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Hygiene opt-out for idents in expansion of declarative macros #47992

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Hygiene opt-out for idents in expansion of declarative macros #47992

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93af903
Implemented hygiene opt-out for idents in expansion of declarative ma…
alexreg Feb 4, 2018
4739674
Do parsing of `#` prefix properly.
alexreg Feb 6, 2018
2750e65
Disable hygiene opt-out syntax for legacy `macro_rules`.
alexreg Feb 6, 2018
d397378
Added support for `#` opt-out syntax on lifetimes.
alexreg Feb 6, 2018
7206157
Added run-pass and compile-fail tests.
alexreg Feb 7, 2018
ad54054
Added missing argument to call to `quoted::parse`.
alexreg Feb 7, 2018
8c000de
Wrapped long lines of code.
alexreg Apr 6, 2018
e9991a0
Fixed bug with modification of `SyntaxContext` for escaped idents.
alexreg May 6, 2018
61c2a4d
Added compile-fail test for `$#metavar` hygiene opt-out syntax.
alexreg May 9, 2018
c7f158b
Added feature gate (`macro_hygiene_optout`).
alexreg May 9, 2018
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2 changes: 1 addition & 1 deletion src/libsyntax/ext/expand.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -677,7 +677,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
IdentTT(ref expander, tt_span, allow_internal_unstable) => {
if ident.name == keywords::Invalid.name() {
self.cx.span_err(path.span,
&format!("macro {}! expects an ident argument", path));
&format!("macro {}! expects an ident argument", path));
self.cx.trace_macros_diag();
kind.dummy(span)
} else {
Expand Down
10 changes: 6 additions & 4 deletions src/libsyntax/ext/tt/macro_parser.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -332,7 +332,8 @@ fn nameize<I: Iterator<Item = NamedMatch>>(
}
}
}
TokenTree::MetaVar(..) | TokenTree::Token(..) => (),
TokenTree::MetaVar(..) |
TokenTree::Token(..) => (),
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Nit/meta: it's harder to see important changes when formatting changes are mixed in (quite a few of them in this PR!).

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This is for consistency, since the code was previously not consistent!

}

Ok(())
Expand Down Expand Up @@ -540,7 +541,7 @@ fn inner_parse_loop(
//
// At the beginning of the loop, if we reach the end of the delimited submatcher,
// we pop the stack to backtrack out of the descent.
seq @ TokenTree::Delimited(..) | seq @ TokenTree::Token(_, DocComment(..)) => {
seq @ TokenTree::Delimited(..) | seq @ TokenTree::Token(_, DocComment(..), _) => {
let lower_elts = mem::replace(&mut item.top_elts, Tt(seq));
let idx = item.idx;
item.stack.push(MatcherTtFrame {
Expand All @@ -552,7 +553,7 @@ fn inner_parse_loop(
}

// We just matched a normal token. We can just advance the parser.
TokenTree::Token(_, ref t) if token_name_eq(t, token) => {
TokenTree::Token(_, ref t, _) if token_name_eq(t, token) => {
item.idx += 1;
next_items.push(item);
}
Expand All @@ -561,7 +562,8 @@ fn inner_parse_loop(
// rules. NOTE that this is not necessarily an error unless _all_ items in
// `cur_items` end up doing this. There may still be some other matchers that do
// end up working out.
TokenTree::Token(..) | TokenTree::MetaVar(..) => {}
TokenTree::Token(..) |
TokenTree::MetaVar(..) => {}
}
}
}
Expand Down
60 changes: 41 additions & 19 deletions src/libsyntax/ext/tt/macro_rules.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -121,7 +121,7 @@ fn generic_extension<'cx>(cx: &'cx mut ExtCtxt,
};

let rhs_spans = rhs.iter().map(|t| t.span()).collect::<Vec<_>>();
// rhs has holes ( `$id` and `$(...)` that need filled)
// rhs has holes ( `$id` and `$(...)` which need to be filled)
let mut tts = transcribe(cx, Some(named_matches), rhs);

