[`cmp_owned`]: https://rust-lang.github.io/rust-clippy/master/index.html#cmp_owned
[`cognitive_complexity`]: https://rust-lang.github.io/rust-clippy/master/index.html#cognitive_complexity
[`collapsible_if`]: https://rust-lang.github.io/rust-clippy/master/index.html#collapsible_if
+[`comparison_chain`]: https://rust-lang.github.io/rust-clippy/master/index.html#comparison_chain
[`copy_iterator`]: https://rust-lang.github.io/rust-clippy/master/index.html#copy_iterator
[`crosspointer_transmute`]: https://rust-lang.github.io/rust-clippy/master/index.html#crosspointer_transmute
[`dbg_macro`]: https://rust-lang.github.io/rust-clippy/master/index.html#dbg_macro
A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
-[There are 316 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
+[There are 317 lints included in this crate!](https://rust-lang.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:
--- /dev/null
+use crate::utils::{if_sequence, parent_node_is_if_expr, span_help_and_lint, SpanlessEq};
+use rustc::hir::*;
+use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
+use rustc::{declare_lint_pass, declare_tool_lint};
+
+declare_clippy_lint! {
+ /// **What it does:** Checks comparison chains written with `if` that can be
+ /// rewritten with `match` and `cmp`.
+ ///
+ /// **Why is this bad?** `if` is not guaranteed to be exhaustive and conditionals can get
+ /// repetitive
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **Example:**
+ /// ```rust,ignore
+ /// # fn a() {}
+ /// # fn b() {}
+ /// # fn c() {}
+ /// fn f(x: u8, y: u8) {
+ /// if x > y {
+ /// a()
+ /// } else if x < y {
+ /// b()
+ /// } else {
+ /// c()
+ /// }
+ /// }
+ /// ```
+ ///
+ /// Could be written:
+ ///
+ /// ```rust,ignore
+ /// use std::cmp::Ordering;
+ /// # fn a() {}
+ /// # fn b() {}
+ /// # fn c() {}
+ /// fn f(x: u8, y: u8) {
+ /// match x.cmp(y) {
+ /// Ordering::Greater => a(),
+ /// Ordering::Less => b(),
+ /// Ordering::Equal => c()
+ /// }
+ /// }
+ /// ```
+ pub COMPARISON_CHAIN,
+ style,
+ "`if`s that can be rewritten with `match` and `cmp`"
+}
+
+declare_lint_pass!(ComparisonChain => [COMPARISON_CHAIN]);
+
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ComparisonChain {
+ fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
+ if expr.span.from_expansion() {
+ return;
+ }
+
+ // We only care about the top-most `if` in the chain
+ if parent_node_is_if_expr(expr, cx) {
+ return;
+ }
+
+ // Check that there exists at least one explicit else condition
+ let (conds, _) = if_sequence(expr);
+ if conds.len() < 2 {
+ return;
+ }
+
+ for cond in conds.windows(2) {
+ if let (
+ &ExprKind::Binary(ref kind1, ref lhs1, ref rhs1),
+ &ExprKind::Binary(ref kind2, ref lhs2, ref rhs2),
+ ) = (&cond[0].node, &cond[1].node)
+ {
+ if !kind_is_cmp(kind1.node) || !kind_is_cmp(kind2.node) {
+ return;
+ }
+
+ // Check that both sets of operands are equal
+ let mut spanless_eq = SpanlessEq::new(cx);
+ if (!spanless_eq.eq_expr(lhs1, lhs2) || !spanless_eq.eq_expr(rhs1, rhs2))
+ && (!spanless_eq.eq_expr(lhs1, rhs2) || !spanless_eq.eq_expr(rhs1, lhs2))
+ {
+ return;
+ }
+ } else {
+ // We only care about comparison chains
+ return;
+ }
+ }
+ span_help_and_lint(
+ cx,
+ COMPARISON_CHAIN,
+ expr.span,
+ "`if` chain can be rewritten with `match`",
+ "Consider rewriting the `if` chain to use `cmp` and `match`.",
+ )
+ }
+}
+
+fn kind_is_cmp(kind: BinOpKind) -> bool {
+ match kind {
+ BinOpKind::Lt | BinOpKind::Gt | BinOpKind::Eq => true,
+ _ => false,
+ }
+}
-use crate::utils::{get_parent_expr, higher, same_tys, snippet, span_lint_and_then, span_note_and_lint};
+use crate::utils::{get_parent_expr, higher, if_sequence, same_tys, snippet, span_lint_and_then, span_note_and_lint};
use crate::utils::{SpanlessEq, SpanlessHash};
use rustc::hir::*;
use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
use rustc::ty::Ty;
use rustc::{declare_lint_pass, declare_tool_lint};
use rustc_data_structures::fx::FxHashMap;
-use smallvec::SmallVec;
+use std::cmp::Ordering;
use std::collections::hash_map::Entry;
use std::hash::BuildHasherDefault;
use syntax::symbol::Symbol;
}
}
-/// Returns the list of condition expressions and the list of blocks in a
-/// sequence of `if/else`.
