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Tweak error for invalid `break expr` 

Point at loop head on invalid `break expr`.
Suggest removing `expr` or using label if available.
This commit is contained in:
Esteban Küber 2021-01-20 17:25:27 -08:00
parent 060dba67b7
commit 8a13abba1d
6 changed files with 180 additions and 80 deletions
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76
compiler/rustc_passes/src/loops.rs
View File

@ -90,47 +90,83 @@ impl<'a, 'hir> Visitor<'hir> for CheckLoopVisitor<'a, 'hir> {
};
if let Some(Node::Block(_)) = loop_id.and_then(|id| self.hir_map.find(id)) {
return;
}
return;
}
if opt_expr.is_some() {
let loop_kind = if let Some(loop_id) = loop_id {
Some(match self.hir_map.expect_expr(loop_id).kind {
hir::ExprKind::Loop(_, _, source) => source,
if let Some(break_expr) = opt_expr {
let (head, label, loop_kind) = if let Some(loop_id) = loop_id {
match self.hir_map.expect_expr(loop_id).kind {
hir::ExprKind::Loop(_, label, source, sp) => {
(Some(sp), label, Some(source))
}
ref r => {
span_bug!(e.span, "break label resolved to a non-loop: {:?}", r)
}
})
}
} else {
None
(None, None, None)
};
match loop_kind {
None | Some(hir::LoopSource::Loop) => (),
Some(kind) => {
struct_span_err!(
let mut err = struct_span_err!(
self.sess,
e.span,
E0571,
"`break` with value from a `{}` loop",
kind.name()
)
.span_label(
);
err.span_label(
e.span,
"can only break with a value inside \
`loop` or breakable block",
)
.span_suggestion(
"can only break with a value inside `loop` or breakable block",
);
if let Some(head) = head {
err.span_label(
head,
&format!(
"you can't `break` with a value in a `{}` loop",
kind.name()
),
);
}
err.span_suggestion(
e.span,
&format!(
"instead, use `break` on its own \
without a value inside this `{}` loop",
kind.name()
"use `break` on its own without a value inside this `{}` loop",
kind.name(),
),
"break".to_string(),
Applicability::MaybeIncorrect,
)
.emit();
);
if let Some(label) = label {
match break_expr.kind {
hir::ExprKind::Path(hir::QPath::Resolved(
None,
hir::Path {
segments: [segment],
res: hir::def::Res::Err,
..
},
)) if label.ident.to_string()
== format!("'{}", segment.ident) =>
{
// This error is redundant, we will have already emitted a
// suggestion to use the label when `segment` wasn't found
// (hence the `Res::Err` check).
err.delay_as_bug();
}
_ => {
err.span_suggestion(
break_expr.span,
"alternatively, you might have meant to use the \
available loop label",
label.ident.to_string(),
Applicability::MaybeIncorrect,
);
}
}
}
err.emit();
}
}
}

27
src/test/ui/label/label_misspelled.rs
View File

@ -1,8 +1,4 @@
fn main() {
'LOOP: loop {
LOOP;
//~^ ERROR cannot find value `LOOP` in this scope
};
'while_loop: while true { //~ WARN denote infinite loops with
while_loop;
//~^ ERROR cannot find value `while_loop` in this scope
@ -15,6 +11,10 @@ fn main() {
for_loop;
//~^ ERROR cannot find value `for_loop` in this scope
};
'LOOP: loop {
LOOP;
//~^ ERROR cannot find value `LOOP` in this scope
};
}
fn foo() {
@ -25,16 +25,29 @@ fn foo() {
'while_loop: while true { //~ WARN denote infinite loops with
break while_loop;
//~^ ERROR cannot find value `while_loop` in this scope
//~| ERROR `break` with value from a `while` loop
};
'while_let: while let Some(_) = Some(()) {
break while_let;
//~^ ERROR cannot find value `while_let` in this scope
//~| ERROR `break` with value from a `while` loop
}
'for_loop: for _ in 0..3 {
break for_loop;
//~^ ERROR cannot find value `for_loop` in this scope
//~| ERROR `break` with value from a `for` loop
};
}
fn bar() {
let foo = ();
'while_loop: while true { //~ WARN denote infinite loops with
break foo;
//~^ ERROR `break` with value from a `while` loop
};
'while_let: while let Some(_) = Some(()) {
break foo;
//~^ ERROR `break` with value from a `while` loop
}
'for_loop: for _ in 0..3 {
break foo;
//~^ ERROR `break` with value from a `for` loop
};
}

