mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-23 03:23:33 +00:00
574 lines
20 KiB
Rust
574 lines
20 KiB
Rust
// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Lints concerned with the grouping of digits with underscores in integral or
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//! floating-point literal expressions.
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use crate::rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass, in_external_macro, LintContext};
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use crate::rustc::{declare_tool_lint, lint_array};
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use if_chain::if_chain;
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use crate::syntax::ast::*;
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use crate::syntax_pos;
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use crate::utils::{snippet_opt, span_lint_and_sugg};
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/// **What it does:** Warns if a long integral or floating-point constant does
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/// not contain underscores.
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///
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/// **Why is this bad?** Reading long numbers is difficult without separators.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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///
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/// ```rust
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/// 61864918973511
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/// ```
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declare_clippy_lint! {
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pub UNREADABLE_LITERAL,
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style,
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"long integer literal without underscores"
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}
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/// **What it does:** Warns for mistyped suffix in literals
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///
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/// **Why is this bad?** This is most probably a typo
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///
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/// **Known problems:**
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/// - Recommends a signed suffix, even though the number might be too big and an unsigned
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/// suffix is required
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/// - Does not match on `_128` since that is a valid grouping for decimal and octal numbers
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///
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/// **Example:**
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///
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/// ```rust
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/// 2_32
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/// ```
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declare_clippy_lint! {
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pub MISTYPED_LITERAL_SUFFIXES,
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correctness,
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"mistyped literal suffix"
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}
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/// **What it does:** Warns if an integral or floating-point constant is
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/// grouped inconsistently with underscores.
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///
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/// **Why is this bad?** Readers may incorrectly interpret inconsistently
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/// grouped digits.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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///
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/// ```rust
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/// 618_64_9189_73_511
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/// ```
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declare_clippy_lint! {
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pub INCONSISTENT_DIGIT_GROUPING,
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style,
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"integer literals with digits grouped inconsistently"
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}
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/// **What it does:** Warns if the digits of an integral or floating-point
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/// constant are grouped into groups that
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/// are too large.
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///
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/// **Why is this bad?** Negatively impacts readability.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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///
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/// ```rust
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/// 6186491_8973511
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/// ```
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declare_clippy_lint! {
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pub LARGE_DIGIT_GROUPS,
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style,
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"grouping digits into groups that are too large"
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}
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/// **What it does:** Warns if there is a better representation for a numeric literal.
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///
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/// **Why is this bad?** Especially for big powers of 2 a hexadecimal representation is more
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/// readable than a decimal representation.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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///
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/// `255` => `0xFF`
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/// `65_535` => `0xFFFF`
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/// `4_042_322_160` => `0xF0F0_F0F0`
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declare_clippy_lint! {
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pub DECIMAL_LITERAL_REPRESENTATION,
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restriction,
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"using decimal representation when hexadecimal would be better"
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}
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#[derive(Debug, PartialEq)]
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pub(super) enum Radix {
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Binary,
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Octal,
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Decimal,
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Hexadecimal,
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}
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impl Radix {
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/// Return a reasonable digit group size for this radix.
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crate fn suggest_grouping(&self) -> usize {
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match *self {
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Radix::Binary | Radix::Hexadecimal => 4,
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Radix::Octal | Radix::Decimal => 3,
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}
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}
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}
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#[derive(Debug)]
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pub(super) struct DigitInfo<'a> {
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/// Characters of a literal between the radix prefix and type suffix.
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crate digits: &'a str,
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/// Which radix the literal was represented in.
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crate radix: Radix,
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/// The radix prefix, if present.
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crate prefix: Option<&'a str>,
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/// The type suffix, including preceding underscore if present.
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crate suffix: Option<&'a str>,
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/// True for floating-point literals.
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crate float: bool,
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}
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impl<'a> DigitInfo<'a> {
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crate fn new(lit: &'a str, float: bool) -> Self {
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// Determine delimiter for radix prefix, if present, and radix.
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let radix = if lit.starts_with("0x") {
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Radix::Hexadecimal
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} else if lit.starts_with("0b") {
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Radix::Binary
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} else if lit.starts_with("0o") {
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Radix::Octal
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} else {
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Radix::Decimal
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};
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// Grab part of the literal after prefix, if present.
