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Temporarily accept [i|u][32|size] suffixes on a tuple index and warn #60186

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merged 2 commits into from
Apr 24, 2019
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Temporarily accept [i|u][32|size] suffixes on a tuple index and warn #60186

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e3fb331
Temporarily accept [i|u][32|size] suffixes on a tuple index and warn
estebank Apr 22, 2019
4c01573
review comment: change linked ticket
estebank Apr 23, 2019
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34 changes: 31 additions & 3 deletions src/libsyntax/parse/parser.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1145,9 +1145,34 @@ impl<'a> Parser<'a> {
if text.is_empty() {
self.span_bug(sp, "found empty literal suffix in Some")
}
self.struct_span_err(sp, &format!("suffixes on {} are invalid", kind))
.span_label(sp, format!("invalid suffix `{}`", text))
.emit();
let mut err = if kind == "a tuple index" &&
["i32", "u32", "isize", "usize"].contains(&text.to_string().as_str())
{
// #59553: warn instead of reject out of hand to allow the fix to percolate
// through the ecosystem when people fix their macros
let mut err = self.struct_span_warn(
sp,
&format!("suffixes on {} are invalid", kind),
);
err.note(&format!(
"`{}` is *temporarily* accepted on tuple index fields as it was \
incorrectly accepted on stable for a few releases",
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This affects my opinion, by the way -- what is the range of time in which it was accepted? I was assuming it has been accepted forever.

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Bisected (using godbolt) to 1.27 being the point at which it was allowed;
Test program:

fn main() {
    let x = (0,);
    x.0usize;
}

text,
));
err.help(
"on proc macros, you'll want to use `syn::Index::from` or \
`proc_macro::Literal::*_unsuffixed` for code that will desugar \
to tuple field access",
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👍 to giving some explicit help here!

);
err.note(
"for more context, see https://github.com/rust-lang/rust/issues/59553",
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);
err
} else {
self.struct_span_err(sp, &format!("suffixes on {} are invalid", kind))
};
err.span_label(sp, format!("invalid suffix `{}`", text));
err.emit();
}
}
}
Expand Down Expand Up @@ -1455,6 +1480,9 @@ impl<'a> Parser<'a> {
fn struct_span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> {
self.sess.span_diagnostic.struct_span_err(sp, m)
}
fn struct_span_warn<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> {
self.sess.span_diagnostic.struct_span_warn(sp, m)
}
crate fn span_bug<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> ! {
self.sess.span_diagnostic.span_bug(sp, m)
}
Expand Down