88
src/test/ui/label/label_misspelled.stderr
View File

@ -1,13 +1,5 @@
error[E0425]: cannot find value `LOOP` in this scope
--> $DIR/label_misspelled.rs:3:9
|
LL | 'LOOP: loop {
| ----- a label with a similar name exists
LL | LOOP;
| ^^^^ not found in this scope
error[E0425]: cannot find value `while_loop` in this scope
--> $DIR/label_misspelled.rs:7:9
--> $DIR/label_misspelled.rs:3:9
|
LL | 'while_loop: while true {
| ----------- a label with a similar name exists
@ -15,7 +7,7 @@ LL | while_loop;
| ^^^^^^^^^^ not found in this scope
error[E0425]: cannot find value `while_let` in this scope
--> $DIR/label_misspelled.rs:11:9
--> $DIR/label_misspelled.rs:7:9
|
LL | 'while_let: while let Some(_) = Some(()) {
| ---------- a label with a similar name exists
@ -23,13 +15,21 @@ LL | while_let;
| ^^^^^^^^^ not found in this scope
error[E0425]: cannot find value `for_loop` in this scope
--> $DIR/label_misspelled.rs:15:9
--> $DIR/label_misspelled.rs:11:9
|
LL | 'for_loop: for _ in 0..3 {
| --------- a label with a similar name exists
LL | for_loop;
| ^^^^^^^^ not found in this scope
error[E0425]: cannot find value `LOOP` in this scope
--> $DIR/label_misspelled.rs:15:9
|
LL | 'LOOP: loop {
| ----- a label with a similar name exists
LL | LOOP;
| ^^^^ not found in this scope
error[E0425]: cannot find value `LOOP` in this scope
--> $DIR/label_misspelled.rs:22:15
|
@ -53,7 +53,7 @@ LL | break while_loop;
| help: use the similarly named label: `'while_loop`
error[E0425]: cannot find value `while_let` in this scope
--> $DIR/label_misspelled.rs:31:15
--> $DIR/label_misspelled.rs:30:15
|
LL | 'while_let: while let Some(_) = Some(()) {
| ---------- a label with a similar name exists
@ -64,7 +64,7 @@ LL | break while_let;
| help: use the similarly named label: `'while_let`
error[E0425]: cannot find value `for_loop` in this scope
--> $DIR/label_misspelled.rs:36:15
--> $DIR/label_misspelled.rs:34:15
|
LL | 'for_loop: for _ in 0..3 {
| --------- a label with a similar name exists
@ -75,7 +75,7 @@ LL | break for_loop;
| help: use the similarly named label: `'for_loop`
warning: denote infinite loops with `loop { ... }`
--> $DIR/label_misspelled.rs:6:5
--> $DIR/label_misspelled.rs:2:5
|
LL | 'while_loop: while true {
| ^^^^^^^^^^^^^^^^^^^^^^^ help: use `loop`
@ -88,40 +88,64 @@ warning: denote infinite loops with `loop { ... }`
LL | 'while_loop: while true {
| ^^^^^^^^^^^^^^^^^^^^^^^ help: use `loop`
error[E0571]: `break` with value from a `while` loop
--> $DIR/label_misspelled.rs:26:9
warning: denote infinite loops with `loop { ... }`
--> $DIR/label_misspelled.rs:41:5
|
LL | break while_loop;
| ^^^^^^^^^^^^^^^^ can only break with a value inside `loop` or breakable block
|
help: instead, use `break` on its own without a value inside this `while` loop
|
LL | break;
| ^^^^^
LL | 'while_loop: while true {
| ^^^^^^^^^^^^^^^^^^^^^^^ help: use `loop`
error[E0571]: `break` with value from a `while` loop
--> $DIR/label_misspelled.rs:31:9
--> $DIR/label_misspelled.rs:42:9
|
LL | break while_let;
| ^^^^^^^^^^^^^^^ can only break with a value inside `loop` or breakable block
LL | 'while_loop: while true {
| ----------------------- you can't `break` with a value in a `while` loop
LL | break foo;
| ^^^^^^^^^ can only break with a value inside `loop` or breakable block
|
help: instead, use `break` on its own without a value inside this `while` loop
help: use `break` on its own without a value inside this `while` loop
|
LL | break;
| ^^^^^
help: alternatively, you might have meant to use the available loop label
|
LL | break 'while_loop;
| ^^^^^^^^^^^
error[E0571]: `break` with value from a `while` loop
--> $DIR/label_misspelled.rs:46:9
|
LL | 'while_let: while let Some(_) = Some(()) {
| ---------------------------------------- you can't `break` with a value in a `while` loop
LL | break foo;
| ^^^^^^^^^ can only break with a value inside `loop` or breakable block
|
help: use `break` on its own without a value inside this `while` loop
|
LL | break;
| ^^^^^
help: alternatively, you might have meant to use the available loop label
|
LL | break 'while_let;
| ^^^^^^^^^^
error[E0571]: `break` with value from a `for` loop
--> $DIR/label_misspelled.rs:36:9
--> $DIR/label_misspelled.rs:50:9
|
LL | break for_loop;
| ^^^^^^^^^^^^^^ can only break with a value inside `loop` or breakable block
LL | 'for_loop: for _ in 0..3 {
| ------------------------ you can't `break` with a value in a `for` loop
LL | break foo;
| ^^^^^^^^^ can only break with a value inside `loop` or breakable block
|
help: instead, use `break` on its own without a value inside this `for` loop
help: use `break` on its own without a value inside this `for` loop
|
LL | break;
| ^^^^^
help: alternatively, you might have meant to use the available loop label
|
LL | break 'for_loop;
| ^^^^^^^^^
error: aborting due to 11 previous errors; 2 warnings emitted
error: aborting due to 11 previous errors; 3 warnings emitted
Some errors have detailed explanations: E0425, E0571.
For more information about an error, try `rustc --explain E0425`.

