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syntax::deriving: indicate from which trait type errors (etc) arise

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using the expansion info.

Previously something like

    struct NotEq;

    #[deriving(Eq)]
    struct Error {
        foo: NotEq
    }

would just point to the `foo` field, with no mention of the
`deriving(Eq)`. With this patch, the compiler creates a note saying "in
expansion of #[deriving(Eq)]" pointing to the Eq.
This commit is contained in:
Huon Wilson 2013-12-07 13:43:22 +11:00
parent 3ef933647a
commit 0c0e73eed6
1 changed files with 22 additions and 4 deletions
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26
src/libsyntax/ext/deriving/generic.rs
View file

@ -899,7 +899,9 @@ impl<'self> MethodDef<'self> {
let summary = enum_def.variants.map(|v| {
let ident = v.node.name;
let summary = match v.node.kind {
ast::tuple_variant_kind(ref args) => Unnamed(args.map(|va| va.ty.span)),
ast::tuple_variant_kind(ref args) => {
Unnamed(args.map(|va| trait_.set_expn_info(va.ty.span)))
}
ast::struct_variant_kind(struct_def) => {
trait_.summarise_struct(struct_def)
}
@ -919,11 +921,27 @@ enum StructType {
// general helper methods.
impl<'a> TraitDef<'a> {
fn set_expn_info(&self, mut to_set: Span) -> Span {
let trait_name = match self.path.path.last_opt() {
None => self.cx.span_bug(self.span, "trait with empty path in generic `deriving`"),
Some(name) => *name
};
to_set.expn_info = Some(@codemap::ExpnInfo {
call_site: to_set,
callee: codemap::NameAndSpan {
name: format!("deriving({})", trait_name).to_managed(),
format: codemap::MacroAttribute,
span: Some(self.span)
}
});
to_set
}
fn summarise_struct(&self, struct_def: &struct_def) -> StaticFields {
let mut named_idents = ~[];
let mut just_spans = ~[];
for field in struct_def.fields.iter(){
let sp = field.span;
let sp = self.set_expn_info(field.span);
match field.node.kind {
ast::named_field(ident, _) => named_idents.push((ident, sp)),
ast::unnamed_field => just_spans.push(sp),
@ -973,7 +991,7 @@ impl<'a> TraitDef<'a> {
let mut struct_type = Unknown;
for (i, struct_field) in struct_def.fields.iter().enumerate() {
let sp = struct_field.span;
let sp = self.set_expn_info(struct_field.span);
let opt_id = match struct_field.node.kind {
ast::named_field(ident, _) if (struct_type == Unknown ||
struct_type == Record) => {
@ -1031,7 +1049,7 @@ impl<'a> TraitDef<'a> {
let mut paths = ~[];
let mut ident_expr = ~[];
for (i, va) in variant_args.iter().enumerate() {
let sp = va.ty.span;
let sp = self.set_expn_info(va.ty.span);
let path = cx.path_ident(sp, cx.ident_of(format!("{}_{}", prefix, i)));
paths.push(path.clone());