id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
4510	[program_options]: implicit_value and positional options conflict	Soren Soe <soren.soe@…>	Vladimir Prus	"Hello,

Thanks for a great library.  
I just updated to 1.43 and it appears options with implicit values no longer work if there are also positional options.


In fact libs/src/program_options/example/options_description.cpp fails in 1.43:

{{{
1.43% options_description --verbose foo
in option 'verbose': invalid option value
}}}

In 1.38 this worked fine

{{{
1.38% options_description --verbose foo
Input files are: foo
Verbosity enabled.  Level is 1
Optimization level is 10
Listen port is 0
}}}

I briefly looked at the library source code and see new code added in cmdline.cpp: 

{{{
 /* If an key option is followed by a positional option,
     can can consume more tokens (e.g. it's multitoke option),
    give those tokens to it.  */
 ...
}}}

It seems that in order to make implicit options work in presence of positional options, the semantic()->max_tokens() function must return 0, that is, you can never specify a value for an implicit option.   I don't know if this is desired, but it will work for me.

Thank you,

Soren Soe"	Bugs	new	Boost 1.44.0	program_options	Boost 1.44.0	Problem