diff --git a/src/libsyntax/parse/token.rs b/src/libsyntax/parse/token.rs index 8da79f92768a1..35a745ccdee32 100644 --- a/src/libsyntax/parse/token.rs +++ b/src/libsyntax/parse/token.rs @@ -565,7 +565,7 @@ impl Token { } } -#[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Hash)] +#[derive(Clone, RustcEncodable, RustcDecodable, Eq, Hash)] /// For interpolation during macro expansion. pub enum Nonterminal { NtItem(P), @@ -591,6 +591,22 @@ pub enum Nonterminal { 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 { diff --git a/src/test/ui/macros/nonterminal-matching.rs b/src/test/ui/macros/nonterminal-matching.rs new file mode 100644 index 0000000000000..4dcb8afa94eab --- /dev/null +++ b/src/test/ui/macros/nonterminal-matching.rs @@ -0,0 +1,36 @@ +// 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 or the MIT license +// , 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() {} diff --git a/src/test/ui/macros/nonterminal-matching.stderr b/src/test/ui/macros/nonterminal-matching.stderr new file mode 100644 index 0000000000000..bf2221d52a492 --- /dev/null +++ b/src/test/ui/macros/nonterminal-matching.stderr @@ -0,0 +1,11 @@ +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 +