From f6dc93c88d0f6cd3132cbc66db68518e0a68b636 Mon Sep 17 00:00:00 2001
From: Ulya Trofimovich <skvadrik@gmail.com>
Date: Mon, 19 Nov 2018 23:22:33 +0000
Subject: [PATCH] Dump header on stdout if filename is not set, but
 /*!header:re2c:on*/ is used.

---
 re2c/bootstrap/src/ast/lex.cc | 336 +++++++++++++++++-----------------
 re2c/src/ast/lex.re           |   1 +
 re2c/src/code/output.cc       |  58 +++---
 re2c/src/code/output.h        |   4 +-
 re2c/test/header/header_03.c  |  28 +++
 re2c/test/header/header_03.re |  16 ++
 6 files changed, 241 insertions(+), 202 deletions(-)
 create mode 100644 re2c/test/header/header_03.c
 create mode 100644 re2c/test/header/header_03.re

diff --git a/re2c/bootstrap/src/ast/lex.cc b/re2c/bootstrap/src/ast/lex.cc
index 82e586b2..f8095737 100644
--- a/re2c/bootstrap/src/ast/lex.cc
+++ b/re2c/bootstrap/src/ast/lex.cc
@@ -1,4 +1,3 @@
-/* Generated by re2c 1.1.1 on Sun Nov 18 12:18:36 2018 */
 #line 1 "../src/ast/lex.re"
 #include "src/util/c99_stdint.h"
 #include <stddef.h>
@@ -47,7 +46,7 @@ echo:
     ptr = cur;
 
 
-#line 51 "src/ast/lex.cc"
+#line 50 "src/ast/lex.cc"
 {
 	YYCTYPE yych;
 	unsigned int yyaccept = 0;
@@ -105,19 +104,19 @@ echo:
 		}
 	}
 	++YYCURSOR;
-#line 148 "../src/ast/lex.re"
+#line 149 "../src/ast/lex.re"
 	{
         if (cur != eof) goto echo;
         out.wraw(tok, ptr);
         return Stop;
     }
-#line 115 "src/ast/lex.cc"
+#line 114 "src/ast/lex.cc"
 yy4:
 	++YYCURSOR;
 yy5:
-#line 166 "../src/ast/lex.re"
+#line 167 "../src/ast/lex.re"
 	{ goto echo; }
-#line 121 "src/ast/lex.cc"
+#line 120 "src/ast/lex.cc"
 yy6:
 	yyaccept = 0;
 	yych = (YYCTYPE)*(YYMARKER = ++YYCURSOR);
@@ -126,13 +125,13 @@ yy6:
 	}
 	if (yych == '#') goto yy14;
 yy7:
-#line 160 "../src/ast/lex.re"
+#line 161 "../src/ast/lex.re"
 	{
         cline++;
         pos = cur;
         goto echo;
     }
-#line 136 "src/ast/lex.cc"
+#line 135 "src/ast/lex.cc"
 yy8:
 	yych = (YYCTYPE)*++YYCURSOR;
 	if (yych == '\n') goto yy6;
@@ -180,7 +179,7 @@ yy16:
         out.wraw(tok, ptr);
         return Parse;
     }
-#line 184 "src/ast/lex.cc"
+#line 183 "src/ast/lex.cc"
 yy18:
 	yych = (YYCTYPE)*++YYCURSOR;
 	if (yych == '!') goto yy20;
@@ -459,13 +458,13 @@ yy76:
 yy78:
 	++YYCURSOR;
 	YYCURSOR = YYCTXMARKER;
-#line 154 "../src/ast/lex.re"
+#line 155 "../src/ast/lex.re"
 	{
         out.wraw(tok, ptr + 1);
         set_sourceline();
         goto echo;
     }
-#line 469 "src/ast/lex.cc"
+#line 468 "src/ast/lex.cc"
 yy80:
 	yych = (YYCTYPE)*++YYCURSOR;
 	if (yych == '\n') goto yy78;
@@ -593,7 +592,7 @@ yy108:
         lex_end_of_comment(out);
         goto echo;
     }
-#line 597 "src/ast/lex.cc"
+#line 596 "src/ast/lex.cc"
 yy110:
 	yych = (YYCTYPE)*++YYCURSOR;
 	if (yych == 'h') goto yy120;
@@ -621,7 +620,7 @@ yy115:
         out.wraw(tok, ptr);
         return Reuse;
     }
-#line 625 "src/ast/lex.cc"
+#line 624 "src/ast/lex.cc"
 yy117:
 	yych = (YYCTYPE)*++YYCURSOR;
 	if (yych == 'r') goto yy125;
@@ -678,7 +677,7 @@ yy129:
         lex_tags(out, true);
         goto echo;
     }
-#line 682 "src/ast/lex.cc"
+#line 681 "src/ast/lex.cc"
 yy131:
 	++YYCURSOR;
 #line 75 "../src/ast/lex.re"
@@ -686,7 +685,7 @@ yy131:
         out.wraw(tok, ptr);
         return Rules;
     }
-#line 690 "src/ast/lex.cc"
+#line 689 "src/ast/lex.cc"
 yy133:
 	++YYCURSOR;
 #line 121 "../src/ast/lex.re"
@@ -695,7 +694,7 @@ yy133:
         lex_tags(out, false);
         goto echo;
     }
-#line 699 "src/ast/lex.cc"
+#line 698 "src/ast/lex.cc"
 yy135:
 	++YYCURSOR;
 #line 112 "../src/ast/lex.re"
@@ -707,7 +706,7 @@ yy135:
         lex_end_of_comment(out);
         goto echo;
     }
-#line 711 "src/ast/lex.cc"
+#line 710 "src/ast/lex.cc"
 yy137:
 	yych = (YYCTYPE)*++YYCURSOR;
 	if (yych == '2') goto yy142;
@@ -724,7 +723,7 @@ yy139:
         lex_end_of_comment(out);
         goto echo;
     }
-#line 728 "src/ast/lex.cc"
+#line 727 "src/ast/lex.cc"
 yy141:
 	yych = (YYCTYPE)*++YYCURSOR;
 	if (yych == 'e') goto yy144;
@@ -750,7 +749,7 @@ yy145:
         lex_end_of_comment(out);
         goto echo;
     }
-#line 754 "src/ast/lex.cc"
+#line 753 "src/ast/lex.cc"
 yy147:
 	yych = (YYCTYPE)*++YYCURSOR;
 	if (yych == 'f') goto yy149;
@@ -770,6 +769,7 @@ yy150:
 	{
         out.wraw(tok, ptr);
         out.header_mode(true);
+        out.need_header = true;
         lex_end_of_comment(out);
         goto echo;
     }
@@ -786,7 +786,7 @@ yy152:
 #line 787 "src/ast/lex.cc"
 yy154:
 	++YYCURSOR;
-#line 140 "../src/ast/lex.re"
+#line 141 "../src/ast/lex.re"
 	{
         out.wraw(tok, ptr);
         out.header_mode(false);
@@ -796,7 +796,7 @@ yy154:
     }
 #line 798 "src/ast/lex.cc"
 }
-#line 167 "../src/ast/lex.re"
+#line 168 "../src/ast/lex.re"
 
