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improve parent expr check

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This commit is contained in:
J-ZhengLi 2022-03-29 15:23:19 +08:00
parent 4b128624ed
commit 448a26d696
3 changed files with 32 additions and 12 deletions
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20
clippy_lints/src/matches/needless_match.rs
View file

@ -14,7 +14,7 @@ use rustc_span::sym;
use rustc_typeck::hir_ty_to_ty;
pub(crate) fn check_match(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>], expr: &Expr<'_>) {
if arms.len() > 1 && !is_coercion_casting(cx, ex, expr) && check_all_arms(cx, ex, arms) {
if arms.len() > 1 && expr_ty_matches_p_ty(cx, ex, expr) && check_all_arms(cx, ex, arms) {
let mut applicability = Applicability::MachineApplicable;
span_lint_and_sugg(
cx,
@ -49,7 +49,7 @@ pub(crate) fn check_match(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>],
/// ```
pub(crate) fn check(cx: &LateContext<'_>, ex: &Expr<'_>) {
if let Some(ref if_let) = higher::IfLet::hir(cx, ex) {
if !is_else_clause(cx.tcx, ex) && !is_coercion_casting(cx, if_let.let_expr, ex) && check_if_let(cx, if_let) {
if !is_else_clause(cx.tcx, ex) && expr_ty_matches_p_ty(cx, if_let.let_expr, ex) && check_if_let(cx, if_let) {
let mut applicability = Applicability::MachineApplicable;
span_lint_and_sugg(
cx,
@ -119,39 +119,35 @@ fn strip_return<'hir>(expr: &'hir Expr<'hir>) -> &'hir Expr<'hir> {
/// Manually check for coercion casting by checking if the type of the match operand or let expr
/// differs with the assigned local variable or the funtion return type.
fn is_coercion_casting(cx: &LateContext<'_>, match_expr: &Expr<'_>, expr: &Expr<'_>) -> bool {
if let Some(p_node) = get_parent_node(cx.tcx, expr.hir_id) {
fn expr_ty_matches_p_ty(cx: &LateContext<'_>, expr: &Expr<'_>, p_expr: &Expr<'_>) -> bool {
if let Some(p_node) = get_parent_node(cx.tcx, p_expr.hir_id) {
match p_node {
// Compare match_expr ty with local in `let local = match match_expr {..}`
Node::Local(local) => {
let results = cx.typeck_results();
return !same_type_and_consts(results.node_type(local.hir_id), results.expr_ty(match_expr));
return same_type_and_consts(results.node_type(local.hir_id), results.expr_ty(expr));
},
// compare match_expr ty with RetTy in `fn foo() -> RetTy`
Node::Item(..) => {
if let Some(fn_decl) = p_node.fn_decl() {
if let FnRetTy::Return(ret_ty) = fn_decl.output {
return !same_type_and_consts(
hir_ty_to_ty(cx.tcx, ret_ty),
cx.typeck_results().expr_ty(match_expr),
);
return same_type_and_consts(hir_ty_to_ty(cx.tcx, ret_ty), cx.typeck_results().expr_ty(expr));
}
}
},
// check the parent expr for this whole block `{ match match_expr {..} }`
Node::Block(block) => {
if let Some(block_parent_expr) = get_parent_expr_for_hir(cx, block.hir_id) {
return is_coercion_casting(cx, match_expr, block_parent_expr);
return expr_ty_matches_p_ty(cx, expr, block_parent_expr);
}
},
// recursively call on `if xxx {..}` etc.
Node::Expr(p_expr) => {
return is_coercion_casting(cx, match_expr, p_expr);
return expr_ty_matches_p_ty(cx, expr, p_expr);
},
_ => {},
}
}
false
}

12
tests/ui/needless_match.fixed
View file

@ -182,4 +182,16 @@ mod issue8551 {
}
}
trait Tr {
fn as_mut(&mut self) -> Result<&mut i32, &mut i32>;
}
impl Tr for Result<i32, i32> {
fn as_mut(&mut self) -> Result<&mut i32, &mut i32> {
match self {
Ok(x) => Ok(x),
Err(e) => Err(e),
}
}
}
fn main() {}

12
tests/ui/needless_match.rs
View file

@ -219,4 +219,16 @@ mod issue8551 {
}
}
trait Tr {
fn as_mut(&mut self) -> Result<&mut i32, &mut i32>;
}
impl Tr for Result<i32, i32> {
fn as_mut(&mut self) -> Result<&mut i32, &mut i32> {
match self {
Ok(x) => Ok(x),
Err(e) => Err(e),
}
}
}
fn main() {}