It affects code readability.
     ///
     /// ### Example
     /// ```no_run
     /// fn foo(a: i32, _a: i32) {}
     /// ```
     ///
     /// Use instead:
     /// ```no_run
     /// fn bar(a: i32, _b: i32) {}
     /// ```
     #[clippy::version = "pre 1.29.0"]
     pub DUPLICATE_UNDERSCORE_ARGUMENT,
     style,
     "function arguments having names which only differ by an underscore"
 }

 declare_clippy_lint! {
     /// ### What it does
     /// Detects expressions of the form `--x`.
     ///
     /// ### Why is this bad?
     /// It can mislead C/C++ programmers to think `x` was
     /// decremented.
     ///
     /// ### Example
     /// ```no_run
     /// let mut x = 3;
     /// --x;
     /// ```
     #[clippy::version = "pre 1.29.0"]
     pub DOUBLE_NEG,
     style,
     "`--x`, which is a double negation of `x` and not a pre-decrement as in C/C++"
 }

 declare_clippy_lint! {
     /// ### What it does
     /// Warns on hexadecimal literals with mixed-case letter
     /// digits.
     ///
     /// ### Why is this bad?
     /// It looks confusing.
     ///
     /// ### Example
     /// ```no_run
     /// # let _ =
     /// 0x1a9BAcD
     /// # ;
     /// ```
     ///
     /// Use instead:
     /// ```no_run
     /// # let _ =
     /// 0x1A9BACD
     /// # ;
     /// ```
     #[clippy::version = "pre 1.29.0"]
     pub MIXED_CASE_HEX_LITERALS,
     style,
     "hex literals whose letter digits are not consistently upper- or lowercased"
 }

 declare_clippy_lint! {
     /// ### What it does
     /// Warns if literal suffixes are not separated by an
     /// underscore.
     /// To enforce unseparated literal suffix style,
     /// see the `separated_literal_suffix` lint.
     ///
     /// ### Why is this bad?
     /// Suffix style should be consistent.
     ///
     /// ### Example
     /// ```no_run
     /// # let _ =
     /// 123832i32
     /// # ;
     /// ```
     ///
     /// Use instead:
     /// ```no_run
     /// # let _ =
     /// 123832_i32
     /// # ;
     /// ```
     #[clippy::version = "pre 1.29.0"]
     pub UNSEPARATED_LITERAL_SUFFIX,
     restriction,
     "literals whose suffix is not separated by an underscore"
 }

 declare_clippy_lint! {
     /// ### What it does
     /// Warns if literal suffixes are separated by an underscore.
     /// To enforce separated literal suffix style,
     /// see the `unseparated_literal_suffix` lint.
     ///
     /// ### Why is this bad?
     /// Suffix style should be consistent.
     ///
     /// ### Example
     /// ```no_run
     /// # let _ =
     /// 123832_i32
     /// # ;
     /// ```
     ///
     /// Use instead:
     /// ```no_run
     /// # let _ =
     /// 123832i32
     /// # ;
     /// ```
     #[clippy::version = "1.58.0"]
     pub SEPARATED_LITERAL_SUFFIX,
     restriction,
     "literals whose suffix is separated by an underscore"
 }

 declare_clippy_lint! {
     /// ### What it does
     /// Warns if an integral constant literal starts with `0`.
     ///
     /// ### Why is this bad?
     /// In some languages (including the infamous C language
     /// and most of its
     /// family), this marks an octal constant. In Rust however, this is a decimal
     /// constant. This could
     /// be confusing for both the writer and a reader of the constant.
     ///
     /// ### Example
     ///
     /// In Rust:
     /// ```no_run
     /// fn main() {
     ///     let a = 0123;
     ///     println!("{}", a);
     /// }
     /// ```
     ///
     /// prints `123`, while in C:
     ///
     /// ```c
     /// #include <stdio.h>
     ///
     /// int main() {
     ///     int a = 0123;
     ///     printf("%d\n", a);
     /// }
     /// ```
     ///
     /// prints `83` (as `83 == 0o123` while `123 == 0o173`).
     #[clippy::version = "pre 1.29.0"]
     pub ZERO_PREFIXED_LITERAL,
     complexity,
     "integer literals starting with `0`"
 }