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let (prefix, sans_prefix) = if let Radix::Decimal = radix {
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(None, lit)
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} else {
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let (p, s) = lit.split_at(2);
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(Some(p), s)
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};
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let len = sans_prefix.len();
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let mut last_d = '\0';
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for (d_idx, d) in sans_prefix.char_indices() {
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let suffix_start = if last_d == '_' {
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d_idx - 1
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} else {
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d_idx
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};
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if float && (d == 'f' || d == 'e' || d == 'E') ||
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!float && (d == 'i' || d == 'u' || is_possible_suffix_index(&sans_prefix, suffix_start, len)) {
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let (digits, suffix) = sans_prefix.split_at(suffix_start);
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return Self {
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digits,
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radix,
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prefix,
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suffix: Some(suffix),
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float,
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};
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}
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last_d = d
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}
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// No suffix found
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Self {
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digits: sans_prefix,
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radix,
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prefix,
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suffix: None,
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float,
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}
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}
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/// Returns literal formatted in a sensible way.
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crate fn grouping_hint(&self) -> String {
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let group_size = self.radix.suggest_grouping();
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if self.digits.contains('.') {
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let mut parts = self.digits.split('.');
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let int_part_hint = parts
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.next()
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.expect("split always returns at least one element")
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.chars()
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.rev()
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.filter(|&c| c != '_')
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.collect::<Vec<_>>()
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.chunks(group_size)
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.map(|chunk| chunk.into_iter().rev().collect())
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.rev()
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.collect::<Vec<String>>()
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.join("_");
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let frac_part_hint = parts
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.next()
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.expect("already checked that there is a `.`")
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.chars()
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.filter(|&c| c != '_')
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.collect::<Vec<_>>()
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.chunks(group_size)
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.map(|chunk| chunk.into_iter().collect())
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.collect::<Vec<String>>()
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.join("_");
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format!(
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"{}.{}{}",
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int_part_hint,
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frac_part_hint,
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self.suffix.unwrap_or("")
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)
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} else {
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let filtered_digits_vec = self.digits
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.chars()
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.filter(|&c| c != '_')
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.rev()
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.collect::<Vec<_>>();
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let mut hint = filtered_digits_vec
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.chunks(group_size)
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.map(|chunk| chunk.into_iter().rev().collect())
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.rev()
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.collect::<Vec<String>>()
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.join("_");
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// Forces hexadecimal values to be grouped by 4 being filled with zeroes (e.g 0x00ab_cdef)
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let nb_digits_to_fill = filtered_digits_vec.len() % 4;
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if self.radix == Radix::Hexadecimal && nb_digits_to_fill != 0 {
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hint = format!("{:0>4}{}", &hint[..nb_digits_to_fill], &hint[nb_digits_to_fill..]);
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}
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let suffix_hint = match self.suffix {
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Some(suffix) if is_mistyped_suffix(suffix) => {
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format!("_i{}", &suffix[1..])
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},
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Some(suffix) => suffix.to_string(),
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None => String::new()
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};
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format!(
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"{}{}{}",
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self.prefix.unwrap_or(""),
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hint,
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suffix_hint
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)
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}
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}
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}
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enum WarningType {
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UnreadableLiteral,
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InconsistentDigitGrouping,
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LargeDigitGroups,
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DecimalRepresentation,
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MistypedLiteralSuffix
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}
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impl WarningType {
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crate fn display(&self, grouping_hint: &str, cx: &EarlyContext<'_>, span: syntax_pos::Span) {
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match self {
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WarningType::MistypedLiteralSuffix => {
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span_lint_and_sugg(
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cx,
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MISTYPED_LITERAL_SUFFIXES,
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span,
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"mistyped literal suffix",
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"did you mean to write",
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grouping_hint.to_string()
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)
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},
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WarningType::UnreadableLiteral => span_lint_and_sugg(
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cx,
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UNREADABLE_LITERAL,
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span,
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"long literal lacking separators",
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"consider",
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grouping_hint.to_owned(),
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),
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WarningType::LargeDigitGroups => span_lint_and_sugg(
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cx,
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LARGE_DIGIT_GROUPS,
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span,
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"digit groups should be smaller",
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"consider",
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grouping_hint.to_owned(),
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),
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WarningType::InconsistentDigitGrouping => span_lint_and_sugg(
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cx,
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INCONSISTENT_DIGIT_GROUPING,
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span,
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"digits grouped inconsistently by underscores",
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"consider",
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grouping_hint.to_owned(),
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),
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WarningType::DecimalRepresentation => span_lint_and_sugg(
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cx,
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DECIMAL_LITERAL_REPRESENTATION,
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span,
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"integer literal has a better hexadecimal representation",
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"consider",
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grouping_hint.to_owned(),
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),
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};
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}
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}
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#[derive(Copy, Clone)]
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pub struct LiteralDigitGrouping;
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impl LintPass for LiteralDigitGrouping {
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fn get_lints(&self) -> LintArray {
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lint_array!(
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UNREADABLE_LITERAL,
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INCONSISTENT_DIGIT_GROUPING,
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LARGE_DIGIT_GROUPS
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)
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}
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}
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impl EarlyLintPass for LiteralDigitGrouping {
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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.node {
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self.check_lit(cx, lit)
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}
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}
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}
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impl LiteralDigitGrouping {
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fn check_lit(self, cx: &EarlyContext<'_>, lit: &Lit) {
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match lit.node {
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LitKind::Int(..) => {
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// Lint integral literals.