-/// E.g., this returns `([a, b], [c, d, e])` for the expression
-/// `if a { c } else if b { d } else { e }`.
-fn if_sequence(mut expr: &Expr) -> (SmallVec<[&Expr; 1]>, SmallVec<[&Block; 1]>) {
- let mut conds = SmallVec::new();
- let mut blocks: SmallVec<[&Block; 1]> = SmallVec::new();
-
- while let Some((ref cond, ref then_expr, ref else_expr)) = higher::if_block(&expr) {
- conds.push(&**cond);
- if let ExprKind::Block(ref block, _) = then_expr.node {
- blocks.push(block);
- } else {
- panic!("ExprKind::If node is not an ExprKind::Block");
- }
-
- if let Some(ref else_expr) = *else_expr {
- expr = else_expr;
- } else {
- break;
- }
- }
-
- // final `else {..}`
- if !blocks.is_empty() {
- if let ExprKind::Block(ref block, _) = expr.node {
- blocks.push(&**block);
- }
- }
-
- (conds, blocks)
-}
-
/// Returns the list of bindings in a pattern.
fn bindings<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, pat: &Pat) -> FxHashMap<Symbol, Ty<'tcx>> {
fn bindings_impl<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, pat: &Pat, map: &mut FxHashMap<Symbol, Ty<'tcx>>) {
where
Eq: Fn(&T, &T) -> bool,
{
- if exprs.len() < 2 {
- None
- } else if exprs.len() == 2 {
- if eq(&exprs[0], &exprs[1]) {
- Some((&exprs[0], &exprs[1]))
- } else {
- None
- }
- } else {
- None
+ match exprs.len().cmp(&2) {
+ Ordering::Greater | Ordering::Less => None,
+ Ordering::Equal => {
+ if eq(&exprs[0], &exprs[1]) {
+ Some((&exprs[0], &exprs[1]))
+ } else {
+ None
+ }
+ },
}
}
pub mod checked_conversions;
pub mod cognitive_complexity;
pub mod collapsible_if;
+pub mod comparison_chain;
pub mod copies;
pub mod copy_iterator;
pub mod dbg_macro;
reg.register_late_lint_pass(box integer_division::IntegerDivision);
reg.register_late_lint_pass(box inherent_to_string::InherentToString);
reg.register_late_lint_pass(box trait_bounds::TraitBounds);
+ reg.register_late_lint_pass(box comparison_chain::ComparisonChain);
reg.register_lint_group("clippy::restriction", Some("clippy_restriction"), vec![
arithmetic::FLOAT_ARITHMETIC,
bytecount::NAIVE_BYTECOUNT,
cognitive_complexity::COGNITIVE_COMPLEXITY,
collapsible_if::COLLAPSIBLE_IF,
+ comparison_chain::COMPARISON_CHAIN,
copies::IFS_SAME_COND,
copies::IF_SAME_THEN_ELSE,
derive::DERIVE_HASH_XOR_EQ,
block_in_if_condition::BLOCK_IN_IF_CONDITION_EXPR,
block_in_if_condition::BLOCK_IN_IF_CONDITION_STMT,
collapsible_if::COLLAPSIBLE_IF,
+ comparison_chain::COMPARISON_CHAIN,
doc::MISSING_SAFETY_DOC,
enum_variants::ENUM_VARIANT_NAMES,
enum_variants::MODULE_INCEPTION,
//! This lint is **warn** by default
use crate::utils::sugg::Sugg;
-use crate::utils::{higher, span_lint, span_lint_and_sugg};
+use crate::utils::{higher, parent_node_is_if_expr, span_lint, span_lint_and_sugg};
use rustc::hir::*;
use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
use rustc::{declare_lint_pass, declare_tool_lint};
}
}
-fn parent_node_is_if_expr<'a, 'b>(expr: &Expr, cx: &LateContext<'a, 'b>) -> bool {
- let parent_id = cx.tcx.hir().get_parent_node(expr.hir_id);
- let parent_node = cx.tcx.hir().get(parent_id);
-