 }
 
@@ -820,18 +820,18 @@ void Scanner::lex_end_of_comment(OutputFile &out)
 	}
 yy158:
 	++YYCURSOR;
-#line 174 "../src/ast/lex.re"
+#line 175 "../src/ast/lex.re"
 	{ fatal_lc(get_cline(), get_column(), "expected end of block"); }
 #line 826 "src/ast/lex.cc"
 yy160:
 	++YYCURSOR;
 yy161:
-#line 176 "../src/ast/lex.re"
+#line 177 "../src/ast/lex.re"
 	{ continue; }
 #line 832 "src/ast/lex.cc"
 yy162:
 	++YYCURSOR;
-#line 177 "../src/ast/lex.re"
+#line 178 "../src/ast/lex.re"
 	{ ++ignored; continue; }
 #line 837 "src/ast/lex.cc"
 yy164:
@@ -842,7 +842,7 @@ yy165:
 	yych = (YYCTYPE)*++YYCURSOR;
 	if (yych != '/') goto yy161;
 	++YYCURSOR;
-#line 178 "../src/ast/lex.re"
+#line 179 "../src/ast/lex.re"
 	{
             if (ignored > 0) {
                 cline += ignored;
@@ -853,7 +853,7 @@ yy165:
         }
 #line 855 "src/ast/lex.cc"
 }
-#line 186 "../src/ast/lex.re"
+#line 187 "../src/ast/lex.re"
 }
 }
 
@@ -919,7 +919,7 @@ void Scanner::lex_tags(OutputFile &out, bool mtags)
 	}
 	++YYCURSOR;
 yy171:
-#line 193 "../src/ast/lex.re"
+#line 194 "../src/ast/lex.re"
 	{ fatal_lc(get_cline(), get_column(), "unrecognized configuration"); }
 #line 925 "src/ast/lex.cc"
 yy172:
@@ -929,12 +929,12 @@ yy172:
 	if (yybm[0+yych] & 128) {
 		goto yy172;
 	}
-#line 198 "../src/ast/lex.re"
+#line 199 "../src/ast/lex.re"
 	{ continue; }
 #line 935 "src/ast/lex.cc"
 yy175:
 	++YYCURSOR;
-#line 199 "../src/ast/lex.re"
+#line 200 "../src/ast/lex.re"
 	{ ++cline; continue; }
 #line 940 "src/ast/lex.cc"
 yy177:
@@ -955,7 +955,7 @@ yy180:
 	goto yy171;
 yy181:
 	++YYCURSOR;
-#line 200 "../src/ast/lex.re"
+#line 201 "../src/ast/lex.re"
 	{
             out.wdelay_tags(new ConfTags(fmt, sep), mtags);
             tok = pos = cur;
@@ -998,7 +998,7 @@ yy191:
 	goto yy184;
 yy192:
 	++YYCURSOR;
-#line 195 "../src/ast/lex.re"
+#line 196 "../src/ast/lex.re"
 	{ fmt = lex_conf_string(); continue; }
 #line 1004 "src/ast/lex.cc"
 yy194:
@@ -1009,11 +1009,11 @@ yy194:
 	yych = (YYCTYPE)*++YYCURSOR;
 	if (yych != 'r') goto yy184;
 	++YYCURSOR;
-#line 196 "../src/ast/lex.re"
+#line 197 "../src/ast/lex.re"
 	{ sep = lex_conf_string(); continue; }
 #line 1015 "src/ast/lex.cc"
 }
-#line 205 "../src/ast/lex.re"
+#line 206 "../src/ast/lex.re"
 }
 }
 
