Merge pull request #2116 from niklasf/range-plus-minus-one
Lint range_plus_one and range_minus_one (closes #329)
This commit is contained in:
commit
8ce9c244ea
4 changed files with 214 additions and 7 deletions
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@ -263,7 +263,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry) {
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reg.register_late_lint_pass(box loops::Pass);
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reg.register_late_lint_pass(box loops::Pass);
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reg.register_late_lint_pass(box lifetimes::LifetimePass);
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reg.register_late_lint_pass(box lifetimes::LifetimePass);
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reg.register_late_lint_pass(box entry::HashMapLint);
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reg.register_late_lint_pass(box entry::HashMapLint);
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reg.register_late_lint_pass(box ranges::StepByZero);
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reg.register_late_lint_pass(box ranges::Pass);
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reg.register_late_lint_pass(box types::CastPass);
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reg.register_late_lint_pass(box types::CastPass);
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reg.register_late_lint_pass(box types::TypeComplexityPass::new(conf.type_complexity_threshold));
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reg.register_late_lint_pass(box types::TypeComplexityPass::new(conf.type_complexity_threshold));
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reg.register_late_lint_pass(box matches::MatchPass);
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reg.register_late_lint_pass(box matches::MatchPass);
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@ -1,7 +1,10 @@
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use rustc::lint::*;
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use rustc::lint::*;
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use rustc::hir::*;
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use rustc::hir::*;
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use utils::{is_integer_literal, paths, snippet, span_lint};
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use syntax::ast::RangeLimits;
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use syntax::codemap::Spanned;
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use utils::{is_integer_literal, paths, snippet, span_lint, span_lint_and_then};
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use utils::{get_trait_def_id, higher, implements_trait};
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use utils::{get_trait_def_id, higher, implements_trait};
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use utils::sugg::Sugg;
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/// **What it does:** Checks for calling `.step_by(0)` on iterators,
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/// **What it does:** Checks for calling `.step_by(0)` on iterators,
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/// which never terminates.
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/// which never terminates.
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@ -38,16 +41,57 @@ declare_lint! {
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"zipping iterator with a range when `enumerate()` would do"
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"zipping iterator with a range when `enumerate()` would do"
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}
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}
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/// **What it does:** Checks for exclusive ranges where 1 is added to the
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/// upper bound, e.g. `x..(y+1)`.
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///
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/// **Why is this bad?** The code is more readable with an inclusive range
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/// like `x..=y`.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// for x..(y+1) { .. }
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/// ```
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declare_lint! {
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pub RANGE_PLUS_ONE,
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Allow,
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"`x..(y+1)` reads better as `x..=y`"
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}
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/// **What it does:** Checks for inclusive ranges where 1 is subtracted from
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/// the upper bound, e.g. `x..=(y-1)`.
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///
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/// **Why is this bad?** The code is more readable with an exclusive range
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/// like `x..y`.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// for x..=(y-1) { .. }
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/// ```
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declare_lint! {
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pub RANGE_MINUS_ONE,
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Warn,
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"`x..=(y-1)` reads better as `x..y`"
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}
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#[derive(Copy, Clone)]
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#[derive(Copy, Clone)]
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pub struct StepByZero;
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pub struct Pass;
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impl LintPass for StepByZero {
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impl LintPass for Pass {
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fn get_lints(&self) -> LintArray {
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fn get_lints(&self) -> LintArray {
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lint_array!(ITERATOR_STEP_BY_ZERO, RANGE_ZIP_WITH_LEN)
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lint_array!(
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ITERATOR_STEP_BY_ZERO,
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RANGE_ZIP_WITH_LEN,
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RANGE_PLUS_ONE,
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RANGE_MINUS_ONE
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)
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}
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}
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}
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}
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for StepByZero {
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
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fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
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fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
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if let ExprMethodCall(ref path, _, ref args) = expr.node {
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if let ExprMethodCall(ref path, _, ref args) = expr.node {
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let name = path.name.as_str();
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let name = path.name.as_str();
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@ -92,6 +136,46 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for StepByZero {
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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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// exclusive range plus one: x..(y+1)
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if_let_chain! {[
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let Some(higher::Range { start, end: Some(end), limits: RangeLimits::HalfOpen }) = higher::range(expr),
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let Some(y) = y_plus_one(end),
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], {
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span_lint_and_then(
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cx,
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RANGE_PLUS_ONE,
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expr.span,
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"an inclusive range would be more readable",
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|db| {
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let start = start.map_or("".to_owned(), |x| Sugg::hir(cx, x, "x").to_string());
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let end = Sugg::hir(cx, y, "y");
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db.span_suggestion(expr.span,
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"use",
