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Recover ternary expression as error

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This commit is contained in:
clubby789 2023-10-26 11:35:11 +00:00
parent 041f0313cf
commit e81a5c65d9
3 changed files with 22 additions and 139 deletions
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20
compiler/rustc_parse/src/parser/diagnostics.rs
View file

@ -504,8 +504,10 @@ impl<'a> Parser<'a> {
// Special-case "expected `;`" errors // Special-case "expected `;`" errors
if expected.contains(&TokenType::Token(token::Semi)) { if expected.contains(&TokenType::Token(token::Semi)) {
if self.prev_token == token::Question && self.maybe_recover_from_ternary_operator() { // If the user is trying to write a ternary expression, recover it and
return Ok(true); // return an Err to prevent a cascade of irrelevant diagnostics
if self.prev_token == token::Question && let Err(e) = self.maybe_recover_from_ternary_operator() {
return Err(e);
} }
if self.token.span == DUMMY_SP || self.prev_token.span == DUMMY_SP { if self.token.span == DUMMY_SP || self.prev_token.span == DUMMY_SP {
@ -1428,10 +1430,10 @@ impl<'a> Parser<'a> {
/// Rust has no ternary operator (`cond ? then : else`). Parse it and try /// Rust has no ternary operator (`cond ? then : else`). Parse it and try
/// to recover from it if `then` and `else` are valid expressions. Returns /// to recover from it if `then` and `else` are valid expressions. Returns
/// whether it was a ternary operator. /// an err if this appears to be a ternary expression.
pub(super) fn maybe_recover_from_ternary_operator(&mut self) -> bool { pub(super) fn maybe_recover_from_ternary_operator(&mut self) -> PResult<'a, ()> {
if self.prev_token != token::Question { if self.prev_token != token::Question {
return false; return PResult::Ok(());
} }
let lo = self.prev_token.span.lo(); let lo = self.prev_token.span.lo();
@ -1449,8 +1451,9 @@ impl<'a> Parser<'a> {
if self.eat_noexpect(&token::Colon) { if self.eat_noexpect(&token::Colon) {
match self.parse_expr() { match self.parse_expr() {
Ok(_) => { Ok(_) => {
self.sess.emit_err(TernaryOperator { span: self.token.span.with_lo(lo) }); return Err(self
return true; .sess
.create_err(TernaryOperator { span: self.token.span.with_lo(lo) }));
} }
Err(err) => { Err(err) => {
err.cancel(); err.cancel();
@ -1459,8 +1462,7 @@ impl<'a> Parser<'a> {
} }
} }
self.restore_snapshot(snapshot); self.restore_snapshot(snapshot);
Ok(())
false
} }
pub(super) fn maybe_recover_from_bad_type_plus(&mut self, ty: &Ty) -> PResult<'a, ()> { pub(super) fn maybe_recover_from_bad_type_plus(&mut self, ty: &Ty) -> PResult<'a, ()> {