@@ -1132,7 +1132,7 @@ scan:
 yy201:
 	++YYCURSOR;
 yy202:
-#line 329 "../src/ast/lex.re"
+#line 330 "../src/ast/lex.re"
 	{
         fatal_lc(get_cline(), get_column(), "unexpected character: '%c'", *tok);
         goto scan;
@@ -1145,7 +1145,7 @@ yy203:
 	if (yybm[0+yych] & 16) {
 		goto yy203;
 	}
-#line 310 "../src/ast/lex.re"
+#line 311 "../src/ast/lex.re"
 	{ goto scan; }
 #line 1151 "src/ast/lex.cc"
 yy206:
@@ -1158,7 +1158,7 @@ yy206:
 		if (yych == '#') goto yy236;
 	}
 yy207:
-#line 317 "../src/ast/lex.re"
+#line 318 "../src/ast/lex.re"
 	{
         pos = cur;
         cline++;
@@ -1177,7 +1177,7 @@ yy208:
 	goto yy202;
 yy209:
 	++YYCURSOR;
-#line 227 "../src/ast/lex.re"
+#line 228 "../src/ast/lex.re"
 	{ yylval.regexp = lex_str('"'); return TOKEN_REGEXP; }
 #line 1183 "src/ast/lex.cc"
 yy211:
@@ -1197,13 +1197,13 @@ yy212:
 	goto yy202;
 yy213:
 	++YYCURSOR;
-#line 226 "../src/ast/lex.re"
+#line 227 "../src/ast/lex.re"
 	{ yylval.regexp = lex_str('\''); return TOKEN_REGEXP; }
 #line 1203 "src/ast/lex.cc"
 yy215:
 	++YYCURSOR;
 yy216:
-#line 237 "../src/ast/lex.re"
+#line 238 "../src/ast/lex.re"
 	{ return *tok; }
 #line 1209 "src/ast/lex.cc"
 yy217:
@@ -1212,7 +1212,7 @@ yy217:
 	goto yy216;
 yy218:
 	++YYCURSOR;
-#line 305 "../src/ast/lex.re"
+#line 306 "../src/ast/lex.re"
 	{
         yylval.regexp = ast_dot(cline, get_column());
         return TOKEN_REGEXP;
@@ -1229,7 +1229,7 @@ yy221:
 	goto yy202;
 yy222:
 	++YYCURSOR;
-#line 219 "../src/ast/lex.re"
+#line 220 "../src/ast/lex.re"
 	{ return lex_clist(); }
 #line 1235 "src/ast/lex.cc"
 yy224:
@@ -1244,7 +1244,7 @@ yy226:
 	if (yybm[0+yych] & 32) {
 		goto yy225;
 	}
-#line 282 "../src/ast/lex.re"
+#line 283 "../src/ast/lex.re"
 	{
         if (!globopts->FFlag || lex_namedef_context_re2c()) {
             yylval.str = new std::string (tok, tok_len());
@@ -1271,7 +1271,7 @@ yy226:
 yy228:
 	yych = (YYCTYPE)*++YYCURSOR;
 	if (yych == '^') goto yy251;
-#line 228 "../src/ast/lex.re"
+#line 229 "../src/ast/lex.re"
 	{ yylval.regexp = lex_cls(false); return TOKEN_REGEXP; }
 #line 1277 "src/ast/lex.cc"
 yy230:
@@ -1296,7 +1296,7 @@ yy231:
 		}
 	}
 yy232:
-#line 214 "../src/ast/lex.re"
+#line 215 "../src/ast/lex.re"
 	{ lex_code_in_braces(); return TOKEN_CODE; }
 #line 1302 "src/ast/lex.cc"
 yy233:
@@ -1349,7 +1349,7 @@ yy238:
 		}
 	}
 yy240:
-#line 231 "../src/ast/lex.re"
+#line 232 "../src/ast/lex.re"
 	{
         const std::string *name = new std::string(tok + 1, tok_len() - 1);
         yylval.regexp = ast_tag(cline, get_column(), name, tok[0] == '#');
@@ -1358,33 +1358,33 @@ yy240:
 #line 1359 "src/ast/lex.cc"
 yy241:
 	++YYCURSOR;
-#line 224 "../src/ast/lex.re"
+#line 225 "../src/ast/lex.re"
 	{ tok = cur; return 0; }
 #line 1364 "src/ast/lex.cc"
 yy243:
 	++YYCURSOR;
-#line 222 "../src/ast/lex.re"
+#line 223 "../src/ast/lex.re"
 	{ lex_c_comment(); goto scan; }
 #line 1369 "src/ast/lex.cc"
 yy245:
 	++YYCURSOR;
-#line 221 "../src/ast/lex.re"
+#line 222 "../src/ast/lex.re"
 	{ lex_cpp_comment(); goto scan; }
 #line 1374 "src/ast/lex.cc"
 yy247:
 	yych = (YYCTYPE)*++YYCURSOR;
 	if (yych == '>') goto yy261;
-#line 215 "../src/ast/lex.re"
+#line 216 "../src/ast/lex.re"
 	{ lex_code_indented(); return TOKEN_CODE; }
 #line 1380 "src/ast/lex.cc"
 yy249:
 	++YYCURSOR;
-#line 217 "../src/ast/lex.re"
+#line 218 "../src/ast/lex.re"
 	{ lex_cgoto(); return TOKEN_CNEXT; }
 #line 1385 "src/ast/lex.cc"
 yy251:
 	++YYCURSOR;
-#line 229 "../src/ast/lex.re"
+#line 230 "../src/ast/lex.re"
 	{ yylval.regexp = lex_cls(true);  return TOKEN_REGEXP; }
 #line 1390 "src/ast/lex.cc"
 yy253:
@@ -1394,7 +1394,7 @@ yy253:
 yy254:
 	++YYCURSOR;
 yy255:
-#line 266 "../src/ast/lex.re"
+#line 267 "../src/ast/lex.re"
 	{
         fatal_lc(get_cline(), get_column(),
             "illegal closure form, use '{n}', '{n,}', '{n,m}' where n and m are numbers");
@@ -1438,7 +1438,7 @@ yy260:
 	goto yy235;
 yy261:
 	++YYCURSOR;
-#line 218 "../src/ast/lex.re"
+#line 219 "../src/ast/lex.re"
 	{ lex_cgoto(); return TOKEN_CJUMP; }
 #line 1444 "src/ast/lex.cc"
 yy263:
@@ -1454,7 +1454,7 @@ yy264:
 	goto yy255;
 yy265:
 	++YYCURSOR;
-#line 239 "../src/ast/lex.re"
+#line 240 "../src/ast/lex.re"
 	{
         if (!s_to_u32_unsafe (tok + 1, cur - 1, yylval.bounds.min)) {
             fatal_lc(get_cline(), get_column(), "repetition count overflow");
@@ -1465,7 +1465,7 @@ yy265:
 #line 1466 "src/ast/lex.cc"
 yy267:
 	++YYCURSOR;
-#line 271 "../src/ast/lex.re"
+#line 272 "../src/ast/lex.re"
 	{
         if (!globopts->FFlag) {
             fatal_lc(get_cline(), get_column(),
@@ -1493,7 +1493,7 @@ yy271:
 	goto yy235;
 yy273:
 	++YYCURSOR;
-#line 258 "../src/ast/lex.re"
+#line 259 "../src/ast/lex.re"
 	{
         if (!s_to_u32_unsafe (tok + 1, cur - 2, yylval.bounds.min)) {
             fatal_lc(get_cline(), get_column(), "repetition lower bound overflow");
@@ -1508,12 +1508,12 @@ yy275:
 	goto yy235;
 yy276:
 	++YYCURSOR;
-#line 280 "../src/ast/lex.re"
+#line 281 "../src/ast/lex.re"
 	{ return TOKEN_CONF; }
 #line 1514 "src/ast/lex.cc"
 yy278:
 	++YYCURSOR;
-#line 247 "../src/ast/lex.re"
+#line 248 "../src/ast/lex.re"
 	{
         const char * p = strchr (tok, ',');
         if (!s_to_u32_unsafe (tok + 1, p, yylval.bounds.min)) {
@@ -1580,7 +1580,7 @@ yy285:
 yy287:
 	++YYCURSOR;
 	YYCURSOR = YYCTXMARKER;
-#line 312 "../src/ast/lex.re"
+#line 313 "../src/ast/lex.re"
 	{
         set_sourceline ();
         return TOKEN_LINE_INFO;
@@ -1611,7 +1611,7 @@ yy293:
 	if (yych == '\n') goto yy235;
 	goto yy290;
 }
-#line 333 "../src/ast/lex.re"
+#line 334 "../src/ast/lex.re"
 
 }
 
@@ -1673,7 +1673,7 @@ bool Scanner::lex_namedef_context_re2c()
 		}
 	}
 yy296:
-#line 340 "../src/ast/lex.re"
+#line 341 "../src/ast/lex.re"
 	{ return false; }
 #line 1679 "src/ast/lex.cc"
 yy297:
@@ -1692,11 +1692,11 @@ yy300:
 	if (yych == '>') goto yy299;
 	++YYCURSOR;
 	YYCURSOR = YYCTXMARKER;
-#line 339 "../src/ast/lex.re"
+#line 340 "../src/ast/lex.re"
 	{ return true; }
 #line 1698 "src/ast/lex.cc"
 }
-#line 341 "../src/ast/lex.re"
+#line 342 "../src/ast/lex.re"
 
