The following reply was made to PR bin/36444; it has been noted by GNATS.

From: christos@zoulas.com (Christos Zoulas)
To: gnats-bugs@NetBSD.org, gnats-admin@netbsd.org,
	netbsd-bugs@netbsd.org
Cc: 
Subject: Re: bin/36444: flex generates bad C++ code
Date: Tue, 5 Jun 2007 10:56:33 -0400

 On Jun 5,  2:30pm, mlelstv@serpens.de (mlelstv@serpens.de) wrote:
 -- Subject: bin/36444: flex generates bad C++ code
 
 | >Number:         36444
 | >Category:       bin
 | >Synopsis:       flex generates bad C++ code
 | >Confidential:   no
 | >Severity:       serious
 | >Priority:       medium
 | >Responsible:    bin-bug-people
 | >State:          open
 | >Class:          sw-bug
 | >Submitter-Id:   net
 | >Arrival-Date:   Tue Jun 05 14:30:01 +0000 2007
 | >Originator:     Michael van Elst
 | >Release:        NetBSD 4.0_BETA2
 | >Organization:
 | -- 
 |                                 Michael van Elst
 | Internet: mlelstv@serpens.de
 |                                 "A potential Snark may lurk in every tree."
 | >Environment:
 | 	
 | 	
 | System: NetBSD henery 4.0_BETA2 NetBSD 4.0_BETA2 (HENERY) #1: Sun Jun 3 12:09:36 CEST 2007 mlelstv@henery:/home/netbsd4/obj/home/netbsd4/src/sys/arch/i386/compile/HENERY i386
 | Architecture: i386
 | Machine: i386
 | >Description:
 | 
 | When compiling a flex source from the net/irrtoolkit-nox11 package,
 | I get an error message from the C++ compiler about the ambigous
 | call to an overloaded function.
 | 
 | >How-To-Repeat:
 | 
 | Here is a test case that shows the problem:
 | 
 | -------- snip --------
 | %option case-insensitive
 | 
 | %{
 | #include <cstdio>
 | #include <cstring>
 | %}
 | 
 | %%
 | 
 | [A-Z][A-Z0-9]* {
 | 	printf("word = %s\n",yytext);
 | }
 | 
 | %%
 | 
 | class Object {
 | public:
 | 	char *contents;
 | 	unsigned long size;
 | 	Object(const char buf[]) {
 | 		contents = strdup(buf);
 | 		size = strlen(buf);
 | 	}
 | };
 | 
 | int length(const char *s)
 | {
 | 	return strlen(s);
 | }
 | 
 | int main() {
 | 	Object *o = new Object("1 Word");
 | 	void *p;
 | 	p = yy_scan_bytes(o->contents, o->size);
 | 	BEGIN(INITIAL);
 | }
 | 
 | extern "C" {
 | int yywrap() {
 | 	return 1;
 | }
 | }
 | -------- snip --------
 | 
 | % flex c.l
 | % % c++ lex.yy.c 
 | c.l: In function 'int main()':
 | c.l:34: error: call of overloaded 'yy_scan_bytes(char*&, long unsigned int&)' is ambiguous
 | lex.yy.c:1321: note: candidates are: yy_buffer_state* yy_scan_bytes(const char*, yy_size_t)
 | lex.yy.c:1355: note:                 yy_buffer_state* yy_scan_bytes(const char*, int)
 | 
 | The reason for this is a change in src/usr.bin/lex/flex.skl:1.21
 | 
 | | Traditional flex uses int instead of yy_size_t for some api functions.
 | | Unfortunately this mangles differently in c++, so we get undefined symbols.
 | | So we define the old function prototype to keep things happy.
 | 
 | This creates function duplicates for C (using yy_size_t) and C++ (using int)
 | that cause the ambiguity.
 | 
 | >Fix:
 | 
 | Reverting the change in flex.skl:1.21 solves the problem.
 
 The problem should be fixed by changing:
 
  	unsigned long size;
 to:
 	yy_size_t size;
 or:
 	int size;
 or even:
 	size_t size;
 	
 We could add a few more yy_scan_bytes() functions so that we have explicit
 matches for unsigned long and long, but it is not worth the trouble. Passing
 a long where an int is expected is not a good practice anyway.
 
 christos