119 lines
4.1 KiB
Rust
119 lines
4.1 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::ty::is_type_lang_item;
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use rustc_ast::ast::LitKind;
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use rustc_errors::Applicability;
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use rustc_hir::intravisit::{walk_expr, Visitor};
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use rustc_hir::{Arm, Expr, ExprKind, LangItem, PatKind};
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use rustc_lint::LateContext;
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use rustc_middle::ty;
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use rustc_span::symbol::Symbol;
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use rustc_span::Span;
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use super::MATCH_STR_CASE_MISMATCH;
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#[derive(Debug)]
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enum CaseMethod {
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LowerCase,
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AsciiLowerCase,
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UpperCase,
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AsciiUppercase,
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}
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pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, scrutinee: &'tcx Expr<'_>, arms: &'tcx [Arm<'_>]) {
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if let ty::Ref(_, ty, _) = cx.typeck_results().expr_ty(scrutinee).kind()
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&& let ty::Str = ty.kind()
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{
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let mut visitor = MatchExprVisitor { cx, case_method: None };
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visitor.visit_expr(scrutinee);
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if let Some(case_method) = visitor.case_method {
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if let Some((bad_case_span, bad_case_sym)) = verify_case(&case_method, arms) {
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lint(cx, &case_method, bad_case_span, bad_case_sym.as_str());
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}
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}
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}
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}
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struct MatchExprVisitor<'a, 'tcx> {
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cx: &'a LateContext<'tcx>,
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case_method: Option<CaseMethod>,
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}
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impl<'a, 'tcx> Visitor<'tcx> for MatchExprVisitor<'a, 'tcx> {
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fn visit_expr(&mut self, ex: &'tcx Expr<'_>) {
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match ex.kind {
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ExprKind::MethodCall(segment, receiver, [], _) if self.case_altered(segment.ident.as_str(), receiver) => {},
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_ => walk_expr(self, ex),
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}
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}
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}
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impl<'a, 'tcx> MatchExprVisitor<'a, 'tcx> {
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fn case_altered(&mut self, segment_ident: &str, receiver: &Expr<'_>) -> bool {
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if let Some(case_method) = get_case_method(segment_ident) {
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let ty = self.cx.typeck_results().expr_ty(receiver).peel_refs();
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if is_type_lang_item(self.cx, ty, LangItem::String) || ty.kind() == &ty::Str {
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self.case_method = Some(case_method);
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return true;
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}
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}
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false
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}
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}
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fn get_case_method(segment_ident_str: &str) -> Option<CaseMethod> {
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match segment_ident_str {
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"to_lowercase" => Some(CaseMethod::LowerCase),
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"to_ascii_lowercase" => Some(CaseMethod::AsciiLowerCase),
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"to_uppercase" => Some(CaseMethod::UpperCase),
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"to_ascii_uppercase" => Some(CaseMethod::AsciiUppercase),
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_ => None,
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}
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}
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fn verify_case<'a>(case_method: &'a CaseMethod, arms: &'a [Arm<'_>]) -> Option<(Span, Symbol)> {
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let case_check = match case_method {
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CaseMethod::LowerCase => |input: &str| -> bool { input.chars().all(|c| c.to_lowercase().next() == Some(c)) },
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CaseMethod::AsciiLowerCase => |input: &str| -> bool { !input.chars().any(|c| c.is_ascii_uppercase()) },
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CaseMethod::UpperCase => |input: &str| -> bool { input.chars().all(|c| c.to_uppercase().next() == Some(c)) },
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CaseMethod::AsciiUppercase => |input: &str| -> bool { !input.chars().any(|c| c.is_ascii_lowercase()) },
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};
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for arm in arms {
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if let PatKind::Lit(Expr {
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kind: ExprKind::Lit(lit),
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..
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}) = arm.pat.kind
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&& let LitKind::Str(symbol, _) = lit.node
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&& let input = symbol.as_str()
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&& !case_check(input)
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{
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return Some((lit.span, symbol));
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}
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}
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None
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}
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fn lint(cx: &LateContext<'_>, case_method: &CaseMethod, bad_case_span: Span, bad_case_str: &str) {
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let (method_str, suggestion) = match case_method {
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CaseMethod::LowerCase => ("to_lowercase", bad_case_str.to_lowercase()),
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CaseMethod::AsciiLowerCase => ("to_ascii_lowercase", bad_case_str.to_ascii_lowercase()),
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CaseMethod::UpperCase => ("to_uppercase", bad_case_str.to_uppercase()),
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CaseMethod::AsciiUppercase => ("to_ascii_uppercase", bad_case_str.to_ascii_uppercase()),
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};
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span_lint_and_sugg(
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cx,
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MATCH_STR_CASE_MISMATCH,
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bad_case_span,
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"this `match` arm has a differing case than its expression",
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format!("consider changing the case of this arm to respect `{method_str}`"),
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format!("\"{suggestion}\""),
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Applicability::MachineApplicable,
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);
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}
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