 }
 
@@ -1750,7 +1750,7 @@ bool Scanner::lex_namedef_context_flex()
 		YYCTXMARKER = YYCURSOR;
 		goto yy306;
 	}
-#line 349 "../src/ast/lex.re"
+#line 350 "../src/ast/lex.re"
 	{ return false; }
 #line 1756 "src/ast/lex.cc"
 yy306:
@@ -1767,17 +1767,17 @@ yy306:
 		if (yych == '{') goto yy309;
 	}
 	YYCURSOR = YYCTXMARKER;
-#line 348 "../src/ast/lex.re"
+#line 349 "../src/ast/lex.re"
 	{ return true; }
 #line 1773 "src/ast/lex.cc"
 yy309:
 	++YYCURSOR;
 	YYCURSOR = YYCTXMARKER;
-#line 347 "../src/ast/lex.re"
+#line 348 "../src/ast/lex.re"
 	{ return false; }
 #line 1779 "src/ast/lex.cc"
 }
-#line 350 "../src/ast/lex.re"
+#line 351 "../src/ast/lex.re"
 
 }
 
@@ -1836,7 +1836,7 @@ yy311:
 	if (yych <= '!') goto yy315;
 	if (yych == '>') goto yy318;
 yy314:
-#line 360 "../src/ast/lex.re"
+#line 361 "../src/ast/lex.re"
 	{ goto cond; }
 #line 1842 "src/ast/lex.cc"
 yy315:
@@ -1845,16 +1845,16 @@ yy315:
 	yych = (YYCTYPE)*YYCURSOR;
 	if (yych == '\t') goto yy315;
 	if (yych == ' ') goto yy315;
-#line 358 "../src/ast/lex.re"
+#line 359 "../src/ast/lex.re"
 	{ kind = TOKEN_CSETUP; goto cond; }
 #line 1851 "src/ast/lex.cc"
 yy318:
 	++YYCURSOR;
-#line 359 "../src/ast/lex.re"
+#line 360 "../src/ast/lex.re"
 	{ kind = TOKEN_CZERO; goto end; }
 #line 1856 "src/ast/lex.cc"
 }
-#line 361 "../src/ast/lex.re"
+#line 362 "../src/ast/lex.re"
 
 cond:
     tok = cur;
@@ -1911,12 +1911,12 @@ cond:
 	}
 yy322:
 	++YYCURSOR;
-#line 367 "../src/ast/lex.re"
+#line 368 "../src/ast/lex.re"
 	{ goto error; }
 #line 1917 "src/ast/lex.cc"
 yy324:
 	++YYCURSOR;
-#line 366 "../src/ast/lex.re"
+#line 367 "../src/ast/lex.re"
 	{ if (!cl->empty()) goto error; cl->insert("*"); goto next; }
 #line 1922 "src/ast/lex.cc"
 yy326:
@@ -1926,11 +1926,11 @@ yy326:
 	if (yybm[0+yych] & 128) {
 		goto yy326;
 	}
-#line 365 "../src/ast/lex.re"
+#line 366 "../src/ast/lex.re"
 	{ cl->insert(std::string(tok, tok_len())); goto next; }
 #line 1932 "src/ast/lex.cc"
 }
-#line 368 "../src/ast/lex.re"
+#line 369 "../src/ast/lex.re"
 
 next:
 
@@ -1985,7 +1985,7 @@ next:
 	}
 	++YYCURSOR;
 yy332:
-#line 373 "../src/ast/lex.re"
+#line 374 "../src/ast/lex.re"
 	{ goto error; }
 #line 1991 "src/ast/lex.cc"
 yy333:
@@ -2009,12 +2009,12 @@ yy334:
 	if (yybm[0+yych] & 128) {
 		goto yy334;
 	}
-#line 371 "../src/ast/lex.re"
+#line 372 "../src/ast/lex.re"
 	{ goto cond; }
 #line 2015 "src/ast/lex.cc"
 yy337:
 	++YYCURSOR;
-#line 372 "../src/ast/lex.re"
+#line 373 "../src/ast/lex.re"
 	{ goto end; }
 #line 2020 "src/ast/lex.cc"
 yy339:
@@ -2034,7 +2034,7 @@ yy339:
 	YYCURSOR = YYMARKER;
 	goto yy332;
 }
-#line 374 "../src/ast/lex.re"
+#line 375 "../src/ast/lex.re"
 
 end:
     yylval.clist = cl;
@@ -2093,11 +2093,11 @@ yy342:
 	if (yybm[0+yych] & 128) {
 		goto yy343;
 	}
-#line 386 "../src/ast/lex.re"
+#line 387 "../src/ast/lex.re"
 	{ goto name; }
 #line 2099 "src/ast/lex.cc"
 }
-#line 387 "../src/ast/lex.re"
+#line 388 "../src/ast/lex.re"
 
 name:
     tok = cur;
@@ -2150,7 +2150,7 @@ name:
 	}
 yy348:
 	++YYCURSOR;
-#line 392 "../src/ast/lex.re"
+#line 393 "../src/ast/lex.re"
 	{ fatal_l(get_cline(), "syntax error in condition goto"); }
 #line 2156 "src/ast/lex.cc"
 yy350:
@@ -2160,11 +2160,11 @@ yy350:
 	if (yybm[0+yych] & 128) {
 		goto yy350;
 	}
-#line 391 "../src/ast/lex.re"
+#line 392 "../src/ast/lex.re"
 	{ yylval.str = new std::string (tok, tok_len ()); return; }
 #line 2166 "src/ast/lex.cc"
 }
-#line 393 "../src/ast/lex.re"
+#line 394 "../src/ast/lex.re"
 
 }
 
@@ -2202,13 +2202,13 @@ code:
 	}
 yy355:
 	++YYCURSOR;
-#line 410 "../src/ast/lex.re"
+#line 411 "../src/ast/lex.re"
 	{ fail_if_eof(); goto code; }
 #line 2208 "src/ast/lex.cc"
 yy357:
 	++YYCURSOR;
 yy358:
-#line 415 "../src/ast/lex.re"
+#line 416 "../src/ast/lex.re"
 	{ goto code; }
 #line 2214 "src/ast/lex.cc"
 yy359:
@@ -2221,7 +2221,7 @@ yy359:
 		if (yych == ' ') goto yy367;
 	}
 yy360:
-#line 403 "../src/ast/lex.re"
+#line 404 "../src/ast/lex.re"
 	{
         while (isspace(tok[0])) ++tok;
         while (cur > tok && isspace(cur[-1])) --cur;
@@ -2235,7 +2235,7 @@ yy361:
 	goto yy358;
 yy362:
 	++YYCURSOR;
-#line 414 "../src/ast/lex.re"
+#line 415 "../src/ast/lex.re"
 	{ lex_string(cur[-1]); goto code; }
 #line 2241 "src/ast/lex.cc"
 yy364:
@@ -2245,27 +2245,27 @@ yy364:
 	goto yy358;
 yy365:
 	++YYCURSOR;
-#line 411 "../src/ast/lex.re"
+#line 412 "../src/ast/lex.re"
 	{ fatal_l(get_cline(), "Curly braces are not allowed after ':='"); }
 #line 2251 "src/ast/lex.cc"
 yy367:
 	++YYCURSOR;
 	YYCURSOR -= 1;
-#line 402 "../src/ast/lex.re"
+#line 403 "../src/ast/lex.re"
 	{ goto code; }
 #line 2257 "src/ast/lex.cc"
 yy369:
 	++YYCURSOR;
-#line 412 "../src/ast/lex.re"
+#line 413 "../src/ast/lex.re"
 	{ lex_c_comment(); goto code; }
 #line 2262 "src/ast/lex.cc"
 yy371:
 	++YYCURSOR;
-#line 413 "../src/ast/lex.re"
+#line 414 "../src/ast/lex.re"
 	{ lex_cpp_comment(); goto code; }
 #line 2267 "src/ast/lex.cc"
 }
-#line 416 "../src/ast/lex.re"
+#line 417 "../src/ast/lex.re"
 
