From f5d71a9b3cf3018ec646acb6f8fa731fb8ca902e Mon Sep 17 00:00:00 2001 From: Aaron Hill Date: Sun, 30 Aug 2020 18:08:16 -0400 Subject: [PATCH] Don't use `zip` to compare iterators during pretty-print hack If the right-hand iterator has exactly one more element than the left-hand iterator, then both iterators will be fully consumed, but the extra element will never be compared. --- compiler/rustc_parse/src/lib.rs | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) diff --git a/compiler/rustc_parse/src/lib.rs b/compiler/rustc_parse/src/lib.rs index 72a34b86ae20b..21bbdc9ba8dce 100644 --- a/compiler/rustc_parse/src/lib.rs +++ b/compiler/rustc_parse/src/lib.rs @@ -3,6 +3,7 @@ #![feature(bool_to_option)] #![feature(crate_visibility_modifier)] #![feature(bindings_after_at)] +#![feature(iter_order_by)] #![feature(or_patterns)] use rustc_ast as ast; @@ -459,14 +460,10 @@ pub fn tokenstream_probably_equal_for_proc_macro( // Break tokens after we expand any nonterminals, so that we break tokens // that are produced as a result of nonterminal expansion. - let mut t1 = first.trees().filter(semantic_tree).flat_map(expand_nt).flat_map(break_tokens); - let mut t2 = other.trees().filter(semantic_tree).flat_map(expand_nt).flat_map(break_tokens); - for (t1, t2) in t1.by_ref().zip(t2.by_ref()) { - if !tokentree_probably_equal_for_proc_macro(&t1, &t2, sess) { - return false; - } - } - t1.next().is_none() && t2.next().is_none() + let t1 = first.trees().filter(semantic_tree).flat_map(expand_nt).flat_map(break_tokens); + let t2 = other.trees().filter(semantic_tree).flat_map(expand_nt).flat_map(break_tokens); + + t1.eq_by(t2, |t1, t2| tokentree_probably_equal_for_proc_macro(&t1, &t2, sess)) } // See comments in `Nonterminal::to_tokenstream` for why we care about