42 lines
1.4 KiB
Rust
42 lines
1.4 KiB
Rust
use rustc::lint::*;
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use rustc_front::hir::*;
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use syntax::codemap::Spanned;
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use utils::{match_type, is_integer_literal};
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declare_lint! {
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pub RANGE_STEP_BY_ZERO, Warn,
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"using Range::step_by(0), which produces an infinite iterator"
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}
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#[derive(Copy,Clone)]
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pub struct StepByZero;
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impl LintPass for StepByZero {
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fn get_lints(&self) -> LintArray {
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lint_array!(RANGE_STEP_BY_ZERO)
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}
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}
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impl LateLintPass for StepByZero {
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fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
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if let ExprMethodCall(Spanned { node: ref name, .. }, _,
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ref args) = expr.node {
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// Only warn on literal ranges.
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if name.as_str() == "step_by" && args.len() == 2 &&
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is_range(cx, &args[0]) && is_integer_literal(&args[1], 0) {
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cx.span_lint(RANGE_STEP_BY_ZERO, expr.span,
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"Range::step_by(0) produces an infinite iterator. \
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Consider using `std::iter::repeat()` instead")
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}
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}
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}
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}
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fn is_range(cx: &LateContext, expr: &Expr) -> bool {
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// No need for walk_ptrs_ty here because step_by moves self, so it
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// can't be called on a borrowed range.
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let ty = cx.tcx.expr_ty(expr);
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// Note: RangeTo and RangeFull don't have step_by
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match_type(cx, ty, &["core", "ops", "Range"]) || match_type(cx, ty, &["core", "ops", "RangeFrom"])
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}
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