 }
 
@@ -2337,13 +2337,13 @@ code:
 	}
 yy375:
 	++YYCURSOR;
-#line 436 "../src/ast/lex.re"
+#line 437 "../src/ast/lex.re"
 	{ fail_if_eof(); goto code; }
 #line 2343 "src/ast/lex.cc"
 yy377:
 	++YYCURSOR;
 yy378:
-#line 440 "../src/ast/lex.re"
+#line 441 "../src/ast/lex.re"
 	{ goto code; }
 #line 2349 "src/ast/lex.cc"
 yy379:
@@ -2353,7 +2353,7 @@ yy379:
 	}
 	if (yych == '#') goto yy392;
 yy380:
-#line 435 "../src/ast/lex.re"
+#line 436 "../src/ast/lex.re"
 	{ pos = cur; cline++; goto code; }
 #line 2359 "src/ast/lex.cc"
 yy381:
@@ -2362,7 +2362,7 @@ yy381:
 	goto yy378;
 yy382:
 	++YYCURSOR;
-#line 439 "../src/ast/lex.re"
+#line 440 "../src/ast/lex.re"
 	{ lex_string(cur[-1]); goto code; }
 #line 2368 "src/ast/lex.cc"
 yy384:
@@ -2372,12 +2372,12 @@ yy384:
 	goto yy378;
 yy385:
 	++YYCURSOR;
-#line 433 "../src/ast/lex.re"
+#line 434 "../src/ast/lex.re"
 	{ ++depth; goto code; }
 #line 2378 "src/ast/lex.cc"
 yy387:
 	++YYCURSOR;
-#line 425 "../src/ast/lex.re"
+#line 426 "../src/ast/lex.re"
 	{
         if (--depth == 0) {
             yylval.code = new Code(get_fname (), line, tok, tok_len ());
@@ -2411,12 +2411,12 @@ yy392:
 	}
 yy394:
 	++YYCURSOR;
-#line 437 "../src/ast/lex.re"
+#line 438 "../src/ast/lex.re"
 	{ lex_c_comment(); goto code; }
 #line 2417 "src/ast/lex.cc"
 yy396:
 	++YYCURSOR;
-#line 438 "../src/ast/lex.re"
+#line 439 "../src/ast/lex.re"
 	{ lex_cpp_comment(); goto code; }
 #line 2422 "src/ast/lex.cc"
 yy398:
@@ -2475,7 +2475,7 @@ yy406:
 yy408:
 	++YYCURSOR;
 	YYCURSOR = YYCTXMARKER;
-#line 434 "../src/ast/lex.re"
+#line 435 "../src/ast/lex.re"
 	{ set_sourceline (); goto code; }
 #line 2481 "src/ast/lex.cc"
 yy410:
@@ -2503,7 +2503,7 @@ yy414:
 	if (yych == '\n') goto yy391;
 	goto yy411;
 }
-#line 441 "../src/ast/lex.re"
+#line 442 "../src/ast/lex.re"
 
 }
 
@@ -2537,18 +2537,18 @@ loop:
 	}
 yy417:
 	++YYCURSOR;
-#line 451 "../src/ast/lex.re"
+#line 452 "../src/ast/lex.re"
 	{ fail_if_eof(); goto loop; }
 #line 2543 "src/ast/lex.cc"
 yy419:
 	++YYCURSOR;
 yy420:
-#line 452 "../src/ast/lex.re"
+#line 453 "../src/ast/lex.re"
 	{ goto loop; }
 #line 2549 "src/ast/lex.cc"
 yy421:
 	++YYCURSOR;
-#line 450 "../src/ast/lex.re"
+#line 451 "../src/ast/lex.re"
 	{ pos = cur; ++cline; goto loop; }
 #line 2554 "src/ast/lex.cc"
 yy423:
@@ -2557,7 +2557,7 @@ yy423:
 	goto yy420;
 yy424:
 	++YYCURSOR;
-#line 448 "../src/ast/lex.re"
+#line 449 "../src/ast/lex.re"
 	{ if (cur[-1] == delim) return; else goto loop; }
 #line 2563 "src/ast/lex.cc"
 yy426:
@@ -2570,11 +2570,11 @@ yy426:
 	}
 yy427:
 	++YYCURSOR;
-#line 449 "../src/ast/lex.re"
+#line 450 "../src/ast/lex.re"
 	{ goto loop; }
 #line 2576 "src/ast/lex.cc"
 }
-#line 453 "../src/ast/lex.re"
+#line 454 "../src/ast/lex.re"
 
 }
 
@@ -2598,18 +2598,18 @@ loop:
 	}
 yy431:
 	++YYCURSOR;
-#line 462 "../src/ast/lex.re"
+#line 463 "../src/ast/lex.re"
 	{ fail_if_eof(); goto loop; }
 #line 2604 "src/ast/lex.cc"
 yy433:
 	++YYCURSOR;
 yy434:
-#line 463 "../src/ast/lex.re"
+#line 464 "../src/ast/lex.re"
 	{ goto loop; }
 #line 2610 "src/ast/lex.cc"
 yy435:
 	++YYCURSOR;
-#line 461 "../src/ast/lex.re"
+#line 462 "../src/ast/lex.re"
 	{ pos = cur; ++cline; goto loop; }
 #line 2615 "src/ast/lex.cc"
 yy437:
@@ -2620,11 +2620,11 @@ yy438:
 	yych = (YYCTYPE)*++YYCURSOR;
 	if (yych != '/') goto yy434;
 	++YYCURSOR;
-#line 460 "../src/ast/lex.re"
+#line 461 "../src/ast/lex.re"
 	{ return; }
 #line 2626 "src/ast/lex.cc"
 }
-#line 464 "../src/ast/lex.re"
+#line 465 "../src/ast/lex.re"
 
