78 lines
2.5 KiB
Rust
78 lines
2.5 KiB
Rust
use clippy_utils::source::snippet_with_applicability;
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use clippy_utils::ty::is_type_diagnostic_item;
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use if_chain::if_chain;
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use rustc_ast::ast;
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use rustc_errors::Applicability;
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use rustc_hir as hir;
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use rustc_lint::LateContext;
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use rustc_middle::ty::{self, Ty};
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use rustc_span::symbol::sym;
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pub(super) fn derefs_to_slice<'tcx>(
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cx: &LateContext<'tcx>,
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expr: &'tcx hir::Expr<'tcx>,
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ty: Ty<'tcx>,
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) -> Option<&'tcx hir::Expr<'tcx>> {
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fn may_slice<'a>(cx: &LateContext<'a>, ty: Ty<'a>) -> bool {
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match ty.kind() {
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ty::Slice(_) => true,
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ty::Adt(def, _) if def.is_box() => may_slice(cx, ty.boxed_ty()),
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ty::Adt(..) => is_type_diagnostic_item(cx, ty, sym::vec_type),
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ty::Array(_, size) => size
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.try_eval_usize(cx.tcx, cx.param_env)
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.map_or(false, |size| size < 32),
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ty::Ref(_, inner, _) => may_slice(cx, inner),
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_ => false,
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}
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}
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if let hir::ExprKind::MethodCall(ref path, _, ref args, _) = expr.kind {
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if path.ident.name == sym::iter && may_slice(cx, cx.typeck_results().expr_ty(&args[0])) {
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Some(&args[0])
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} else {
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None
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}
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} else {
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match ty.kind() {
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ty::Slice(_) => Some(expr),
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ty::Adt(def, _) if def.is_box() && may_slice(cx, ty.boxed_ty()) => Some(expr),
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ty::Ref(_, inner, _) => {
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if may_slice(cx, inner) {
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Some(expr)
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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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}
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pub(super) fn get_hint_if_single_char_arg(
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cx: &LateContext<'_>,
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arg: &hir::Expr<'_>,
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applicability: &mut Applicability,
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) -> Option<String> {
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if_chain! {
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if let hir::ExprKind::Lit(lit) = &arg.kind;
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if let ast::LitKind::Str(r, style) = lit.node;
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let string = r.as_str();
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if string.chars().count() == 1;
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then {
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let snip = snippet_with_applicability(cx, arg.span, &string, applicability);
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let ch = if let ast::StrStyle::Raw(nhash) = style {
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let nhash = nhash as usize;
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// for raw string: r##"a"##
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&snip[(nhash + 2)..(snip.len() - 1 - nhash)]
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} else {
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// for regular string: "a"
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&snip[1..(snip.len() - 1)]
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};
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let hint = format!("'{}'", if ch == "'" { "\\'" } else { ch });
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Some(hint)
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} else {
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None
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}
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}
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}
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