}
}
-#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Hash)]
+#[derive(Clone, RustcEncodable, RustcDecodable, Eq, Hash)]
/// For interpolation during macro expansion.
pub enum Nonterminal {
NtItem(P<ast::Item>),
NtArg(ast::Arg),
}
+impl PartialEq for Nonterminal {
+ fn eq(&self, rhs: &Self) -> bool {
+ match (self, rhs) {
+ (NtIdent(ident_lhs, is_raw_lhs), NtIdent(ident_rhs, is_raw_rhs)) =>
+ ident_lhs == ident_rhs && is_raw_lhs == is_raw_rhs,
+ (NtLifetime(ident_lhs), NtLifetime(ident_rhs)) => ident_lhs == ident_rhs,
+ (NtTT(tt_lhs), NtTT(tt_rhs)) => tt_lhs == tt_rhs,
+ // FIXME: Assume that all "complex" nonterminal are not equal, we can't compare them
+ // correctly based on data from AST. This will prevent them from matching each other
+ // in macros. The comparison will become possible only when each nonterminal has an
+ // attached token stream from which it was parsed.
+ _ => false,
+ }
+ }
+}
+
impl fmt::Debug for Nonterminal {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
--- /dev/null
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Check that we are refusing to match on complex nonterminals for which tokens are
+// unavailable and we'd have to go through AST comparisons.
+
+#![feature(decl_macro, macro_lifetime_matcher)]
+
+macro simple_nonterminal($nt_ident: ident, $nt_lifetime: lifetime, $nt_tt: tt) {
+ macro n(a $nt_ident b $nt_lifetime c $nt_tt d) {
+ struct S;
+ }
+
+ n!(a $nt_ident b $nt_lifetime c $nt_tt d);
+}
+
+macro complex_nonterminal($nt_item: item) {
+ macro n(a $nt_item b) {
+ struct S;
+ }
+
+ n!(a $nt_item b); //~ ERROR no rules expected the token `enum E { }`
+}
+
+simple_nonterminal!(a, 'a, (x, y, z)); // OK
+
+complex_nonterminal!(enum E {});
+
+fn main() {}
--- /dev/null
+error: no rules expected the token `enum E { }`
+ --> $DIR/nonterminal-matching.rs:29:10
+ |
+LL | n!(a $nt_item b); //~ ERROR no rules expected the token `enum E { }`
+ | ^^^^^^^^
+...
+LL | complex_nonterminal!(enum E {});
+ | -------------------------------- in this macro invocation
+
+error: aborting due to previous error
+