[erlang-bugs] R12B-3 +native pattern-matching bug

Mikael Pettersson <>
Fri Aug 8 20:25:06 CEST 2008


Kristoffer Warming writes:
 > Hi :)
 > 
 > I am seeing faulty pattern matching in Erlang apps compiled to R12B-3
 > with +native, on 64-bit. Applies to older versions as well
 > 
 > More specificially this happens in Mochiweb in mochiweb_http.erl:request/2
 > Here is the code:
 > 
 > request(Socket, Body) ->
 >     case gen_tcp:recv(Socket, 0, ?IDLE_TIMEOUT) of
 >         {ok, {http_request, Method, Path, Version}} ->
 > 
 > headers(Socket, {Method, Path, Version}, [], Body);
 >         {error, {http_error, "\r\n"}} ->
 > 
 > request(Socket, Body);
 >         {error, {http_error, "\n"}} ->
 > 
 > request(Socket, Body);
 >         _Other ->
 > 
 > io:format("~nOther = ~p~n", [_Other]),   %my debug line
 > 
 > gen_tcp:close(Socket),
 >             exit(normal)
 >     end.
 > 
 > I put debugline under the default condition, to see what the case was.
 > Oddly enough it gave me this output:
 > 
 > Other = {ok,{http_request,'GET',{abs_path,"/"},{1,1}}}
 > 
 > which is a perfect match for the first condition.
 > ...And It matches up just fine, if not compiled with +native
 > 
 > I also tried replacing the {http_request,Method,Path,Version} pattern with
 > _Message, and that gave a successful a match. _Message contained the same as
 > Other (without the 'ok')
 > 
 > To reproduce: grab Mochiweb source code (r84 of this writing), append
 > +native to ERLC_FLAGS in support/include.mk. Execute
 > `scripts/new_mochiweb.erl foo` to get skeleton files, and append
 > +native to foo/support/include.mk. here as well.
 > make,  and ./start-dev.sh

It would help if you could supply a small standalone test case.



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