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|
use super::{contains_return, BIND_INSTEAD_OF_MAP};
use clippy_utils::diagnostics::{multispan_sugg_with_applicability, span_lint_and_sugg, span_lint_and_then};
use clippy_utils::peel_blocks;
use clippy_utils::source::{snippet, snippet_with_context};
use clippy_utils::visitors::find_all_ret_expressions;
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
use rustc_hir::{LangItem, QPath};
use rustc_lint::LateContext;
use rustc_span::Span;
pub(crate) struct OptionAndThenSome;
impl BindInsteadOfMap for OptionAndThenSome {
const VARIANT_LANG_ITEM: LangItem = LangItem::OptionSome;
const BAD_METHOD_NAME: &'static str = "and_then";
const GOOD_METHOD_NAME: &'static str = "map";
}
pub(crate) struct ResultAndThenOk;
impl BindInsteadOfMap for ResultAndThenOk {
const VARIANT_LANG_ITEM: LangItem = LangItem::ResultOk;
const BAD_METHOD_NAME: &'static str = "and_then";
const GOOD_METHOD_NAME: &'static str = "map";
}
pub(crate) struct ResultOrElseErrInfo;
impl BindInsteadOfMap for ResultOrElseErrInfo {
const VARIANT_LANG_ITEM: LangItem = LangItem::ResultErr;
const BAD_METHOD_NAME: &'static str = "or_else";
const GOOD_METHOD_NAME: &'static str = "map_err";
}
pub(crate) trait BindInsteadOfMap {
const VARIANT_LANG_ITEM: LangItem;
const BAD_METHOD_NAME: &'static str;
const GOOD_METHOD_NAME: &'static str;
fn no_op_msg(cx: &LateContext<'_>) -> Option<String> {
let variant_id = cx.tcx.lang_items().get(Self::VARIANT_LANG_ITEM)?;
let item_id = cx.tcx.parent(variant_id);
Some(format!(
"using `{}.{}({})`, which is a no-op",
cx.tcx.item_name(item_id),
Self::BAD_METHOD_NAME,
cx.tcx.item_name(variant_id),
))
}
fn lint_msg(cx: &LateContext<'_>) -> Option<String> {
let variant_id = cx.tcx.lang_items().get(Self::VARIANT_LANG_ITEM)?;
let item_id = cx.tcx.parent(variant_id);
Some(format!(
"using `{}.{}(|x| {}(y))`, which is more succinctly expressed as `{}(|x| y)`",
cx.tcx.item_name(item_id),
Self::BAD_METHOD_NAME,
cx.tcx.item_name(variant_id),
Self::GOOD_METHOD_NAME
))
}
fn lint_closure_autofixable(
cx: &LateContext<'_>,
expr: &hir::Expr<'_>,
recv: &hir::Expr<'_>,
closure_expr: &hir::Expr<'_>,
closure_args_span: Span,
) -> bool {
if let hir::ExprKind::Call(some_expr, [inner_expr]) = closure_expr.kind
&& let hir::ExprKind::Path(QPath::Resolved(_, path)) = some_expr.kind
&& Self::is_variant(cx, path.res)
&& !contains_return(inner_expr)
&& let Some(msg) = Self::lint_msg(cx)
{
let mut app = Applicability::MachineApplicable;
let some_inner_snip = snippet_with_context(cx, inner_expr.span, closure_expr.span.ctxt(), "_", &mut app).0;
let closure_args_snip = snippet(cx, closure_args_span, "..");
let option_snip = snippet(cx, recv.span, "..");
let note = format!(
"{option_snip}.{}({closure_args_snip} {some_inner_snip})",
Self::GOOD_METHOD_NAME
);
span_lint_and_sugg(cx, BIND_INSTEAD_OF_MAP, expr.span, &msg, "try", note, app);
true
} else {
false
}
}
fn lint_closure(cx: &LateContext<'_>, expr: &hir::Expr<'_>, closure_expr: &hir::Expr<'_>) -> bool {
let mut suggs = Vec::new();
let can_sugg: bool = find_all_ret_expressions(cx, closure_expr, |ret_expr| {
if !ret_expr.span.from_expansion()
&& let hir::ExprKind::Call(func_path, [arg]) = ret_expr.kind
&& let hir::ExprKind::Path(QPath::Resolved(_, path)) = func_path.kind
&& Self::is_variant(cx, path.res)
&& !contains_return(arg)
{
suggs.push((ret_expr.span, arg.span.source_callsite()));
true
} else {
false
}
});
let (span, msg) = if can_sugg
&& let hir::ExprKind::MethodCall(segment, ..) = expr.kind
&& let Some(msg) = Self::lint_msg(cx)
{
(segment.ident.span, msg)
} else {
return false;
};
span_lint_and_then(cx, BIND_INSTEAD_OF_MAP, expr.span, &msg, |diag| {
multispan_sugg_with_applicability(
diag,
"try",
Applicability::MachineApplicable,
std::iter::once((span, Self::GOOD_METHOD_NAME.into())).chain(
suggs
.into_iter()
.map(|(span1, span2)| (span1, snippet(cx, span2, "_").into())),
),
);
});
true
}
/// Lint use of `_.and_then(|x| Some(y))` for `Option`s
fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, recv: &hir::Expr<'_>, arg: &hir::Expr<'_>) -> bool {
if let Some(adt) = cx.typeck_results().expr_ty(recv).ty_adt_def()
&& let Some(vid) = cx.tcx.lang_items().get(Self::VARIANT_LANG_ITEM)
&& adt.did() == cx.tcx.parent(vid)
{
} else {
return false;
}
match arg.kind {
hir::ExprKind::Closure(&hir::Closure { body, fn_decl_span, .. }) => {
let closure_body = cx.tcx.hir().body(body);
let closure_expr = peel_blocks(closure_body.value);
if Self::lint_closure_autofixable(cx, expr, recv, closure_expr, fn_decl_span) {
true
} else {
Self::lint_closure(cx, expr, closure_expr)
}
},
// `_.and_then(Some)` case, which is no-op.
hir::ExprKind::Path(QPath::Resolved(_, path)) if Self::is_variant(cx, path.res) => {
if let Some(msg) = Self::no_op_msg(cx) {
span_lint_and_sugg(
cx,
BIND_INSTEAD_OF_MAP,
expr.span,
&msg,
"use the expression directly",
snippet(cx, recv.span, "..").into(),
Applicability::MachineApplicable,
);
}
true
},
_ => false,
}
}
fn is_variant(cx: &LateContext<'_>, res: Res) -> bool {
if let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), id) = res {
if let Some(variant_id) = cx.tcx.lang_items().get(Self::VARIANT_LANG_ITEM) {
return cx.tcx.parent(id) == variant_id;
}
}
false
}
}
|
