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Add lint for misstyped literal casting

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This commit is contained in:
Michael A. Plikk 2018-09-02 23:07:55 +02:00
parent 131c8f86b2
commit 38d287fecd
6 changed files with 145 additions and 18 deletions
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2
clippy_lints/src/lib.rs
View file

@ -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,
@ -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,

85
clippy_lints/src/literal_representation.rs
View file

@ -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.
///
@ -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
}
@ -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('.') {
@ -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
)
}
}
@ -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,
@ -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)
});
}
@ -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,
@ -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()
@ -504,3 +553,7 @@ impl LiteralRepresentation {
Ok(())
}
}
fn is_mistyped_suffix(suffix: &str) -> bool {
["_8", "_16", "_32", "_64"].contains(&suffix)
}