 }
 
@@ -2647,18 +2647,18 @@ loop:
 	}
 yy443:
 	++YYCURSOR;
-#line 472 "../src/ast/lex.re"
+#line 473 "../src/ast/lex.re"
 	{ fail_if_eof(); goto loop; }
 #line 2653 "src/ast/lex.cc"
 yy445:
 	++YYCURSOR;
 yy446:
-#line 473 "../src/ast/lex.re"
+#line 474 "../src/ast/lex.re"
 	{ goto loop; }
 #line 2659 "src/ast/lex.cc"
 yy447:
 	++YYCURSOR;
-#line 471 "../src/ast/lex.re"
+#line 472 "../src/ast/lex.re"
 	{ pos = cur; ++cline; return; }
 #line 2664 "src/ast/lex.cc"
 yy449:
@@ -2666,7 +2666,7 @@ yy449:
 	if (yych == '\n') goto yy447;
 	goto yy446;
 }
-#line 474 "../src/ast/lex.re"
+#line 475 "../src/ast/lex.re"
 
 }
 
@@ -2684,16 +2684,16 @@ fst:
 	if (YYLIMIT <= YYCURSOR) YYFILL(1);
 	yych = (YYCTYPE)*YYCURSOR;
 	if (yych == ']') goto yy453;
-#line 486 "../src/ast/lex.re"
+#line 487 "../src/ast/lex.re"
 	{ l = lex_cls_chr(); goto snd; }
 #line 2690 "src/ast/lex.cc"
 yy453:
 	++YYCURSOR;
-#line 485 "../src/ast/lex.re"
+#line 486 "../src/ast/lex.re"
 	{ return ast_cls(cline, c0, cls, neg); }
 #line 2695 "src/ast/lex.cc"
 }
-#line 487 "../src/ast/lex.re"
+#line 488 "../src/ast/lex.re"
 
 snd:
     
@@ -2704,7 +2704,7 @@ snd:
 	yych = (YYCTYPE)*(YYMARKER = YYCURSOR);
 	if (yych == '-') goto yy458;
 yy457:
-#line 490 "../src/ast/lex.re"
+#line 491 "../src/ast/lex.re"
 	{ u = l; goto add; }
 #line 2710 "src/ast/lex.cc"
 yy458:
@@ -2715,7 +2715,7 @@ yy458:
 yy460:
 	++YYCURSOR;
 	YYCURSOR -= 1;
-#line 491 "../src/ast/lex.re"
+#line 492 "../src/ast/lex.re"
 	{
             u = lex_cls_chr();
             if (l > u) {
@@ -2726,7 +2726,7 @@ yy460:
         }
 #line 2728 "src/ast/lex.cc"
 }
-#line 499 "../src/ast/lex.re"
+#line 500 "../src/ast/lex.re"
 
 add:
     cls->push_back(ASTRange(l, u, c));
@@ -2755,18 +2755,18 @@ uint32_t Scanner::lex_cls_chr()
 	}
 yy464:
 	++YYCURSOR;
-#line 511 "../src/ast/lex.re"
+#line 512 "../src/ast/lex.re"
 	{ fail_if_eof(); return 0; }
 #line 2761 "src/ast/lex.cc"
 yy466:
 	++YYCURSOR;
 yy467:
-#line 517 "../src/ast/lex.re"
+#line 518 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>(tok[0]); }
 #line 2767 "src/ast/lex.cc"
 yy468:
 	++YYCURSOR;
-#line 512 "../src/ast/lex.re"
+#line 513 "../src/ast/lex.re"
 	{ fatal_lc(l, c, "newline in character class"); }
 #line 2772 "src/ast/lex.cc"
 yy470:
@@ -2827,13 +2827,13 @@ yy471:
 		}
 	}
 yy472:
-#line 515 "../src/ast/lex.re"
+#line 516 "../src/ast/lex.re"
 	{ fatal_lc(l, c, "syntax error in escape sequence"); }
 #line 2833 "src/ast/lex.cc"
 yy473:
 	++YYCURSOR;
 yy474:
-#line 530 "../src/ast/lex.re"
+#line 531 "../src/ast/lex.re"
 	{
             warn.useless_escape(cline, get_column(), tok[1]);
             return static_cast<uint8_t>(tok[1]);
@@ -2845,7 +2845,7 @@ yy475:
 	goto yy474;
 yy476:
 	++YYCURSOR;
-#line 528 "../src/ast/lex.re"
+#line 529 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>('-'); }
 #line 2851 "src/ast/lex.cc"
 yy478:
@@ -2854,7 +2854,7 @@ yy478:
 	if (yych <= '/') goto yy479;
 	if (yych <= '7') goto yy503;
 yy479:
-#line 514 "../src/ast/lex.re"
+#line 515 "../src/ast/lex.re"
 	{ fatal_lc(l, c, "syntax error in octal escape sequence"); }
 #line 2860 "src/ast/lex.cc"
 yy480:
@@ -2872,7 +2872,7 @@ yy481:
 		if (yych <= 'f') goto yy505;
 	}
 yy482:
-#line 513 "../src/ast/lex.re"
+#line 514 "../src/ast/lex.re"
 	{ fatal_lc(l, c, "syntax error in hexadecimal escape sequence"); }
 #line 2878 "src/ast/lex.cc"
 yy483:
@@ -2890,47 +2890,47 @@ yy483:
 	}
 yy484:
 	++YYCURSOR;
-#line 527 "../src/ast/lex.re"
+#line 528 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>('\\'); }
 #line 2896 "src/ast/lex.cc"
 yy486:
 	++YYCURSOR;
-#line 529 "../src/ast/lex.re"
+#line 530 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>(']'); }
 #line 2901 "src/ast/lex.cc"
 yy488:
 	++YYCURSOR;
-#line 520 "../src/ast/lex.re"
+#line 521 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>('\a'); }
 #line 2906 "src/ast/lex.cc"
 yy490:
 	++YYCURSOR;
-#line 521 "../src/ast/lex.re"
+#line 522 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>('\b'); }
 #line 2911 "src/ast/lex.cc"
 yy492:
 	++YYCURSOR;
-#line 522 "../src/ast/lex.re"
+#line 523 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>('\f'); }
 #line 2916 "src/ast/lex.cc"
 yy494:
 	++YYCURSOR;
-#line 523 "../src/ast/lex.re"
+#line 524 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>('\n'); }
 #line 2921 "src/ast/lex.cc"
 yy496:
 	++YYCURSOR;
-#line 524 "../src/ast/lex.re"
+#line 525 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>('\r'); }
 #line 2926 "src/ast/lex.cc"
 yy498:
 	++YYCURSOR;
-#line 525 "../src/ast/lex.re"
+#line 526 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>('\t'); }
 #line 2931 "src/ast/lex.cc"
 yy500:
 	++YYCURSOR;
-#line 526 "../src/ast/lex.re"
+#line 527 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>('\v'); }
 #line 2936 "src/ast/lex.cc"
 yy502:
@@ -2995,7 +2995,7 @@ yy507:
 	}
 yy508:
 	++YYCURSOR;
-#line 519 "../src/ast/lex.re"
+#line 520 "../src/ast/lex.re"
 	{ return unesc_oct(tok, cur); }
 #line 3001 "src/ast/lex.cc"
 yy510:
@@ -3024,7 +3024,7 @@ yy511:
 	}
 yy512:
 	++YYCURSOR;
-#line 518 "../src/ast/lex.re"
+#line 519 "../src/ast/lex.re"
 	{ return unesc_hex(tok, cur); }
 #line 3030 "src/ast/lex.cc"
 yy514:
@@ -3050,7 +3050,7 @@ yy515:
 		goto yy504;
 	}
 }
-#line 534 "../src/ast/lex.re"
+#line 535 "../src/ast/lex.re"
 
