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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::{is_lang_ctor, path_def_id};
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_hir::LangItem::{OptionNone, OptionSome};
use rustc_lint::LateContext;
use rustc_middle::ty::DefIdTree;
use rustc_span::symbol::sym;
use super::OPTION_MAP_OR_NONE;
use super::RESULT_MAP_OR_INTO_OPTION;
// The expression inside a closure may or may not have surrounding braces
// which causes problems when generating a suggestion.
fn reduce_unit_expression<'a>(expr: &'a hir::Expr<'_>) -> Option<(&'a hir::Expr<'a>, &'a [hir::Expr<'a>])> {
match expr.kind {
hir::ExprKind::Call(func, arg_char) => Some((func, arg_char)),
hir::ExprKind::Block(block, _) => {
match (block.stmts, block.expr) {
(&[], Some(inner_expr)) => {
// If block only contains an expression,
// reduce `|x| { x + 1 }` to `|x| x + 1`
reduce_unit_expression(inner_expr)
},
_ => None,
}
},
_ => None,
}
}
/// lint use of `_.map_or(None, _)` for `Option`s and `Result`s
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
expr: &'tcx hir::Expr<'_>,
recv: &'tcx hir::Expr<'_>,
def_arg: &'tcx hir::Expr<'_>,
map_arg: &'tcx hir::Expr<'_>,
) {
let is_option = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(recv), sym::Option);
let is_result = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(recv), sym::Result);
// There are two variants of this `map_or` lint:
// (1) using `map_or` as an adapter from `Result<T,E>` to `Option<T>`
// (2) using `map_or` as a combinator instead of `and_then`
//
// (For this lint) we don't care if any other type calls `map_or`
if !is_option && !is_result {
return;
}
let default_arg_is_none = if let hir::ExprKind::Path(ref qpath) = def_arg.kind {
is_lang_ctor(cx, qpath, OptionNone)
} else {
return;
};
if !default_arg_is_none {
// nothing to lint!
return;
}
let f_arg_is_some = if let hir::ExprKind::Path(ref qpath) = map_arg.kind {
is_lang_ctor(cx, qpath, OptionSome)
} else {
false
};
if is_option {
let self_snippet = snippet(cx, recv.span, "..");
if_chain! {
if let hir::ExprKind::Closure(&hir::Closure { body, fn_decl_span, .. }) = map_arg.kind;
let arg_snippet = snippet(cx, fn_decl_span, "..");
let body = cx.tcx.hir().body(body);
if let Some((func, [arg_char])) = reduce_unit_expression(body.value);
if let Some(id) = path_def_id(cx, func).map(|ctor_id| cx.tcx.parent(ctor_id));
if Some(id) == cx.tcx.lang_items().option_some_variant();
then {
let func_snippet = snippet(cx, arg_char.span, "..");
let msg = "called `map_or(None, ..)` on an `Option` value. This can be done more directly by calling \
`map(..)` instead";
return span_lint_and_sugg(
cx,
OPTION_MAP_OR_NONE,
expr.span,
msg,
"try using `map` instead",
format!("{0}.map({1} {2})", self_snippet, arg_snippet,func_snippet),
Applicability::MachineApplicable,
);
}
}
let func_snippet = snippet(cx, map_arg.span, "..");
let msg = "called `map_or(None, ..)` on an `Option` value. This can be done more directly by calling \
`and_then(..)` instead";
span_lint_and_sugg(
cx,
OPTION_MAP_OR_NONE,
expr.span,
msg,
"try using `and_then` instead",
format!("{0}.and_then({1})", self_snippet, func_snippet),
Applicability::MachineApplicable,
);
} else if f_arg_is_some {
let msg = "called `map_or(None, Some)` on a `Result` value. This can be done more directly by calling \
`ok()` instead";
let self_snippet = snippet(cx, recv.span, "..");
span_lint_and_sugg(
cx,
RESULT_MAP_OR_INTO_OPTION,
expr.span,
msg,
"try using `ok` instead",
format!("{0}.ok()", self_snippet),
Applicability::MachineApplicable,
);
}
}
|
