Re: EPICS 3.15.9 build system weird behaviour upon missing g++

[Andrew Johnson via Tech-talk <tech-talk at aps.anl.gov>]

Hi Dmitry,

On 4/30/23 12:51 AM, Dmitry Yu. Bolkhovityanov via Tech-talk wrote:

Well, that's an elegant albeit a rather non-obvoius implementation.

It's a pity this isn't described somewhere in documentation.  Computed variable names, while giving much flexibility, are extremely tricky and turn Makefiles into difficult to study, plus "double-indirect" references entangle things even more (you can't find anything until you know exactly what to find).

Actually there is documentation for some aspects of the build system. The Build Facility chapter of the EPICS Application Developers guide isn't perfectly up to date (even to the 3.15.9 release you're using) but it does cover most of the features that are intended to be available to Makefile authors. Unfortunately the architect and author of much of the code retired quite a few years ago and wasn't able to complete an update of that document before she left, but there are things in that document which show why we use computed variable names (it just wouldn't be possible to provide the flexibility it gives us without using that mechanism or using an external preprocessor like CMake).

- Andrew

-- 
Complexity is free, it's Simplicity that takes work.