[cfe-dev] New warning for mismatched include case

[Chris Lattner]

On Jul 24, 2012, at 12:40 PM, Jason Haslam wrote:

> On Jul 23, 2012, at 7:00 PM, Chris Lattner wrote:
> 
>> 
>> On Jul 23, 2012, at 9:16 AM, Jason Haslam wrote:
>> 
>>> This updated patch adds a fixit and a test. The test fails on case-sensitive systems. Is it possible to test for an error on some platforms and a warning on others?
>> 
>> Very cool, it would be really great to get this warning.  However, there is high risks of slowing down compile times here, have you done any analysis of the compile-time cost of this?
> 
> I have done some performance testing. I see less than 1% slowdown over parts of LLVM. For example, I build the LLVMSupport library repeatedly until the build time becomes more-or-less consistent. Then do the same thing with the warning enabled. I don't know if there's a better way to test this.

This is with the warning enabled, right?  I haven't looked closely at the implementation yet, but you're doing entire directory scans to resolve the original case.  I'm not aware of a better way to find the original case, but this is very delicate.  It is not uncommon to include hundreds of headers in dozens of different directories.

-Chris