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Auto merge of #7166 - TaKO8Ki:refactor_misc_early_module, r=llogiq

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Refactor: arrange lints in misc_early module

This PR arranges misc_early lints so that they can be accessed more easily.
Basically, I refactored them following the instruction described in #6680.

cc: `@Y-Nak,` `@flip1995,` `@magurotuna`

changelog: Move lints in misc_early module into their own modules.
This commit is contained in:
bors 2021-05-06 07:46:52 +00:00
commit 7191675ab1
12 changed files with 636 additions and 571 deletions
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569
clippy_lints/src/misc_early.rs
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@ -1,569 +0,0 @@
use clippy_utils::diagnostics::{span_lint, span_lint_and_help, span_lint_and_sugg, span_lint_and_then};
use clippy_utils::source::snippet_opt;
use rustc_ast::ast::{
BindingMode, Expr, ExprKind, GenericParamKind, Generics, Lit, LitFloatType, LitIntType, LitKind, Mutability,
NodeId, Pat, PatKind, UnOp,
};
use rustc_ast::visit::FnKind;
use rustc_data_structures::fx::FxHashMap;
use rustc_errors::Applicability;
use rustc_hir::PrimTy;
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::source_map::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.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// # struct Foo {
/// # a: i32,
/// # b: i32,
/// # c: i32,
/// # }
/// let f = Foo { a: 0, b: 0, c: 0 };
///
/// // Bad
/// match f {
/// Foo { a: _, b: 0, .. } => {},
/// Foo { a: _, b: _, c: _ } => {},
/// }
///
/// // Good
/// match f {
/// Foo { b: 0, .. } => {},
/// Foo { .. } => {},
/// }
/// ```
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.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// // Bad
/// fn foo(a: i32, _a: i32) {}
///
/// // Good
/// fn bar(a: i32, _b: i32) {}
/// ```
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.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// let mut x = 3;
/// --x;
/// ```
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.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// // Bad
/// let y = 0x1a9BAcD;
///
/// // Good
/// let y = 0x1A9BACD;
/// ```
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.
///
/// **Why is this bad?** It is much less readable.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// // Bad
/// let y = 123832i32;
///
/// // Good
/// let y = 123832_i32;
/// ```
pub UNSEPARATED_LITERAL_SUFFIX,
pedantic,
"literals whose suffix is not 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.
///
/// **Known problems:** None.
///
/// **Example:**
///
/// In Rust:
/// ```rust
/// 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`).
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.
///
/// **Known problems:** None.
///
/// **Example:**
///
/// ```ignore
/// impl<u32> Foo<u32> {
/// fn impl_func(&self) -> u32 {
/// 42
/// }
/// }
/// ```
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.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// # let v = Some("abc");
///
/// // Bad
/// match v {
/// Some(x) => (),
/// y @ _ => (),
/// }
///
/// // Good
/// match v {
/// Some(x) => (),
/// y => (),
/// }
/// ```
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.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// # struct TupleStruct(u32, u32, u32);
/// # let t = TupleStruct(1, 2, 3);
/// // Bad
/// match t {
/// TupleStruct(0, .., _) => (),
/// _ => (),
/// }
///
/// // Good
/// match t {
/// TupleStruct(0, ..) => (),
/// _ => (),
/// }
/// ```
pub UNNEEDED_WILDCARD_PATTERN,
complexity,
"tuple patterns with a wildcard pattern (`_`) is next to a rest pattern (`..`)"
}
declare_lint_pass!(MiscEarlyLints => [
UNNEEDED_FIELD_PATTERN,
DUPLICATE_UNDERSCORE_ARGUMENT,
DOUBLE_NEG,
MIXED_CASE_HEX_LITERALS,
UNSEPARATED_LITERAL_SUFFIX,
ZERO_PREFIXED_LITERAL,
BUILTIN_TYPE_SHADOW,
REDUNDANT_PATTERN,
UNNEEDED_WILDCARD_PATTERN,
]);
impl EarlyLintPass for MiscEarlyLints {
fn check_generics(&mut self, cx: &EarlyContext<'_>, gen: &Generics) {
for param in &gen.params {
if let GenericParamKind::Type { .. } = param.kind {
if let Some(prim_ty) = PrimTy::from_name(param.ident.name) {
span_lint(
cx,
BUILTIN_TYPE_SHADOW,
param.ident.span,
&format!("this generic shadows the built-in type `{}`", prim_ty.name()),
);
}
}
}
}
fn check_pat(&mut self, cx: &EarlyContext<'_>, pat: &Pat) {
if let PatKind::Struct(ref npat, ref pfields, _) = pat.kind {
let mut wilds = 0;
let type_name = npat
.segments
.last()
.expect("A path must have at least one segment")
.ident
.name;
for field in pfields {
if let PatKind::Wild = field.pat.kind {
wilds += 1;
}
}
if !pfields.is_empty() && wilds == pfields.len() {
span_lint_and_help(
cx,
UNNEEDED_FIELD_PATTERN,
pat.span,
"all the struct fields are matched to a wildcard pattern, consider using `..`",
None,
&format!("try with `{} {{ .. }}` instead", type_name),
);
return;
}
if wilds > 0 {
for field in pfields {
if let PatKind::Wild = field.pat.kind {
wilds -= 1;
if wilds > 0 {
span_lint(
cx,
UNNEEDED_FIELD_PATTERN,
field.span,
"you matched a field with a wildcard pattern, consider using `..` instead",
