Blueprint for language specs system

Current ModelManagerInterface::ProjectPart has following problems:

• Pure C can be set only for whole ProjectPart. Objective C headers and objective C++ headers/sources cannot be set.
• C++ language extensions not handled.
• Project managers for autotools and cmake assume that any file is C++ source
• ProjectManager can use only C++ flags and must ignore C/ObjC/ObjC++ flags.
• QMake project manager doesn’t read OBJECTIVE_HEADERS variable

How clang can handle different languages:

• Clang supports 4 languages: C, C++, ObjectiveC and ObjectiveC++. Each language has headers and implementation files. Like in such code:
  
  1. QStringList ClangCodeModel::Utils::clangLanguageOption(bool cxxEnabled,
  2.                                                       bool isHeader,
  3.                                                       bool isObjC)
  4. {
  5.     QStringList opts;
  6.     opts += QLatin1String("-x");
  7.  
  8.     if (cxxEnabled && isHeader && isObjC)
  9.         opts += QLatin1String("objective-c++-header");
  10.     else if (!cxxEnabled && isHeader && isObjC)
  11.         opts += QLatin1String("objective-c-header");
  12.     else if (cxxEnabled && !isHeader && isObjC)
  13.         opts += QLatin1String("objective-c++");
  14.     else if (!cxxEnabled && !isHeader && isObjC)
  15.         opts += QLatin1String("objective-c");
  16.     else if (cxxEnabled && isHeader && !isObjC)
  17.         opts += QLatin1String("c++-header");
  18.     else if (!cxxEnabled && isHeader && !isObjC)
  19.         opts += QLatin1String("c-header");
  20.     else if (cxxEnabled && !isHeader && !isObjC)
  21.         opts += QLatin1String("c++");
  22.     else // !cxxEnabled && !isHeader && !isObjC
  23.         opts += QLatin1String("c");
  24.  
  25.     return opts;
  26. }
• If file directly included to project, than it language and isHeader flag can be determined by each project manager plugin. Otherwise, we can use dependency table and assume that <iostream> file is “c++-header”, because it included only by C++ files. (sergey shambir: I don’t know how to handle inclusion from both C++ and ObjectiveC++ files. Probably it should have type of file from which it was opened in editor).
• Each language can have extensions: GNU, Microsoft and Borland. Only one extensions group used.
• Each language can have own set of flags, at least in QMAKE
• Each language can have several standards: c89, c99 and c11; c++98 and c++11