-use rustc::lint::*;
-use rustc::hir::*;
-use syntax::ast::RangeLimits;
-use syntax::codemap::Spanned;
-use crate::utils::{is_integer_literal, paths, snippet, span_lint, span_lint_and_then};
-use crate::utils::{get_trait_def_id, higher, implements_trait};
-use crate::utils::sugg::Sugg;
+use if_chain::if_chain;
+use rustc_ast::ast::RangeLimits;
+use rustc_errors::Applicability;
+use rustc_hir::{BinOpKind, Expr, ExprKind, QPath};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::source_map::Spanned;
-/// **What it does:** Checks for calling `.step_by(0)` on iterators,
-/// which never terminates.
-///
-/// **Why is this bad?** This very much looks like an oversight, since with
-/// `loop { .. }` there is an obvious better way to endlessly loop.
-///
-/// **Known problems:** None.
-///
-/// **Example:**
-/// ```rust
-/// for x in (5..5).step_by(0) { .. }
-/// ```
-declare_clippy_lint! {
- pub ITERATOR_STEP_BY_ZERO,
- correctness,
- "using `Iterator::step_by(0)`, which produces an infinite iterator"
-}
+use crate::utils::sugg::Sugg;
+use crate::utils::{higher, SpanlessEq};
+use crate::utils::{is_integer_const, snippet, snippet_opt, span_lint, span_lint_and_then};
-/// **What it does:** Checks for zipping a collection with the range of
-/// `0.._.len()`.
-///
-/// **Why is this bad?** The code is better expressed with `.enumerate()`.
-///
-/// **Known problems:** None.
-///
-/// **Example:**
-/// ```rust
-/// x.iter().zip(0..x.len())
-/// ```
declare_clippy_lint! {
+ /// **What it does:** Checks for zipping a collection with the range of
+ /// `0.._.len()`.
+ ///
+ /// **Why is this bad?** The code is better expressed with `.enumerate()`.
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **Example:**
+ /// ```rust
+ /// # let x = vec![1];
+ /// x.iter().zip(0..x.len());
+ /// ```
+ /// Could be written as
+ /// ```rust
+ /// # let x = vec![1];
+ /// x.iter().enumerate();
+ /// ```
pub RANGE_ZIP_WITH_LEN,
complexity,
"zipping iterator with a range when `enumerate()` would do"
}
-/// **What it does:** Checks for exclusive ranges where 1 is added to the
-/// upper bound, e.g. `x..(y+1)`.
-///
-/// **Why is this bad?** The code is more readable with an inclusive range
-/// like `x..=y`.
-///
-/// **Known problems:** None.
-///
-/// **Example:**
-/// ```rust
-/// for x..(y+1) { .. }
-/// ```
declare_clippy_lint! {
+ /// **What it does:** Checks for exclusive ranges where 1 is added to the
+ /// upper bound, e.g., `x..(y+1)`.
+ ///
+ /// **Why is this bad?** The code is more readable with an inclusive range
+ /// like `x..=y`.
+ ///
+ /// **Known problems:** Will add unnecessary pair of parentheses when the
+ /// expression is not wrapped in a pair but starts with a opening parenthesis
+ /// and ends with a closing one.
+ /// I.e., `let _ = (f()+1)..(f()+1)` results in `let _ = ((f()+1)..=f())`.
+ ///
+ /// Also in many cases, inclusive ranges are still slower to run than
+ /// exclusive ranges, because they essentially add an extra branch that
+ /// LLVM may fail to hoist out of the loop.
+ ///
+ /// **Example:**
+ /// ```rust,ignore
+ /// for x..(y+1) { .. }
+ /// ```
+ /// Could be written as
+ /// ```rust,ignore
+ /// for x..=y { .. }
+ /// ```
pub RANGE_PLUS_ONE,
- nursery,
+ pedantic,
"`x..(y+1)` reads better as `x..=y`"
}
-/// **What it does:** Checks for inclusive ranges where 1 is subtracted from
-/// the upper bound, e.g. `x..=(y-1)`.
-///
-/// **Why is this bad?** The code is more readable with an exclusive range
-/// like `x..y`.
-///
-/// **Known problems:** None.
-///
-/// **Example:**
-/// ```rust
-/// for x..=(y-1) { .. }
-/// ```
declare_clippy_lint! {
+ /// **What it does:** Checks for inclusive ranges where 1 is subtracted from
+ /// the upper bound, e.g., `x..=(y-1)`.
+ ///
+ /// **Why is this bad?** The code is more readable with an exclusive range
+ /// like `x..y`.
