title: meson.build: ERROR: File does not exist, while in reality it does
body: <p>From a trivial <code>meson.build</code> file, I get the following error:</p>
  
  <blockquote>
    <p>meson.build:27:0: ERROR: File dataStructures.hpp does not exist.</p>
  
  <pre><code>dataStructures.hpp,
  </code></pre>
  </blockquote>
  
  <p>The <code>meson.build</code> file is:</p>
  
  <pre><code>headers += [
      'dataStructures.hpp',
      'interface.hpp',
      'platform.hpp',
      'progArgs.hpp',
  ]
  </code></pre>
  
  <p>The file reported as missing is present and it is in the same directory the meson.build file is.</p>
  
  <p>If I remove the 'dataStructures.hpp' string from the list, I get the same error for the second file 'interface.hpp'.</p>
  
  <p>What am I doing wrong?</p>
  
  <hr>
  
  <p>More details follow.</p>
  
  <pre><code>&gt; 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
  </code></pre>
  
  <p>In the full log there is no much more than what already reported.</p>
  
  <p>This is the project directory structure:</p>
  
  <pre><code>test/
     meson.build
     src/
         meson.build
         sources
         config/
              meson.build
              sources
         testers/
              meson.build
              sources
         utilities/
              meson.build
              sources
  </code></pre>