 declare_clippy_lint! {
     /// ### What it does
     /// Warns if a generic shadows a built-in type.
     ///
     /// ### Why is this bad?
     /// This gives surprising type errors.
     ///
     /// ### Example
     ///
     /// ```ignore
     /// impl<u32> Foo<u32> {
     ///     fn impl_func(&self) -> u32 {
     ///         42
     ///     }
     /// }
     /// ```
     #[clippy::version = "pre 1.29.0"]
     pub BUILTIN_TYPE_SHADOW,
     style,
     "shadowing a builtin type"
 }

 declare_clippy_lint! {
     /// ### 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.
     ///
     /// ### Example
     /// ```no_run
     /// # let v = Some("abc");
     /// match v {
     ///     Some(x) => (),
     ///     y @ _ => (),
     /// }
     /// ```
     ///
     /// Use instead:
     /// ```no_run
     /// # let v = Some("abc");
     /// match v {
     ///     Some(x) => (),
     ///     y => (),
     /// }
     /// ```
     #[clippy::version = "pre 1.29.0"]
     pub REDUNDANT_PATTERN,
     style,
     "using `name @ _` in a pattern"
 }

 declare_clippy_lint! {
     /// ### What it does
     /// Checks for tuple patterns with a wildcard
     /// pattern (`_`) is next to a rest pattern (`..`).
     ///
     /// _NOTE_: While `_, ..` means there is at least one element left, `..`
     /// means there are 0 or more elements left. This can make a difference
     /// when refactoring, but shouldn't result in errors in the refactored code,
     /// since the wildcard pattern isn't used anyway.
     ///
     /// ### Why is this bad?
     /// The wildcard pattern is unneeded as the rest pattern
     /// can match that element as well.
     ///
     /// ### Example
     /// ```no_run
     /// # struct TupleStruct(u32, u32, u32);
     /// # let t = TupleStruct(1, 2, 3);
     /// match t {
     ///     TupleStruct(0, .., _) => (),
     ///     _ => (),
     /// }
     /// ```
     ///
     /// Use instead:
     /// ```no_run
     /// # struct TupleStruct(u32, u32, u32);
     /// # let t = TupleStruct(1, 2, 3);
     /// match t {
     ///     TupleStruct(0, ..) => (),
     ///     _ => (),
     /// }
     /// ```
     #[clippy::version = "1.40.0"]
     pub UNNEEDED_WILDCARD_PATTERN,
     complexity,
     "tuple patterns with a wildcard pattern (`_`) is next to a rest pattern (`..`)"
 }

 declare_clippy_lint! {
     /// ### What it does
     /// Checks for `[all @ ..]` patterns.
     ///
     /// ### Why is this bad?
     /// In all cases, `all` works fine and can often make code simpler, as you possibly won't need
     /// to convert from say a `Vec` to a slice by dereferencing.
     ///
     /// ### Example
     /// ```rust,ignore
     /// if let [all @ ..] = &*v {
     ///     // NOTE: Type is a slice here
     ///     println!("all elements: {all:#?}");
     /// }
     /// ```
     /// Use instead:
     /// ```rust,ignore
     /// if let all = v {
     ///     // NOTE: Type is a `Vec` here
     ///     println!("all elements: {all:#?}");
     /// }
     /// // or
     /// println!("all elements: {v:#?}");
     /// ```
     #[clippy::version = "1.72.0"]
     pub REDUNDANT_AT_REST_PATTERN,
     complexity,
     "checks for `[all @ ..]` where `all` would suffice"
 }

 declare_lint_pass!(MiscEarlyLints => [
     UNNEEDED_FIELD_PATTERN,
     DUPLICATE_UNDERSCORE_ARGUMENT,
     DOUBLE_NEG,
     MIXED_CASE_HEX_LITERALS,
     UNSEPARATED_LITERAL_SUFFIX,
     SEPARATED_LITERAL_SUFFIX,
     ZERO_PREFIXED_LITERAL,
     BUILTIN_TYPE_SHADOW,
     REDUNDANT_PATTERN,
     UNNEEDED_WILDCARD_PATTERN,
     REDUNDANT_AT_REST_PATTERN,
 ]);

 impl EarlyLintPass for MiscEarlyLints {
     fn check_generics(&mut self, cx: &EarlyContext<'_>, gen: &Generics) {
         for param in &gen.params {
             builtin_type_shadow::check(cx, param);
         }
     }

