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proc_macro: Use an item's tokens if available

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This partly resolves the `FIXME` located in `src/libproc_macro/lib.rs` when
interpreting interpolated tokens. All instances of `ast::Item` which have a list
of tokens attached to them now use that list of tokens to losslessly get
converted into a `TokenTree` instead of going through stringification and losing
span information.

cc #43081
This commit is contained in:
Alex Crichton
2017-07-10 17:49:18 -07:00
parent 9b2f7624ec
commit 36f2816a1e
1 changed files with 20 additions and 8 deletions
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28
src/libproc_macro/lib.rs
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@@ -509,14 +509,26 @@ impl TokenTree {
Ident(ident) | Lifetime(ident) => TokenNode::Term(Term(ident.name)),
Literal(..) | DocComment(..) => TokenNode::Literal(self::Literal(token)),
Interpolated(ref nt) => __internal::with_sess(|(sess, _)| {
TokenNode::Group(Delimiter::None, TokenStream(nt.1.force(|| {
// FIXME(jseyfried): Avoid this pretty-print + reparse hack
let name = "<macro expansion>".to_owned();
let source = pprust::token_to_string(&token);
parse_stream_from_source_str(name, source, sess, Some(span))
})))
}),
Interpolated(ref nt) => {
let mut node = None;
if let Nonterminal::NtItem(ref item) = nt.0 {
if let Some(ref tokens) = item.tokens {
node = Some(TokenNode::Group(Delimiter::None,
TokenStream(tokens.clone())));
}
}
node.unwrap_or_else(|| {
__internal::with_sess(|(sess, _)| {
TokenNode::Group(Delimiter::None, TokenStream(nt.1.force(|| {
// FIXME(jseyfried): Avoid this pretty-print + reparse hack
let name = "<macro expansion>".to_owned();
let source = pprust::token_to_string(&token);
parse_stream_from_source_str(name, source, sess, Some(span))
})))
})
})
}
OpenDelim(..) | CloseDelim(..) => unreachable!(),
Whitespace | Comment | Shebang(..) | Eof => unreachable!(),