Also consider match guards for divergence check

Plus, add some tests for the divergence check.
This commit is contained in:
est31 2022-10-16 03:56:40 +02:00
parent 96ea5b2cd6
commit dcde480a66
3 changed files with 120 additions and 16 deletions

View File

@ -194,8 +194,11 @@ fn is_never(cx: &LateContext<'_>, expr: &'_ Expr<'_>) -> bool {
ControlFlow::Continue(Descend::No)
},
ExprKind::Match(match_expr, match_arms, _) => {
let diverges =
expr_diverges(cx, match_expr) || match_arms.iter().all(|arm| expr_diverges(cx, arm.body));
let diverges = expr_diverges(cx, match_expr)
|| match_arms.iter().all(|arm| {
let guard_diverges = arm.guard.as_ref().map_or(false, |g| expr_diverges(cx, g.body()));
guard_diverges || expr_diverges(cx, arm.body)
});
if diverges {
return ControlFlow::Break(());
}

View File

@ -3,6 +3,7 @@
clippy::collapsible_else_if,
clippy::unused_unit,
clippy::let_unit_value,
clippy::match_single_binding,
clippy::never_loop
)]
#![warn(clippy::manual_let_else)]
@ -55,6 +56,38 @@ fn fire() {
if true { return } else { panic!() }
};
// Diverging after an if still makes the block diverge:
let v = if let Some(v_some) = g() {
v_some
} else {
if true {}
panic!();
};
// A match diverges if all branches diverge:
// Note: the corresponding let-else requires a ; at the end of the match
// as otherwise the type checker does not turn it into a ! type.
let v = if let Some(v_some) = g() {
v_some
} else {
match () {
_ if panic!() => {},
_ => panic!(),
}
};
// An if's expression can cause divergence:
let v = if let Some(v_some) = g() { v_some } else { if panic!() {} };
// An expression of a match can cause divergence:
let v = if let Some(v_some) = g() {
v_some
} else {
match panic!() {
_ => {},
}
};
// Top level else if
let v = if let Some(v_some) = g() {
v_some

