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[needless_return] Recursively remove unneeded semicolons

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This commit is contained in:
kraktus 2022-09-19 12:07:53 +02:00
parent 23d1d07861
commit 5c0cb0deaa
4 changed files with 244 additions and 64 deletions
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65
clippy_lints/src/returns.rs
View File

@ -1,4 +1,4 @@
use clippy_utils::diagnostics::{span_lint_hir_and_then, span_lint_and_then};
use clippy_utils::diagnostics::{span_lint_and_then, span_lint_hir_and_then};
use clippy_utils::source::{snippet_opt, snippet_with_context};
use clippy_utils::{fn_def_id, path_to_local_id};
use if_chain::if_chain;
@ -9,7 +9,7 @@
use rustc_middle::lint::in_external_macro;
use rustc_middle::ty::subst::GenericArgKind;
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::source_map::Span;
use rustc_span::source_map::{Span, DUMMY_SP};
declare_clippy_lint! {
/// ### What it does
@ -73,8 +73,8 @@ enum RetReplacement {
}
impl RetReplacement {
fn sugg_help(&self) -> &'static str {
match *self {
fn sugg_help(self) -> &'static str {
match self {
Self::Empty => "remove `return`",
Self::Block => "replace `return` with an empty block",
Self::Unit => "replace `return` with a unit value",
@ -160,24 +160,30 @@ fn check_fn(
} else {
RetReplacement::Empty
};
check_final_expr(cx, body.value, body.value.span, replacement);
check_final_expr(cx, body.value, vec![], replacement);
},
FnKind::ItemFn(..) | FnKind::Method(..) => {
check_block_return(cx, &body.value.kind);
check_block_return(cx, &body.value.kind, vec![]);
},
}
}
}
// if `expr` is a block, check if there are needless returns in it
fn check_block_return<'tcx>(cx: &LateContext<'tcx>, expr_kind: &ExprKind<'tcx>) {
fn check_block_return<'tcx>(cx: &LateContext<'tcx>, expr_kind: &ExprKind<'tcx>, semi_spans: Vec<Span>) {
if let ExprKind::Block(block, _) = expr_kind {
if let Some(block_expr) = block.expr {
check_final_expr(cx, block_expr, block_expr.span, RetReplacement::Empty);
check_final_expr(cx, block_expr, semi_spans, RetReplacement::Empty);
} else if let Some(stmt) = block.stmts.iter().last() {
match stmt.kind {
StmtKind::Expr(expr) | StmtKind::Semi(expr) => {
check_final_expr(cx, expr, stmt.span, RetReplacement::Empty);
StmtKind::Expr(expr) => {
check_final_expr(cx, expr, semi_spans, RetReplacement::Empty);
},
StmtKind::Semi(semi_expr) => {
let mut semi_spans_and_this_one = semi_spans;
// we only want the span containing the semicolon so we can remove it later. From `entry.rs:382`
semi_spans_and_this_one.push(stmt.span.trim_start(semi_expr.span).unwrap_or(DUMMY_SP));
check_final_expr(cx, semi_expr, semi_spans_and_this_one, RetReplacement::Empty);
},
_ => (),
}
@ -185,8 +191,15 @@ fn check_block_return<'tcx>(cx: &LateContext<'tcx>, expr_kind: &ExprKind<'tcx>)
}
}
fn check_final_expr<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>, span: Span, replacement: RetReplacement) {
match &expr.peel_drop_temps().kind {
fn check_final_expr<'tcx>(
cx: &LateContext<'tcx>,
expr: &'tcx Expr<'tcx>,
semi_spans: Vec<Span>, /* containing all the places where we would need to remove semicolons if finding an
* needless return */
replacement: RetReplacement,
) {
let peeled_drop_expr = expr.peel_drop_temps();
match &peeled_drop_expr.kind {
// simple return is always "bad"
ExprKind::Ret(ref inner) => {
if cx.tcx.hir().attrs(expr.hir_id).is_empty() {
@ -194,7 +207,8 @@ fn check_final_expr<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>, span:
if !borrows {
emit_return_lint(
cx,
span,
peeled_drop_expr.span,
semi_spans,
inner.as_ref().map(|i| i.span),
replacement,
);
@ -202,9 +216,9 @@ fn check_final_expr<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>, span:
}
},
ExprKind::If(_, then, else_clause_opt) => {
check_block_return(cx, &then.kind);
check_block_return(cx, &then.kind, semi_spans.clone());
if let Some(else_clause) = else_clause_opt {
check_block_return(cx, &else_clause.kind)
check_block_return(cx, &else_clause.kind, semi_spans);
}
},
// a match expr, check all arms
@ -213,17 +227,18 @@ fn check_final_expr<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>, span:
// (except for unit type functions) so we don't match it
ExprKind::Match(_, arms, MatchSource::Normal) => {
for arm in arms.iter() {
check_final_expr(cx, arm.body, arm.body.span, RetReplacement::Unit);
check_final_expr(cx, arm.body, semi_spans.clone(), RetReplacement::Unit);
}
},
// if it's a whole block, check it
other_expr_kind => check_block_return(cx, &other_expr_kind),
other_expr_kind => check_block_return(cx, other_expr_kind, semi_spans),
}
}
fn emit_return_lint(
cx: &LateContext<'_>,
ret_span: Span,
semi_spans: Vec<Span>,
inner_span: Option<Span>,
replacement: RetReplacement,
) {
@ -243,15 +258,13 @@ fn emit_return_lint(
} else {
replacement.sugg_help()
};
span_lint_and_then(
cx,
NEEDLESS_RETURN,
ret_span,
"unneeded `return` statement",
|diag| {
diag.span_suggestion(ret_span, sugg_help, return_replacement, applicability);
},
);
span_lint_and_then(cx, NEEDLESS_RETURN, ret_span, "unneeded `return` statement", |diag| {
diag.span_suggestion_hidden(ret_span, sugg_help, return_replacement, applicability);
// for each parent statement, we need to remove the semicolon
for semi_stmt_span in semi_spans {
diag.tool_only_span_suggestion(semi_stmt_span, "remove this semicolon", "", applicability);
}
});
}
fn last_statement_borrows<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> bool {

