[Qt-creator] Compiling Qt Creator in under 3 minutes

[Christian Kandeler]

On 05/21/2014 09:28 PM, Jussi Pakkanen wrote:
> On Wed, May 21, 2014 at 10:10 PM, André Pönitz <apoenitz at t-online.de
> <mailto:apoenitz at t-online.de>> wrote:
>
>     I am not sure I understood what the unity build does. Closest I can
>     imagine
>     is that it concatenates some (or all?) translation units into one
>     and tries
>     to compile the result. Of course that would not work with normal C++
>     projects
>     but would impose rather harsh restriction on naming conventions and code
>     structure, so this can't be what is meant as this interpretation
>     conflicts
>     with the "in theory unity builds should not require any code changes".
>
>
> There is a more involved explanation in Meson wiki:
>
> https://sourceforge.net/p/meson/wiki/Unity%20builds/

"There may also be some bugs in the source that need to be fixed before 
Unity compiles work. As an example, if both src1.c and src2.c contain a 
static function or variable of the same name, there will be a clash."

How on earth is that a bug? That's a perfectly legal and normal thing to 
do, as the concept of translation units is well-defined. By merging them 
all together, one can probably even introduce subtle semantic changes 
(though admittedly that's just a gut feeling, I don't have a concrete 
example).
What is the use case anyway? I guess it can only be an area where 
incremental builds are irrelevant. CI?


Christian