bjoernager/rust
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macros: allow subdiagnostic-kind-less variants

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Sometimes it is convenient to return a subdiagnostic enum where one or
more of the variants don't add anything to the diagnostic.

Signed-off-by: David Wood <david.wood@huawei.com>
This commit is contained in:
David Wood 2022-10-14 11:09:52 +01:00
parent 7fbaf27696
commit 1045e69e73
3 changed files with 59 additions and 55 deletions
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21
compiler/rustc_macros/src/diagnostics/subdiagnostic.rs
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@ -41,7 +41,8 @@ impl SubdiagnosticDeriveBuilder {
}
}
if matches!(ast.data, syn::Data::Enum(..)) {
let is_enum = matches!(ast.data, syn::Data::Enum(..));
if is_enum {
for attr in &ast.attrs {
// Always allow documentation comments.
if is_doc_comment(attr) {
@ -67,6 +68,7 @@ impl SubdiagnosticDeriveBuilder {
span_field: None,
applicability: None,
has_suggestion_parts: false,
is_enum,
};
builder.into_tokens().unwrap_or_else(|v| v.to_compile_error())
});
@ -127,6 +129,9 @@ struct SubdiagnosticDeriveVariantBuilder<'parent, 'a> {
/// Set to true when a `#[suggestion_part]` field is encountered, used to generate an error
/// during finalization if still `false`.
has_suggestion_parts: bool,
/// Set to true when this variant is an enum variant rather than just the body of a struct.
is_enum: bool,
}
impl<'parent, 'a> HasFieldMap for SubdiagnosticDeriveVariantBuilder<'parent, 'a> {
@ -457,10 +462,16 @@ impl<'parent, 'a> SubdiagnosticDeriveVariantBuilder<'parent, 'a> {
pub fn into_tokens(&mut self) -> Result<TokenStream, DiagnosticDeriveError> {
let kind_slugs = self.identify_kind()?;
if kind_slugs.is_empty() {
throw_span_err!(
self.variant.ast().ident.span().unwrap(),
"subdiagnostic kind not specified"
);
if self.is_enum {
// It's okay for a variant to not be a subdiagnostic at all..
return Ok(quote! {});
} else {
// ..but structs should always be _something_.
throw_span_err!(
self.variant.ast().ident.span().unwrap(),
"subdiagnostic kind not specified"
);
}
};
let kind_stats: KindsStatistics = kind_slugs.iter().map(|(kind, _slug)| kind).collect();