 }
 
@@ -3077,13 +3077,13 @@ uint32_t Scanner::lex_str_chr(char quote, bool &end)
 	}
 yy518:
 	++YYCURSOR;
-#line 544 "../src/ast/lex.re"
+#line 545 "../src/ast/lex.re"
 	{ fail_if_eof(); return 0; }
 #line 3083 "src/ast/lex.cc"
 yy520:
 	++YYCURSOR;
 yy521:
-#line 550 "../src/ast/lex.re"
+#line 551 "../src/ast/lex.re"
 	{
             end = tok[0] == quote;
             return static_cast<uint8_t>(tok[0]);
@@ -3091,7 +3091,7 @@ yy521:
 #line 3092 "src/ast/lex.cc"
 yy522:
 	++YYCURSOR;
-#line 545 "../src/ast/lex.re"
+#line 546 "../src/ast/lex.re"
 	{ fatal_lc(l, c, "newline in character string"); }
 #line 3097 "src/ast/lex.cc"
 yy524:
@@ -3147,13 +3147,13 @@ yy525:
 		}
 	}
 yy526:
-#line 548 "../src/ast/lex.re"
+#line 549 "../src/ast/lex.re"
 	{ fatal_lc(l, c, "syntax error in escape sequence"); }
 #line 3153 "src/ast/lex.cc"
 yy527:
 	++YYCURSOR;
 yy528:
-#line 564 "../src/ast/lex.re"
+#line 565 "../src/ast/lex.re"
 	{
             if (tok[1] != quote) {
                 warn.useless_escape(cline, get_column(), tok[1]);
@@ -3171,7 +3171,7 @@ yy530:
 	if (yych <= '/') goto yy531;
 	if (yych <= '7') goto yy553;
 yy531:
-#line 547 "../src/ast/lex.re"
+#line 548 "../src/ast/lex.re"
 	{ fatal_lc(l, c, "syntax error in octal escape sequence"); }
 #line 3177 "src/ast/lex.cc"
 yy532:
@@ -3189,7 +3189,7 @@ yy533:
 		if (yych <= 'f') goto yy555;
 	}
 yy534:
-#line 546 "../src/ast/lex.re"
+#line 547 "../src/ast/lex.re"
 	{ fatal_lc(l, c, "syntax error in hexadecimal escape sequence"); }
 #line 3195 "src/ast/lex.cc"
 yy535:
@@ -3207,42 +3207,42 @@ yy535:
 	}
 yy536:
 	++YYCURSOR;
-#line 563 "../src/ast/lex.re"
+#line 564 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>('\\'); }
 #line 3213 "src/ast/lex.cc"
 yy538:
 	++YYCURSOR;
-#line 556 "../src/ast/lex.re"
+#line 557 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>('\a'); }
 #line 3218 "src/ast/lex.cc"
 yy540:
 	++YYCURSOR;
-#line 557 "../src/ast/lex.re"
+#line 558 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>('\b'); }
 #line 3223 "src/ast/lex.cc"
 yy542:
 	++YYCURSOR;
-#line 558 "../src/ast/lex.re"
+#line 559 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>('\f'); }
 #line 3228 "src/ast/lex.cc"
 yy544:
 	++YYCURSOR;
-#line 559 "../src/ast/lex.re"
+#line 560 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>('\n'); }
 #line 3233 "src/ast/lex.cc"
 yy546:
 	++YYCURSOR;
-#line 560 "../src/ast/lex.re"
+#line 561 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>('\r'); }
 #line 3238 "src/ast/lex.cc"
 yy548:
 	++YYCURSOR;
-#line 561 "../src/ast/lex.re"
+#line 562 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>('\t'); }
 #line 3243 "src/ast/lex.cc"
 yy550:
 	++YYCURSOR;
-#line 562 "../src/ast/lex.re"
+#line 563 "../src/ast/lex.re"
 	{ return static_cast<uint8_t>('\v'); }
 #line 3248 "src/ast/lex.cc"
 yy552:
@@ -3307,7 +3307,7 @@ yy557:
 	}
 yy558:
 	++YYCURSOR;
-#line 555 "../src/ast/lex.re"
+#line 556 "../src/ast/lex.re"
 	{ return unesc_oct(tok, cur); }
 #line 3313 "src/ast/lex.cc"
 yy560:
@@ -3336,7 +3336,7 @@ yy561:
 	}
 yy562:
 	++YYCURSOR;
-#line 554 "../src/ast/lex.re"
+#line 555 "../src/ast/lex.re"
 	{ return unesc_hex(tok, cur); }
 #line 3342 "src/ast/lex.cc"
 yy564:
@@ -3362,7 +3362,7 @@ yy565:
 		goto yy554;
 	}
 }
-#line 570 "../src/ast/lex.re"
+#line 571 "../src/ast/lex.re"
 
 }
 
@@ -3440,7 +3440,7 @@ sourceline:
 		}
 	}
 	++YYCURSOR;
-#line 607 "../src/ast/lex.re"
+#line 608 "../src/ast/lex.re"
 	{
         --cur;
         tok = cur;
@@ -3450,12 +3450,12 @@ sourceline:
 yy570:
 	++YYCURSOR;
 yy571:
-#line 613 "../src/ast/lex.re"
+#line 614 "../src/ast/lex.re"
 	{ goto sourceline; }
 #line 3456 "src/ast/lex.cc"
 yy572:
 	++YYCURSOR;
-#line 602 "../src/ast/lex.re"
+#line 603 "../src/ast/lex.re"
 	{
         tok = cur;
         return;
@@ -3477,7 +3477,7 @@ yy576:
 	if (yybm[0+yych] & 64) {
 		goto yy576;
 	}
-#line 589 "../src/ast/lex.re"
+#line 590 "../src/ast/lex.re"
 	{
         if (!s_to_u32_unsafe (tok, cur, cline)) {
             fatal_lc(get_cline(), get_column(), "line number overflow");
@@ -3501,7 +3501,7 @@ yy581:
 	goto yy571;
 yy582:
 	++YYCURSOR;
-#line 596 "../src/ast/lex.re"
+#line 597 "../src/ast/lex.re"
 	{
         in.escaped_file_name = std::string (tok + 1, tok_len () - 2); // strip quotes
         strrreplace (in.escaped_file_name, "\\", "\\\\");
@@ -3516,7 +3516,7 @@ yy584:
 	if (yych == '\n') goto yy581;
 	goto yy579;
 }
-#line 614 "../src/ast/lex.re"
+#line 615 "../src/ast/lex.re"
 