4
src/test/ui/loops/loop-break-value-no-repeat.stderr
View File

@ -1,10 +1,12 @@
error[E0571]: `break` with value from a `for` loop
--> $DIR/loop-break-value-no-repeat.rs:12:9
|
LL | for _ in &[1,2,3] {
| ----------------- you can't `break` with a value in a `for` loop
LL | break 22
| ^^^^^^^^ can only break with a value inside `loop` or breakable block
|
help: instead, use `break` on its own without a value inside this `for` loop
help: use `break` on its own without a value inside this `for` loop
|
LL | break
| ^^^^^

1
src/test/ui/loops/loop-break-value.rs
View File

@ -94,6 +94,5 @@ fn main() {
'LOOP: for _ in 0 .. 9 {
break LOOP;
//~^ ERROR cannot find value `LOOP` in this scope
//~| ERROR `break` with value from a `for` loop
}
}

64
src/test/ui/loops/loop-break-value.stderr
View File

@ -20,32 +20,48 @@ LL | 'while_loop: while true {
error[E0571]: `break` with value from a `while` loop
--> $DIR/loop-break-value.rs:28:9
|
LL | 'while_loop: while true {
| ----------------------- you can't `break` with a value in a `while` loop
LL | break;
LL | break ();
| ^^^^^^^^ can only break with a value inside `loop` or breakable block
|
help: instead, use `break` on its own without a value inside this `while` loop
help: use `break` on its own without a value inside this `while` loop
|
LL | break;
| ^^^^^
help: alternatively, you might have meant to use the available loop label
|
LL | break 'while_loop;
| ^^^^^^^^^^^
error[E0571]: `break` with value from a `while` loop
--> $DIR/loop-break-value.rs:30:13
|
LL | 'while_loop: while true {
| ----------------------- you can't `break` with a value in a `while` loop
...
LL | break 'while_loop 123;
| ^^^^^^^^^^^^^^^^^^^^^ can only break with a value inside `loop` or breakable block
|
help: instead, use `break` on its own without a value inside this `while` loop
help: use `break` on its own without a value inside this `while` loop
|
LL | break;
| ^^^^^
help: alternatively, you might have meant to use the available loop label
|
LL | break 'while_loop 'while_loop;
| ^^^^^^^^^^^
error[E0571]: `break` with value from a `while` loop
--> $DIR/loop-break-value.rs:38:12
|
LL | while let Some(_) = Some(()) {
| ---------------------------- you can't `break` with a value in a `while` loop
LL | if break () {
| ^^^^^^^^ can only break with a value inside `loop` or breakable block
|
help: instead, use `break` on its own without a value inside this `while` loop
help: use `break` on its own without a value inside this `while` loop
|
LL | if break {
| ^^^^^
@ -53,10 +69,12 @@ LL | if break {
error[E0571]: `break` with value from a `while` loop
--> $DIR/loop-break-value.rs:43:9
|
LL | while let Some(_) = Some(()) {
| ---------------------------- you can't `break` with a value in a `while` loop
LL | break None;
| ^^^^^^^^^^ can only break with a value inside `loop` or breakable block
|
help: instead, use `break` on its own without a value inside this `while` loop
help: use `break` on its own without a value inside this `while` loop
|
LL | break;
| ^^^^^
