Rollup merge of #71976 - mibac138:let-recovery, r=estebank
Improve diagnostics for `let x += 1` Fixes(?) #66736 The code responsible for the `E0404` errors is [here](https://github.com/rust-lang/rust/blob/master/src/librustc_parse/parser/ty.rs#L399-L424) which I don't think can be easily modified to prevent emitting an error in one specific case. Because of this I couldn't get rid of `E0404` and instead added `E0067` along with a help message which will fix the problem. r? @estebank
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commit
39f8784eb6
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@ -216,8 +216,28 @@ impl<'a> Parser<'a> {
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}
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/// Parses the RHS of a local variable declaration (e.g., '= 14;').
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fn parse_initializer(&mut self, skip_eq: bool) -> PResult<'a, Option<P<Expr>>> {
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if self.eat(&token::Eq) || skip_eq { Ok(Some(self.parse_expr()?)) } else { Ok(None) }
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fn parse_initializer(&mut self, eq_optional: bool) -> PResult<'a, Option<P<Expr>>> {
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let eq_consumed = match self.token.kind {
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token::BinOpEq(..) => {
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// Recover `let x <op>= 1` as `let x = 1`
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self.struct_span_err(
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self.token.span,
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"can't reassign to an uninitialized variable",
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)
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.span_suggestion_short(
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self.token.span,
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"initialize the variable",
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"=".to_string(),
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Applicability::MaybeIncorrect,
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)
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.emit();
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self.bump();
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true
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}
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_ => self.eat(&token::Eq),
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};
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Ok(if eq_consumed || eq_optional { Some(self.parse_expr()?) } else { None })
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}
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/// Parses a block. No inner attributes are allowed.
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@ -0,0 +1,8 @@
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fn main() {
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let a: i8 *= 1; //~ ERROR can't reassign to an uninitialized variable
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let _ = a;
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let b += 1; //~ ERROR can't reassign to an uninitialized variable
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let _ = b;
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let c *= 1; //~ ERROR can't reassign to an uninitialized variable
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let _ = c;
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}
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@ -0,0 +1,20 @@
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error: can't reassign to an uninitialized variable
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--> $DIR/let-binop.rs:2:15
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LL | let a: i8 *= 1;
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| ^^ help: initialize the variable
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error: can't reassign to an uninitialized variable
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--> $DIR/let-binop.rs:4:11
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LL | let b += 1;
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| ^^ help: initialize the variable
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error: can't reassign to an uninitialized variable
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--> $DIR/let-binop.rs:6:11
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LL | let c *= 1;
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| ^^ help: initialize the variable
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error: aborting due to 3 previous errors
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