bjoernager/rust
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improve diagnostics for angle args

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This commit is contained in:
b-naber 2020-12-15 17:43:24 +01:00
parent f2de221b00
commit 728d257839
3 changed files with 28 additions and 50 deletions
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55
compiler/rustc_parse/src/parser/path.rs
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@ -185,7 +185,6 @@ impl<'a> Parser<'a> {
pub(super) fn parse_path_segment(&mut self, style: PathStyle) -> PResult<'a, PathSegment> {
let ident = self.parse_path_segment_ident()?;
let is_args_start = |token: &Token| {
matches!(
token.kind,
@ -420,7 +419,10 @@ impl<'a> Parser<'a> {
match arg {
Some(arg) => {
if self.check(&token::Colon) | self.check(&token::Eq) {
let (ident, gen_args) = self.get_ident_from_generic_arg(arg, lo)?;
let (ident, gen_args) = match self.get_ident_from_generic_arg(arg) {
Ok(ident_gen_args) => ident_gen_args,
Err(arg) => return Ok(Some(AngleBracketedArg::Arg(arg))),
};
let kind = if self.eat(&token::Colon) {
// Parse associated type constraint bound.
@ -561,50 +563,15 @@ impl<'a> Parser<'a> {
fn get_ident_from_generic_arg(
&self,
gen_arg: GenericArg,
lo: Span,
) -> PResult<'a, (Ident, Option<GenericArgs>)> {
let gen_arg_span = gen_arg.span();
match gen_arg {
GenericArg::Type(t) => match t.into_inner().kind {
ast::TyKind::Path(qself, mut path) => {
if let Some(qself) = qself {
let mut err = self.struct_span_err(
gen_arg_span,
"qualified paths cannot be used in associated type constraints",
);
err.span_label(
qself.path_span,
"not allowed in associated type constraints",
);
return Err(err);
}
if path.segments.len() == 1 {
let path_seg = path.segments.remove(0);
let ident = path_seg.ident;
let gen_args = path_seg.args.map(|args| args.into_inner());
return Ok((ident, gen_args));
}
let err = self.struct_span_err(
path.span,
"paths with multiple segments cannot be used in associated type constraints",
);
return Err(err);
) -> Result<(Ident, Option<GenericArgs>), GenericArg> {
if let GenericArg::Type(ty) = &gen_arg {
if let ast::TyKind::Path(qself, path) = &ty.kind {
if qself.is_none() && path.segments.len() == 1 {
let seg = &path.segments[0];
return Ok((seg.ident, seg.args.as_deref().cloned()));
}
_ => {
let span = lo.to(self.prev_token.span);
let err = self.struct_span_err(
span,
"only path types can be used in associated type constraints",
);
return Err(err);
}
},
_ => {
let span = lo.to(self.prev_token.span);
let err = self
.struct_span_err(span, "only types can be used in associated type constraints");
return Err(err);
}
}
Err(gen_arg)
}
}