);
} else {
let mut normal = vec![];
for field in pfields {
match field.pat.kind {
PatKind::Wild => {},
_ => {
if let Ok(n) = cx.sess().source_map().span_to_snippet(field.span) {
normal.push(n);
}
},
}
}
span_lint_and_help(
cx,
UNNEEDED_FIELD_PATTERN,
field.span,
"you matched a field with a wildcard pattern, consider using `..` \
instead",
None,
&format!("try with `{} {{ {}, .. }}`", type_name, normal[..].join(", ")),
);
}
}
}
}
}
if let PatKind::Ident(left, ident, Some(ref right)) = pat.kind {
let left_binding = match left {
BindingMode::ByRef(Mutability::Mut) => "ref mut ",
BindingMode::ByRef(Mutability::Not) => "ref ",
BindingMode::ByValue(..) => "",
};
if let PatKind::Wild = right.kind {
span_lint_and_sugg(
cx,
REDUNDANT_PATTERN,
pat.span,
&format!(
"the `{} @ _` pattern can be written as just `{}`",
ident.name, ident.name,
),
"try",
format!("{}{}", left_binding, ident.name),
Applicability::MachineApplicable,
);
}
}
check_unneeded_wildcard_pattern(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!(
"`{}` already exists, having another argument having almost the same \
name makes code comprehension and documentation more difficult",
arg_name
),
);
}
} 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;
}
match expr.kind {
ExprKind::Unary(UnOp::Neg, ref inner) => {
if let ExprKind::Unary(UnOp::Neg, _) = inner.kind {
span_lint(
cx,
DOUBLE_NEG,
expr.span,
"`--x` could be misinterpreted as pre-decrement by C programmers, is usually a no-op",
);
}
},
ExprKind::Lit(ref lit) => Self::check_lit(cx, lit),
_ => (),
}
}
}
impl MiscEarlyLints {
fn check_lit(cx: &EarlyContext<'_>, lit: &Lit) {
// 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, lit.span) {
Some(snip) if snip.chars().next().map_or(false, |c| c.is_digit(10)) => snip,
_ => return,
};
if let 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 => "",
};
let maybe_last_sep_idx = if let Some(val) = lit_snip.len().checked_sub(suffix.len() + 1) {
val
} else {
return; // It's useless so shouldn't lint.
};
// Do not lint when literal is unsuffixed.
if !suffix.is_empty() && lit_snip.as_bytes()[maybe_last_sep_idx] != b'_' {
span_lint_and_sugg(
cx,
UNSEPARATED_LITERAL_SUFFIX,
lit.span,
"integer type suffix should be separated by an underscore",
"add an underscore",
format!("{}_{}", &lit_snip[..=maybe_last_sep_idx], suffix),
Applicability::MachineApplicable,
);
}
if lit_snip.starts_with("0x") {
if maybe_last_sep_idx <= 2 {
// It's meaningless or causes range error.
return;
}
let mut seen = (false, false);
for ch in lit_snip.as_bytes()[2..=maybe_last_sep_idx].iter() {
match ch {
b'a'..=b'f' => seen.0 = true,
b'A'..=b'F' => seen.1 = true,
_ => {},
}
if seen.0 && seen.1 {
span_lint(
cx,
MIXED_CASE_HEX_LITERALS,
lit.span,
"inconsistent casing in hexadecimal literal",
);
break;
}
}
} else if lit_snip.starts_with("0b") || lit_snip.starts_with("0o") {
/* nothing to do */
} else if value != 0 && lit_snip.starts_with('0') {
span_lint_and_then(
cx,
ZERO_PREFIXED_LITERAL,
lit.span,
"this is a decimal constant",
|diag| {
diag.span_suggestion(
lit.span,
"if you mean to use a decimal constant, remove the `0` to avoid confusion",
lit_snip.trim_start_matches(|c| c == '_' || c == '0').to_string(),
Applicability::MaybeIncorrect,
);
diag.span_suggestion(
lit.span,
"if you mean to use an octal constant, use `0o`",
format!("0o{}", lit_snip.trim_start_matches(|c| c == '_' || c == '0')),
Applicability::MaybeIncorrect,
);
},
);
}
} else if let LitKind::Float(_, LitFloatType::Suffixed(float_ty)) = lit.kind {
let suffix = float_ty.name_str();
let maybe_last_sep_idx = if let Some(val) = lit_snip.len().checked_sub(suffix.len() + 1) {
val
} else {
return; // It's useless so shouldn't lint.
};
if lit_snip.as_bytes()[maybe_last_sep_idx] != b'_' {
span_lint_and_sugg(
cx,
UNSEPARATED_LITERAL_SUFFIX,
lit.span,
"float type suffix should be separated by an underscore",
"add an underscore",
format!("{}_{}", &lit_snip[..=maybe_last_sep_idx], suffix),
Applicability::MachineApplicable,
);
}
}
}
}
fn check_unneeded_wildcard_pattern(cx: &EarlyContext<'_>, pat: &Pat) {
if let PatKind::TupleStruct(_, ref patterns) | PatKind::Tuple(ref patterns) = pat.kind {
fn span_lint(cx: &EarlyContext<'_>, span: Span, only_one: bool) {
span_lint_and_sugg(
cx,
UNNEEDED_WILDCARD_PATTERN,
span,
if only_one {
"this pattern is unneeded as the `..` pattern can match that element"
} else {
"these patterns are unneeded as the `..` pattern can match those elements"
},
if only_one { "remove it" } else { "remove them" },
"".to_string(),
Applicability::MachineApplicable,
);
}
if let Some(rest_index) = patterns.iter().position(|pat| pat.is_rest()) {
if let Some((left_index, left_pat)) = patterns[..rest_index]
.iter()
.rev()
.take_while(|pat| matches!(pat.kind, PatKind::Wild))
.enumerate()
.last()
{
span_lint(cx, left_pat.span.until(patterns[rest_index].span), left_index == 0);
}
if let Some((right_index, right_pat)) = patterns[rest_index + 1..]
.iter()
.take_while(|pat| matches!(pat.kind, PatKind::Wild))
.enumerate()
.last()
{
span_lint(
cx,
patterns[rest_index].span.shrink_to_hi().to(right_pat.span),
right_index == 0,
);
}
}
}
}

