--- /dev/null
+//! Lints concerned with the grouping of digits with underscores in integral or
+//! floating-point literal expressions.
+
+use crate::utils::{
+ in_macro,
+ numeric_literal::{NumericLiteral, Radix},
+ snippet_opt, span_lint_and_sugg,
+};
+use if_chain::if_chain;
+use rustc_ast::ast::{Expr, ExprKind, Lit, LitKind};
+use rustc_errors::Applicability;
+use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
+use rustc_middle::lint::in_external_macro;
+use rustc_session::{declare_tool_lint, impl_lint_pass};
+
+declare_clippy_lint! {
+ /// **What it does:** Warns if a long integral or floating-point constant does
+ /// not contain underscores.
+ ///
+ /// **Why is this bad?** Reading long numbers is difficult without separators.
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **Example:**
+ ///
+ /// ```rust
+ /// // Bad
+ /// let x: u64 = 61864918973511;
+ ///
+ /// // Good
+ /// let x: u64 = 61_864_918_973_511;
+ /// ```
+ pub UNREADABLE_LITERAL,
+ pedantic,
+ "long literal without underscores"
+}
+
+declare_clippy_lint! {
+ /// **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 `_127` since that is a valid grouping for decimal and octal numbers
+ ///
+ /// **Example:**
+ ///
+ /// ```rust
+ /// // Probably mistyped
+ /// 2_32;
+ ///
+ /// // Good
+ /// 2_i32;
+ /// ```
+ pub MISTYPED_LITERAL_SUFFIXES,
+ correctness,
+ "mistyped literal suffix"
+}
+
+declare_clippy_lint! {
+ /// **What it does:** Warns if an integral or floating-point constant is
+ /// grouped inconsistently with underscores.
+ ///
+ /// **Why is this bad?** Readers may incorrectly interpret inconsistently
+ /// grouped digits.
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **Example:**
+ ///
+ /// ```rust
+ /// // Bad
+ /// let x: u64 = 618_64_9189_73_511;
+ ///
+ /// // Good
+ /// let x: u64 = 61_864_918_973_511;
+ /// ```
+ pub INCONSISTENT_DIGIT_GROUPING,
+ style,
+ "integer literals with digits grouped inconsistently"
+}
+
+declare_clippy_lint! {
+ /// **What it does:** Warns if hexadecimal or binary literals are not grouped
+ /// by nibble or byte.
+ ///
+ /// **Why is this bad?** Negatively impacts readability.
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **Example:**
+ ///
+ /// ```rust
+ /// let x: u32 = 0xFFF_FFF;
+ /// let y: u8 = 0b01_011_101;
+ /// ```
+ pub UNUSUAL_BYTE_GROUPINGS,
+ style,
+ "binary or hex literals that aren't grouped by four"
+}
+
+declare_clippy_lint! {
+ /// **What it does:** Warns if the digits of an integral or floating-point
+ /// constant are grouped into groups that
+ /// are too large.
+ ///
+ /// **Why is this bad?** Negatively impacts readability.
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **Example:**
+ ///
+ /// ```rust
+ /// let x: u64 = 6186491_8973511;
+ /// ```
+ pub LARGE_DIGIT_GROUPS,
+ pedantic,
+ "grouping digits into groups that are too large"
+}
+
+declare_clippy_lint! {
+ /// **What it does:** Warns if there is a better representation for a numeric literal.
+ ///
+ /// **Why is this bad?** Especially for big powers of 2 a hexadecimal representation is more
+ /// readable than a decimal representation.