- match parent_node {
- rustc::hir::Node::Expr(e) => higher::if_block(&e).is_some(),
- rustc::hir::Node::Arm(e) => higher::if_block(&e.body).is_some(),
- _ => false,
- }
-}
-
declare_lint_pass!(BoolComparison => [BOOL_COMPARISON]);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for BoolComparison {
use crate::utils::{span_lint, span_lint_and_then};
use rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
use rustc::{declare_tool_lint, impl_lint_pass};
+use std::cmp::Ordering;
use syntax::ast::*;
use syntax::attr;
use syntax::source_map::Span;
continue;
}
let mut split_at = None;
- if existing_name.len > count {
- if existing_name.len - count != 1 || levenstein_not_1(&interned_name, &existing_name.interned) {
- continue;
- }
- } else if existing_name.len < count {
- if count - existing_name.len != 1 || levenstein_not_1(&existing_name.interned, &interned_name) {
- continue;
- }
- } else {
- let mut interned_chars = interned_name.chars();
- let mut existing_chars = existing_name.interned.chars();
- let first_i = interned_chars.next().expect("we know we have at least one char");
- let first_e = existing_chars.next().expect("we know we have at least one char");
- let eq_or_numeric = |(a, b): (char, char)| a == b || a.is_numeric() && b.is_numeric();
+ match existing_name.len.cmp(&count) {
+ Ordering::Greater => {
+ if existing_name.len - count != 1 || levenstein_not_1(&interned_name, &existing_name.interned) {
+ continue;
+ }
+ },
+ Ordering::Less => {
+ if count - existing_name.len != 1 || levenstein_not_1(&existing_name.interned, &interned_name) {
+ continue;
+ }
+ },
+ Ordering::Equal => {
+ let mut interned_chars = interned_name.chars();
+ let mut existing_chars = existing_name.interned.chars();
+ let first_i = interned_chars.next().expect("we know we have at least one char");
+ let first_e = existing_chars.next().expect("we know we have at least one char");
+ let eq_or_numeric = |(a, b): (char, char)| a == b || a.is_numeric() && b.is_numeric();
- if eq_or_numeric((first_i, first_e)) {
- let last_i = interned_chars.next_back().expect("we know we have at least two chars");
- let last_e = existing_chars.next_back().expect("we know we have at least two chars");
- if eq_or_numeric((last_i, last_e)) {
- if interned_chars
- .zip(existing_chars)
- .filter(|&ie| !eq_or_numeric(ie))
- .count()
- != 1
- {
- continue;
+ if eq_or_numeric((first_i, first_e)) {
+ let last_i = interned_chars.next_back().expect("we know we have at least two chars");
+ let last_e = existing_chars.next_back().expect("we know we have at least two chars");
+ if eq_or_numeric((last_i, last_e)) {
+ if interned_chars
+ .zip(existing_chars)
+ .filter(|&ie| !eq_or_numeric(ie))
+ .count()
+ != 1
+ {
+ continue;
+ }
+ } else {
+ let second_last_i = interned_chars
+ .next_back()
+ .expect("we know we have at least three chars");
+ let second_last_e = existing_chars
+ .next_back()
+ .expect("we know we have at least three chars");
+ if !eq_or_numeric((second_last_i, second_last_e))
+ || second_last_i == '_'
+ || !interned_chars.zip(existing_chars).all(eq_or_numeric)
