Accept const char*[] argv in Args constructor

[ronen]

This makes it easier to run tests using string literals.

Currently this fails:

const char *v[] = { "arg0", "arg1" };
Args(2, v);          #   error: invalid conversion from 'const char**' to 'char**' 

and this warns (fails if you fail on warnings):

char *v[] = { "arg0", "arg1" };  # warning: ISO C++ forbids converting a string constant to 'char*' 
Args(2, v);         

And so the only workable solution is to use const_cast

[codecov[bot]]

Codecov Report

Merging #56 into master will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #56   +/-   ##
=======================================
  Coverage   93.69%   93.69%           
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  Files           2        2           
  Lines         682      682           
=======================================
  Hits          639      639           
  Misses         43       43

Impacted Files	Coverage Δ
include/clara.hpp	91.86% <ø> (ø)	:arrow_up:

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[philsquared]

Thanks for this. I've been meaning to get to it anyway. However, because we need to be able to pass the args in as they come from main(), the standard signature of which uses non-const char arrays, this needs to be provided as an overload, rather than just changing the signature (in fact, some time ago - in the previous version of Clara IIRC - I did have the const in there, but it broke too many people).

So I've now added it as an overload (char const** and char**, to make them easier to interoperate).

https://github.com/catchorg/Clara/commit/caff01f4e38222bf905ea3db49748bf824835edf

[horenmar]

Actually IIRC you should be able to do char const * const * and accept std main arguments that way.

[philsquared]

that's not been my experience

[philsquared]

With just:

Args( int argc, char const** argv ) { /* ... */ }

char* args[] = { (char*)"TestApp", (char*)"hello" };
auto result = cli.parse( Args( 2, args ) );

ClaraTests.cpp:423:34: error: no matching constructor for initialization of 'clara::detail::Args'
        auto result = cli.parse( Args( 2, args ) );

[philsquared]

wait - missed a const - adding that in makes it work - yet it hasn't done previously. Need to check back...

[philsquared]

I can't find any record of the const* const* version being reported as a problem - and it works on all the compilers we claim to support - so I must have dreamt it! In which case I'm certainly in favour of using that signature as the simplest (and most expressive) option! Thanks.

[ronen]

cool thx