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Add lint for misstyped literal casting
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Michael A. Plikk committed Sep 5, 2018
1 parent 131c8f8 commit 8bf219d
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Showing 6 changed files with 138 additions and 18 deletions.
3 changes: 3 additions & 0 deletions CHANGELOG.md
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Expand Up @@ -645,6 +645,7 @@ All notable changes to this project will be documented in this file.
[`cmp_owned`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#cmp_owned
[`collapsible_if`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#collapsible_if
[`const_static_lifetime`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#const_static_lifetime
[`copy_iterator`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#copy_iterator
[`crosspointer_transmute`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#crosspointer_transmute
[`cyclomatic_complexity`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#cyclomatic_complexity
[`decimal_literal_representation`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#decimal_literal_representation
Expand Down Expand Up @@ -748,6 +749,7 @@ All notable changes to this project will be documented in this file.
[`misrefactored_assign_op`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#misrefactored_assign_op
[`missing_docs_in_private_items`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#missing_docs_in_private_items
[`missing_inline_in_public_items`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#missing_inline_in_public_items
[`mistyped_literal_suffixes`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#mistyped_literal_suffixes
[`mixed_case_hex_literals`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#mixed_case_hex_literals
[`module_inception`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#module_inception
[`modulo_one`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#modulo_one
Expand Down Expand Up @@ -800,6 +802,7 @@ All notable changes to this project will be documented in this file.
[`print_with_newline`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#print_with_newline
[`println_empty_string`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#println_empty_string
[`ptr_arg`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#ptr_arg
[`ptr_offset_with_cast`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#ptr_offset_with_cast
[`pub_enum_variant_names`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#pub_enum_variant_names
[`question_mark`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#question_mark
[`range_minus_one`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#range_minus_one
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2 changes: 1 addition & 1 deletion README.md
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Expand Up @@ -9,7 +9,7 @@ We are currently in the process of discussing Clippy 1.0 via the RFC process in

A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.

[There are 273 lints included in this crate!](https://rust-lang-nursery.github.io/rust-clippy/master/index.html)
[There are 275 lints included in this crate!](https://rust-lang-nursery.github.io/rust-clippy/master/index.html)

We have a bunch of lint categories to allow you to choose how much Clippy is supposed to ~~annoy~~ help you:

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2 changes: 2 additions & 0 deletions clippy_lints/src/lib.rs
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Expand Up @@ -543,6 +543,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
lifetimes::NEEDLESS_LIFETIMES,
literal_representation::INCONSISTENT_DIGIT_GROUPING,
literal_representation::LARGE_DIGIT_GROUPS,
literal_representation::MISTYPED_LITERAL_SUFFIXES,
literal_representation::UNREADABLE_LITERAL,
loops::EMPTY_LOOP,
loops::EXPLICIT_COUNTER_LOOP,
Expand Down Expand Up @@ -869,6 +870,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
infinite_iter::INFINITE_ITER,
inline_fn_without_body::INLINE_FN_WITHOUT_BODY,
invalid_ref::INVALID_REF,
literal_representation::MISTYPED_LITERAL_SUFFIXES,
loops::FOR_LOOP_OVER_OPTION,
loops::FOR_LOOP_OVER_RESULT,
loops::ITER_NEXT_LOOP,
Expand Down
85 changes: 69 additions & 16 deletions clippy_lints/src/literal_representation.rs
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Expand Up @@ -26,6 +26,26 @@ declare_clippy_lint! {
"long integer literal without underscores"
}

/// **What it does:** Warns for mistyped suffix in literals
///
/// **Why is this bad?** This is most probably a typo
///
/// **Known problems:**
/// - Recommends a signed suffix, even though the number might be too big and an unsigned
/// suffix is required
/// - Does not match on `_128` since that is a valid grouping for decimal and octal numbers
///
/// **Example:**
///
/// ```rust
/// 2_32
/// ```
declare_clippy_lint! {
pub MISTYPED_LITERAL_SUFFIXES,
correctness,
"mistyped literal suffix"
}

/// **What it does:** Warns if an integral or floating-point constant is
/// grouped inconsistently with underscores.
///
Expand Down Expand Up @@ -137,16 +157,22 @@ impl<'a> DigitInfo<'a> {

let mut last_d = '\0';
for (d_idx, d) in sans_prefix.char_indices() {
if !float && (d == 'i' || d == 'u') || float && (d == 'f' || d == 'e' || d == 'E') {
let suffix_start = if last_d == '_' { d_idx - 1 } else { d_idx };
let (digits, suffix) = sans_prefix.split_at(suffix_start);
return Self {
digits,
radix,
prefix,
suffix: Some(suffix),
float,
};
let suffix_start = if last_d == '_' {
d_idx - 1
} else {
d_idx
};
let (digits, suffix) = sans_prefix.split_at(suffix_start);
if !float && (d == 'i' || d == 'u') ||
float && (d == 'f' || d == 'e' || d == 'E') ||
!float && is_mistyped_suffix(suffix) {
return Self {
digits,
radix,
prefix,
suffix: Some(suffix),
float,
};
}
last_d = d
}
Expand All @@ -161,7 +187,7 @@ impl<'a> DigitInfo<'a> {
}
}