// Replace all the tokens for the corresponding positions in the macro, to maintain
Expand Down Expand Up @@ -202,7 +202,7 @@ pub fn compile(sess: &ParseSess, features: &Features, def: &ast::Item) -> Syntax
quoted::TokenTree::Sequence(DUMMY_SP, Lrc::new(quoted::SequenceRepetition {
tts: vec![
quoted::TokenTree::MetaVarDecl(DUMMY_SP, lhs_nm, ast::Ident::from_str("tt")),
quoted::TokenTree::Token(DUMMY_SP, token::FatArrow),
quoted::TokenTree::Token(DUMMY_SP, token::FatArrow, quoted::TokenHygiene::DefSite),
quoted::TokenTree::MetaVarDecl(DUMMY_SP, rhs_nm, ast::Ident::from_str("tt")),
],
separator: Some(if body.legacy { token::Semi } else { token::Comma }),
Expand All @@ -211,7 +211,8 @@ pub fn compile(sess: &ParseSess, features: &Features, def: &ast::Item) -> Syntax
})),
// to phase into semicolon-termination instead of semicolon-separation
quoted::TokenTree::Sequence(DUMMY_SP, Lrc::new(quoted::SequenceRepetition {
tts: vec![quoted::TokenTree::Token(DUMMY_SP, token::Semi)],
tts: vec![quoted::TokenTree::Token(DUMMY_SP, token::Semi,
quoted::TokenHygiene::DefSite)],
separator: None,
op: quoted::KleeneOp::ZeroOrMore,
num_captures: 0
Expand All @@ -237,7 +238,12 @@ pub fn compile(sess: &ParseSess, features: &Features, def: &ast::Item) -> Syntax
s.iter().map(|m| {
if let MatchedNonterminal(ref nt) = *m {
if let NtTT(ref tt) = **nt {
let tt = quoted::parse(tt.clone().into(), true, sess, features, &def.attrs)
let tt = quoted::parse(tt.clone().into(),
false,
true,
sess,
features,
&def.attrs)
.pop().unwrap();
valid &= check_lhs_nt_follows(sess, features, &def.attrs, &tt);
return tt;
Expand All @@ -254,7 +260,12 @@ pub fn compile(sess: &ParseSess, features: &Features, def: &ast::Item) -> Syntax
s.iter().map(|m| {
if let MatchedNonterminal(ref nt) = *m {
if let NtTT(ref tt) = **nt {
return quoted::parse(tt.clone().into(), false, sess, features, &def.attrs)
return quoted::parse(tt.clone().into(),
!body.legacy && features.macro_hygiene_optout,
false,
sess,
features,
&def.attrs)
.pop().unwrap();
}
}
Expand Down Expand Up @@ -328,7 +339,9 @@ fn check_lhs_no_empty_seq(sess: &ParseSess, tts: &[quoted::TokenTree]) -> bool {
use self::quoted::TokenTree;
for tt in tts {
match *tt {
TokenTree::Token(..) | TokenTree::MetaVar(..) | TokenTree::MetaVarDecl(..) => (),
TokenTree::Token(..) |
TokenTree::MetaVar(..) |
TokenTree::MetaVarDecl(..) => (),
TokenTree::Delimited(_, ref del) => if !check_lhs_no_empty_seq(sess, &del.tts) {
return false;
},
Expand Down Expand Up @@ -410,7 +423,9 @@ impl FirstSets {
let mut first = TokenSet::empty();
for tt in tts.iter().rev() {
match *tt {
TokenTree::Token(..) | TokenTree::MetaVar(..) | TokenTree::MetaVarDecl(..) => {
TokenTree::Token(..) |
TokenTree::MetaVar(..) |
TokenTree::MetaVarDecl(..) => {
first.replace_with(tt.clone());
}
TokenTree::Delimited(span, ref delimited) => {
Expand Down Expand Up @@ -440,7 +455,8 @@ impl FirstSets {

if let (Some(ref sep), true) = (seq_rep.separator.clone(),
subfirst.maybe_empty) {
first.add_one_maybe(TokenTree::Token(sp, sep.clone()));
first.add_one_maybe(TokenTree::Token(sp, sep.clone(),
quoted::TokenHygiene::DefSite));
}

// Reverse scan: Sequence comes before `first`.
Expand Down Expand Up @@ -470,7 +486,9 @@ impl FirstSets {
for tt in tts.iter() {
assert!(first.maybe_empty);
match *tt {
TokenTree::Token(..) | TokenTree::MetaVar(..) | TokenTree::MetaVarDecl(..) => {
TokenTree::Token(..) |
TokenTree::MetaVar(..) |
TokenTree::MetaVarDecl(..) => {
first.add_one(tt.clone());
return first;
}
Expand All @@ -487,7 +505,8 @@ impl FirstSets {

if let (Some(ref sep), true) = (seq_rep.separator.clone(),
subfirst.maybe_empty) {
first.add_one_maybe(TokenTree::Token(sp, sep.clone()));
first.add_one_maybe(TokenTree::Token(sp, sep.clone(),
quoted::TokenHygiene::DefSite));
}