54
tests/ui/parser/ternary_operator.rs
View file

@ -1,76 +1,30 @@
// A good chunk of these errors aren't shown to the user, but are still fn a() {
// required in the test for it to pass.
fn a() { //~ NOTE this function should return `Result` or `Option` to accept `?`
let x = 5 > 2 ? true : false; let x = 5 > 2 ? true : false;
//~^ ERROR Rust has no ternary operator //~^ ERROR Rust has no ternary operator
//~| HELP use an `if-else` expression instead //~| HELP use an `if-else` expression instead
//~| ERROR the `?` operator can only be applied to values that implement `Try` [E0277]
//~| HELP the trait `Try` is not implemented for `{integer}`
//~| ERROR the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`) [E0277]
//~| HELP the trait `FromResidual<_>` is not implemented for `()`
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE the `?` operator cannot be applied to type `{integer}`
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE cannot use the `?` operator in a function that returns `()`
//~| NOTE in this expansion of desugaring of operator `?`
} }
fn b() { //~ NOTE this function should return `Result` or `Option` to accept `?` fn b() {
let x = 5 > 2 ? { true } : { false }; let x = 5 > 2 ? { true } : { false };
//~^ ERROR Rust has no ternary operator //~^ ERROR Rust has no ternary operator
//~| HELP use an `if-else` expression instead //~| HELP use an `if-else` expression instead
//~| ERROR the `?` operator can only be applied to values that implement `Try` [E0277]
//~| HELP the trait `Try` is not implemented for `{integer}`
//~| ERROR the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`) [E0277]
//~| HELP the trait `FromResidual<_>` is not implemented for `()`
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE the `?` operator cannot be applied to type `{integer}`
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE cannot use the `?` operator in a function that returns `()`
//~| NOTE in this expansion of desugaring of operator `?`
} }
fn c() { //~ NOTE this function should return `Result` or `Option` to accept `?` fn c() {
let x = 5 > 2 ? f32::MAX : f32::MIN; let x = 5 > 2 ? f32::MAX : f32::MIN;
//~^ ERROR Rust has no ternary operator //~^ ERROR Rust has no ternary operator
//~| HELP use an `if-else` expression instead //~| HELP use an `if-else` expression instead
//~| ERROR the `?` operator can only be applied to values that implement `Try` [E0277]
//~| HELP the trait `Try` is not implemented for `{integer}`
//~| ERROR the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`) [E0277]
//~| HELP the trait `FromResidual<_>` is not implemented for `()`
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE the `?` operator cannot be applied to type `{integer}`
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE cannot use the `?` operator in a function that returns `()`
//~| NOTE in this expansion of desugaring of operator `?`
} }
fn bad() { fn bad() {
// regression test for #117208 // regression test for #117208
v ? return; v ? return;
//~^ ERROR expected one of //~^ ERROR expected one of
//~| NOTE expected one of
} }
fn main() { //~ NOTE this function should return `Result` or `Option` to accept `?` fn main() {
let x = 5 > 2 ? { let x = vec![]: Vec<u16>; x } : { false }; let x = 5 > 2 ? { let x = vec![]: Vec<u16>; x } : { false };
//~^ ERROR Rust has no ternary operator //~^ ERROR Rust has no ternary operator
//~| HELP use an `if-else` expression instead //~| HELP use an `if-else` expression instead
//~| ERROR expected one of `.`, `;`, `?`, `else`, or an operator, found `:` //~| ERROR expected one of `.`, `;`, `?`, `else`, or an operator, found `:`
//~| NOTE expected one of `.`, `;`, `?`, `else`, or an operator
//~| ERROR the `?` operator can only be applied to values that implement `Try` [E0277]
//~| HELP the trait `Try` is not implemented for `{integer}`
//~| ERROR the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`) [E0277]
//~| HELP the trait `FromResidual<_>` is not implemented for `()`
//~| NOTE type ascription syntax has been removed, see issue #101728 <https://github.com/rust-lang/rust/issues/101728>
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE the `?` operator cannot be applied to type `{integer}`
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE cannot use the `?` operator in a function that returns `()`
//~| NOTE in this expansion of desugaring of operator `?`
} }