27
tests/ui/needless_return.fixed
View File

@ -233,4 +233,31 @@ fn issue_9361() -> i32 {
return 1 + 2;
}
fn issue8336(x: i32) -> bool {
if x > 0 {
println!("something");
true
} else {
false
}
}
fn issue8156(x: u8) -> u64 {
match x {
80 => {
10
},
_ => {
100
},
}
}
// Ideally the compiler should throw `unused_braces` in this case
fn issue9192() -> i32 {
{
0
}
}
fn main() {}

27
tests/ui/needless_return.rs
View File

@ -233,4 +233,31 @@ fn issue_9361() -> i32 {
return 1 + 2;
}
fn issue8336(x: i32) -> bool {
if x > 0 {
println!("something");
return true;
} else {
return false;
};
}
fn issue8156(x: u8) -> u64 {
match x {
80 => {
return 10;
},
_ => {
return 100;
},
};
}
// Ideally the compiler should throw `unused_braces` in this case
fn issue9192() -> i32 {
{
return 0;
};
}
fn main() {}

189
tests/ui/needless_return.stderr
View File

@ -2,225 +2,338 @@ error: unneeded `return` statement
--> $DIR/needless_return.rs:27:5
|
LL | return true;
| ^^^^^^^^^^^^ help: remove `return`: `true`
| ^^^^^^^^^^^
|
= note: `-D clippy::needless-return` implied by `-D warnings`
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:31:5
|
LL | return true;
| ^^^^^^^^^^^^ help: remove `return`: `true`
| ^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:36:9
|
LL | return true;
| ^^^^^^^^^^^^ help: remove `return`: `true`
| ^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:38:9
|
LL | return false;
| ^^^^^^^^^^^^^ help: remove `return`: `false`
| ^^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:44:17
|
LL | true => return false,
| ^^^^^^^^^^^^ help: remove `return`: `false`
| ^^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:46:13
|
LL | return true;
| ^^^^^^^^^^^^ help: remove `return`: `true`
| ^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:53:9
|
LL | return true;
| ^^^^^^^^^^^^ help: remove `return`: `true`
| ^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:55:16
|
LL | let _ = || return true;
| ^^^^^^^^^^^ help: remove `return`: `true`
| ^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:59:5
|
LL | return the_answer!();
| ^^^^^^^^^^^^^^^^^^^^^ help: remove `return`: `the_answer!()`
| ^^^^^^^^^^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:63:5
|
LL | return;
| ^^^^^^^ help: remove `return`
| ^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:68:9
|
LL | return;
| ^^^^^^^ help: remove `return`
| ^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:70:9
|
LL | return;
| ^^^^^^^ help: remove `return`
| ^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:77:14
|
LL | _ => return,
| ^^^^^^ help: replace `return` with a unit value: `()`
| ^^^^^^
|
= help: replace `return` with a unit value
error: unneeded `return` statement
--> $DIR/needless_return.rs:86:13
|
LL | return;
| ^^^^^^^ help: remove `return`
| ^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:88:14
|
LL | _ => return,
| ^^^^^^ help: replace `return` with a unit value: `()`
| ^^^^^^
|
= help: replace `return` with a unit value
error: unneeded `return` statement
--> $DIR/needless_return.rs:101:9
|
LL | return String::from("test");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `return`: `String::from("test")`
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:103:9
|
LL | return String::new();
| ^^^^^^^^^^^^^^^^^^^^^ help: remove `return`: `String::new()`
| ^^^^^^^^^^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:125:32
|
LL | bar.unwrap_or_else(|_| return)
| ^^^^^^ help: replace `return` with an empty block: `{}`
