42 lines
1.6 KiB
Rust
42 lines
1.6 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_note;
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use rustc_ast::LitKind;
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use rustc_hir::{Expr, ExprKind};
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use rustc_lint::LateContext;
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use rustc_span::source_map::Spanned;
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use super::SUSPICIOUS_SPLITN;
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pub(super) fn check(cx: &LateContext<'_>, method_name: &str, expr: &Expr<'_>, self_arg: &Expr<'_>, count: u128) {
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if count <= 1
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&& let Some(call_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id)
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&& let Some(impl_id) = cx.tcx.impl_of_method(call_id)
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&& cx.tcx.impl_trait_ref(impl_id).is_none()
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&& let self_ty = cx.tcx.type_of(impl_id).instantiate_identity()
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&& (self_ty.is_slice() || self_ty.is_str())
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{
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// Ignore empty slice and string literals when used with a literal count.
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if matches!(self_arg.kind, ExprKind::Array([]))
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|| matches!(self_arg.kind, ExprKind::Lit(Spanned { node: LitKind::Str(s, _), .. }) if s.is_empty())
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{
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return;
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}
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let (msg, note_msg) = if count == 0 {
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(
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format!("`{method_name}` called with `0` splits"),
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"the resulting iterator will always return `None`",
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)
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} else {
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(
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format!("`{method_name}` called with `1` split"),
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if self_ty.is_slice() {
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"the resulting iterator will always return the entire slice followed by `None`"
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} else {
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"the resulting iterator will always return the entire string followed by `None`"
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},
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)
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};
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span_lint_and_note(cx, SUSPICIOUS_SPLITN, expr.span, msg, None, note_msg);
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}
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}
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