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Improve parsing errors and suggestions for bad if statements

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This commit is contained in:
Michael Goulet 2022-05-27 21:58:48 -07:00
parent 3bdec3c8ab
commit d1ba2d25d4
21 changed files with 325 additions and 143 deletions
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19
compiler/rustc_parse/src/parser/stmt.rs
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@ -432,10 +432,23 @@ impl<'a> Parser<'a> {
//
// which is valid in other languages, but not Rust.
match self.parse_stmt_without_recovery(false, ForceCollect::No) {
// If the next token is an open brace (e.g., `if a b {`), the place-
// inside-a-block suggestion would be more likely wrong than right.
// If the next token is an open brace, e.g., we have:
//
// if expr other_expr {
// ^ ^ ^- lookahead(1) is a brace
// | |- current token is not "else"
// |- (statement we just parsed)
//
// the place-inside-a-block suggestion would be more likely wrong than right.
//
// FIXME(compiler-errors): this should probably parse an arbitrary expr and not
// just lookahead one token, so we can see if there's a brace after _that_,
// since we want to protect against:
// `if 1 1 + 1 {` being suggested as `if { 1 } 1 + 1 {`
// + +
Ok(Some(_))
if self.look_ahead(1, |t| t == &token::OpenDelim(Delimiter::Brace))
if (!self.token.is_keyword(kw::Else)
&& self.look_ahead(1, |t| t == &token::OpenDelim(Delimiter::Brace)))
|| do_not_suggest_help => {}
// Do not suggest `if foo println!("") {;}` (as would be seen in test for #46836).
Ok(Some(Stmt { kind: StmtKind::Empty, .. })) => {}