Install header files under /usr/include/h3 (!2) · Merge requests · PostgreSQL / libh3 · GitLab

The header files such as h3api.h should not be installed under /usr/include, but /usr/include/h3/h3api.h.

Why it should be? it seems that there is 2 use-cases.

Install header files under /usr/include/h3. use it from application

Official example do that (include <h3/h3api.h>):

https://github.com/uber/h3/blob/1d5346bb30082e10b8da60a6d288bc1998295d61/examples/edge.c#L21

for Debian package, this is right solution.
Use vendored h3 header file from application.

h3api.h is not placed under h3 in source tree (src/h3lib/include/h3api.h), so if you use vendored version of h3, include <h3api.h> is correct.

For example, h3-pg is designed to use with vendored h3.

https://github.com/postgis/h3-pg/blob/main/cmake/h3/CMakeLists.txt

Thus, using from third-party application (not limited hg-pg), libh3-dev should install header files under /usr/include/h3 as system-wide.