From 12f748758d0fb4c74cd872a01f96dd48e8242944 Mon Sep 17 00:00:00 2001
From: Ulya Trofimovich <skvadrik@gmail.com>
Date: Wed, 11 May 2016 14:48:25 +0100
Subject: [PATCH] Don't loose tags on epsilon-loops in NFA.

---
 re2c/src/ir/dfa/determinization.cc   |  8 +++++---
 re2c/src/ir/nfa/nfa.h                | 10 +++++-----
 re2c/test/tags/nondet_iter.--tags.c  | 10 ++++++++++
 re2c/test/tags/nondet_iter.--tags.re | 10 ++++++++++
 4 files changed, 30 insertions(+), 8 deletions(-)
 create mode 100644 re2c/test/tags/nondet_iter.--tags.c
 create mode 100644 re2c/test/tags/nondet_iter.--tags.re

diff --git a/re2c/src/ir/dfa/determinization.cc b/re2c/src/ir/dfa/determinization.cc
index db4d2582..ba9c85d4 100644
--- a/re2c/src/ir/dfa/determinization.cc
+++ b/re2c/src/ir/dfa/determinization.cc
@@ -66,11 +66,13 @@ struct kitem_t
 static void closure(kitem_t *const kernel, kitem_t *&kend,
 	nfa_state_t *n, bool *tags, bool *badtags, size_t ntags)
 {
-	if (n->mark) {
+	// trace the first iteration of each loop:
+	// epsilon-loops may add ney tags and reveal conflicts
+	if (n->loop > 1) {
 		return;
 	}
 
-	n->mark = true;
+	++n->loop;
 	switch (n->type) {
 		case nfa_state_t::ALT:
 			closure(kernel, kend, n->alt.out2, tags, badtags, ntags);
@@ -101,7 +103,7 @@ static void closure(kitem_t *const kernel, kitem_t *&kend,
 			break;
 		}
 	}
-	n->mark = false;
+	--n->loop;
 }
 
 static size_t find_state(kitem_t *kernel, kitem_t *kend,
diff --git a/re2c/src/ir/nfa/nfa.h b/re2c/src/ir/nfa/nfa.h
index f93d4438..b3e60187 100644
--- a/re2c/src/ir/nfa/nfa.h
+++ b/re2c/src/ir/nfa/nfa.h
@@ -35,7 +35,7 @@ struct nfa_state_t
 		} tag;
 	};
 	size_t rule;
-	bool mark;
+	uint8_t loop;
 
 	void make_alt(size_t r, nfa_state_t *s1, nfa_state_t *s2)
 	{
@@ -43,7 +43,7 @@ struct nfa_state_t
 		alt.out1 = s1;
 		alt.out2 = s2;
 		rule = r;
-		mark = false;
+		loop = 0;
 	}
 	void make_ran(size_t r, nfa_state_t *s, const Range *p)
 	{
@@ -51,7 +51,7 @@ struct nfa_state_t
 		ran.out = s;
 		ran.ran = p;
 		rule = r;
-		mark = false;
+		loop = 0;
 	}
 	void make_tag(size_t r, nfa_state_t *s, size_t i)
 	{
@@ -59,13 +59,13 @@ struct nfa_state_t
 		tag.out = s;
 		tag.info = i;
 		rule = r;
-		mark = false;
+		loop = 0;
 	}
 	void make_fin(size_t r)
 	{
 		type = FIN;
 		rule = r;
-		mark = false;
+		loop = 0;
 	}
 };
 
diff --git a/re2c/test/tags/nondet_iter.--tags.c b/re2c/test/tags/nondet_iter.--tags.c
new file mode 100644
index 00000000..759a4fc6
--- /dev/null
+++ b/re2c/test/tags/nondet_iter.--tags.c
@@ -0,0 +1,10 @@
+re2c: error: line 5: tag 'b' is nondeterministic [-Werror-nondeterministic-tags]
+re2c: error: line 6: tag 'e' is nondeterministic [-Werror-nondeterministic-tags]
+re2c: error: line 8: tag 'c' is nondeterministic [-Werror-nondeterministic-tags]
+re2c: error: line 9: tag 'f' is nondeterministic [-Werror-nondeterministic-tags]
+re2c: warning: line 2: rule matches empty string [-Wmatch-empty-string]
+re2c: warning: line 3: rule matches empty string [-Wmatch-empty-string]
+re2c: warning: line 5: rule matches empty string [-Wmatch-empty-string]
+re2c: warning: line 6: rule matches empty string [-Wmatch-empty-string]
+re2c: warning: line 8: rule matches empty string [-Wmatch-empty-string]
+re2c: warning: line 9: rule matches empty string [-Wmatch-empty-string]
diff --git a/re2c/test/tags/nondet_iter.--tags.re b/re2c/test/tags/nondet_iter.--tags.re
new file mode 100644
index 00000000..6943d58f
--- /dev/null
+++ b/re2c/test/tags/nondet_iter.--tags.re
@@ -0,0 +1,10 @@
+/*!re2c
+    ((@a "a")*)* { @a }
+    (("d" @d)*)* { @d }
+
+    (@b "b"*)* { @b }
+    ("e"* @e)* { @e }
+
+    (@c "c"+)* { @c }
+    ("f"+ @f)* { @f }
+*/
-- 
2.40.0