     fn check_pat(&mut self, cx: &EarlyContext<'_>, pat: &Pat) {
         if in_external_macro(cx.sess(), pat.span) {
             return;
         }

         unneeded_field_pattern::check(cx, pat);
         redundant_pattern::check(cx, pat);
         redundant_at_rest_pattern::check(cx, pat);
         unneeded_wildcard_pattern::check(cx, pat);
     }

     fn check_fn(&mut self, cx: &EarlyContext<'_>, fn_kind: FnKind<'_>, _: Span, _: NodeId) {
         let mut registered_names: FxHashMap<String, Span> = FxHashMap::default();

         for arg in &fn_kind.decl().inputs {
             if let PatKind::Ident(_, ident, None) = arg.pat.kind {
                 let arg_name = ident.to_string();

                 if let Some(arg_name) = arg_name.strip_prefix('_') {
                     if let Some(correspondence) = registered_names.get(arg_name) {
                         span_lint(
                             cx,
                             DUPLICATE_UNDERSCORE_ARGUMENT,
                             *correspondence,
                             &format!(
                                 "`{arg_name}` already exists, having another argument having almost the same \
                                  name makes code comprehension and documentation more difficult"
                             ),
                         );
                     }
                 } else {
                     registered_names.insert(arg_name, arg.pat.span);
                 }
             }
         }
     }

     fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
         if in_external_macro(cx.sess(), expr.span) {
             return;
         }

         if let ExprKind::Lit(lit) = expr.kind {
             MiscEarlyLints::check_lit(cx, lit, expr.span);
         }
         double_neg::check(cx, expr);
     }
 }

 impl MiscEarlyLints {
     fn check_lit(cx: &EarlyContext<'_>, lit: token::Lit, span: Span) {
         // We test if first character in snippet is a number, because the snippet could be an expansion
         // from a built-in macro like `line!()` or a proc-macro like `#[wasm_bindgen]`.
         // Note that this check also covers special case that `line!()` is eagerly expanded by compiler.
         // See <https://github.com/rust-lang/rust-clippy/issues/4507> for a regression.
         // FIXME: Find a better way to detect those cases.
         let lit_snip = match snippet_opt(cx, span) {
             Some(snip) if snip.chars().next().map_or(false, |c| c.is_ascii_digit()) => snip,
             _ => return,
         };

         let lit_kind = LitKind::from_token_lit(lit);
         if let Ok(LitKind::Int(value, lit_int_type)) = lit_kind {
             let suffix = match lit_int_type {
                 LitIntType::Signed(ty) => ty.name_str(),
                 LitIntType::Unsigned(ty) => ty.name_str(),
                 LitIntType::Unsuffixed => "",
             };
             literal_suffix::check(cx, span, &lit_snip, suffix, "integer");
             if lit_snip.starts_with("0x") {
                 mixed_case_hex_literals::check(cx, span, suffix, &lit_snip);
             } else if lit_snip.starts_with("0b") || lit_snip.starts_with("0o") {
                 // nothing to do
             } else if value != 0 && lit_snip.starts_with('0') {
                 zero_prefixed_literal::check(cx, span, &lit_snip);
             }
         } else if let Ok(LitKind::Float(_, LitFloatType::Suffixed(float_ty))) = lit_kind {
             let suffix = float_ty.name_str();
             literal_suffix::check(cx, span, &lit_snip, suffix, "float");
         }
     }
 }
	mod builtin_type_shadow;
	mod double_neg;
	mod literal_suffix;
	mod mixed_case_hex_literals;
	mod redundant_at_rest_pattern;
	mod redundant_pattern;
	mod unneeded_field_pattern;
	mod unneeded_wildcard_pattern;
	mod zero_prefixed_literal;

	use clippy_utils::diagnostics::span_lint;
	use clippy_utils::source::snippet_opt;
	use rustc_ast::ast::{Expr, ExprKind, Generics, LitFloatType, LitIntType, LitKind, NodeId, Pat, PatKind};
	use rustc_ast::token;
	use rustc_ast::visit::FnKind;
	use rustc_data_structures::fx::FxHashMap;
	use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
	use rustc_middle::lint::in_external_macro;
	use rustc_session::{declare_lint_pass, declare_tool_lint};
	use rustc_span::Span;

