[CMake] AUTOMOC with files on different folders

[Attila Krasznahorkay]

Hi Tiago,

Indeed, that page is quite a bit misleading. And it seems to be "liked" by Google a lot, as most people come across it. (I also found it myself when looking for CMake documentation early on.)

In general, listing all source files belonging to a library/executable, even the ones that are not compiled, is a good habit. As it makes the generated VS and Xcode projects much nicer to use.

I didn't look at the internals of the Qt CMake code. I just realised this behaviour while trying to make our own code work. (It's an intuitive behaviour, so it wasn't too hard to figure out.) I guess the code has some fallback to search for headers in the same place as their corresponding source file. Which can make the project still work without declaring the header files, as long as they are in the same directory with the source files. I imagine that doing something more complicated to look for the headers would not be so easy. (I can't even think of a reliable way of doing it myself. You can't just rely on the include paths of your component, as that would introduce a lot of possible problems.)

All in all, I just accepted this behaviour as-is.

Cheers,
           Attila

> On 12 May 2016, at 05:20, Hendrik Sattler <post at hendrik-sattler.de> wrote:
> 
> 
> 
> Am 12. Mai 2016 00:00:12 MESZ, schrieb Tiago Macarios <tiagomacarios at gmail.com>:
>> Hi Attila,
>> 
>> Thank you for your help. You are right, if I apply the following
>> modifications it works indeed:
>> 
>> set( proj_HEADER
>>   include/a.h
>> )
>> 
>> add_library(proj SHARED ${proj_SOURCE} ${proj_HEADER})
>> 
>> But now I got a second question. Why is adding the header files
>> necessary?
>> (Sorry the possibly naive question)
>> 
>> I thought that adding the header files to the target was an
>> anti-pattern (
>> http://voices.canonical.com/jussi.pakkanen/2013/03/26/a-list-of-common-cmake-antipatterns/
>> ). Is it related to moc generating header files during the build? If so
>> why
>> is it not a problem when everything is on the same folder?
> 
> That same page has a Errata section at the end. 
> 
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