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **Example:**
+ ///
+ /// `255` => `0xFF`
+ /// `65_535` => `0xFFFF`
+ /// `4_042_322_160` => `0xF0F0_F0F0`
+ pub DECIMAL_LITERAL_REPRESENTATION,
+ restriction,
+ "using decimal representation when hexadecimal would be better"
+}
+
+enum WarningType {
+ UnreadableLiteral,
+ InconsistentDigitGrouping,
+ LargeDigitGroups,
+ DecimalRepresentation,
+ MistypedLiteralSuffix,
+ UnusualByteGroupings,
+}
+
+impl WarningType {
+ fn display(&self, suggested_format: String, cx: &EarlyContext<'_>, span: rustc_span::Span) {
+ match self {
+ Self::MistypedLiteralSuffix => span_lint_and_sugg(
+ cx,
+ MISTYPED_LITERAL_SUFFIXES,
+ span,
+ "mistyped literal suffix",
+ "did you mean to write",
+ suggested_format,
+ Applicability::MaybeIncorrect,
+ ),
+ Self::UnreadableLiteral => span_lint_and_sugg(
+ cx,
+ UNREADABLE_LITERAL,
+ span,
+ "long literal lacking separators",
+ "consider",
+ suggested_format,
+ Applicability::MachineApplicable,
+ ),
+ Self::LargeDigitGroups => span_lint_and_sugg(
+ cx,
+ LARGE_DIGIT_GROUPS,
+ span,
+ "digit groups should be smaller",
+ "consider",
+ suggested_format,
+ Applicability::MachineApplicable,
+ ),
+ Self::InconsistentDigitGrouping => span_lint_and_sugg(
+ cx,
+ INCONSISTENT_DIGIT_GROUPING,
+ span,
+ "digits grouped inconsistently by underscores",
+ "consider",
+ suggested_format,
+ Applicability::MachineApplicable,
+ ),
+ Self::DecimalRepresentation => span_lint_and_sugg(
+ cx,
+ DECIMAL_LITERAL_REPRESENTATION,
+ span,
+ "integer literal has a better hexadecimal representation",
+ "consider",
+ suggested_format,
+ Applicability::MachineApplicable,
+ ),
+ Self::UnusualByteGroupings => span_lint_and_sugg(
+ cx,
+ UNUSUAL_BYTE_GROUPINGS,
+ span,
+ "digits of hex or binary literal not grouped by four",
+ "consider",
+ suggested_format,
+ Applicability::MachineApplicable,
+ ),
+ };
+ }
+}
+
+#[allow(clippy::module_name_repetitions)]
+#[derive(Copy, Clone)]
+pub struct LiteralDigitGrouping {
+ lint_fraction_readability: bool,
+}
+
+impl_lint_pass!(LiteralDigitGrouping => [
+ UNREADABLE_LITERAL,
+ INCONSISTENT_DIGIT_GROUPING,
+ LARGE_DIGIT_GROUPS,
+ MISTYPED_LITERAL_SUFFIXES,
+ UNUSUAL_BYTE_GROUPINGS,
+]);
+
+impl EarlyLintPass for LiteralDigitGrouping {
+ fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
+ if in_external_macro(cx.sess(), expr.span) {
+ return;
+ }
+
+ if let ExprKind::Lit(ref lit) = expr.kind {
+ self.check_lit(cx, lit)
+ }
+ }
+}
+
+// Length of each UUID hyphenated group in hex digits.
+const UUID_GROUP_LENS: [usize; 5] = [8, 4, 4, 4, 12];
+
+impl LiteralDigitGrouping {
+ pub fn new(lint_fraction_readability: bool) -> Self {
+ Self {
+ lint_fraction_readability,
+ }
+ }
+
+ fn check_lit(self, cx: &EarlyContext<'_>, lit: &Lit) {
+ if_chain! {
+ if let Some(src) = snippet_opt(cx, lit.span);
+ if let Some(mut num_lit) = NumericLiteral::from_lit(&src, &lit);
+ then {
+ if !Self::check_for_mistyped_suffix(cx, lit.span, &mut num_lit) {
+ return;
+ }
+
+ if Self::is_literal_uuid_formatted(&mut num_lit) {
+ return;
+ }
+
+ let result = (|| {
+
+ let integral_group_size = Self::get_group_size(num_lit.integer.split('_'), num_lit.radix, true)?;
+ if let Some(fraction) = num_lit.fraction {
+ let fractional_group_size = Self::get_group_size(
+ fraction.rsplit('_'),
+ num_lit.radix,
+ self.lint_fraction_readability)?;
+
+ let consistent = Self::parts_consistent(integral_group_size,
+ fractional_group_size,
+ num_lit.integer.len(),
+ fraction.len());
+ if !consistent {
+ return Err(WarningType::InconsistentDigitGrouping);
+ };
+ }
+
+ Ok(())
+ })();
+
+
+ if let Err(warning_type) = result {
+ let should_warn = match warning_type {
+ | WarningType::UnreadableLiteral
+ | WarningType::InconsistentDigitGrouping
+ | WarningType::UnusualByteGroupings
+ | WarningType::LargeDigitGroups => {
+ !in_macro(lit.span)
+ }
+ WarningType::DecimalRepresentation | WarningType::MistypedLiteralSuffix => {
+ true
+ }
+ };
+ if should_warn {
+ warning_type.display(num_lit.format(), cx, lit.span)
+ }
+ }
+ }
+ }
+ }
+
+ // Returns `false` if the check fails
+ fn check_for_mistyped_suffix(
+ cx: &EarlyContext<'_>,
+ span: rustc_span::Span,
+ num_lit: &mut NumericLiteral<'_>,
+ ) -> bool {
+ if num_lit.suffix.is_some() {
+ return true;
+ }
+
+ let (part, mistyped_suffixes, missing_char) = if let Some((_, exponent)) = &mut num_lit.exponent {
+ (exponent, &["32", "64"][..], 'f')
+ } else if num_lit.fraction.is_some() {
+ (&mut num_lit.integer, &["32", "64"][..], 'f')
+ } else {
+ (&mut num_lit.integer, &["8", "16", "32", "64"][..], 'i')
+ };
+
+ let mut split = part.rsplit('_');
+ let last_group = split.next().expect("At least one group");
+ if split.next().is_some() && mistyped_suffixes.contains(&last_group) {
+ *part = &part[..part.len() - last_group.len()];
+ let mut sugg = num_lit.format();
+ sugg.push('_');
+ sugg.push(missing_char);
+ sugg.push_str(last_group);
+ WarningType::MistypedLiteralSuffix.display(sugg, cx, span);
+ false
+ } else {
+ true
+ }
+ }
+
+ /// Checks whether the numeric literal matches the formatting of a UUID.
