personal header files are not found if they are alphabetically first in the folder.

[andrewdavidjamesburke]

Given an arduino file named:

m.ino

Now, should you have your own includes in the same directory, for example:

s.h
t.h

There will be no issue importing them.

#include "s.h"
#include "t.h"

However, should they be named as such:

#include "a.h"
#include "t.h"

I am recieving an error in this situation:

'a.h' No such file or directory.

renaming it to a number that alphabetically larger than the source file m.ino and deleting the c_cpp_properties.json and the output folder, results in a build that once again, works.

I am not sure if the is an arduino thing, or vscode thing, but its definitely a bug, at least for me.
I do not wish to use external library folders.

[adiazulay]

I seem to remember a similar issue to this, and I think this happens if your parent directory name doesn't match the name of the .ino file.

[benmcmorran]

I can reproduce this behavior, but only when the .ino file is named differently than the parent directory (e.g. sketch.ino in a directory named myproject doesn't work, but myproject.ino does). The requirement that the sketch and directory have the same name comes from Arduino itself and is unlikely to change. @Triangle4 does renaming your sketch or parent directory solve the issue?

[andrewdavidjamesburke]

Thank you, I had no idea that requirement existed! I had a feeling it had to be something simple.

[benmcmorran]

Glad that works! I opened #1448 to track improving the warnings in the extension for this case.