From: Ulya Trofimovich <skvadrik@gmail.com>
Date: Mon, 23 Jan 2017 21:02:24 +0000 (+0000)
Subject: Update tags after reading character in TDFAs without lookahead.
X-Git-Tag: 1.0~39^2~144
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=65780565a0cc80dc7d103f0e7f5dcf084d2bfdbb;p=re2c

Update tags after reading character in TDFAs without lookahead.

Fixed forgotten special case when tags and cursor increment
are hoisted out of conditional branches.

Found by slyfox's fuzzer. :)
---

diff --git a/re2c/src/codegen/go_emit.cc b/re2c/src/codegen/go_emit.cc
index a8f91504..f9aa0246 100644
--- a/re2c/src/codegen/go_emit.cc
+++ b/re2c/src/codegen/go_emit.cc
@@ -227,12 +227,14 @@ void Go::emit (OutputFile & o, uint32_t ind, const DFA &dfa)
 		return;
 	}
 
+	const bool lookahead = o.block().opts->lookahead;
+	o.wdelay_skip(ind, skip && !lookahead);
 	code_lines_t code;
 	gen_settags(code, dfa, tags, o.block().opts);
 	for (size_t i = 0; i < code.size(); ++i) {
 		o.wind(ind).wstring(code[i]);
 	}
-	o.wdelay_skip(ind, skip);
+	o.wdelay_skip(ind, skip && lookahead);
 
 	if (type == SWITCH_IF) {
 		info.switchif->emit (o, ind, dfa);
diff --git a/re2c/test/tags/skip_before_tags.i--tags--no-lookahead.c b/re2c/test/tags/skip_before_tags.i--tags--no-lookahead.c
new file mode 100644
index 00000000..b1909f08
--- /dev/null
+++ b/re2c/test/tags/skip_before_tags.i--tags--no-lookahead.c
@@ -0,0 +1,30 @@
+/* Generated by re2c */
+
+{
+	YYCTYPE yych;
+	yyt1 = NULL;
+	yyt2 = YYCURSOR;
+	goto yy0;
+yy1:
+yy0:
+	if (YYLIMIT <= YYCURSOR) YYFILL(1);
+	yych = *YYCURSOR;
+	switch (yych) {
+	case 'a':
+		++YYCURSOR;
+		goto yy3;
+	default:	goto yy2;
+	}
+yy2:
+	a = yyt1;
+	{}
+yy3:
+	if (YYLIMIT <= YYCURSOR) YYFILL(1);
+	yych = *YYCURSOR++;
+	yyt1 = yyt2;
+	yyt2 = YYCURSOR;
+	goto yy1;
+}
+
+re2c: warning: line 3: rule matches empty string [-Wmatch-empty-string]
+re2c: warning: line 3: tag 'a' is non-deterministic and induces 2 parallel instances [-Wnondeterministic-tags]
diff --git a/re2c/test/tags/skip_before_tags.i--tags--no-lookahead.re b/re2c/test/tags/skip_before_tags.i--tags--no-lookahead.re
new file mode 100644
index 00000000..7e17c2d6
--- /dev/null
+++ b/re2c/test/tags/skip_before_tags.i--tags--no-lookahead.re
@@ -0,0 +1,5 @@
+/*!re2c
+
+(@a "a" [^])* {}
+
+*/