57 lines
2.0 KiB
Rust
57 lines
2.0 KiB
Rust
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use clippy_utils::consts::{constant, Constant};
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use clippy_utils::diagnostics::span_lint_and_note;
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use if_chain::if_chain;
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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(
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cx: &LateContext<'_>,
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method_name: &str,
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expr: &Expr<'_>,
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self_arg: &Expr<'_>,
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count_arg: &Expr<'_>,
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) {
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if_chain! {
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if let Some((Constant::Int(count), _)) = constant(cx, cx.typeck_results(), count_arg);
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if count <= 1;
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if let Some(call_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id);
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if let Some(impl_id) = cx.tcx.impl_of_method(call_id);
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let lang_items = cx.tcx.lang_items();
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if lang_items.slice_impl() == Some(impl_id) || lang_items.str_impl() == Some(impl_id);
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then {
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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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) && matches!(count_arg.kind, ExprKind::Lit(_))
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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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(format!("`{}` called with `0` splits", method_name),
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"the resulting iterator will always return `None`")
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} else {
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(format!("`{}` called with `1` split", method_name),
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if lang_items.slice_impl() == Some(impl_id) {
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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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span_lint_and_note(
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cx,
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SUSPICIOUS_SPLITN,
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expr.span,
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&msg,
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None,
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note_msg,
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);
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}
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}
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}
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