title: vscode cannot find header when compile while Intellisense can
body: <p><strong>Question Updated:</strong>
  I'm trying to build a c++ project on vscode using the C/C++ extension. The compiler complains about not finding header files (actually boost headers). I have included path to the root folder of boost, and Intellisense is also able to parse the header paths, but not the compiler. I checked the included header in my source is in the corresponding path in my filesystem. Is there any solution to make the compiler see the include headers?</p>
  
  <p>This is my <code>c_cpp_properties.json</code> file:</p>
  
  <pre><code>{
      "configurations": [
          {
              "name": "Win32",
              "includePath": [
                  "${workspaceFolder}/**",
                  "C:/Users/zz_ro/Documents/source/boost_1_70_0"
              ],
              "defines": [
                  "_DEBUG",
                  "UNICODE",
                  "_UNICODE"
              ],
              "windowsSdkVersion": "10.0.17763.0",
              "compilerPath": "C:/mingw/bin/g++.exe",
              "cStandard": "c11",
              "cppStandard": "c++11",
              "intelliSenseMode": "gcc-x64"
          }
      ],
      "version": 4
  }
  </code></pre>
  
  <p>and this is my <code>helloworld.cpp</code> file:</p>
  
  <pre class="lang-cpp prettyprint-override"><code>#include "boost/math/constants/constants.hpp"
  #include "boost/multiprecision/cpp_dec_float.hpp"
  #include &lt;iostream&gt;
  #include &lt;limits&gt;
  int main()
  {
      using boost::multiprecision::cpp_dec_float_50;
      cpp_dec_float_50 seventh = cpp_dec_float_50(1) / 7;
      std::cout.precision(std::numeric_limits&lt;cpp_dec_float_50&gt;::digits10);
      std::cout &lt;&lt; seventh &lt;&lt; std::endl;
  }
  </code></pre>
  
  <p>And here is the compiler output:</p>
  
  <pre><code>helloworld.cpp:1:46: fatal error: boost/math/constants/constants.hpp: No such file or directory
   #include "boost/math/constants/constants.hpp"
                                                ^
  compilation terminated.
  The terminal process terminated with exit code: 1
  </code></pre>
  
  <p>If I change my <code>tasks.json</code> from</p>
  
  <pre><code>{
      // See https://go.microsoft.com/fwlink/?LinkId=733558
      // for the documentation about the tasks.json format
      "version": "2.0.0",
      "tasks": [
          {
              "label": "build hello world",
              "type": "shell",
              "command": "g++",
              "args": [
                  "-g",
                  "helloworld.cpp",
                  "-o",                               
                  "helloworld"                
              ],
              "group": {
                  "kind": "build",
                  "isDefault": true
              }
          }
      ]
  }
  </code></pre>
  
  <p>to </p>
  
  <pre><code>{
      // See https://go.microsoft.com/fwlink/?LinkId=733558
      // for the documentation about the tasks.json format
      "version": "2.0.0",
      "tasks": [
          {
              "label": "build hello world",
              "type": "shell",
              "command": "g++",
              "args": [
                  "-g",
                  "-IC:\\Users\\zz_ro\\Documents\\source\\boost_1_70_0", 
                  "helloworld.cpp",
                  "-o",                               
                  "helloworld"                
              ],
              "group": {
                  "kind": "build",
                  "isDefault": true
              }
          }
      ]
  }
  </code></pre>
  
  <p>by just manually passing the include path as an argument to <code>g++.exe</code> and the compilation will go through. It confuses me that in the tutorial (<a href="https://code.visualstudio.com/docs/cpp/config-mingw#_next-steps" rel="noreferrer">vscode tutorial</a>) there is no mention about manually inserting include path to <code>g++.exe</code> via command line parameters, where all of these are supposed to be done by modifying the includePath variable in <code>c_cpp_property.json</code>. Did I misunderstand the tutorial or I didn't set the includePath value properly?</p>