diff --git a/compiler/rustc_parse/messages.ftl b/compiler/rustc_parse/messages.ftl index 9787d98c1a49a..86e41253b29f8 100644 --- a/compiler/rustc_parse/messages.ftl +++ b/compiler/rustc_parse/messages.ftl @@ -722,6 +722,10 @@ parse_sugg_wrap_pattern_in_parens = wrap the pattern in parentheses parse_switch_mut_let_order = switch the order of `mut` and `let` + +parse_ternary_operator = Rust has no ternary operator + .help = use an `if-else` expression instead + parse_tilde_const_lifetime = `~const` may only modify trait bounds, not lifetime bounds parse_tilde_is_not_unary_operator = `~` cannot be used as a unary operator diff --git a/compiler/rustc_parse/src/errors.rs b/compiler/rustc_parse/src/errors.rs index 96e1c0e3c6d9e..903b0e078768e 100644 --- a/compiler/rustc_parse/src/errors.rs +++ b/compiler/rustc_parse/src/errors.rs @@ -365,6 +365,14 @@ pub(crate) enum IfExpressionMissingThenBlockSub { AddThenBlock(#[primary_span] Span), } +#[derive(Diagnostic)] +#[diag(parse_ternary_operator)] +#[help] +pub struct TernaryOperator { + #[primary_span] + pub span: Span, +} + #[derive(Subdiagnostic)] #[suggestion(parse_extra_if_in_let_else, applicability = "maybe-incorrect", code = "")] pub(crate) struct IfExpressionLetSomeSub { diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs index c3cf6437afa07..7d04a335c9e0b 100644 --- a/compiler/rustc_parse/src/parser/diagnostics.rs +++ b/compiler/rustc_parse/src/parser/diagnostics.rs @@ -14,7 +14,7 @@ use crate::errors::{ PatternMethodParamWithoutBody, QuestionMarkInType, QuestionMarkInTypeSugg, SelfParamNotFirst, StructLiteralBodyWithoutPath, StructLiteralBodyWithoutPathSugg, StructLiteralNeedingParens, StructLiteralNeedingParensSugg, SuggAddMissingLetStmt, SuggEscapeIdentifier, SuggRemoveComma, - UnexpectedConstInGenericParam, UnexpectedConstParamDeclaration, + TernaryOperator, UnexpectedConstInGenericParam, UnexpectedConstParamDeclaration, UnexpectedConstParamDeclarationSugg, UnmatchedAngleBrackets, UseEqInstead, }; @@ -500,6 +500,10 @@ impl<'a> Parser<'a> { // Special-case "expected `;`" errors if expected.contains(&TokenType::Token(token::Semi)) { + if self.prev_token == token::Question && self.maybe_recover_from_ternary_operator() { + return Ok(true); + } + if self.token.span == DUMMY_SP || self.prev_token.span == DUMMY_SP { // Likely inside a macro, can't provide meaningful suggestions. } else if !sm.is_multiline(self.prev_token.span.until(self.token.span)) { @@ -1330,6 +1334,45 @@ impl<'a> Parser<'a> { } } + /// Rust has no ternary operator (`cond ? then : else`). Parse it and try + /// to recover from it if `then` and `else` are valid expressions. Returns + /// whether it was a ternary operator. + pub(super) fn maybe_recover_from_ternary_operator(&mut self) -> bool { + if self.prev_token != token::Question { + return false; + } + + let lo = self.prev_token.span.lo(); + let snapshot = self.create_snapshot_for_diagnostic(); + + if match self.parse_expr() { + Ok(_) => true, + Err(err) => { + err.cancel(); + // The colon can sometimes be mistaken for type + // ascription. Catch when this happens and continue. + self.token == token::Colon + } + } { + if self.eat_noexpect(&token::Colon) { + match self.parse_expr() { + Ok(_) => { + self.sess.emit_err(TernaryOperator { span: self.token.span.with_lo(lo) }); + return true; + } + Err(err) => { + err.cancel(); + self.restore_snapshot(snapshot); + } + }; + } + } else { + self.restore_snapshot(snapshot); + }; + + false + } + pub(super) fn maybe_recover_from_bad_type_plus(&mut self, ty: &Ty) -> PResult<'a, ()> { // Do not add `+` to expected tokens. if !self.token.is_like_plus() { @@ -2111,7 +2154,7 @@ impl<'a> Parser<'a> { } _ => ( self.token.span, - format!