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|
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::source::snippet;
use clippy_utils::ty::is_type_diagnostic_item;
use clippy_utils::{match_def_path, meets_msrv, msrvs, path_to_local_id, paths, peel_blocks};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_lint::LateContext;
use rustc_middle::ty;
use rustc_semver::RustcVersion;
use rustc_span::sym;
use super::OPTION_AS_REF_DEREF;
/// lint use of `_.as_ref().map(Deref::deref)` for `Option`s
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
expr: &hir::Expr<'_>,
as_ref_recv: &hir::Expr<'_>,
map_arg: &hir::Expr<'_>,
is_mut: bool,
msrv: Option<RustcVersion>,
) {
if !meets_msrv(msrv, msrvs::OPTION_AS_DEREF) {
return;
}
let same_mutability = |m| (is_mut && m == &hir::Mutability::Mut) || (!is_mut && m == &hir::Mutability::Not);
let option_ty = cx.typeck_results().expr_ty(as_ref_recv);
if !is_type_diagnostic_item(cx, option_ty, sym::Option) {
return;
}
let deref_aliases: [&[&str]; 9] = [
&paths::DEREF_TRAIT_METHOD,
&paths::DEREF_MUT_TRAIT_METHOD,
&paths::CSTRING_AS_C_STR,
&paths::OS_STRING_AS_OS_STR,
&paths::PATH_BUF_AS_PATH,
&paths::STRING_AS_STR,
&paths::STRING_AS_MUT_STR,
&paths::VEC_AS_SLICE,
&paths::VEC_AS_MUT_SLICE,
];
let is_deref = match map_arg.kind {
hir::ExprKind::Path(ref expr_qpath) => cx
.qpath_res(expr_qpath, map_arg.hir_id)
.opt_def_id()
.map_or(false, |fun_def_id| {
deref_aliases.iter().any(|path| match_def_path(cx, fun_def_id, path))
}),
hir::ExprKind::Closure(&hir::Closure { body, .. }) => {
let closure_body = cx.tcx.hir().body(body);
let closure_expr = peel_blocks(closure_body.value);
match &closure_expr.kind {
hir::ExprKind::MethodCall(_, receiver, [], _) => {
if_chain! {
if path_to_local_id(receiver, closure_body.params[0].pat.hir_id);
let adj = cx
.typeck_results()
.expr_adjustments(receiver)
.iter()
.map(|x| &x.kind)
.collect::<Box<[_]>>();
if let [ty::adjustment::Adjust::Deref(None), ty::adjustment::Adjust::Borrow(_)] = *adj;
then {
let method_did = cx.typeck_results().type_dependent_def_id(closure_expr.hir_id).unwrap();
deref_aliases.iter().any(|path| match_def_path(cx, method_did, path))
} else {
false
}
}
},
hir::ExprKind::AddrOf(hir::BorrowKind::Ref, m, inner) if same_mutability(m) => {
if_chain! {
if let hir::ExprKind::Unary(hir::UnOp::Deref, inner1) = inner.kind;
if let hir::ExprKind::Unary(hir::UnOp::Deref, inner2) = inner1.kind;
then {
path_to_local_id(inner2, closure_body.params[0].pat.hir_id)
} else {
false
}
}
},
_ => false,
}
},
_ => false,
};
if is_deref {
let current_method = if is_mut {
format!(".as_mut().map({})", snippet(cx, map_arg.span, ".."))
} else {
format!(".as_ref().map({})", snippet(cx, map_arg.span, ".."))
};
let method_hint = if is_mut { "as_deref_mut" } else { "as_deref" };
let hint = format!("{}.{}()", snippet(cx, as_ref_recv.span, ".."), method_hint);
let suggestion = format!("try using {} instead", method_hint);
let msg = format!(
"called `{0}` on an Option value. This can be done more directly \
by calling `{1}` instead",
current_method, hint
);
span_lint_and_sugg(
cx,
OPTION_AS_REF_DEREF,
expr.span,
&msg,
&suggestion,
hint,
Applicability::MachineApplicable,
);
}
}
|