| ^^^^^^
|
= help: replace `return` with an empty block
error: unneeded `return` statement
--> $DIR/needless_return.rs:130:13
|
LL | return;
| ^^^^^^^ help: remove `return`
| ^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:132:20
|
LL | let _ = || return;
| ^^^^^^ help: replace `return` with an empty block: `{}`
| ^^^^^^
|
= help: replace `return` with an empty block
error: unneeded `return` statement
--> $DIR/needless_return.rs:138:32
|
LL | res.unwrap_or_else(|_| return Foo)
| ^^^^^^^^^^ help: remove `return`: `Foo`
| ^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:147:5
|
LL | return true;
| ^^^^^^^^^^^^ help: remove `return`: `true`
| ^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:151:5
|
LL | return true;
| ^^^^^^^^^^^^ help: remove `return`: `true`
| ^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:156:9
|
LL | return true;
| ^^^^^^^^^^^^ help: remove `return`: `true`
| ^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:158:9
|
LL | return false;
| ^^^^^^^^^^^^^ help: remove `return`: `false`
| ^^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:164:17
|
LL | true => return false,
| ^^^^^^^^^^^^ help: remove `return`: `false`
| ^^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:166:13
|
LL | return true;
| ^^^^^^^^^^^^ help: remove `return`: `true`
| ^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:173:9
|
LL | return true;
| ^^^^^^^^^^^^ help: remove `return`: `true`
| ^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:175:16
|
LL | let _ = || return true;
| ^^^^^^^^^^^ help: remove `return`: `true`
| ^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:179:5
|
LL | return the_answer!();
| ^^^^^^^^^^^^^^^^^^^^^ help: remove `return`: `the_answer!()`
| ^^^^^^^^^^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:183:5
|
LL | return;
| ^^^^^^^ help: remove `return`
| ^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:188:9
|
LL | return;
| ^^^^^^^ help: remove `return`
| ^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:190:9
|
LL | return;
| ^^^^^^^ help: remove `return`
| ^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:197:14
|
LL | _ => return,
| ^^^^^^ help: replace `return` with a unit value: `()`
| ^^^^^^
|
= help: replace `return` with a unit value
error: unneeded `return` statement
--> $DIR/needless_return.rs:210:9
|
LL | return String::from("test");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `return`: `String::from("test")`
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:212:9
|
LL | return String::new();
| ^^^^^^^^^^^^^^^^^^^^^ help: remove `return`: `String::new()`
| ^^^^^^^^^^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:228:5
|
LL | return format!("Hello {}", "world!");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `return`: `format!("Hello {}", "world!")`
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: remove `return`
error: aborting due to 37 previous errors
error: unneeded `return` statement
--> $DIR/needless_return.rs:239:9
|
LL | return true;
| ^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:241:9
|
LL | return false;
| ^^^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:248:13
|
LL | return 10;
| ^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:251:13
|
LL | return 100;
| ^^^^^^^^^^
|
= help: remove `return`
error: unneeded `return` statement
--> $DIR/needless_return.rs:259:9
|
LL | return 0;
| ^^^^^^^^
|
= help: remove `return`
error: aborting due to 42 previous errors