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **Example:**
+ /// ```rust,ignore
+ /// for x..=(y-1) { .. }
+ /// ```
+ /// Could be written as
+ /// ```rust,ignore
+ /// for x..y { .. }
+ /// ```
pub RANGE_MINUS_ONE,
- style,
+ complexity,
"`x..=(y-1)` reads better as `x..y`"
}
-#[derive(Copy, Clone)]
-pub struct Pass;
-
-impl LintPass for Pass {
- fn get_lints(&self) -> LintArray {
- lint_array!(ITERATOR_STEP_BY_ZERO, RANGE_ZIP_WITH_LEN, RANGE_PLUS_ONE, RANGE_MINUS_ONE)
- }
-}
+declare_lint_pass!(Ranges => [
+ RANGE_ZIP_WITH_LEN,
+ RANGE_PLUS_ONE,
+ RANGE_MINUS_ONE
+]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
- if let ExprMethodCall(ref path, _, ref args) = expr.node {
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Ranges {
+ fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) {
+ if let ExprKind::MethodCall(ref path, _, ref args) = expr.kind {
let name = path.ident.as_str();
-
- // Range with step_by(0).
- if name == "step_by" && args.len() == 2 && has_step_by(cx, &args[0]) {
- use crate::consts::{constant, Constant};
- if let Some((Constant::Int(0), _)) = constant(cx, cx.tables, &args[1]) {
- span_lint(
- cx,
- ITERATOR_STEP_BY_ZERO,
- expr.span,
- "Iterator::step_by(0) will panic at runtime",
- );
- }
- } else if name == "zip" && args.len() == 2 {
- let iter = &args[0].node;
+ if name == "zip" && args.len() == 2 {
+ let iter = &args[0].kind;
let zip_arg = &args[1];
if_chain! {
- // .iter() call
- if let ExprMethodCall(ref iter_path, _, ref iter_args ) = *iter;
- if iter_path.ident.name == "iter";
- // range expression in .zip() call: 0..x.len()
+ // `.iter()` call
+ if let ExprKind::MethodCall(ref iter_path, _, ref iter_args ) = *iter;
+ if iter_path.ident.name == sym!(iter);
+ // range expression in `.zip()` call: `0..x.len()`
if let Some(higher::Range { start: Some(start), end: Some(end), .. }) = higher::range(cx, zip_arg);
- if is_integer_literal(start, 0);
- // .len() call
- if let ExprMethodCall(ref len_path, _, ref len_args) = end.node;
- if len_path.ident.name == "len" && len_args.len() == 1;
- // .iter() and .len() called on same Path
- if let ExprPath(QPath::Resolved(_, ref iter_path)) = iter_args[0].node;
- if let ExprPath(QPath::Resolved(_, ref len_path)) = len_args[0].node;
- if iter_path.segments == len_path.segments;
+ if is_integer_const(cx, start, 0);
+ // `.len()` call
+ if let ExprKind::MethodCall(ref len_path, _, ref len_args) = end.kind;
+ if len_path.ident.name == sym!(len) && len_args.len() == 1;
+ // `.iter()` and `.len()` called on same `Path`
+ if let ExprKind::Path(QPath::Resolved(_, ref iter_path)) = iter_args[0].kind;
+ if let ExprKind::Path(QPath::Resolved(_, ref len_path)) = len_args[0].kind;
+ if SpanlessEq::new(cx).eq_path_segments(&iter_path.segments, &len_path.segments);
then {
span_lint(cx,
RANGE_ZIP_WITH_LEN,
expr.span,
- &format!("It is more idiomatic to use {}.iter().enumerate()",
+ &format!("It is more idiomatic to use `{}.iter().enumerate()`",
snippet(cx, iter_args[0].span, "_")));
}
}
}
}
- // exclusive range plus one: x..(y+1)
- if_chain! {
- if let Some(higher::Range { start, end: Some(end), limits: RangeLimits::HalfOpen }) = higher::range(cx, expr);
- if let Some(y) = y_plus_one(end);
- then {
- span_lint_and_then(
- cx,
- RANGE_PLUS_ONE,
- expr.span,
- "an inclusive range would be more readable",
- |db| {
- let start = start.map_or("".to_owned(), |x| Sugg::hir(cx, x, "x").to_string());
- let end = Sugg::hir(cx, y, "y");
- db.span_suggestion(expr.span,
- "use",
- format!("{}..={}", start, end));
- },
- );
- }
- }
+ check_exclusive_range_plus_one(cx, expr);
+ check_inclusive_range_minus_one(cx, expr);