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if_chain! {
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if let Some(src) = snippet_opt(cx, lit.span);
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if let Some(firstch) = src.chars().next();
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if char::to_digit(firstch, 10).is_some();
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then {
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let digit_info = DigitInfo::new(&src, false);
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let _ = Self::do_lint(digit_info.digits, digit_info.suffix).map_err(|warning_type| {
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warning_type.display(&digit_info.grouping_hint(), cx, lit.span)
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});
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}
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}
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},
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LitKind::Float(..) | LitKind::FloatUnsuffixed(..) => {
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// Lint floating-point literals.
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if_chain! {
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if let Some(src) = snippet_opt(cx, lit.span);
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if let Some(firstch) = src.chars().next();
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if char::to_digit(firstch, 10).is_some();
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then {
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let digit_info = DigitInfo::new(&src, true);
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// Separate digits into integral and fractional parts.
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let parts: Vec<&str> = digit_info
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.digits
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.split_terminator('.')
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.collect();
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// Lint integral and fractional parts separately, and then check consistency of digit
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// groups if both pass.
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let _ = Self::do_lint(parts[0], None)
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.map(|integral_group_size| {
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if parts.len() > 1 {
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// Lint the fractional part of literal just like integral part, but reversed.
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let fractional_part = &parts[1].chars().rev().collect::<String>();
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let _ = Self::do_lint(fractional_part, None)
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.map(|fractional_group_size| {
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let consistent = Self::parts_consistent(integral_group_size,
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fractional_group_size,
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parts[0].len(),
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parts[1].len());
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if !consistent {
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WarningType::InconsistentDigitGrouping.display(&digit_info.grouping_hint(),
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cx,
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lit.span);
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}
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})
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.map_err(|warning_type| warning_type.display(&digit_info.grouping_hint(),
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cx,
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lit.span));
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}
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})
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.map_err(|warning_type| warning_type.display(&digit_info.grouping_hint(), cx, lit.span));
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}
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}
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},
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_ => (),
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}
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}
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/// Given the sizes of the digit groups of both integral and fractional
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/// parts, and the length
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/// of both parts, determine if the digits have been grouped consistently.
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fn parts_consistent(int_group_size: usize, frac_group_size: usize, int_size: usize, frac_size: usize) -> bool {
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match (int_group_size, frac_group_size) {
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// No groups on either side of decimal point - trivially consistent.
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(0, 0) => true,
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// Integral part has grouped digits, fractional part does not.
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(_, 0) => frac_size <= int_group_size,
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// Fractional part has grouped digits, integral part does not.
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(0, _) => int_size <= frac_group_size,
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// Both parts have grouped digits. Groups should be the same size.
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(_, _) => int_group_size == frac_group_size,
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}
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}
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/// Performs lint on `digits` (no decimal point) and returns the group
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/// size on success or `WarningType` when emitting a warning.
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fn do_lint(digits: &str, suffix: Option<&str>) -> Result<usize, WarningType> {
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if let Some(suffix) = suffix {
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if is_mistyped_suffix(suffix) {
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return Err(WarningType::MistypedLiteralSuffix);
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}
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}
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// Grab underscore indices with respect to the units digit.
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let underscore_positions: Vec<usize> = digits
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.chars()
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.rev()
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.enumerate()
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.filter_map(|(idx, digit)| if digit == '_' { Some(idx) } else { None })
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.collect();
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if underscore_positions.is_empty() {
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// Check if literal needs underscores.
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if digits.len() > 5 {
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Err(WarningType::UnreadableLiteral)
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} else {
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Ok(0)
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}
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} else {
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// Check consistency and the sizes of the groups.
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let group_size = underscore_positions[0];
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let consistent = underscore_positions
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.windows(2)
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.all(|ps| ps[1] - ps[0] == group_size + 1)
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// number of digits to the left of the last group cannot be bigger than group size.