@ -64,21 +82,30 @@ LL | break;
error[E0571]: `break` with value from a `while` loop
--> $DIR/loop-break-value.rs:49:13
|
LL | 'while_let_loop: while let Some(_) = Some(()) {
| --------------------------------------------- you can't `break` with a value in a `while` loop
LL | loop {
LL | break 'while_let_loop "nope";
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can only break with a value inside `loop` or breakable block
|
help: instead, use `break` on its own without a value inside this `while` loop
help: use `break` on its own without a value inside this `while` loop
|
LL | break;
| ^^^^^
help: alternatively, you might have meant to use the available loop label
|
LL | break 'while_let_loop 'while_let_loop;
| ^^^^^^^^^^^^^^^
error[E0571]: `break` with value from a `for` loop
--> $DIR/loop-break-value.rs:56:9
|
LL | for _ in &[1,2,3] {
| ----------------- you can't `break` with a value in a `for` loop
LL | break ();
| ^^^^^^^^ can only break with a value inside `loop` or breakable block
|
help: instead, use `break` on its own without a value inside this `for` loop
help: use `break` on its own without a value inside this `for` loop
|
LL | break;
| ^^^^^
@ -86,10 +113,13 @@ LL | break;
error[E0571]: `break` with value from a `for` loop
--> $DIR/loop-break-value.rs:57:9
|
LL | for _ in &[1,2,3] {
| ----------------- you can't `break` with a value in a `for` loop
LL | break ();
LL | break [()];
| ^^^^^^^^^^ can only break with a value inside `loop` or breakable block
|
help: instead, use `break` on its own without a value inside this `for` loop
help: use `break` on its own without a value inside this `for` loop
|
LL | break;
| ^^^^^
@ -97,24 +127,20 @@ LL | break;
error[E0571]: `break` with value from a `for` loop
--> $DIR/loop-break-value.rs:64:13
|
LL | 'for_loop: for _ in &[1,2,3] {
| ---------------------------- you can't `break` with a value in a `for` loop
...
LL | break 'for_loop Some(17);
| ^^^^^^^^^^^^^^^^^^^^^^^^ can only break with a value inside `loop` or breakable block
|
help: instead, use `break` on its own without a value inside this `for` loop
help: use `break` on its own without a value inside this `for` loop
|
LL | break;
| ^^^^^
error[E0571]: `break` with value from a `for` loop
--> $DIR/loop-break-value.rs:95:9
help: alternatively, you might have meant to use the available loop label
|
LL | break LOOP;
| ^^^^^^^^^^ can only break with a value inside `loop` or breakable block
|
help: instead, use `break` on its own without a value inside this `for` loop
|
LL | break;
| ^^^^^
LL | break 'for_loop 'for_loop;
| ^^^^^^^^^
error[E0308]: mismatched types
--> $DIR/loop-break-value.rs:4:31
@ -173,7 +199,7 @@ LL | break;
| expected integer, found `()`
| help: give it a value of the expected type: `break value`
error: aborting due to 18 previous errors; 1 warning emitted
error: aborting due to 17 previous errors; 1 warning emitted
Some errors have detailed explanations: E0308, E0425, E0571.
For more information about an error, try `rustc --explain E0308`.