Support for autoconf config.h

[ghost]

Autoconf minimises the number of compiler define (-D) flags needed by adding them to a file config.h generated by the autoheader tool. This tiny patch adds support for this mechanism (while not affecting non-autoconf builds).

[jtsiomb]

Hello!
I don't understand, what's the point of adding that conditional config.h include, if the library doesn't use autoconf to build?

Also you can't just add a config.h file willy nilly in the public header file of a library which is going to be installed system-wide. You need to also install the config.h file for that to work. But if you do that, you would also have to change installation and usage, instead of a single $(PREFIX)/include/kdtree.h file, a whole directory would be needed to avoid conflicts with other config.h files. Which would lead to changes in user programs having to include kdtree/kdtree.h instead of just kdtree.h.

I have done all that in the past if there is a benefit to it. But what would we gain in kdtree's case by all that breakage?

[ghost]

Hi John

It is just to ease the use-case where kdtree is incorporated into a project which does use autoconf, for example https://github.com/jjgreen/vfplot/blob/master/src/libkdtree/ (there I modify the c file to have the include). Note the change is not to the public header file, but to the c file, so only used to pass compile-time options to the functions therein. There's no suggestion of including or installing the config.h publicly.

It's not great amount of work for me to add the include when I update kdtree; I just thought the facility might be useful of others -- please feel free to close this if you disagree!

[jtsiomb]

My mistake, for some reason I thought it was in the header file. In kdtree.c it's pretty innocuous, and if it helps the use case of integrating into a 3rd-party project, I might as well add that.