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&& (digits.len() - underscore_positions.last()
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.expect("there's at least one element") <= group_size + 1);
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if !consistent {
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return Err(WarningType::InconsistentDigitGrouping);
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} else if group_size > 4 {
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return Err(WarningType::LargeDigitGroups);
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}
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Ok(group_size)
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}
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}
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}
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|
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#[derive(Copy, Clone)]
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pub struct LiteralRepresentation {
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threshold: u64,
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}
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impl LintPass for LiteralRepresentation {
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fn get_lints(&self) -> LintArray {
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lint_array!(DECIMAL_LITERAL_REPRESENTATION)
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}
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}
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impl EarlyLintPass for LiteralRepresentation {
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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.node {
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self.check_lit(cx, lit)
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}
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}
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}
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impl LiteralRepresentation {
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pub fn new(threshold: u64) -> Self {
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Self {
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threshold,
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}
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}
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fn check_lit(self, cx: &EarlyContext<'_>, lit: &Lit) {
|
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// Lint integral literals.
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if_chain! {
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if let LitKind::Int(..) = lit.node;
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if let Some(src) = snippet_opt(cx, lit.span);
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if let Some(firstch) = src.chars().next();
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if char::to_digit(firstch, 10).is_some();
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then {
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let digit_info = DigitInfo::new(&src, false);
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if digit_info.radix == Radix::Decimal {
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let val = digit_info.digits
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.chars()
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.filter(|&c| c != '_')
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.collect::<String>()
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.parse::<u128>().unwrap();
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if val < u128::from(self.threshold) {
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return
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}
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let hex = format!("{:#X}", val);
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let digit_info = DigitInfo::new(&hex[..], false);
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let _ = Self::do_lint(digit_info.digits).map_err(|warning_type| {
|
|
warning_type.display(&digit_info.grouping_hint(), cx, lit.span)
|
|
});
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn do_lint(digits: &str) -> Result<(), WarningType> {
|
|
if digits.len() == 1 {
|
|
// Lint for 1 digit literals, if someone really sets the threshold that low
|
|
if digits == "1" || digits == "2" || digits == "4" || digits == "8" || digits == "3" || digits == "7"
|
|
|| digits == "F"
|
|
{
|
|
return Err(WarningType::DecimalRepresentation);
|
|
}
|
|
} else if digits.len() < 4 {
|
|
// Lint for Literals with a hex-representation of 2 or 3 digits
|
|
let f = &digits[0..1]; // first digit
|
|
let s = &digits[1..]; // suffix
|
|
// Powers of 2
|
|
if ((f.eq("1") || f.eq("2") || f.eq("4") || f.eq("8")) && s.chars().all(|c| c == '0'))
|
|
// Powers of 2 minus 1
|
|
|| ((f.eq("1") || f.eq("3") || f.eq("7") || f.eq("F")) && s.chars().all(|c| c == 'F'))
|
|
{
|
|
return Err(WarningType::DecimalRepresentation);
|
|
}
|
|
} else {
|
|
// Lint for Literals with a hex-representation of 4 digits or more
|
|
let f = &digits[0..1]; // first digit
|
|
let m = &digits[1..digits.len() - 1]; // middle digits, except last
|
|
let s = &digits[1..]; // suffix
|
|
// Powers of 2 with a margin of +15/-16
|
|
if ((f.eq("1") || f.eq("2") || f.eq("4") || f.eq("8")) && m.chars().all(|c| c == '0'))
|
|
|| ((f.eq("1") || f.eq("3") || f.eq("7") || f.eq("F")) && m.chars().all(|c| c == 'F'))
|
|
// Lint for representations with only 0s and Fs, while allowing 7 as the first
|
|
// digit
|
|
|| ((f.eq("7") || f.eq("F")) && s.chars().all(|c| c == '0' || c == 'F'))
|
|
{
|
|
return Err(WarningType::DecimalRepresentation);
|
|
}
|
|
}
|
|
|
|
Ok(())
|
|
}
|
|
}
|
|
|
|
fn is_mistyped_suffix(suffix: &str) -> bool {
|
|
["_8", "_16", "_32", "_64"].contains(&suffix)
|
|
}
|
|
|
|
fn is_possible_suffix_index(lit: &str, idx: usize, len: usize) -> bool {
|
|
((len > 3 && idx == len - 3) || (len > 2 && idx == len - 2)) &&
|
|
is_mistyped_suffix(lit.split_at(idx).1)
|
|
}
|