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format!("{}..={}", start, end));
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},
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);
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}}
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// inclusive range minus one: x..=(y-1)
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if_let_chain! {[
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let Some(higher::Range { start, end: Some(end), limits: RangeLimits::Closed }) = higher::range(expr),
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let Some(y) = y_minus_one(end),
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], {
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span_lint_and_then(
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cx,
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RANGE_MINUS_ONE,
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expr.span,
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"an exclusive range would be more readable",
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|db| {
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let start = start.map_or("".to_owned(), |x| Sugg::hir(cx, x, "x").to_string());
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let end = Sugg::hir(cx, y, "y");
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db.span_suggestion(expr.span,
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"use",
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format!("{}..{}", start, end));
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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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}
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@ -102,3 +186,25 @@ fn has_step_by(cx: &LateContext, expr: &Expr) -> bool {
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get_trait_def_id(cx, &paths::ITERATOR).map_or(false, |iterator_trait| implements_trait(cx, ty, iterator_trait, &[]))
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get_trait_def_id(cx, &paths::ITERATOR).map_or(false, |iterator_trait| implements_trait(cx, ty, iterator_trait, &[]))
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}
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}
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fn y_plus_one(expr: &Expr) -> Option<&Expr> {
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match expr.node {
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ExprBinary(Spanned { node: BiAdd, .. }, ref lhs, ref rhs) => {
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if is_integer_literal(lhs, 1) {
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Some(rhs)
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} else if is_integer_literal(rhs, 1) {
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Some(lhs)
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} else {
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None
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}
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},
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_ => None,
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}
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}
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fn y_minus_one(expr: &Expr) -> Option<&Expr> {
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match expr.node {
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ExprBinary(Spanned { node: BiSub, .. }, ref lhs, ref rhs) if is_integer_literal(rhs, 1) => Some(lhs),
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_ => None,
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}
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}
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34
tests/ui/range_plus_minus_one.rs
Normal file
34
tests/ui/range_plus_minus_one.rs
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@ -0,0 +1,34 @@
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#![feature(inclusive_range_syntax)]
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fn f() -> usize {
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42
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}
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#[warn(range_plus_one)]
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fn main() {
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for _ in 0..2 { }
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for _ in 0..=2 { }
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for _ in 0..3+1 { }
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for _ in 0..=3+1 { }
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for _ in 0..1+5 { }
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for _ in 0..=1+5 { }
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for _ in 1..1+1 { }
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for _ in 1..=1+1 { }
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for _ in 0..13+13 { }
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for _ in 0..=13-7 { }
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for _ in 0..(1+f()) { }
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for _ in 0..=(1+f()) { }
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let _ = ..11-1;
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let _ = ..=11-1;
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let _ = ..=(11-1);
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let _ = (f()+1)..(f()+1);
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let mut vec: Vec<()> = std::vec::Vec::new();
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vec.drain(..);
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}
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67
tests/ui/range_plus_minus_one.stderr
Normal file
67
tests/ui/range_plus_minus_one.stderr
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@ -0,0 +1,67 @@
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error: an inclusive range would be more readable
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--> $DIR/range_plus_minus_one.rs:12:14
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12 | for _ in 0..3+1 { }
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| ------
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| help: use: `0..=3`
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= note: `-D range-plus-one` implied by `-D warnings`
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error: an inclusive range would be more readable
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--> $DIR/range_plus_minus_one.rs:15:14
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15 | for _ in 0..1+5 { }
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| ------
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| help: use: `0..=5`
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error: an inclusive range would be more readable
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--> $DIR/range_plus_minus_one.rs:18:14
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18 | for _ in 1..1+1 { }
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| ------
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| help: use: `1..=1`
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error: an inclusive range would be more readable
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--> $DIR/range_plus_minus_one.rs:24:14
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24 | for _ in 0..(1+f()) { }
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| ----------
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| help: use: `0..=f()`
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error: an exclusive range would be more readable
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--> $DIR/range_plus_minus_one.rs:28:13
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28 | let _ = ..=11-1;
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| -------
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| help: use: `..11`
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= note: `-D range-minus-one` implied by `-D warnings`
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error: an exclusive range would be more readable
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--> $DIR/range_plus_minus_one.rs:29:13
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29 | let _ = ..=(11-1);
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| ---------
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| help: use: `..11`
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error: an inclusive range would be more readable
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--> $DIR/range_plus_minus_one.rs:30:13
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30 | let _ = (f()+1)..(f()+1);
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| ----------------
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| help: use: `(f()+1)..=f()`
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| in this macro invocation
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