("expected expression, found {}", super::token_descr(&self.token),), + format!("expected expression, found {}", super::token_descr(&self.token)), ), }; let mut err = self.struct_span_err(span, msg); diff --git a/tests/ui/parser/ternary_operator.rs b/tests/ui/parser/ternary_operator.rs new file mode 100644 index 0000000000000..23d537e77f79e --- /dev/null +++ b/tests/ui/parser/ternary_operator.rs @@ -0,0 +1,69 @@ +// A good chunk of these errors aren't shown to the user, but are still +// 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; + //~^ ERROR Rust has no ternary operator + //~| 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 `?` + let x = 5 > 2 ? { true } : { false }; + //~^ ERROR Rust has no ternary operator + //~| 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 `?` + let x = 5 > 2 ? f32::MAX : f32::MIN; + //~^ ERROR Rust has no ternary operator + //~| 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 main() { //~ NOTE this function should return `Result` or `Option` to accept `?` + let x = 5 > 2 ? { let x = vec![]: Vec; x } : { false }; + //~^ ERROR Rust has no ternary operator + //~| HELP use an `if-else` expression instead + //~| 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 + //~| 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 `?` +} diff --git a/tests/ui/parser/ternary_operator.stderr b/tests/ui/parser/ternary_operator.stderr new file mode 100644 index 0000000000000..af9565bbead1b --- /dev/null +++ b/tests/ui/parser/ternary_operator.stderr @@ -0,0 +1,115 @@ +error: Rust has no ternary operator + --> $DIR/ternary_operator.rs:5:19 + | +LL | let x = 5 > 2 ? true : false; + | ^^^^^^^^^^^^^^^ + | + = help: use an `if-else` expression instead + +error: Rust has no ternary operator + --> $DIR/ternary_operator.rs:21:19 + | +LL | let x = 5 > 2 ? { true } : { false }; + | ^^^^^^^^^^^^^^^^^^^^^^^ + | + = help: use an `if-else` expression instead + +error: Rust has no ternary operator + --> $DIR/ternary_operator.rs:37:19 + | +LL | let x = 5 > 2 ? f32::MAX : f32::MIN; + | ^^^^^^^^^^^^^^^^^^^^^^ + | + = help: use an `if-else` expression instead + +error: expected one of `.`, `;`, `?`, `else`, or an operator, found `:` + --> $DIR/ternary_operator.rs:53:37 + | +LL | let x = 5 > 2 ? { let x = vec![]: Vec; x } : { false }; + | ^ expected one of `.`, `;`, `?`, `else`, or an operator + | + = note: type ascription syntax has been removed, see issue #101728 + +error: Rust has no ternary operator + --> $DIR/ternary_operator.rs:53:19 + | +LL | let x = 5 > 2 ? { let x = vec![]: Vec; x } : { false }; + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | + = help: use an `if-else` expression instead + +error[E0277]: the `?` operator can only be applied to values that implement `Try` + --> $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:53:17 + | +LL | let x = 5 > 2 ? { let x = vec![]: Vec; 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:53:19 + | +LL | fn main() { + | --------- this function should return `Result` or `Option` to accept `?` +LL | let x = 5 > 2 ? { let x = vec![]: Vec; x } : { false }; + | ^ cannot use the `?` operator in a function that returns `()` + | + = help: the trait `FromResidual<_>` is not implemented for `()` + +error: aborting due to 13 previous errors + +For more information about this error, try `rustc --explain E0277`.