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Don't suggest to_string().to_string in USELESS_FORMAT

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This commit is contained in:
mcarton 2018-10-03 20:59:59 +02:00
parent 7eebd5b20c
commit 5173ed0c03
3 changed files with 39 additions and 7 deletions
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24
clippy_lints/src/format.rs
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@ -57,12 +57,24 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
if check_single_piece(&args[0]);
if let Some(format_arg) = get_single_string_arg(cx, &args[1]);
if check_unformatted(&args[2]);
if let ExprKind::AddrOf(_, ref format_arg) = format_arg.node;
then {
let sugg = format!("{}.to_string()", snippet(cx, format_arg, "<arg>").into_owned());
let (message, sugg) = if_chain! {
if let ExprKind::MethodCall(ref path, ref span, ref expr) = format_arg.node;
if path.ident.as_interned_str() == "to_string";
then {
("`to_string()` is enough",
snippet(cx, format_arg.span, "<arg>").to_string())
} else {
("consider using .to_string()",
format!("{}.to_string()", snippet(cx, format_arg.span, "<arg>")))
}
};
span_lint_and_then(cx, USELESS_FORMAT, span, "useless use of `format!`", |db| {
db.span_suggestion_with_applicability(
expr.span,
"consider using .to_string()",
message,
sugg,
Applicability::MachineApplicable,
);
@ -113,9 +125,9 @@ fn check_single_piece(expr: &Expr) -> bool {
/// ::std::fmt::Display::fmt)],
/// }
/// ```
/// and that type of `__arg0` is `&str` or `String`
/// then returns the span of first element of the matched tuple
fn get_single_string_arg(cx: &LateContext<'_, '_>, expr: &Expr) -> Option<Span> {
/// and that the type of `__arg0` is `&str` or `String`,
/// then returns the span of first element of the matched tuple.
fn get_single_string_arg<'a>(cx: &LateContext<'_, '_>, expr: &'a Expr) -> Option<&'a Expr> {
if_chain! {
if let ExprKind::AddrOf(_, ref expr) = expr.node;
if let ExprKind::Match(ref match_expr, ref arms, _) = expr.node;
@ -134,7 +146,7 @@ fn get_single_string_arg(cx: &LateContext<'_, '_>, expr: &Expr) -> Option<Span>
let ty = walk_ptrs_ty(cx.tables.pat_ty(&pat[0]));
if ty.sty == ty::Str || match_type(cx, ty, &paths::STRING) {
if let ExprKind::Tup(ref values) = match_expr.node {
return Some(values[0].span);
return Some(&values[0]);
}
}
}