 }
 
diff --git a/re2c/src/ast/lex.re b/re2c/src/ast/lex.re
index f891b09d..693e871b 100644
--- a/re2c/src/ast/lex.re
+++ b/re2c/src/ast/lex.re
@@ -133,6 +133,7 @@ echo:
     "/*!header:re2c:on" {
         out.wraw(tok, ptr);
         out.header_mode(true);
+        out.need_header = true;
         lex_end_of_comment(out);
         goto echo;
     }
diff --git a/re2c/src/code/output.cc b/re2c/src/code/output.cc
index 45490820..7c240dff 100644
--- a/re2c/src/code/output.cc
+++ b/re2c/src/code/output.cc
@@ -78,6 +78,7 @@ OutputFile::OutputFile(Warn &w)
     , state_goto(false)
     , cond_goto(false)
     , warn_condition_order(true)
+    , need_header(false)
     , warn(w)
 {}
 
@@ -431,13 +432,26 @@ static void foldexpr(std::vector<OutputFragment*> &frags)
     }
 }
 
-void OutputFile::emit_blocks(const std::string &filename,
-    FILE *file, blocks_t &blocks,
+bool OutputFile::emit_blocks(const std::string &fname, blocks_t &blocks,
     const uniq_vector_t<std::string> &global_types,
     const std::set<std::string> &global_stags,
     const std::set<std::string> &global_mtags,
     size_t max_fill, size_t max_nmatch)
 {
+    FILE *file = NULL;
+    std::string filename = fname;
+    if (filename.empty()) {
+        filename = "<stdout>";
+        file = stdout;
+    }
+    else {
+        file = fopen(filename.c_str(), "w");
+        if (!file) {
+            error("cannot open output file: %s", filename.c_str());
+            return false;
+        }
+    }
+
     fix_first_block_opts(blocks);
 
     unsigned int line_count = 1;
@@ -529,6 +543,9 @@ void OutputFile::emit_blocks(const std::string &filename,
             line_count += f.count_lines();
         }
     }
+
+    fclose(file);
+    return true;
 }
 
 static bool have_cond_frag(const blocks_t &blocks)
@@ -575,47 +592,24 @@ bool OutputFile::emit(size_t maxfill, size_t nmatch)
 
     // global options are last block's options
     const opt_t *opts = block().opts;
+    bool ok = true;
 
     // emit .h file
-    const std::string &header = opts->header_file;
-    if (!header.empty()) {
-        FILE *file = fopen(header.c_str(), "w");
-
-        if (!file) {
-            error("cannot open header file: %s", header.c_str());
-            return false;
-        }
-
-        emit_blocks(header, file, hblocks, conds, stags, mtags, maxfill, nmatch);
-
+    if (!opts->header_file.empty() || need_header) {
+        // old-style -t, --type-headers usage implies condition generation
         if (!conds.empty() && !have_cond_frag(hblocks)) {
-            std::ostringstream os;
+            std::ostream &os = hblocks.back()->fragments.back ()->stream;
             os << std::endl;
             output_types(os, 0, opts, conds);
-            fwrite(os.str().c_str(), 1, os.str().size(), file);
         }
 
-        fclose(file);
+        ok &= emit_blocks(opts->header_file, hblocks, conds, stags, mtags, maxfill, nmatch);
     }
 
     // emit .c file
-    FILE *file = NULL;
-    std::string filename = cblocks.back()->opts->output_file;
-    if (filename.empty()) {
-        filename = "<stdout>";
-        file = stdout;
-    }
-    else {
-        file = fopen(filename.c_str(), "w");
-        if (!file) {
-            error("cannot open output file: %s", filename.c_str());
-            return false;
-        }
-    }
-    emit_blocks(filename, file, cblocks, conds, stags, mtags, maxfill, nmatch);
-    fclose(file);
+    ok &= emit_blocks(opts->output_file, cblocks, conds, stags, mtags, maxfill, nmatch);
 
-    return true;
+    return ok;
 }
 
 Output::Output(Warn &w)
diff --git a/re2c/src/code/output.h b/re2c/src/code/output.h
index aea5ae91..965fcdeb 100644
--- a/re2c/src/code/output.h
+++ b/re2c/src/code/output.h
@@ -122,6 +122,7 @@ public:
     bool state_goto;
     bool cond_goto;
     bool warn_condition_order;
+    bool need_header;
     Warn &warn;
 
     explicit OutputFile(Warn &w);
@@ -167,8 +168,7 @@ public:
 
     bool emit(size_t max_fill, size_t max_nmatch);
 
-    void emit_blocks(const std::string &filename,
-        FILE *file, blocks_t &blocks,
+    bool emit_blocks(const std::string &fname, blocks_t &blocks,
         const uniq_vector_t<std::string> &global_types,
         const std::set<std::string> &global_stags,
         const std::set<std::string> &global_mtags,
diff --git a/re2c/test/header/header_03.c b/re2c/test/header/header_03.c
new file mode 100644
index 00000000..03278441
--- /dev/null
+++ b/re2c/test/header/header_03.c
@@ -0,0 +1,28 @@
+/* Generated by re2c */
+#line 1 "header/header_03.re"
+#line 1 "header/header_03.re"
+
+
+#line 6 "header/header_03.re"
+
+
+#include "header_03.h"
+
+void lex(const YYCTYPE *YYCURSOR)
+{
+    
+#line 15 "header/header_03.c"
+{
+	YYCTYPE yych;
+	yych = *YYCURSOR++;
+#line 14 "header/header_03.re"
+	{ return; }
+#line 21 "header/header_03.c"
+}
+#line 15 "header/header_03.re"
+
+}
+/* Generated by re2c */
+
+#define YYCTYPE char
+void lex(const YYCTYPE *);
diff --git a/re2c/test/header/header_03.re b/re2c/test/header/header_03.re
new file mode 100644
index 00000000..fc9fba32
--- /dev/null
+++ b/re2c/test/header/header_03.re
@@ -0,0 +1,16 @@
+/*!re2c re2c:flags:type-header = "header_03.h"; */
+
+/*!header:re2c:on*/
+#define YYCTYPE char
+void lex(const YYCTYPE *);
+/*!header:re2c:off*/
+
+#include "header_03.h"
+
+void lex(const YYCTYPE *YYCURSOR)
+{
+    /*!re2c
+        re2c:yyfill:enable = 0;
+        * { return; }
+    */
+}
-- 
2.40.0