87
tests/ui/parser/ternary_operator.stderr
View file

@ -1,5 +1,5 @@
error: Rust has no ternary operator error: Rust has no ternary operator
--> $DIR/ternary_operator.rs:5:19 --> $DIR/ternary_operator.rs:2:19
| |
LL | let x = 5 > 2 ? true : false; LL | let x = 5 > 2 ? true : false;
| ^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^
@ -7,7 +7,7 @@ LL | let x = 5 > 2 ? true : false;
= help: use an `if-else` expression instead = help: use an `if-else` expression instead
error: Rust has no ternary operator error: Rust has no ternary operator
--> $DIR/ternary_operator.rs:21:19 --> $DIR/ternary_operator.rs:8:19
| |
LL | let x = 5 > 2 ? { true } : { false }; LL | let x = 5 > 2 ? { true } : { false };
| ^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^
@ -15,7 +15,7 @@ LL | let x = 5 > 2 ? { true } : { false };
= help: use an `if-else` expression instead = help: use an `if-else` expression instead
error: Rust has no ternary operator error: Rust has no ternary operator
--> $DIR/ternary_operator.rs:37:19 --> $DIR/ternary_operator.rs:14:19
| |
LL | let x = 5 > 2 ? f32::MAX : f32::MIN; LL | let x = 5 > 2 ? f32::MAX : f32::MIN;
| ^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^
@ -23,13 +23,13 @@ LL | let x = 5 > 2 ? f32::MAX : f32::MIN;
= help: use an `if-else` expression instead = help: use an `if-else` expression instead
error: expected one of `.`, `;`, `?`, `}`, or an operator, found keyword `return` error: expected one of `.`, `;`, `?`, `}`, or an operator, found keyword `return`
--> $DIR/ternary_operator.rs:54:9 --> $DIR/ternary_operator.rs:21:9
| |
LL | v ? return; LL | v ? return;
| ^^^^^^ expected one of `.`, `;`, `?`, `}`, or an operator | ^^^^^^ expected one of `.`, `;`, `?`, `}`, or an operator
error: expected one of `.`, `;`, `?`, `else`, or an operator, found `:` error: expected one of `.`, `;`, `?`, `else`, or an operator, found `:`
--> $DIR/ternary_operator.rs:60:37 --> $DIR/ternary_operator.rs:26:37
| |
LL | let x = 5 > 2 ? { let x = vec![]: Vec<u16>; x } : { false }; LL | let x = 5 > 2 ? { let x = vec![]: Vec<u16>; x } : { false };
| ^ expected one of `.`, `;`, `?`, `else`, or an operator | ^ expected one of `.`, `;`, `?`, `else`, or an operator
@ -37,85 +37,12 @@ LL | let x = 5 > 2 ? { let x = vec![]: Vec<u16>; x } : { false };
= note: type ascription syntax has been removed, see issue #101728 <https://github.com/rust-lang/rust/issues/101728> = note: type ascription syntax has been removed, see issue #101728 <https://github.com/rust-lang/rust/issues/101728>
error: Rust has no ternary operator error: Rust has no ternary operator
--> $DIR/ternary_operator.rs:60:19 --> $DIR/ternary_operator.rs:26:19
| |
LL | let x = 5 > 2 ? { let x = vec![]: Vec<u16>; x } : { false }; LL | let x = 5 > 2 ? { let x = vec![]: Vec<u16>; x } : { false };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
= help: use an `if-else` expression instead = help: use an `if-else` expression instead
error[E0277]: the `?` operator can only be applied to values that implement `Try` error: aborting due to 6 previous errors
--> $DIR/ternary_operator.rs:5:17
|
LL | let x = 5 > 2 ? true : false;
| ^^^ the `?` operator cannot be applied to type `{integer}`
|
= help: the trait `Try` is not implemented for `{integer}`
error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
--> $DIR/ternary_operator.rs:5:19
|
LL | fn a() {
| ------ this function should return `Result` or `Option` to accept `?`
LL | let x = 5 > 2 ? true : false;
| ^ cannot use the `?` operator in a function that returns `()`
|
= help: the trait `FromResidual<_>` is not implemented for `()`
error[E0277]: the `?` operator can only be applied to values that implement `Try`
--> $DIR/ternary_operator.rs:21:17
|
LL | let x = 5 > 2 ? { true } : { false };
| ^^^ the `?` operator cannot be applied to type `{integer}`
|
= help: the trait `Try` is not implemented for `{integer}`
error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
--> $DIR/ternary_operator.rs:21:19
|
LL | fn b() {
| ------ this function should return `Result` or `Option` to accept `?`
LL | let x = 5 > 2 ? { true } : { false };
| ^ cannot use the `?` operator in a function that returns `()`
|
= help: the trait `FromResidual<_>` is not implemented for `()`
error[E0277]: the `?` operator can only be applied to values that implement `Try`
--> $DIR/ternary_operator.rs:37:17
|
LL | let x = 5 > 2 ? f32::MAX : f32::MIN;
| ^^^ the `?` operator cannot be applied to type `{integer}`
|
= help: the trait `Try` is not implemented for `{integer}`
error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
--> $DIR/ternary_operator.rs:37:19
|
LL | fn c() {
| ------ this function should return `Result` or `Option` to accept `?`
LL | let x = 5 > 2 ? f32::MAX : f32::MIN;
| ^ cannot use the `?` operator in a function that returns `()`
|
= help: the trait `FromResidual<_>` is not implemented for `()`
error[E0277]: the `?` operator can only be applied to values that implement `Try`
--> $DIR/ternary_operator.rs:60:17
|
LL | let x = 5 > 2 ? { let x = vec![]: Vec<u16>; x } : { false };
| ^^^ the `?` operator cannot be applied to type `{integer}`
|
= help: the trait `Try` is not implemented for `{integer}`
error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
--> $DIR/ternary_operator.rs:60:19
|
LL | fn main() {
| --------- this function should return `Result` or `Option` to accept `?`
LL | let x = 5 > 2 ? { let x = vec![]: Vec<u16>; x } : { false };
| ^ cannot use the `?` operator in a function that returns `()`
|
= help: the trait `FromResidual<_>` is not implemented for `()`
error: aborting due to 14 previous errors
For more information about this error, try `rustc --explain E0277`.