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clippy_lints/src/misc_early/builtin_type_shadow.rs Normal file
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@ -0,0 +1,19 @@
use clippy_utils::diagnostics::span_lint;
use rustc_ast::ast::{GenericParam, GenericParamKind};
use rustc_hir::PrimTy;
use rustc_lint::EarlyContext;
use super::BUILTIN_TYPE_SHADOW;
pub(super) fn check(cx: &EarlyContext<'_>, param: &GenericParam) {
if let GenericParamKind::Type { .. } = param.kind {
if let Some(prim_ty) = PrimTy::from_name(param.ident.name) {
span_lint(
cx,
BUILTIN_TYPE_SHADOW,
param.ident.span,
&format!("this generic shadows the built-in type `{}`", prim_ty.name()),
);
}
}
}

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clippy_lints/src/misc_early/double_neg.rs Normal file
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use super::MiscEarlyLints;
use clippy_utils::diagnostics::span_lint;
use rustc_ast::ast::{Expr, ExprKind, UnOp};
use rustc_lint::EarlyContext;
use super::DOUBLE_NEG;
pub(super) fn check(cx: &EarlyContext<'_>, expr: &Expr) {
match expr.kind {
ExprKind::Unary(UnOp::Neg, ref inner) => {
if let ExprKind::Unary(UnOp::Neg, _) = inner.kind {
span_lint(
cx,
DOUBLE_NEG,
expr.span,
"`--x` could be misinterpreted as pre-decrement by C programmers, is usually a no-op",
);
}
},
ExprKind::Lit(ref lit) => MiscEarlyLints::check_lit(cx, lit),
_ => (),
}
}

