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