bjoernager/rust
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tweak discriminant on non-nullary enum diagnostic

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Adds notes pointing at the non-nullary variants, and uses "custom
discriminant" language to be consistent with the Reference.
This commit is contained in:
Andy Russell 2019-05-22 16:56:51 -04:00
parent f688ba6089
commit 3cbf5864a6
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GPG key ID: BE2221033EDBC374
6 changed files with 63 additions and 26 deletions
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14
src/libsyntax/parse/parser.rs
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@ -7464,7 +7464,6 @@ impl<'a> Parser<'a> {
/// Parses the part of an enum declaration following the `{`.
fn parse_enum_def(&mut self, _generics: &ast::Generics) -> PResult<'a, EnumDef> {
let mut variants = Vec::new();
let mut all_nullary = true;
let mut any_disr = vec![];
while self.token != token::CloseDelim(token::Brace) {
let variant_attrs = self.parse_outer_attributes()?;
@ -7476,11 +7475,9 @@ impl<'a> Parser<'a> {
let ident = self.parse_ident()?;
if self.check(&token::OpenDelim(token::Brace)) {
// Parse a struct variant.
all_nullary = false;
let (fields, recovered) = self.parse_record_struct_body()?;
struct_def = VariantData::Struct(fields, recovered);
} else if self.check(&token::OpenDelim(token::Paren)) {
all_nullary = false;
struct_def = VariantData::Tuple(
self.parse_tuple_struct_body()?,
ast::DUMMY_NODE_ID,
@ -7524,16 +7521,7 @@ impl<'a> Parser<'a> {
}
}
self.expect(&token::CloseDelim(token::Brace))?;
if !any_disr.is_empty() && !all_nullary {
let mut err = self.struct_span_err(
any_disr.clone(),
"discriminator values can only be used with a field-less enum",
);
for sp in any_disr {
err.span_label(sp, "only valid in field-less enums");
}
err.emit();
}
self.maybe_report_invalid_custom_discriminants(any_disr, &variants);
Ok(ast::EnumDef { variants })
}