[cfe-dev] QOI issue for -Wchar-subscripts?

[Marshall Clow]

Given the following bit of code:

> #include <iostream>
> 
> const char k12 = '\014';
> 
> int main( int argc, char *argv [] )
> {
> 	char str[80];
> 	char c = 45;
> 	
> 	str [ '\n' ] = 'a';
> 	str [   23 ] = 'b';
> 	str [  k12 ] = 'c';
> 	str [    c ] = 'd';
> 	
>    return 0;
> }
> 

and the following invocation:
> clang++ ~/junk.cpp -o ~/junk     -Wchar-subscripts ; ~/junk

How many warnings should be emitted?

My answer: 
	Probably one. Maybe two, since 'k12' is also a char - but it's a constant.

What does clang do?
> /Users/marshall/junk.cpp:10:6: warning: array subscript is of type 'char' [-Wchar-subscripts]
>         str [ '\n' ] = 'a';
>             ^ ~~~~
> /Users/marshall/junk.cpp:12:6: warning: array subscript is of type 'char' [-Wchar-subscripts]
>         str [  k12 ] = 'c';
>             ^  ~~~
> /Users/marshall/junk.cpp:13:6: warning: array subscript is of type 'char' [-Wchar-subscripts]
>         str [    c ] = 'd';
>             ^    ~
> 3 warnings generated.

Warning on str [ '\n' ] just doesn't seem to be helpful to me.
[ Note: clang emits only two warnings when compiling this code as C ]

What do other people think?

-- Marshall

Marshall Clow     Idio Software   <mailto:mclow.lists at gmail.com>

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