	declare_clippy_lint! {
	/// ### What it does
	/// Checks for structure field patterns bound to wildcards.
	///
	/// ### Why is this bad?
	/// Using `..` instead is shorter and leaves the focus on
	/// the fields that are actually bound.
	///
	/// ### Example
	/// ```no_run
	/// # struct Foo {
	/// # a: i32,
	/// # b: i32,
	/// # c: i32,
	/// # }
	/// let f = Foo { a: 0, b: 0, c: 0 };
	///
	/// match f {
	/// Foo { a: _, b: 0, .. } => {},
	/// Foo { a: _, b: _, c: _ } => {},
	/// }
	/// ```
	///
	/// Use instead:
	/// ```no_run
	/// # struct Foo {
	/// # a: i32,
	/// # b: i32,
	/// # c: i32,
	/// # }
	/// let f = Foo { a: 0, b: 0, c: 0 };
	///
	/// match f {
	/// Foo { b: 0, .. } => {},
	/// Foo { .. } => {},
	/// }
	/// ```
	#[clippy::version = "pre 1.29.0"]
	pub UNNEEDED_FIELD_PATTERN,
	restriction,
	"struct fields bound to a wildcard instead of using `..`"
	}

	declare_clippy_lint! {
	/// ### What it does
	/// Checks for function arguments having the similar names
	/// differing by an underscore.
	///
	/// ### Why is this bad?
	/// It affects code readability.
	///
	/// ### Example
	/// ```no_run
	/// fn foo(a: i32, _a: i32) {}
	/// ```
	///
	/// Use instead:
	/// ```no_run
	/// fn bar(a: i32, _b: i32) {}
	/// ```
	#[clippy::version = "pre 1.29.0"]
	pub DUPLICATE_UNDERSCORE_ARGUMENT,
	style,
	"function arguments having names which only differ by an underscore"
	}

	declare_clippy_lint! {
	/// ### What it does
	/// Detects expressions of the form `--x`.
	///
	/// ### Why is this bad?
	/// It can mislead C/C++ programmers to think `x` was
	/// decremented.
	///
	/// ### Example
	/// ```no_run
	/// let mut x = 3;
	/// --x;
	/// ```
	#[clippy::version = "pre 1.29.0"]
	pub DOUBLE_NEG,
	style,
	"`--x`, which is a double negation of `x` and not a pre-decrement as in C/C++"
	}

	declare_clippy_lint! {
	/// ### What it does
	/// Warns on hexadecimal literals with mixed-case letter
	/// digits.
	///
	/// ### Why is this bad?
	/// It looks confusing.
	///
	/// ### Example
	/// ```no_run
	/// # let _ =
	/// 0x1a9BAcD
	/// # ;
	/// ```
	///
	/// Use instead:
	/// ```no_run
	/// # let _ =
	/// 0x1A9BACD
	/// # ;
	/// ```
	#[clippy::version = "pre 1.29.0"]
	pub MIXED_CASE_HEX_LITERALS,
	style,
	"hex literals whose letter digits are not consistently upper- or lowercased"
	}

	declare_clippy_lint! {
	/// ### What it does
	/// Warns if literal suffixes are not separated by an
	/// underscore.
	/// To enforce unseparated literal suffix style,
	/// see the `separated_literal_suffix` lint.
	///
	/// ### Why is this bad?
	/// Suffix style should be consistent.
	///
	/// ### Example
	/// ```no_run
	/// # let _ =
	/// 123832i32
	/// # ;
	/// ```
	///
	/// Use instead:
	/// ```no_run
	/// # let _ =
	/// 123832_i32
	/// # ;
	/// ```
	#[clippy::version = "pre 1.29.0"]
	pub UNSEPARATED_LITERAL_SUFFIX,
	restriction,
	"literals whose suffix is not separated by an underscore"
	}

	declare_clippy_lint! {
	/// ### What it does
	/// Warns if literal suffixes are separated by an underscore.
	/// To enforce separated literal suffix style,
	/// see the `unseparated_literal_suffix` lint.
	///
	/// ### Why is this bad?
	/// Suffix style should be consistent.
	///
	/// ### Example
	/// ```no_run
	/// # let _ =
	/// 123832_i32
	/// # ;
	/// ```
	///
	/// Use instead:
	/// ```no_run
	/// # let _ =
	/// 123832i32
	/// # ;
	/// ```
	#[clippy::version = "1.58.0"]
	pub SEPARATED_LITERAL_SUFFIX,
	restriction,
	"literals whose suffix is separated by an underscore"
	}

