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|
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::ty::is_type_diagnostic_item;
use clippy_utils::visitors::contains_unsafe_block;
use clippy_utils::{is_res_lang_ctor, path_res, path_to_local_id};
use rustc_hir::LangItem::{OptionNone, OptionSome};
use rustc_hir::{Arm, Expr, ExprKind, HirId, Pat, PatKind};
use rustc_lint::LateContext;
use rustc_span::{sym, SyntaxContext};
use super::manual_utils::{check_with, SomeExpr};
use super::MANUAL_FILTER;
// Function called on the <expr> of `[&+]Some((ref | ref mut) x) => <expr>`
// Need to check if it's of the form `<expr>=if <cond> {<then_expr>} else {<else_expr>}`
// AND that only one `then/else_expr` resolves to `Some(x)` while the other resolves to `None`
// return the `cond` expression if so.
fn get_cond_expr<'tcx>(
cx: &LateContext<'tcx>,
pat: &Pat<'_>,
expr: &'tcx Expr<'_>,
ctxt: SyntaxContext,
) -> Option<SomeExpr<'tcx>> {
if let Some(block_expr) = peels_blocks_incl_unsafe_opt(expr)
&& let ExprKind::If(cond, then_expr, Some(else_expr)) = block_expr.kind
&& let PatKind::Binding(_, target, ..) = pat.kind
&& (is_some_expr(cx, target, ctxt, then_expr) && is_none_expr(cx, else_expr)
|| is_none_expr(cx, then_expr) && is_some_expr(cx, target, ctxt, else_expr))
// check that one expr resolves to `Some(x)`, the other to `None`
{
return Some(SomeExpr {
expr: peels_blocks_incl_unsafe(cond.peel_drop_temps()),
needs_unsafe_block: contains_unsafe_block(cx, expr),
needs_negated: is_none_expr(cx, then_expr), /* if the `then_expr` resolves to `None`, need to negate the
* cond */
});
};
None
}
fn peels_blocks_incl_unsafe_opt<'a>(expr: &'a Expr<'a>) -> Option<&'a Expr<'a>> {
// we don't want to use `peel_blocks` here because we don't care if the block is unsafe, it's
// checked by `contains_unsafe_block`
if let ExprKind::Block(block, None) = expr.kind {
if block.stmts.is_empty() {
return block.expr;
}
};
None
}
fn peels_blocks_incl_unsafe<'a>(expr: &'a Expr<'a>) -> &'a Expr<'a> {
peels_blocks_incl_unsafe_opt(expr).unwrap_or(expr)
}
// function called for each <expr> expression:
// Some(x) => if <cond> {
// <expr>
// } else {
// <expr>
// }
// Returns true if <expr> resolves to `Some(x)`, `false` otherwise
fn is_some_expr(cx: &LateContext<'_>, target: HirId, ctxt: SyntaxContext, expr: &Expr<'_>) -> bool {
if let Some(inner_expr) = peels_blocks_incl_unsafe_opt(expr) {
// there can be not statements in the block as they would be removed when switching to `.filter`
if let ExprKind::Call(callee, [arg]) = inner_expr.kind {
return ctxt == expr.span.ctxt()
&& is_res_lang_ctor(cx, path_res(cx, callee), OptionSome)
&& path_to_local_id(arg, target);
}
};
false
}
fn is_none_expr(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
if let Some(inner_expr) = peels_blocks_incl_unsafe_opt(expr) {
return is_res_lang_ctor(cx, path_res(cx, inner_expr), OptionNone);
};
false
}
// given the closure: `|<pattern>| <expr>`
// returns `|&<pattern>| <expr>`
fn add_ampersand_if_copy(body_str: String, has_copy_trait: bool) -> String {
if has_copy_trait {
let mut with_ampersand = body_str;
with_ampersand.insert(1, '&');
with_ampersand
} else {
body_str
}
}
pub(super) fn check_match<'tcx>(
cx: &LateContext<'tcx>,
scrutinee: &'tcx Expr<'_>,
arms: &'tcx [Arm<'_>],
expr: &'tcx Expr<'_>,
) {
let ty = cx.typeck_results().expr_ty(expr);
if is_type_diagnostic_item(cx, ty, sym::Option)
&& let [first_arm, second_arm] = arms
&& first_arm.guard.is_none()
&& second_arm.guard.is_none()
{
check(
cx,
expr,
scrutinee,
first_arm.pat,
first_arm.body,
Some(second_arm.pat),
second_arm.body,
);
}
}
pub(super) fn check_if_let<'tcx>(
cx: &LateContext<'tcx>,
expr: &'tcx Expr<'_>,
let_pat: &'tcx Pat<'_>,
let_expr: &'tcx Expr<'_>,
then_expr: &'tcx Expr<'_>,
else_expr: &'tcx Expr<'_>,
) {
check(cx, expr, let_expr, let_pat, then_expr, None, else_expr);
}
fn check<'tcx>(
cx: &LateContext<'tcx>,
expr: &'tcx Expr<'_>,
scrutinee: &'tcx Expr<'_>,
then_pat: &'tcx Pat<'_>,
then_body: &'tcx Expr<'_>,
else_pat: Option<&'tcx Pat<'_>>,
else_body: &'tcx Expr<'_>,
) {
if let Some(sugg_info) = check_with(
cx,
expr,
scrutinee,
then_pat,
then_body,
else_pat,
else_body,
get_cond_expr,
) {
let body_str = add_ampersand_if_copy(sugg_info.body_str, sugg_info.scrutinee_impl_copy);
span_lint_and_sugg(
cx,
MANUAL_FILTER,
expr.span,
"manual implementation of `Option::filter`",
"try",
if sugg_info.needs_brackets {
format!(
"{{ {}{}.filter({body_str}) }}",
sugg_info.scrutinee_str, sugg_info.as_ref_str
)
} else {
format!("{}{}.filter({body_str})", sugg_info.scrutinee_str, sugg_info.as_ref_str)
},
sugg_info.app,
);
}
}
|