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clippy_lints/src/misc_early/mixed_case_hex_literals.rs Normal file
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use clippy_utils::diagnostics::span_lint;
use rustc_ast::ast::Lit;
use rustc_lint::EarlyContext;
use super::MIXED_CASE_HEX_LITERALS;
pub(super) fn check(cx: &EarlyContext<'_>, lit: &Lit, suffix: &str, lit_snip: &str) {
let maybe_last_sep_idx = if let Some(val) = lit_snip.len().checked_sub(suffix.len() + 1) {
val
} else {
return; // It's useless so shouldn't lint.
};
if maybe_last_sep_idx <= 2 {
// It's meaningless or causes range error.
return;
}
let mut seen = (false, false);
for ch in lit_snip.as_bytes()[2..=maybe_last_sep_idx].iter() {
match ch {
b'a'..=b'f' => seen.0 = true,
b'A'..=b'F' => seen.1 = true,
_ => {},
}
if seen.0 && seen.1 {
span_lint(
cx,
MIXED_CASE_HEX_LITERALS,
lit.span,
"inconsistent casing in hexadecimal literal",
);
break;
}
}
}

348
clippy_lints/src/misc_early/mod.rs Normal file
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@ -0,0 +1,348 @@
mod builtin_type_shadow;
mod double_neg;
mod mixed_case_hex_literals;
mod redundant_pattern;
mod unneeded_field_pattern;
mod unneeded_wildcard_pattern;
mod unseparated_literal_suffix;
mod zero_prefixed_literal;
use clippy_utils::diagnostics::span_lint;
use clippy_utils::source::snippet_opt;
use rustc_ast::ast::{Expr, Generics, Lit, LitFloatType, LitIntType, LitKind, NodeId, Pat, PatKind};
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::source_map::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.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// # struct Foo {
/// # a: i32,
/// # b: i32,
/// # c: i32,
/// # }
/// let f = Foo { a: 0, b: 0, c: 0 };
///
/// // Bad
/// match f {
/// Foo { a: _, b: 0, .. } => {},
/// Foo { a: _, b: _, c: _ } => {},
/// }
///
/// // Good
/// match f {
/// Foo { b: 0, .. } => {},
/// Foo { .. } => {},
/// }
/// ```
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.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// // Bad
/// fn foo(a: i32, _a: i32) {}
///
/// // Good
/// fn bar(a: i32, _b: i32) {}
/// ```
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.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// let mut x = 3;
/// --x;
/// ```
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.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// // Bad
/// let y = 0x1a9BAcD;
///
/// // Good
/// let y = 0x1A9BACD;
/// ```
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.
///
/// **Why is this bad?** It is much less readable.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// // Bad
/// let y = 123832i32;
///
/// // Good
/// let y = 123832_i32;
/// ```
pub UNSEPARATED_LITERAL_SUFFIX,
pedantic,
"literals whose suffix is not 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.
///
/// **Known problems:** None.
///
/// **Example:**
///
/// In Rust:
/// ```rust
/// 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`).
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.
///
/// **Known problems:** None.
///
/// **Example:**
///
/// ```ignore
/// impl<u32> Foo<u32> {
/// fn impl_func(&self) -> u32 {
/// 42
/// }
/// }
/// ```
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.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// # let v = Some("abc");
///
/// // Bad
/// match v {
/// Some(x) => (),
/// y @ _ => (),
/// }
///
/// // Good
/// match v {
/// Some(x) => (),
/// y => (),
/// }
/// ```
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.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// # struct TupleStruct(u32, u32, u32);
/// # let t = TupleStruct(1, 2, 3);
/// // Bad
/// match t {
/// TupleStruct(0, .., _) => (),
/// _ => (),
/// }
///
/// // Good
/// match t {
/// TupleStruct(0, ..) => (),
/// _ => (),
/// }
/// ```
pub UNNEEDED_WILDCARD_PATTERN,
complexity,
"tuple patterns with a wildcard pattern (`_`) is next to a rest pattern (`..`)"
}
declare_lint_pass!(MiscEarlyLints => [
UNNEEDED_FIELD_PATTERN,
DUPLICATE_UNDERSCORE_ARGUMENT,
DOUBLE_NEG,
MIXED_CASE_HEX_LITERALS,
UNSEPARATED_LITERAL_SUFFIX,
ZERO_PREFIXED_LITERAL,
BUILTIN_TYPE_SHADOW,
REDUNDANT_PATTERN,
UNNEEDED_WILDCARD_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) {
unneeded_field_pattern::check(cx, pat);
redundant_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!(
"`{}` already exists, having another argument having almost the same \
name makes code comprehension and documentation more difficult",
arg_name
),
);
}
} 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;
}
double_neg::check(cx, expr)
}
}
impl MiscEarlyLints {
fn check_lit(cx: &EarlyContext<'_>, lit: &Lit) {
// 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, lit.span) {
Some(snip) if snip.chars().next().map_or(false, |c| c.is_digit(10)) => snip,
_ => return,
};
if let 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 => "",
};
unseparated_literal_suffix::check(cx, lit, &lit_snip, suffix, "integer");
if lit_snip.starts_with("0x") {
mixed_case_hex_literals::check(cx, lit, 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, lit, &lit_snip)
}
} else if let LitKind::Float(_, LitFloatType::Suffixed(float_ty)) = lit.kind {
let suffix = float_ty.name_str();
unseparated_literal_suffix::check(cx, lit, &lit_snip, suffix, "float")
}
}
}

