-use rustc::lint::*;
+use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
+use rustc::{declare_lint, lint_array};
+use if_chain::if_chain;
use rustc::hir::*;
-use syntax::codemap::Spanned;
-use utils::{is_integer_literal, match_type, paths, snippet, span_lint};
-use utils::higher;
+use syntax::ast::RangeLimits;
+use syntax::source_map::Spanned;
+use crate::utils::{is_integer_literal, paths, snippet, span_lint, span_lint_and_then, snippet_opt};
+use crate::utils::{get_trait_def_id, higher, implements_trait, SpanlessEq};
+use crate::utils::sugg::Sugg;
-/// **What it does:** Checks for iterating over ranges with a `.step_by(0)`,
+/// **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
/// ```rust
/// for x in (5..5).step_by(0) { .. }
/// ```
-declare_lint! {
- pub RANGE_STEP_BY_ZERO,
- Warn,
- "using `Range::step_by(0)`, which produces an infinite iterator"
+declare_clippy_lint! {
+ pub ITERATOR_STEP_BY_ZERO,
+ correctness,
+ "using `Iterator::step_by(0)`, which produces an infinite iterator"
}
-/// **What it does:** Checks for zipping a collection with the range of `0.._.len()`.
+
+/// **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()`.
///
/// ```rust
/// x.iter().zip(0..x.len())
/// ```
-declare_lint! {
+declare_clippy_lint! {
pub RANGE_ZIP_WITH_LEN,
- Warn,
+ complexity,
"zipping iterator with a range when `enumerate()` would do"
}
-#[derive(Copy,Clone)]
-pub struct StepByZero;
+/// **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()+1)).
+///
+/// **Example:**
+/// ```rust
+/// for x..(y+1) { .. }
+/// ```
+declare_clippy_lint! {
+ pub RANGE_PLUS_ONE,
+ complexity,
+ "`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! {
+ pub RANGE_MINUS_ONE,
+ complexity,
+ "`x..=(y-1)` reads better as `x..y`"
+}
+
+#[derive(Copy, Clone)]
+pub struct Pass;
-impl LintPass for StepByZero {
+impl LintPass for Pass {
fn get_lints(&self) -> LintArray {
- lint_array!(RANGE_STEP_BY_ZERO, RANGE_ZIP_WITH_LEN)
+ lint_array!(ITERATOR_STEP_BY_ZERO, RANGE_ZIP_WITH_LEN, RANGE_PLUS_ONE, RANGE_MINUS_ONE)
}
}
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for StepByZero {
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
- if let ExprMethodCall(Spanned { node: ref name, .. }, _, ref args) = expr.node {
- let name = &*name.as_str();
+ if let ExprKind::MethodCall(ref path, _, ref args) = expr.node {
+ let name = path.ident.as_str();
// Range with step_by(0).
- if name == "step_by" && args.len() == 2 && has_step_by(cx, &args[0]) &&
- is_integer_literal(&args[1], 0) {
- span_lint(cx,
- RANGE_STEP_BY_ZERO,
- expr.span,
- "Range::step_by(0) produces an infinite iterator. Consider using `std::iter::repeat()` \
- instead");
+ 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;
let zip_arg = &args[1];
- if_let_chain! {[
+ if_chain! {
// .iter() call
- let ExprMethodCall( Spanned { node: ref iter_name, .. }, _, ref iter_args ) = *iter,
- &*iter_name.as_str() == "iter",
+ if let ExprKind::MethodCall(ref iter_path, _, ref iter_args ) = *iter;
+ if iter_path.ident.name == "iter";
// range expression in .zip() call: 0..x.len()
- let Some(higher::Range { start: Some(ref start), end: Some(ref end), .. }) = higher::range(zip_arg),
- is_integer_literal(start, 0),
+ if let Some(higher::Range { start: Some(start), end: Some(end), .. }) = higher::range(cx, zip_arg);
+ if is_integer_literal(start, 0);
// .len() call
- let ExprMethodCall(Spanned { node: ref len_name, .. }, _, ref len_args) = end.node,
- &*len_name.as_str() == "len" && len_args.len() == 1,
+ if let ExprKind::MethodCall(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
- let ExprPath(QPath::Resolved(_, ref iter_path)) = iter_args[0].node,
- let ExprPath(QPath::Resolved(_, ref len_path)) = len_args[0].node,
- iter_path.segments == len_path.segments
- ], {
- span_lint(cx,
- RANGE_ZIP_WITH_LEN,
- expr.span,
- &format!("It is more idiomatic to use {}.iter().enumerate()",
- snippet(cx, iter_args[0].span, "_")));
- }}
+ if let ExprKind::Path(QPath::Resolved(_, ref iter_path)) = iter_args[0].node;
+ if let ExprKind::Path(QPath::Resolved(_, ref len_path)) = len_args[0].node;
+ 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()",
+ 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");
+ if let Some(is_wrapped) = &snippet_opt(cx, expr.span) {
+ if is_wrapped.starts_with("(") && is_wrapped.ends_with(")") {
+ db.span_suggestion(expr.span,
+ "use",
+ format!("({}..={})", start, end));
+ } else {
+ db.span_suggestion(expr.span,
+ "use",
+ format!("{}..={}", start, end));
+ }
+ }
+ },
+ );
+ }
+ }
+
+ // 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));
+ },
+ );
}
}
}
}
-fn has_step_by(cx: &LateContext, expr: &Expr) -> bool {
+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.tcx.tables().expr_ty(expr);
+ 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, &[]))
+}
- // Note: `RangeTo`, `RangeToInclusive` and `RangeFull` don't have step_by
- match_type(cx, ty, &paths::RANGE)
- || match_type(cx, ty, &paths::RANGE_FROM)
- || match_type(cx, ty, &paths::RANGE_INCLUSIVE)
+fn y_plus_one(expr: &Expr) -> Option<&Expr> {
+ match expr.node {
+ ExprKind::Binary(Spanned { node: BinOpKind::Add, .. }, ref lhs, ref rhs) => if is_integer_literal(lhs, 1) {
+ Some(rhs)
+ } else if is_integer_literal(rhs, 1) {
+ Some(lhs)
+ } else {
+ None
+ },
+ _ => None,
+ }
+}
+
+fn y_minus_one(expr: &Expr) -> Option<&Expr> {
+ match expr.node {
+ ExprKind::Binary(Spanned { node: BinOpKind::Sub, .. }, ref lhs, ref rhs) if is_integer_literal(rhs, 1) => Some(lhs),
+ _ => None,
+ }
}
projects / rust.git / blobdiff