include_dir_vs_header_files.md

Include directory vs Header files

From our target.fbs schema we can see that we track both include_dirs and header_files

header_files:[path]
include_dirs:[string]

Short explanation

• header_files are used to track rebuilds when specific header files are added, removed and updated.
  • This lets use easily track when header files are updated with user input.
• include_directories are used to track rebuilds when include directory is added or removed.
  • This is required by our compiler with the -I flag.

Long explanation

D:.
│   target.h
│
└───internal
        fbs_loader.h
        path.h
        util.h

Depending on the above tree we might choose to just add -I. to our build.

We can now #include our header files in this format

#include "target.h"
#include "internal/fbs_loader.h"
#include "internal/path.h"
#include "internal/util.h"

However when just adding -I. to our build we cannot accurately track header files for rebuilds i.e specifically the header files present inside the internal folder.

Recursively parsing the tree and tracking header files over -I. (in this case) would be computationally expensive.

We might potentially track header files that are not explicitly required by our project if recursive parsing is used.

This can be solved by tracking individual header files per target for rebuilds.