+ }
+}
- // inclusive range minus one: x..=(y-1)
- if_chain! {
- if let Some(higher::Range { start, end: Some(end), limits: RangeLimits::Closed }) = higher::range(cx, expr);
- if let Some(y) = y_minus_one(end);
- then {
- span_lint_and_then(
- cx,
- RANGE_MINUS_ONE,
- expr.span,
- "an exclusive range would be more readable",
- |db| {
- let start = start.map_or("".to_owned(), |x| Sugg::hir(cx, x, "x").to_string());
- let end = Sugg::hir(cx, y, "y");
- db.span_suggestion(expr.span,
- "use",
- format!("{}..{}", start, end));
- },
- );
- }
+// exclusive range plus one: `x..(y+1)`
+fn check_exclusive_range_plus_one(cx: &LateContext<'_, '_>, expr: &Expr<'_>) {
+ if_chain! {
+ if let Some(higher::Range {
+ start,
+ end: Some(end),
+ limits: RangeLimits::HalfOpen
+ }) = higher::range(cx, expr);
+ if let Some(y) = y_plus_one(cx, end);
+ then {
+ let span = if expr.span.from_expansion() {
+ expr.span
+ .ctxt()
+ .outer_expn_data()
+ .call_site
+ } else {
+ expr.span
+ };
+ span_lint_and_then(
+ cx,
+ RANGE_PLUS_ONE,
+ span,
+ "an inclusive range would be more readable",
+ |db| {
+ let start = start.map_or(String::new(), |x| Sugg::hir(cx, x, "x").to_string());
+ let end = Sugg::hir(cx, y, "y");
+ if let Some(is_wrapped) = &snippet_opt(cx, span) {
+ if is_wrapped.starts_with('(') && is_wrapped.ends_with(')') {
+ db.span_suggestion(
+ span,
+ "use",
+ format!("({}..={})", start, end),
+ Applicability::MaybeIncorrect,
+ );
+ } else {
+ db.span_suggestion(
+ span,
+ "use",
+ format!("{}..={}", start, end),
+ Applicability::MachineApplicable, // snippet
+ );
+ }
+ }
+ },
+ );
}
}
}
-fn has_step_by(cx: &LateContext, expr: &Expr) -> bool {
- // No need for walk_ptrs_ty here because step_by moves self, so it
- // can't be called on a borrowed range.
- let ty = cx.tables.expr_ty_adjusted(expr);
-
- get_trait_def_id(cx, &paths::ITERATOR).map_or(false, |iterator_trait| implements_trait(cx, ty, iterator_trait, &[]))
+// inclusive range minus one: `x..=(y-1)`
+fn check_inclusive_range_minus_one(cx: &LateContext<'_, '_>, expr: &Expr<'_>) {
+ if_chain! {
+ if let Some(higher::Range { start, end: Some(end), limits: RangeLimits::Closed }) = higher::range(cx, expr);
+ if let Some(y) = y_minus_one(cx, end);
+ then {
+ span_lint_and_then(
+ cx,
+ RANGE_MINUS_ONE,
+ expr.span,
+ "an exclusive range would be more readable",
+ |db| {
+ let start = start.map_or(String::new(), |x| Sugg::hir(cx, x, "x").to_string());
+ let end = Sugg::hir(cx, y, "y");
+ db.span_suggestion(
+ expr.span,
+ "use",
+ format!("{}..{}", start, end),
+ Applicability::MachineApplicable, // snippet
+ );
+ },
+ );
+ }
+ }
}
-fn y_plus_one(expr: &Expr) -> Option<&Expr> {
- match expr.node {
- ExprBinary(Spanned { node: BiAdd, .. }, ref lhs, ref rhs) => if is_integer_literal(lhs, 1) {
- Some(rhs)
- } else if is_integer_literal(rhs, 1) {
- Some(lhs)
- } else {
- None
+fn y_plus_one<'t>(cx: &LateContext<'_, '_>, expr: &'t Expr<'_>) -> Option<&'t Expr<'t>> {
+ match expr.kind {
+ ExprKind::Binary(
+ Spanned {
+ node: BinOpKind::Add, ..
+ },
+ ref lhs,
+ ref rhs,
+ ) => {
+ if is_integer_const(cx, lhs, 1) {
+ Some(rhs)
+ } else if is_integer_const(cx, rhs, 1) {
+ Some(lhs)
+ } else {
+ None
+ }
},
_ => None,
}
}
-fn y_minus_one(expr: &Expr) -> Option<&Expr> {
- match expr.node {
- ExprBinary(Spanned { node: BiSub, .. }, ref lhs, ref rhs) if is_integer_literal(rhs, 1) => Some(lhs),
+fn y_minus_one<'t>(cx: &LateContext<'_, '_>, expr: &'t Expr<'_>) -> Option<&'t Expr<'t>> {
+ match expr.kind {
+ ExprKind::Binary(
+ Spanned {
+ node: BinOpKind::Sub, ..
+ },
+ ref lhs,
+ ref rhs,
+ ) if is_integer_const(cx, rhs, 1) => Some(lhs),
_ => None,
}
}