+ {
+ // allowed similarity foo_x, foo_y
+ // or too many chars differ (foo_x, boo_y) or (foox, booy)
+ continue;
+ }
+ split_at = interned_name.char_indices().rev().next().map(|(i, _)| i);
}
} else {
- let second_last_i = interned_chars
- .next_back()
- .expect("we know we have at least three chars");
- let second_last_e = existing_chars
- .next_back()
- .expect("we know we have at least three chars");
- if !eq_or_numeric((second_last_i, second_last_e))
- || second_last_i == '_'
+ let second_i = interned_chars.next().expect("we know we have at least two chars");
+ let second_e = existing_chars.next().expect("we know we have at least two chars");
+ if !eq_or_numeric((second_i, second_e))
+ || second_i == '_'
|| !interned_chars.zip(existing_chars).all(eq_or_numeric)
{
- // allowed similarity foo_x, foo_y
- // or too many chars differ (foo_x, boo_y) or (foox, booy)
+ // allowed similarity x_foo, y_foo
+ // or too many chars differ (x_foo, y_boo) or (xfoo, yboo)
continue;
}
- split_at = interned_name.char_indices().rev().next().map(|(i, _)| i);
+ split_at = interned_name.chars().next().map(char::len_utf8);
}
- } else {
- let second_i = interned_chars.next().expect("we know we have at least two chars");
- let second_e = existing_chars.next().expect("we know we have at least two chars");
- if !eq_or_numeric((second_i, second_e))
- || second_i == '_'
- || !interned_chars.zip(existing_chars).all(eq_or_numeric)
- {
- // allowed similarity x_foo, y_foo
- // or too many chars differ (x_foo, y_boo) or (xfoo, yboo)
- continue;
- }
- split_at = interned_name.chars().next().map(char::len_utf8);
- }
+ },
}
span_lint_and_then(
self.0.cx,
let path = cx.get_def_path(did);
path.len() == syms.len() && path.into_iter().zip(syms.iter()).all(|(a, &b)| a.as_str() == b)
}
+
+/// Returns the list of condition expressions and the list of blocks in a
+/// sequence of `if/else`.
+/// E.g., this returns `([a, b], [c, d, e])` for the expression
+/// `if a { c } else if b { d } else { e }`.
+pub fn if_sequence(mut expr: &Expr) -> (SmallVec<[&Expr; 1]>, SmallVec<[&Block; 1]>) {
+ let mut conds = SmallVec::new();
+ let mut blocks: SmallVec<[&Block; 1]> = SmallVec::new();
+
+ while let Some((ref cond, ref then_expr, ref else_expr)) = higher::if_block(&expr) {
+ conds.push(&**cond);
+ if let ExprKind::Block(ref block, _) = then_expr.node {
+ blocks.push(block);
+ } else {
+ panic!("ExprKind::If node is not an ExprKind::Block");
+ }
+
+ if let Some(ref else_expr) = *else_expr {
+ expr = else_expr;
+ } else {
+ break;
+ }
+ }
+
+ // final `else {..}`
+ if !blocks.is_empty() {
+ if let ExprKind::Block(ref block, _) = expr.node {
+ blocks.push(&**block);
+ }
+ }
+
+ (conds, blocks)
+}
+
+pub fn parent_node_is_if_expr<'a, 'b>(expr: &Expr, cx: &LateContext<'a, 'b>) -> bool {
+ let parent_id = cx.tcx.hir().get_parent_node(expr.hir_id);
+ let parent_node = cx.tcx.hir().get(parent_id);
+
+ match parent_node {
+ rustc::hir::Node::Expr(e) => higher::if_block(&e).is_some(),
+ rustc::hir::Node::Arm(e) => higher::if_block(&e.body).is_some(),
