meson.build: ERROR: File does not exist, while in reality it does - meson-build

Question

From a trivial meson.build file, I get the following error:
meson.build:27:0: ERROR: File dataStructures.hpp does not exist.
dataStructures.hpp,
The meson.build file is:
headers += [
'dataStructures.hpp',
'interface.hpp',
'platform.hpp',
'progArgs.hpp',
]
The file reported as missing is present and it is in the same directory the meson.build file is.
If I remove the 'dataStructures.hpp' string from the list, I get the same error for the second file 'interface.hpp'.
What am I doing wrong?
More details follow.
> CC=clang CXX=clang++ meson /dev/shm/test-build
The Meson build system
Version: 0.52.0
Source dir: /home/pietrom/myProgs/test
Build dir: /dev/shm/test-build
Build type: native build
Project name: test
Project version: 0.0.1
C++ compiler for the host machine: clang++ (clang 8.0.1 "clang version 8.0.1 (tags/RELEASE_801/final)")
C++ linker for the host machine: GNU ld.bfd 2.32
Host machine cpu family: x86_64
Host machine cpu: x86_64
src/meson.build:27:0: ERROR: File dataStructures.hpp does not exist.
A full log can be found at /dev/shm/test-build/meson-logs/meson-log.txt
In the full log there is no much more than what already reported.
This is the project directory structure:
test/
meson.build
src/
meson.build
sources
config/
meson.build
sources
testers/
meson.build
sources
utilities/
meson.build
sources

Answer 1

As you don't provide all meson.build file contents, and most importantly the place where it happens - meson.build:27:0: ERROR: File dataStructures.hpp does not exist. - points at line 27 in some meson.build file, I'll try to make a guess that you build executable in root meson.build file, i.e. in test/meson.build however your headers are inside test/src. If that's the case, you don't need to have this array of headers at all, just add
inc = include_directories('./src')
some_test_exe = executable('mytest',
test_sources,
...
include_directories : inc
)
include_directories function creates include object with path relative to your source root.