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Add context for RFC 1685 change in 2018 edition.

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This commit adds a note providing context for the change to argument
names being required in the 2018 edition for trait methods.
This commit is contained in:
David Wood
2018-12-07 10:54:14 +01:00
parent a2fb99bc17
commit e4dc15a969
2 changed files with 10 additions and 4 deletions
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10
src/libsyntax/parse/parser.rs
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@@ -1404,7 +1404,7 @@ impl<'a> Parser<'a> {
// definition...
// We don't allow argument names to be left off in edition 2018.
p.parse_arg_general(p.span.rust_2018())
p.parse_arg_general(p.span.rust_2018(), true)
})?;
generics.where_clause = self.parse_where_clause()?;
@@ -1817,7 +1817,7 @@ impl<'a> Parser<'a> {
/// This version of parse arg doesn't necessarily require
/// identifier names.
fn parse_arg_general(&mut self, require_name: bool) -> PResult<'a, Arg> {
fn parse_arg_general(&mut self, require_name: bool, is_trait_item: bool) -> PResult<'a, Arg> {
maybe_whole!(self, NtArg, |x| x);
if let Ok(Some(_)) = self.parse_self_arg() {
@@ -1849,6 +1849,8 @@ impl<'a> Parser<'a> {
String::from("<identifier>: <type>"),
Applicability::HasPlaceholders,
);
} else if require_name && is_trait_item {
err.note("anonymous parameters are removed in the 2018 edition (see RFC 1685)");
}
return Err(err);
@@ -1914,7 +1916,7 @@ impl<'a> Parser<'a> {
/// Parse a single function argument
crate fn parse_arg(&mut self) -> PResult<'a, Arg> {
self.parse_arg_general(true)
self.parse_arg_general(true, false)
}
/// Parse an argument in a lambda header e.g. |arg, arg|
@@ -5469,7 +5471,7 @@ impl<'a> Parser<'a> {
}
}
} else {
match p.parse_arg_general(named_args) {
match p.parse_arg_general(named_args, false) {
Ok(arg) => Ok(Some(arg)),
Err(mut e) => {
e.emit();