31
clippy_lints/src/misc_early/redundant_pattern.rs Normal file
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@ -0,0 +1,31 @@
use clippy_utils::diagnostics::span_lint_and_sugg;
use rustc_ast::ast::{BindingMode, Mutability, Pat, PatKind};
use rustc_errors::Applicability;
use rustc_lint::EarlyContext;
use super::REDUNDANT_PATTERN;
pub(super) fn check(cx: &EarlyContext<'_>, pat: &Pat) {
if let PatKind::Ident(left, ident, Some(ref right)) = pat.kind {
let left_binding = match left {
BindingMode::ByRef(Mutability::Mut) => "ref mut ",
BindingMode::ByRef(Mutability::Not) => "ref ",
BindingMode::ByValue(..) => "",
};
if let PatKind::Wild = right.kind {
span_lint_and_sugg(
cx,
REDUNDANT_PATTERN,
pat.span,
&format!(
"the `{} @ _` pattern can be written as just `{}`",
ident.name, ident.name,
),
"try",
format!("{}{}", left_binding, ident.name),
Applicability::MachineApplicable,
);
}
}
}

72
clippy_lints/src/misc_early/unneeded_field_pattern.rs Normal file
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@ -0,0 +1,72 @@
use clippy_utils::diagnostics::{span_lint, span_lint_and_help};
use rustc_ast::ast::{Pat, PatKind};
use rustc_lint::{EarlyContext, LintContext};
use super::UNNEEDED_FIELD_PATTERN;
pub(super) fn check(cx: &EarlyContext<'_>, pat: &Pat) {
if let PatKind::Struct(ref npat, ref pfields, _) = pat.kind {
let mut wilds = 0;
let type_name = npat
.segments
.last()
.expect("A path must have at least one segment")
.ident
.name;
for field in pfields {
if let PatKind::Wild = field.pat.kind {
wilds += 1;
}
}
if !pfields.is_empty() && wilds == pfields.len() {
span_lint_and_help(
cx,
UNNEEDED_FIELD_PATTERN,
pat.span,
"all the struct fields are matched to a wildcard pattern, consider using `..`",
None,
&format!("try with `{} {{ .. }}` instead", type_name),
);
return;
}
if wilds > 0 {
for field in pfields {
if let PatKind::Wild = field.pat.kind {
wilds -= 1;
if wilds > 0 {
span_lint(
cx,
UNNEEDED_FIELD_PATTERN,
field.span,
"you matched a field with a wildcard pattern, consider using `..` instead",
);
} else {
let mut normal = vec![];
for field in pfields {
match field.pat.kind {
PatKind::Wild => {},
_ => {
if let Ok(n) = cx.sess().source_map().span_to_snippet(field.span) {
normal.push(n);
}
},
}
}
span_lint_and_help(
cx,
UNNEEDED_FIELD_PATTERN,
field.span,
"you matched a field with a wildcard pattern, consider using `..` \
instead",
None,
&format!("try with `{} {{ {}, .. }}`", type_name, normal[..].join(", ")),
);
}
}
}
}
}
}

