1
Fork 0

Auto merge of #114028 - Centri3:ternary-operator, r=compiler-errors

Gracefully handle ternary operator

Fixes #112578

~~May not be the best way to do this as it doesn't check for a single `:`, so it could perhaps appear even when the actual issue is just a missing semicolon. May not be the biggest deal, though?~~

Nevermind, got it working properly now ^^
This commit is contained in:
bors 2023-07-29 16:45:29 +00:00
commit a04e649c09
5 changed files with 241 additions and 2 deletions

View file

@ -724,6 +724,10 @@ 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

View file

@ -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 {

View file

@ -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);