	declare_clippy_lint! {
	/// ### What it does
	/// Warns if an integral constant literal starts with `0`.
	///
	/// ### Why is this bad?
	/// In some languages (including the infamous C language
	/// and most of its
	/// family), this marks an octal constant. In Rust however, this is a decimal
	/// constant. This could
	/// be confusing for both the writer and a reader of the constant.
	///
	/// ### Example
	///
	/// In Rust:
	/// ```no_run
	/// fn main() {
	/// let a = 0123;
	/// println!("{}", a);
	/// }
	/// ```
	///
	/// prints `123`, while in C:
	///
	/// ```c
	/// #include <stdio.h>
	///
	/// int main() {
	/// int a = 0123;
	/// printf("%d\n", a);
	/// }
	/// ```
	///
	/// prints `83` (as `83 == 0o123` while `123 == 0o173`).
	#[clippy::version = "pre 1.29.0"]
	pub ZERO_PREFIXED_LITERAL,
	complexity,
	"integer literals starting with `0`"
	}

	declare_clippy_lint! {
	/// ### What it does
	/// Warns if a generic shadows a built-in type.
	///
	/// ### Why is this bad?
	/// This gives surprising type errors.
	///
	/// ### Example
	///
	/// ```ignore
	/// impl<u32> Foo<u32> {
	/// fn impl_func(&self) -> u32 {
	/// 42
	/// }
	/// }
	/// ```
	#[clippy::version = "pre 1.29.0"]
	pub BUILTIN_TYPE_SHADOW,
	style,
	"shadowing a builtin type"
	}

	declare_clippy_lint! {
	/// ### 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.
	///
	/// ### Example
	/// ```no_run
	/// # let v = Some("abc");
	/// match v {
	/// Some(x) => (),
	/// y @ _ => (),
	/// }
	/// ```
	///
	/// Use instead:
	/// ```no_run
	/// # let v = Some("abc");
	/// match v {
	/// Some(x) => (),
	/// y => (),
	/// }
	/// ```
	#[clippy::version = "pre 1.29.0"]
	pub REDUNDANT_PATTERN,
	style,
	"using `name @ _` in a pattern"
	}

	declare_clippy_lint! {
	/// ### What it does
	/// Checks for tuple patterns with a wildcard
	/// pattern (`_`) is next to a rest pattern (`..`).
	///
	/// _NOTE_: While `_, ..` means there is at least one element left, `..`
	/// means there are 0 or more elements left. This can make a difference
	/// when refactoring, but shouldn't result in errors in the refactored code,
	/// since the wildcard pattern isn't used anyway.
	///
	/// ### Why is this bad?
	/// The wildcard pattern is unneeded as the rest pattern
	/// can match that element as well.
	///
	/// ### Example
	/// ```no_run
	/// # struct TupleStruct(u32, u32, u32);
	/// # let t = TupleStruct(1, 2, 3);
	/// match t {
	/// TupleStruct(0, .., _) => (),
	/// _ => (),
	/// }
	/// ```
	///
	/// Use instead:
	/// ```no_run
	/// # struct TupleStruct(u32, u32, u32);
	/// # let t = TupleStruct(1, 2, 3);
	/// match t {
	/// TupleStruct(0, ..) => (),
	/// _ => (),
	/// }
	/// ```
	#[clippy::version = "1.40.0"]
	pub UNNEEDED_WILDCARD_PATTERN,
	complexity,
	"tuple patterns with a wildcard pattern (`_`) is next to a rest pattern (`..`)"
	}

	declare_clippy_lint! {
	/// ### What it does
	/// Checks for `[all @ ..]` patterns.
	///
	/// ### Why is this bad?
	/// In all cases, `all` works fine and can often make code simpler, as you possibly won't need
	/// to convert from say a `Vec` to a slice by dereferencing.
	///
	/// ### Example
	/// ```rust,ignore
	/// if let [all @ ..] = &*v {
	/// // NOTE: Type is a slice here
	/// println!("all elements: {all:#?}");
	/// }
	/// ```
	/// Use instead:
	/// ```rust,ignore
	/// if let all = v {
	/// // NOTE: Type is a `Vec` here
	/// println!("all elements: {all:#?}");
	/// }
	/// // or
	/// println!("all elements: {v:#?}");
	/// ```
	#[clippy::version = "1.72.0"]
	pub REDUNDANT_AT_REST_PATTERN,
	complexity,
	"checks for `[all @ ..]` where `all` would suffice"
	}

