[CMake] Where do all the extra clang flags come from in Xcode?

[Ruslan Baratov]

On 18-May-15 15:20, Paul Smith wrote:
> On Mon, 2015-05-18 at 12:32 +0200, Ruslan Baratov via CMake wrote:
>> This table tells you what attribute you need to set to disable/enable
>> specific warning.
> I see, so these are CMake attributes?  That wasn't clear to me.  I
> thought they were attributes of Xcode.
Please take a look at examples I've sent earlier. I have no idea how I 
can make it even more clearer.
>
> I guess my basic question is, why are all these extra flags to disable
> and enable various warnings set in the Xcode generator?
As far as I know this is Xcode defaults. So I guess you need to ask 
Apple's Xcode support team.
>    I expected it
> would work like the makefile generator, where if you don't set any flags
> in CMakeLists.txt then you don't get any warnings enabled (or explicitly
> disabled).  It surprises me that when I take the same CMakeLists.txt
> file and use a Makefile generator and an Xcode generator, I get very
> different compile lines.
I guess you can open a bug with feature request. Note that only it's not 
enough to just set all this attributes to YES, but also you need to read 
compiler flags (+ build types) and change attributes accordingly.
E.g. -Wno-enum-conversion in CMAKE_CXX_FLAGS automatically must add 
property `XCODE_ATTRIBUTE_CLANG_WANR_ENUM_CONVERSION NO` to all targets.
>
> And secondarily, is there any way to get the Xcode generator to work
> like the Makefile generator, where only the warning flags I explicitly
> defined in my CMakeLists.txt file are added to the compile/link lines
> and no others?
>
Again. Take a look at examples I've sent earlier. The helper function 
works exactly like you want. This is the only way known to me to achieve 
this nicely.

Cheer, Ruslo