+ ///
+ /// Returns `true` if the radix is hexadecimal, and the groups match the
+ /// UUID format of 8-4-4-4-12.
+ fn is_literal_uuid_formatted(num_lit: &mut NumericLiteral<'_>) -> bool {
+ if num_lit.radix != Radix::Hexadecimal {
+ return false;
+ }
+
+ // UUIDs should not have a fraction
+ if num_lit.fraction.is_some() {
+ return false;
+ }
+
+ let group_sizes: Vec<usize> = num_lit.integer.split('_').map(str::len).collect();
+ if UUID_GROUP_LENS.len() == group_sizes.len() {
+ UUID_GROUP_LENS.iter().zip(&group_sizes).all(|(&a, &b)| a == b)
+ } else {
+ false
+ }
+ }
+
+ /// Given the sizes of the digit groups of both integral and fractional
+ /// parts, and the length
+ /// of both parts, determine if the digits have been grouped consistently.
+ #[must_use]
+ fn parts_consistent(
+ int_group_size: Option<usize>,
+ frac_group_size: Option<usize>,
+ int_size: usize,
+ frac_size: usize,
+ ) -> bool {
+ match (int_group_size, frac_group_size) {
+ // No groups on either side of decimal point - trivially consistent.
+ (None, None) => true,
+ // Integral part has grouped digits, fractional part does not.
+ (Some(int_group_size), None) => frac_size <= int_group_size,
+ // Fractional part has grouped digits, integral part does not.
+ (None, Some(frac_group_size)) => int_size <= frac_group_size,
+ // Both parts have grouped digits. Groups should be the same size.
+ (Some(int_group_size), Some(frac_group_size)) => int_group_size == frac_group_size,
+ }
+ }
+
+ /// Returns the size of the digit groups (or None if ungrouped) if successful,
+ /// otherwise returns a `WarningType` for linting.
+ fn get_group_size<'a>(
+ groups: impl Iterator<Item = &'a str>,
+ radix: Radix,
+ lint_unreadable: bool,
+ ) -> Result<Option<usize>, WarningType> {
+ let mut groups = groups.map(str::len);
+
+ let first = groups.next().expect("At least one group");
+
+ if (radix == Radix::Binary || radix == Radix::Hexadecimal) && groups.any(|i| i != 4 && i != 2) {
+ return Err(WarningType::UnusualByteGroupings);
+ }
+
+ if let Some(second) = groups.next() {
+ if !groups.all(|x| x == second) || first > second {
+ Err(WarningType::InconsistentDigitGrouping)
+ } else if second > 4 {
+ Err(WarningType::LargeDigitGroups)
+ } else {
+ Ok(Some(second))
+ }
+ } else if first > 5 && lint_unreadable {
+ Err(WarningType::UnreadableLiteral)
+ } else {
+ Ok(None)
+ }
+ }
+}
+
+#[allow(clippy::module_name_repetitions)]
+#[derive(Copy, Clone)]
+pub struct DecimalLiteralRepresentation {
+ threshold: u64,
+}
+
+impl_lint_pass!(DecimalLiteralRepresentation => [DECIMAL_LITERAL_REPRESENTATION]);
+
+impl EarlyLintPass for DecimalLiteralRepresentation {
+ fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
+ if in_external_macro(cx.sess(), expr.span) {
+ return;
+ }
+
+ if let ExprKind::Lit(ref lit) = expr.kind {
+ self.check_lit(cx, lit)
+ }
+ }
+}
+
+impl DecimalLiteralRepresentation {
+ #[must_use]
+ pub fn new(threshold: u64) -> Self {
+ Self { threshold }
+ }
+ fn check_lit(self, cx: &EarlyContext<'_>, lit: &Lit) {
+ // Lint integral literals.
+ if_chain! {
+ if let LitKind::Int(val, _) = lit.kind;
+ if let Some(src) = snippet_opt(cx, lit.span);
+ if let Some(num_lit) = NumericLiteral::from_lit(&src, &lit);
+ if num_lit.radix == Radix::Decimal;
+ if val >= u128::from(self.threshold);
+ then {
+ let hex = format!("{:#X}", val);
+ let num_lit = NumericLiteral::new(&hex, num_lit.suffix, false);
+ let _ = Self::do_lint(num_lit.integer).map_err(|warning_type| {
+ warning_type.display(num_lit.format(), 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(())
+ }
+}
projects / rustc.git / blobdiff