52
clippy_lints/src/misc_early/unneeded_wildcard_pattern.rs Normal file
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@ -0,0 +1,52 @@
use clippy_utils::diagnostics::span_lint_and_sugg;
use rustc_ast::ast::{Pat, PatKind};
use rustc_errors::Applicability;
use rustc_lint::EarlyContext;
use rustc_span::source_map::Span;
use super::UNNEEDED_WILDCARD_PATTERN;
pub(super) fn check(cx: &EarlyContext<'_>, pat: &Pat) {
if let PatKind::TupleStruct(_, ref patterns) | PatKind::Tuple(ref patterns) = pat.kind {
if let Some(rest_index) = patterns.iter().position(|pat| pat.is_rest()) {
if let Some((left_index, left_pat)) = patterns[..rest_index]
.iter()
.rev()
.take_while(|pat| matches!(pat.kind, PatKind::Wild))
.enumerate()
.last()
{
span_lint(cx, left_pat.span.until(patterns[rest_index].span), left_index == 0);
}
if let Some((right_index, right_pat)) = patterns[rest_index + 1..]
.iter()
.take_while(|pat| matches!(pat.kind, PatKind::Wild))
.enumerate()
.last()
{
span_lint(
cx,
patterns[rest_index].span.shrink_to_hi().to(right_pat.span),
right_index == 0,
);
}
}
}
}
fn span_lint(cx: &EarlyContext<'_>, span: Span, only_one: bool) {
span_lint_and_sugg(
cx,
UNNEEDED_WILDCARD_PATTERN,
span,
if only_one {
"this pattern is unneeded as the `..` pattern can match that element"
} else {
"these patterns are unneeded as the `..` pattern can match those elements"
},
if only_one { "remove it" } else { "remove them" },
"".to_string(),
Applicability::MachineApplicable,
);
}

26
clippy_lints/src/misc_early/unseparated_literal_suffix.rs Normal file
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@ -0,0 +1,26 @@
use clippy_utils::diagnostics::span_lint_and_sugg;
use rustc_ast::ast::Lit;
use rustc_errors::Applicability;
use rustc_lint::EarlyContext;
use super::UNSEPARATED_LITERAL_SUFFIX;
pub(super) fn check(cx: &EarlyContext<'_>, lit: &Lit, lit_snip: &str, suffix: &str, sugg_type: &str) {
let maybe_last_sep_idx = if let Some(val) = lit_snip.len().checked_sub(suffix.len() + 1) {
val
} else {
return; // It's useless so shouldn't lint.
};
// Do not lint when literal is unsuffixed.
if !suffix.is_empty() && lit_snip.as_bytes()[maybe_last_sep_idx] != b'_' {
span_lint_and_sugg(
cx,
UNSEPARATED_LITERAL_SUFFIX,
lit.span,
&format!("{} type suffix should be separated by an underscore", sugg_type),
"add an underscore",
format!("{}_{}", &lit_snip[..=maybe_last_sep_idx], suffix),
Applicability::MachineApplicable,
);
}
}

29
clippy_lints/src/misc_early/zero_prefixed_literal.rs Normal file
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@ -0,0 +1,29 @@
use clippy_utils::diagnostics::span_lint_and_then;
use rustc_ast::ast::Lit;
use rustc_errors::Applicability;
use rustc_lint::EarlyContext;
use super::ZERO_PREFIXED_LITERAL;
pub(super) fn check(cx: &EarlyContext<'_>, lit: &Lit, lit_snip: &str) {
span_lint_and_then(
cx,
ZERO_PREFIXED_LITERAL,
lit.span,
"this is a decimal constant",
|diag| {
diag.span_suggestion(
lit.span,
"if you mean to use a decimal constant, remove the `0` to avoid confusion",
lit_snip.trim_start_matches(|c| c == '_' || c == '0').to_string(),
Applicability::MaybeIncorrect,
);
diag.span_suggestion(
lit.span,
"if you mean to use an octal constant, use `0o`",
format!("0o{}", lit_snip.trim_start_matches(|c| c == '_' || c == '0')),
Applicability::MaybeIncorrect,
);
},
);
}

0
tests/ui/builtin-type-shadow.rs → tests/ui/builtin_type_shadow.rs
View File

4
tests/ui/builtin-type-shadow.stderr → tests/ui/builtin_type_shadow.stderr
View File

@ -1,5 +1,5 @@
error: this generic shadows the built-in type `u32`
--> $DIR/builtin-type-shadow.rs:4:8
--> $DIR/builtin_type_shadow.rs:4:8
|
LL | fn foo<u32>(a: u32) -> u32 {
| ^^^
@ -7,7 +7,7 @@ LL | fn foo<u32>(a: u32) -> u32 {
= note: `-D clippy::builtin-type-shadow` implied by `-D warnings`
error[E0308]: mismatched types
--> $DIR/builtin-type-shadow.rs:5:5
--> $DIR/builtin_type_shadow.rs:5:5
|
LL | fn foo<u32>(a: u32) -> u32 {
| --- --- expected `u32` because of return type