bjoernager/rust
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Unconditionally capture tokens for attributes.

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This allows us to avoid synthesizing tokens in `prepend_attr`, since we
have the original tokens available.

We still need to synthesize tokens when expanding `cfg_attr`,
but this is an unavoidable consequence of the syntax of `cfg_attr` -
the user does not supply the `#` and `[]` tokens that a `cfg_attr`
expands to.
This commit is contained in:
Aaron Hill 2020-09-26 19:33:42 -04:00
parent 1eaadebb3d
commit b9b2546417
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GPG key ID: B4087E510E98B164
15 changed files with 153 additions and 120 deletions
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55
compiler/rustc_parse/src/lib.rs
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@ -252,9 +252,7 @@ pub fn nt_to_tokenstream(nt: &Nonterminal, sess: &ParseSess, span: Span) -> Toke
let convert_tokens = |tokens: Option<LazyTokenStream>| tokens.map(|t| t.into_token_stream());
let tokens = match *nt {
Nonterminal::NtItem(ref item) => {
prepend_attrs(sess, &item.attrs, item.tokens.as_ref(), span)
}
Nonterminal::NtItem(ref item) => prepend_attrs(&item.attrs, item.tokens.as_ref()),
Nonterminal::NtBlock(ref block) => convert_tokens(block.tokens.clone()),
Nonterminal::NtStmt(ref stmt) => {
// FIXME: We currently only collect tokens for `:stmt`
@ -279,7 +277,7 @@ pub fn nt_to_tokenstream(nt: &Nonterminal, sess: &ParseSess, span: Span) -> Toke
if expr.tokens.is_none() {
debug!("missing tokens for expr {:?}", expr);
}
prepend_attrs(sess, &expr.attrs, expr.tokens.as_ref(), span)
prepend_attrs(&expr.attrs, expr.tokens.as_ref())
}
};
@ -603,10 +601,8 @@ fn token_probably_equal_for_proc_macro(first: &Token, other: &Token) -> bool {
}
fn prepend_attrs(
sess: &ParseSess,
attrs: &[ast::Attribute],
tokens: Option<&tokenstream::LazyTokenStream>,
span: rustc_span::Span,
) -> Option<tokenstream::TokenStream> {
let tokens = tokens?.clone().into_token_stream();
if attrs.is_empty() {
@ -619,47 +615,12 @@ fn prepend_attrs(
ast::AttrStyle::Outer,
"inner attributes should prevent cached tokens from existing"
);
let source = pprust::attribute_to_string(attr);
let macro_filename = FileName::macro_expansion_source_code(&source);
let item = match attr.kind {
ast::AttrKind::Normal(ref item) => item,
ast::AttrKind::DocComment(..) => {
let stream = parse_stream_from_source_str(macro_filename, source, sess, Some(span));
builder.push(stream);
continue;
}
};
// synthesize # [ $path $tokens ] manually here
let mut brackets = tokenstream::TokenStreamBuilder::new();
// For simple paths, push the identifier directly
if item.path.segments.len() == 1 && item.path.segments[0].args.is_none() {
let ident = item.path.segments[0].ident;
let token = token::Ident(ident.name, ident.as_str().starts_with("r#"));
brackets.push(tokenstream::TokenTree::token(token, ident.span));
// ... and for more complicated paths, fall back to a reparse hack that
// should eventually be removed.
} else {
let stream = parse_stream_from_source_str(macro_filename, source, sess, Some(span));
brackets.push(stream);
}
brackets.push(item.args.outer_tokens());
// The span we list here for `#` and for `[ ... ]` are both wrong in
// that it encompasses more than each token, but it hopefully is "good
// enough" for now at least.
builder.push(tokenstream::TokenTree::token(token::Pound, attr.span));
let delim_span = tokenstream::DelimSpan::from_single(attr.span);
builder.push(tokenstream::TokenTree::Delimited(
delim_span,
token::DelimToken::Bracket,
brackets.build(),
));
builder.push(
attr.tokens
.clone()
.unwrap_or_else(|| panic!("Attribute {:?} is missing tokens!", attr))
.into_token_stream(),
);
}
builder.push(tokens.clone());
Some(builder.build())