[cfe-dev] Passing argv to loadFromCommandLine

[Daniel Dilts]

I was able to pass it the following way, but const_cast makes me cringe.

FixedCompilationDatabase::loadFromCommandLine(argc, const_cast<const
char**>(argv))

On Wed, Apr 15, 2015 at 3:32 PM, Daniel Dilts <diltsman at gmail.com> wrote:

> The problem is that the standard only guarantees that int main(int argc,
> char *argv[]) will be accepted as the signature of main.  Yes, most
> compilers will accept anything that it can decay to const char** argv, but
> that is not guaranteed to work.
>
> I often work with compilers that are of questionable quality (the joys of
> embedded systems).  I don't really trust them to follow the standard
> correctly, and I certainly don't trust them to do something intuitive like
> allowing additional qualifiers on argv.
>
>
> On Wed, Apr 15, 2015 at 3:19 PM, Reid Kleckner <rnk at google.com> wrote:
>
>> Sounds like MSVC is worried you might store pointers to const char *'s
>> into your argv array, and then it would lose const qualifiers. Clang gives
>> a good diagnostic:
>>
>> $ cat t.cpp
>> void f(const char **);
>> int main(int argc, char *argv[]) {
>>   f(argv);
>> }
>>
>> $ clang -c t.cpp
>> t.cpp:3:3: error: no matching function for call to 'f'
>>   f(argv);
>>   ^
>> t.cpp:1:6: note: candidate function not viable: no known conversion from
>> 'char **' to 'const char **' for 1st argument
>> void f(const char **);
>>      ^
>>
>> Maybe use 'const char *argv[]' if you don't intend to modify argv?
>>
>> On Wed, Apr 15, 2015 at 2:37 PM, Daniel Dilts <diltsman at gmail.com> wrote:
>>
>>> I am attempting to call FixedCompilationDatabase::loadFromCommandLine.
>>> Seems pretty straight forward:
>>>
>>> FixedCompilationDatabase::loadFromCommandLine(argc, argv);
>>>
>>> In VS2013 this gives me an error:
>>>
>>> cannot convert argument 2 from 'char *[]' to 'const char **'
>>>
>>> I am using the following signature of main (3.6.1/2 C++11 standard):
>>>
>>> int main(int argc, char* argv[])
>>>
>>> It seems that the compiler should be able to do the conversion
>>> implicitly, but it isn't.  Is this how it is supposed to work?  If it is,
>>> should the signature of loadFromCommandLine change so that argv can be
>>> passed directly?
>>>
>>> _______________________________________________
>>> cfe-dev mailing list
>>> cfe-dev at cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>>>
>>>
>>
>
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