assert!(first.maybe_empty);
Expand Down Expand Up @@ -641,7 +660,9 @@ fn check_matcher_core(sess: &ParseSess,
// First, update `last` so that it corresponds to the set
// of NT tokens that might end the sequence `... token`.
match *token {
TokenTree::Token(..) | TokenTree::MetaVar(..) | TokenTree::MetaVarDecl(..) => {
TokenTree::Token(..) |
TokenTree::MetaVar(..) |
TokenTree::MetaVarDecl(..) => {
let can_be_followed_by_any;
if let Err(bad_frag) = has_legal_fragment_specifier(sess, features, attrs, token) {
let msg = format!("invalid fragment specifier `{}`", bad_frag);
Expand Down Expand Up @@ -692,7 +713,8 @@ fn check_matcher_core(sess: &ParseSess,
let mut new;
let my_suffix = if let Some(ref u) = seq_rep.separator {
new = suffix_first.clone();
new.add_one_maybe(TokenTree::Token(sp, u.clone()));
new.add_one_maybe(TokenTree::Token(sp, u.clone(),
quoted::TokenHygiene::DefSite));
&new
} else {
&suffix_first
Expand Down Expand Up @@ -805,7 +827,7 @@ fn frag_can_be_followed_by_any(frag: &str) -> bool {
fn is_in_follow(tok: &quoted::TokenTree, frag: &str) -> Result<bool, (String, &'static str)> {
use self::quoted::TokenTree;

if let TokenTree::Token(_, token::CloseDelim(_)) = *tok {
if let TokenTree::Token(_, token::CloseDelim(_), _) = *tok {
// closing a token tree can never be matched by any fragment;
// iow, we always require that `(` and `)` match, etc.
Ok(true)
Expand All @@ -822,22 +844,22 @@ fn is_in_follow(tok: &quoted::TokenTree, frag: &str) -> Result<bool, (String, &'
Ok(true)
},
"stmt" | "expr" => match *tok {
TokenTree::Token(_, ref tok) => match *tok {
TokenTree::Token(_, ref tok, _) => match *tok {
FatArrow | Comma | Semi => Ok(true),
_ => Ok(false)
},
_ => Ok(false),
},
"pat" => match *tok {
TokenTree::Token(_, ref tok) => match *tok {
TokenTree::Token(_, ref tok, _) => match *tok {
FatArrow | Comma | Eq | BinOp(token::Or) => Ok(true),
Ident(i, false) if i.name == "if" || i.name == "in" => Ok(true),
_ => Ok(false)
},
_ => Ok(false),
},
"path" | "ty" => match *tok {
TokenTree::Token(_, ref tok) => match *tok {
TokenTree::Token(_, ref tok, _) => match *tok {
OpenDelim(token::DelimToken::Brace) | OpenDelim(token::DelimToken::Bracket) |
Comma | FatArrow | Colon | Eq | Gt | Semi | BinOp(token::Or) => Ok(true),
Ident(i, false) if i.name == "as" || i.name == "where" => Ok(true),
Expand All @@ -858,7 +880,7 @@ fn is_in_follow(tok: &quoted::TokenTree, frag: &str) -> Result<bool, (String, &'
"vis" => {
// Explicitly disallow `priv`, on the off chance it comes back.
match *tok {
TokenTree::Token(_, ref tok) => match *tok {
TokenTree::Token(_, ref tok, _) => match *tok {
Comma => Ok(true),
Ident(i, is_raw) if is_raw || i.name != "priv" => Ok(true),
ref tok => Ok(tok.can_begin_type())
Expand Down Expand Up @@ -931,8 +953,8 @@ fn is_legal_fragment_specifier(sess: &ParseSess,

fn quoted_tt_to_string(tt: &quoted::TokenTree) -> String {
match *tt {
quoted::TokenTree::Token(_, ref tok) => ::print::pprust::token_to_string(tok),
quoted::TokenTree::MetaVar(_, name) => format!("${}", name),
quoted::TokenTree::Token(_, ref tok, _) => ::print::pprust::token_to_string(tok),
quoted::TokenTree::MetaVar(_, name, _) => format!("${}", name),
quoted::TokenTree::MetaVarDecl(_, name, kind) => format!("${}:{}", name, kind),
_ => panic!("unexpected quoted::TokenTree::{{Sequence or Delimited}} \
in follow set checker"),
Expand Down
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