/// Returns digits grouped in a sensible way.
/// Returns literal formatted in a sensible way.
crate fn grouping_hint(&self) -> String {
let group_size = self.radix.suggest_grouping();
if self.digits.contains('.') {
Expand Down Expand Up @@ -211,11 +237,18 @@ impl<'a> DigitInfo<'a> {
if self.radix == Radix::Hexadecimal && nb_digits_to_fill != 0 {
hint = format!("{:0>4}{}", &hint[..nb_digits_to_fill], &hint[nb_digits_to_fill..]);
}
let suffix_hint = match self.suffix {
Some(suffix) if is_mistyped_suffix(suffix) => {
format!("_i{}", &suffix[1..])
},
Some(suffix) => suffix.to_string(),
None => String::new()
};
format!(
"{}{}{}",
self.prefix.unwrap_or(""),
hint,
self.suffix.unwrap_or("")
suffix_hint
)
}
}
Expand All @@ -226,11 +259,22 @@ enum WarningType {
InconsistentDigitGrouping,
LargeDigitGroups,
DecimalRepresentation,
MistypedLiteralSuffix
}

impl WarningType {
crate fn display(&self, grouping_hint: &str, cx: &EarlyContext<'_>, span: syntax_pos::Span) {
match self {
WarningType::MistypedLiteralSuffix => {
span_lint_and_sugg(
cx,
MISTYPED_LITERAL_SUFFIXES,
span,
"mistyped literal suffix",
"did you mean to write",
grouping_hint.to_string()
)
},
WarningType::UnreadableLiteral => span_lint_and_sugg(
cx,
UNREADABLE_LITERAL,
Expand Down Expand Up @@ -303,7 +347,7 @@ impl LiteralDigitGrouping {
if char::to_digit(firstch, 10).is_some();
then {
let digit_info = DigitInfo::new(&src, false);
let _ = Self::do_lint(digit_info.digits).map_err(|warning_type| {
let _ = Self::do_lint(digit_info.digits, digit_info.suffix).map_err(|warning_type| {
warning_type.display(&digit_info.grouping_hint(), cx, lit.span)
});
}
Expand All @@ -325,12 +369,12 @@ impl LiteralDigitGrouping {

// Lint integral and fractional parts separately, and then check consistency of digit
// groups if both pass.
let _ = Self::do_lint(parts[0])
let _ = Self::do_lint(parts[0], None)
.map(|integral_group_size| {
if parts.len() > 1 {
// Lint the fractional part of literal just like integral part, but reversed.
let fractional_part = &parts[1].chars().rev().collect::<String>();
let _ = Self::do_lint(fractional_part)
let _ = Self::do_lint(fractional_part, None)
.map(|fractional_group_size| {
let consistent = Self::parts_consistent(integral_group_size,
fractional_group_size,
Expand Down Expand Up @@ -373,7 +417,12 @@ impl LiteralDigitGrouping {

/// Performs lint on `digits` (no decimal point) and returns the group
/// size on success or `WarningType` when emitting a warning.
fn do_lint(digits: &str) -> Result<usize, WarningType> {
fn do_lint(digits: &str, suffix: Option<&str>) -> Result<usize, WarningType> {
if let Some(suffix) = suffix {
if is_mistyped_suffix(suffix) {
return Err(WarningType::MistypedLiteralSuffix);
}
}
// Grab underscore indices with respect to the units digit.
let underscore_positions: Vec<usize> = digits
.chars()
Expand Down Expand Up @@ -504,3 +553,7 @@ impl LiteralRepresentation {
Ok(())
}
}

fn is_mistyped_suffix(suffix: &str) -> bool {
["_8", "_16", "_32", "_64"].contains(&suffix)
}
10 changes: 10 additions & 0 deletions tests/ui/literals.rs
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Expand Up @@ -43,4 +43,14 @@ fn main() {
let fail11 = 0xabcdeff;
let fail12 = 0xabcabcabcabcabcabc;
let fail13 = 0x1_23456_78901_usize;

let fail14 = 2_32;
let fail15 = 4_64;
let fail16 = 7_8;
let fail17 = 23_16;
let ok18 = 23_128;
let fail19 = 12_3456_21;
let fail20 = 2__8;
let fail21 = 4___16;
let fail22 = 3__4___23;
}
54 changes: 53 additions & 1 deletion tests/ui/literals.stderr
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Expand Up @@ -120,5 +120,57 @@ error: digit groups should be smaller
|
= note: `-D clippy::large-digit-groups` implied by `-D warnings`

error: aborting due to 16 previous errors
error: mistyped literal suffix
--> $DIR/literals.rs:47:18
|
47 | let fail14 = 2_32;
| ^^^^ help: did you mean to write: `2_i32`
|
= note: #[deny(clippy::mistyped_literal_suffixes)] on by default

error: mistyped literal suffix
--> $DIR/literals.rs:48:18
|
48 | let fail15 = 4_64;
| ^^^^ help: did you mean to write: `4_i64`

error: mistyped literal suffix
--> $DIR/literals.rs:49:18
|
49 | let fail16 = 7_8;
| ^^^ help: did you mean to write: `7_i8`

error: mistyped literal suffix
--> $DIR/literals.rs:50:18
|
50 | let fail17 = 23_16;
| ^^^^^ help: did you mean to write: `23_i16`

error: digits grouped inconsistently by underscores
--> $DIR/literals.rs:52:18
|
52 | let fail19 = 12_3456_21;
| ^^^^^^^^^^ help: consider: `12_345_621`
|
= note: `-D clippy::inconsistent-digit-grouping` implied by `-D warnings`

error: mistyped literal suffix
--> $DIR/literals.rs:53:18
|
53 | let fail20 = 2__8;
| ^^^^ help: did you mean to write: `2_i8`

error: mistyped literal suffix
--> $DIR/literals.rs:54:18
|
54 | let fail21 = 4___16;
| ^^^^^^ help: did you mean to write: `4_i16`

error: digits grouped inconsistently by underscores
--> $DIR/literals.rs:55:18
|
55 | let fail22 = 3__4___23;
| ^^^^^^^^^ help: consider: `3_423`

error: aborting due to 24 previous errors

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