	declare_lint_pass!(MiscEarlyLints => [
	UNNEEDED_FIELD_PATTERN,
	DUPLICATE_UNDERSCORE_ARGUMENT,
	DOUBLE_NEG,
	MIXED_CASE_HEX_LITERALS,
	UNSEPARATED_LITERAL_SUFFIX,
	SEPARATED_LITERAL_SUFFIX,
	ZERO_PREFIXED_LITERAL,
	BUILTIN_TYPE_SHADOW,
	REDUNDANT_PATTERN,
	UNNEEDED_WILDCARD_PATTERN,
	REDUNDANT_AT_REST_PATTERN,
	]);

	impl EarlyLintPass for MiscEarlyLints {
	fn check_generics(&mut self, cx: &EarlyContext<'_>, gen: &Generics) {
	for param in &gen.params {
	builtin_type_shadow::check(cx, param);
	}
	}

	fn check_pat(&mut self, cx: &EarlyContext<'_>, pat: &Pat) {
	if in_external_macro(cx.sess(), pat.span) {
	return;
	}

	unneeded_field_pattern::check(cx, pat);
	redundant_pattern::check(cx, pat);
	redundant_at_rest_pattern::check(cx, pat);
	unneeded_wildcard_pattern::check(cx, pat);
	}

	fn check_fn(&mut self, cx: &EarlyContext<'_>, fn_kind: FnKind<'_>, _: Span, _: NodeId) {
	let mut registered_names: FxHashMap<String, Span> = FxHashMap::default();

	for arg in &fn_kind.decl().inputs {
	if let PatKind::Ident(_, ident, None) = arg.pat.kind {
	let arg_name = ident.to_string();

	if let Some(arg_name) = arg_name.strip_prefix('_') {
	if let Some(correspondence) = registered_names.get(arg_name) {
	span_lint(
	cx,
	DUPLICATE_UNDERSCORE_ARGUMENT,
	*correspondence,
	&format!(
	"`{arg_name}` already exists, having another argument having almost the same \
	name makes code comprehension and documentation more difficult"
	),
	);
	}
	} else {
	registered_names.insert(arg_name, arg.pat.span);
	}
	}
	}
	}

	fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
	if in_external_macro(cx.sess(), expr.span) {
	return;
	}

	if let ExprKind::Lit(lit) = expr.kind {
	MiscEarlyLints::check_lit(cx, lit, expr.span);
	}
	double_neg::check(cx, expr);
	}
	}

	impl MiscEarlyLints {
	fn check_lit(cx: &EarlyContext<'_>, lit: token::Lit, span: Span) {
	// We test if first character in snippet is a number, because the snippet could be an expansion
	// from a built-in macro like `line!()` or a proc-macro like `#[wasm_bindgen]`.
	// Note that this check also covers special case that `line!()` is eagerly expanded by compiler.
	// See <https://github.com/rust-lang/rust-clippy/issues/4507> for a regression.
	// FIXME: Find a better way to detect those cases.
	let lit_snip = match snippet_opt(cx, span) {
	Some(snip) if snip.chars().next().map_or(false, \|c\| c.is_ascii_digit()) => snip,
	_ => return,
	};

	let lit_kind = LitKind::from_token_lit(lit);
	if let Ok(LitKind::Int(value, lit_int_type)) = lit_kind {
	let suffix = match lit_int_type {
	LitIntType::Signed(ty) => ty.name_str(),
	LitIntType::Unsigned(ty) => ty.name_str(),
	LitIntType::Unsuffixed => "",
	};
	literal_suffix::check(cx, span, &lit_snip, suffix, "integer");
	if lit_snip.starts_with("0x") {
	mixed_case_hex_literals::check(cx, span, suffix, &lit_snip);
	} else if lit_snip.starts_with("0b") \|\| lit_snip.starts_with("0o") {
	// nothing to do
	} else if value != 0 && lit_snip.starts_with('0') {
	zero_prefixed_literal::check(cx, span, &lit_snip);
	}
	} else if let Ok(LitKind::Float(_, LitFloatType::Suffixed(float_ty))) = lit_kind {
	let suffix = float_ty.name_str();
	literal_suffix::check(cx, span, &lit_snip, suffix, "float");
	}
	}
	}