+ _ => false,
+ }
+}
pub use lint::LINT_LEVELS;
// begin lint list, do not remove this comment, it’s used in `update_lints`
-pub const ALL_LINTS: [Lint; 316] = [
+pub const ALL_LINTS: [Lint; 317] = [
Lint {
name: "absurd_extreme_comparisons",
group: "correctness",
deprecation: None,
module: "collapsible_if",
},
+ Lint {
+ name: "comparison_chain",
+ group: "style",
+ desc: "`if`s that can be rewritten with `match` and `cmp`",
+ deprecation: None,
+ module: "comparison_chain",
+ },
Lint {
name: "copy_iterator",
group: "pedantic",
--- /dev/null
+#![allow(dead_code)]
+#![warn(clippy::comparison_chain)]
+
+fn a() {}
+fn b() {}
+fn c() {}
+
+fn f(x: u8, y: u8, z: u8) {
+ // Ignored: Only one branch
+ if x > y {
+ a()
+ }
+
+ if x > y {
+ a()
+ } else if x < y {
+ b()
+ }
+
+ // Ignored: Only one explicit conditional
+ if x > y {
+ a()
+ } else {
+ b()
+ }
+
+ if x > y {
+ a()
+ } else if x < y {
+ b()
+ } else {
+ c()
+ }
+
+ if x > y {
+ a()
+ } else if y > x {
+ b()
+ } else {
+ c()
+ }
+
+ if x > 1 {
+ a()
+ } else if x < 1 {
+ b()
+ } else if x == 1 {
+ c()
+ }
+
+ // Ignored: Binop args are not equivalent
+ if x > 1 {
+ a()
+ } else if y > 1 {
+ b()
+ } else {
+ c()
+ }
+
+ // Ignored: Binop args are not equivalent
+ if x > y {
+ a()
+ } else if x > z {
+ b()
+ } else if y > z {
+ c()
+ }
+
+ // Ignored: Not binary comparisons
+ if true {
+ a()
+ } else if false {
+ b()
+ } else {
+ c()
+ }
+}
+
+fn main() {}
--- /dev/null
+error: `if` chain can be rewritten with `match`
+ --> $DIR/comparison_chain.rs:14:5
+ |
+LL | / if x > y {
+LL | | a()
+LL | | } else if x < y {
+LL | | b()
+LL | | }
+ | |_____^
+ |
+ = note: `-D clippy::comparison-chain` implied by `-D warnings`
+ = help: Consider rewriting the `if` chain to use `cmp` and `match`.
+
+error: `if` chain can be rewritten with `match`
+ --> $DIR/comparison_chain.rs:27:5
+ |
+LL | / if x > y {
+LL | | a()
+LL | | } else if x < y {
+LL | | b()
+LL | | } else {
+LL | | c()
+LL | | }
+ | |_____^
+ |
+ = help: Consider rewriting the `if` chain to use `cmp` and `match`.
+
+error: `if` chain can be rewritten with `match`
+ --> $DIR/comparison_chain.rs:35:5
+ |
+LL | / if x > y {
+LL | | a()
+LL | | } else if y > x {
+LL | | b()
+LL | | } else {
+LL | | c()
+LL | | }
+ | |_____^
+ |
+ = help: Consider rewriting the `if` chain to use `cmp` and `match`.
+
+error: `if` chain can be rewritten with `match`
+ --> $DIR/comparison_chain.rs:43:5
+ |
+LL | / if x > 1 {
+LL | | a()
+LL | | } else if x < 1 {
+LL | | b()
+LL | | } else if x == 1 {
+LL | | c()
+LL | | }
+ | |_____^
+ |
+ = help: Consider rewriting the `if` chain to use `cmp` and `match`.
+
+error: aborting due to 4 previous errors
+
// run-pass
+#![allow(clippy::comparison_chain)]
#![deny(clippy::if_same_then_else)]
/// Test for https://github.com/rust-lang/rust-clippy/issues/2426
#![warn(clippy::ifs_same_cond)]
-#![allow(clippy::if_same_then_else)] // all empty blocks
+#![allow(clippy::if_same_then_else, clippy::comparison_chain)] // all empty blocks
fn ifs_same_cond() {
let a = 0;
projects / rust.git / commitdiff