View File

@ -1,5 +1,5 @@
error: this could be rewritten as `let...else`
--> $DIR/manual_let_else.rs:17:5
--> $DIR/manual_let_else.rs:18:5
|
LL | let v = if let Some(v_some) = g() { v_some } else { return };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Some(v_some) = g() else { return };`
@ -7,7 +7,7 @@ LL | let v = if let Some(v_some) = g() { v_some } else { return };
= note: `-D clippy::manual-let-else` implied by `-D warnings`
error: this could be rewritten as `let...else`
--> $DIR/manual_let_else.rs:18:5
--> $DIR/manual_let_else.rs:19:5
|
LL | / let v = if let Some(v_some) = g() {
LL | | v_some
@ -24,7 +24,7 @@ LL + };
|
error: this could be rewritten as `let...else`
--> $DIR/manual_let_else.rs:24:5
--> $DIR/manual_let_else.rs:25:5
|
LL | / let v = if let Some(v) = g() {
LL | | // Blocks around the identity should have no impact
@ -45,25 +45,25 @@ LL + };
|
error: this could be rewritten as `let...else`
--> $DIR/manual_let_else.rs:37:9
--> $DIR/manual_let_else.rs:38:9
|
LL | let v = if let Some(v_some) = g() { v_some } else { continue };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Some(v_some) = g() else { continue };`
error: this could be rewritten as `let...else`
--> $DIR/manual_let_else.rs:38:9
--> $DIR/manual_let_else.rs:39:9
|
LL | let v = if let Some(v_some) = g() { v_some } else { break };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Some(v_some) = g() else { break };`
error: this could be rewritten as `let...else`
--> $DIR/manual_let_else.rs:42:5
--> $DIR/manual_let_else.rs:43:5
|
LL | let v = if let Some(v_some) = g() { v_some } else { panic!() };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Some(v_some) = g() else { panic!() };`
error: this could be rewritten as `let...else`
--> $DIR/manual_let_else.rs:45:5
--> $DIR/manual_let_else.rs:46:5
|
LL | / let v = if let Some(v_some) = g() {
LL | | v_some
@ -80,7 +80,7 @@ LL + };
|
error: this could be rewritten as `let...else`
--> $DIR/manual_let_else.rs:52:5
--> $DIR/manual_let_else.rs:53:5
|
LL | / let v = if let Some(v_some) = g() {
LL | | v_some
@ -97,7 +97,75 @@ LL + };
|
error: this could be rewritten as `let...else`
--> $DIR/manual_let_else.rs:59:5
--> $DIR/manual_let_else.rs:60:5
|
LL | / let v = if let Some(v_some) = g() {
LL | | v_some
LL | | } else {
LL | | if true {}
LL | | panic!();
LL | | };
| |______^
|
help: consider writing
|
LL ~ let Some(v_some) = g() else {
LL + if true {}
LL + panic!();
LL + };
|
error: this could be rewritten as `let...else`
--> $DIR/manual_let_else.rs:70:5
|
LL | / let v = if let Some(v_some) = g() {
LL | | v_some
LL | | } else {
LL | | match () {
... |
LL | | }
LL | | };
| |______^
|
help: consider writing
|
LL ~ let Some(v_some) = g() else {
LL + match () {
LL + _ if panic!() => {},
LL + _ => panic!(),
LL + }
LL + };
|
error: this could be rewritten as `let...else`
--> $DIR/manual_let_else.rs:80:5
|
LL | let v = if let Some(v_some) = g() { v_some } else { if panic!() {} };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Some(v_some) = g() else { if panic!() {} };`
error: this could be rewritten as `let...else`
--> $DIR/manual_let_else.rs:83:5
|
LL | / let v = if let Some(v_some) = g() {
LL | | v_some
LL | | } else {
LL | | match panic!() {
LL | | _ => {},
LL | | }
LL | | };
| |______^
|
help: consider writing
|
LL ~ let Some(v_some) = g() else {
LL + match panic!() {
LL + _ => {},
LL + }
LL + };
|
error: this could be rewritten as `let...else`
--> $DIR/manual_let_else.rs:92:5
|
LL | / let v = if let Some(v_some) = g() {
LL | | v_some
@ -118,7 +186,7 @@ LL + } };
|
error: this could be rewritten as `let...else`
--> $DIR/manual_let_else.rs:68:5
--> $DIR/manual_let_else.rs:101:5
|
LL | / let v = if let Some(v_some) = g() {
LL | | v_some
@ -147,7 +215,7 @@ LL + };
|
error: this could be rewritten as `let...else`
--> $DIR/manual_let_else.rs:85:5
--> $DIR/manual_let_else.rs:118:5
|
LL | / let (v, w) = if let Some(v_some) = g().map(|v| (v, 42)) {
LL | | v_some
@ -164,7 +232,7 @@ LL + };
|
error: this could be rewritten as `let...else`
--> $DIR/manual_let_else.rs:92:5
--> $DIR/manual_let_else.rs:125:5
|
LL | / let v = if let (Some(v_some), w_some) = (g(), 0) {
LL | | (w_some, v_some)
@ -181,7 +249,7 @@ LL + };
|
error: this could be rewritten as `let...else`
--> $DIR/manual_let_else.rs:101:13
--> $DIR/manual_let_else.rs:134:13
|
LL | let $n = if let Some(v) = $e { v } else { return };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Some(v) = g() else { return };`
@ -191,5 +259,5 @@ LL | create_binding_if_some!(w, g());
|
= note: this error originates in the macro `create_binding_if_some` (in Nightly builds, run with -Z macro-backtrace for more info)
error: aborting due to 13 previous errors
error: aborting due to 17 previous errors