title: What can I do about "missing ; before X" cascade of errors?
body: <p>I'm not sure what did I do wrong, but suddenly my C++ project throws error for every single line of header files in certain part of that project. There must be something wrong in one of those files, but how am I supposed to find out which of these hundred errors is relevant?</p>
  
  <p>Log looks like:</p>
  
  <pre><code>5&gt;d:\ ... PROJECT_HOME ... \services\src\services\database\techcore\processes\inputdialog\../import/ImportDataSource.h(10): error C2143: syntax error : missing ',' before ')'
  5&gt;d:\ ... PROJECT_HOME ... \services\src\services\database\techcore\processes\inputdialog\../import/ImportDataSource.h(16): error C3861: 'mapping_': identifier not found
  5&gt;d:\ ... PROJECT_HOME ... \services\src\services\database\techcore\processes\inputdialog\../import/ImportDataSource.h(17): error C2143: syntax error : missing ',' before '{'
  5&gt;d:\ ... PROJECT_HOME ... \services\src\services\database\techcore\processes\inputdialog\../import/ImportDataSource.h(17): error C2143: syntax error : missing ';' before '{'
  5&gt;c:\qt\5.3.0-64\qtbase\include\qtwidgets\../../src/widgets/kernel/qaction.h(162): error C2143: syntax error : missing ';' before '{'
  5&gt;c:\qt\5.3.0-64\qtbase\include\qtwidgets\../../src/widgets/kernel/qaction.h(162): error C2065: 'Hover' : undeclared identifier
  5&gt;d:\ ... PROJECT_HOME ... \services\src\services\database\techcore\processes\inputdialog\../import/ImportDataSource.h(30): error C2143: syntax error : missing ';' before '{'
  5&gt;c:\qt\5.3.0-64\qtbase\include\qtwidgets\../../src/widgets/kernel/qaction.h(177): error C2065: 'QGraphicsWidget' : undeclared identifier
  </code></pre>
  
  <p>I intentionally copied part where errors also come from external libraries. The compiler has simply gone crazy. How can I resolve this? How do I find the place that causes this cascade of errors? Is there some validator that could process the files and give mi some hints? I went through most of the files manually and they seem to be correct.</p>
  
  <p>This is not the first time this happened to me, so I decided it's time to ask how to generally solve these problems.</p>