Translate libclang error codes to exceptions

Do not silence the exceptions.

cpp/ycm/ClangCompleter/ClangCompleter.cpp

@@ -16,7 +16,6 @@
 // along with ycmd.  If not, see <http://www.gnu.org/licenses/>.
 
 #include "ClangCompleter.h"
-#include "exceptions.h"
 #include "Result.h"
 #include "Candidate.h"
 #include "TranslationUnit.h"
@@ -84,22 +83,15 @@ std::vector< Diagnostic > ClangCompleter::UpdateTranslationUnit(
                                          flags,
                                          translation_unit_created );
 
-  if ( !unit ) {
-    return std::vector< Diagnostic >();
-  }
-
   try {
     return unit->Reparse( unsaved_files );
-  }
-
-  catch ( ClangParseError & ) {
+  } catch ( const ClangParseError & ) {
     // If unit->Reparse fails, then the underlying TranslationUnit object is not
     // valid anymore and needs to be destroyed and removed from the filename ->
     // TU map.
     translation_unit_store_.Remove( filename );
+    throw;
   }
-
-  return std::vector< Diagnostic >();
 }
 
 
@@ -114,10 +106,6 @@ ClangCompleter::CandidatesForLocationInFile(
   shared_ptr< TranslationUnit > unit =
     translation_unit_store_.GetOrCreate( filename, unsaved_files, flags );
 
-  if ( !unit ) {
-    return std::vector< CompletionData >();
-  }
-
   return unit->CandidatesForLocation( line,
                                       column,
                                       unsaved_files );
@@ -135,10 +123,6 @@ Location ClangCompleter::GetDeclarationLocation(
   shared_ptr< TranslationUnit > unit =
     translation_unit_store_.GetOrCreate( filename, unsaved_files, flags );
 
-  if ( !unit ) {
-    return Location();
-  }
-
   return unit->GetDeclarationLocation( line, column, unsaved_files, reparse );
 }
 
@@ -154,10 +138,6 @@ Location ClangCompleter::GetDefinitionLocation(
   shared_ptr< TranslationUnit > unit =
     translation_unit_store_.GetOrCreate( filename, unsaved_files, flags );
 
-  if ( !unit ) {
-    return Location();
-  }
-
   return unit->GetDefinitionLocation( line, column, unsaved_files, reparse );
 }
 
@@ -173,10 +153,6 @@ std::string ClangCompleter::GetTypeAtLocation(
   shared_ptr< TranslationUnit > unit =
     translation_unit_store_.GetOrCreate( filename, unsaved_files, flags );
 
-  if ( !unit ) {
-    return "no unit";
-  }
-
   return unit->GetTypeAtLocation( line, column, unsaved_files, reparse );
 }
 
@@ -192,10 +168,6 @@ std::string ClangCompleter::GetEnclosingFunctionAtLocation(
   shared_ptr< TranslationUnit > unit =
     translation_unit_store_.GetOrCreate( filename, unsaved_files, flags );
 
-  if ( !unit ) {
-    return "no unit";
-  }
-
   return unit->GetEnclosingFunctionAtLocation( line,
                                                column,
                                                unsaved_files,
@@ -216,10 +188,6 @@ ClangCompleter::GetFixItsForLocationInFile(
   shared_ptr< TranslationUnit > unit =
     translation_unit_store_.GetOrCreate( filename, unsaved_files, flags );
 
-  if ( !unit ) {
-    return std::vector< FixIt >();
-  }
-
   return unit->GetFixItsForLocationInFile( line,
                                            column,
                                            unsaved_files,
@@ -240,10 +208,6 @@ DocumentationData ClangCompleter::GetDocsForLocationInFile(
   shared_ptr< TranslationUnit > unit =
     translation_unit_store_.GetOrCreate( filename, unsaved_files, flags );
 
-  if ( !unit ) {
-    return DocumentationData();
-  }
-
   return unit->GetDocsForLocationInFile( line,
                                          column,
                                          unsaved_files,

cpp/ycm/ClangCompleter/ClangUtils.cpp

@@ -44,4 +44,29 @@ std::string ClangVersion() {
   return CXStringToString( clang_getClangVersion() );
 }
 
+const char *CXErrorCodeToString( CXErrorCode code ) {
+  switch ( code ) {
+    case CXError_Success:
+      return "No error encountered while parsing the translation unit.";
+    case CXError_Failure:
+      return "Failed to parse the translation unit.";
+    case CXError_Crashed:
+      return "Libclang crashed while parsing the translation unit.";
+    case CXError_InvalidArguments:
+      return "Invalid arguments supplied when parsing the translation unit.";
+    case CXError_ASTReadError:
+      return "An AST deserialization error occurred "
+             "while parsing the translation unit.";
+  }
+  return "Unknown error while parsing the translation unit.";
+}
+
+ClangParseError::ClangParseError( const char *what_arg )
+  : std::runtime_error( what_arg ) {
+};
+
+ClangParseError::ClangParseError( CXErrorCode code )
+  : ClangParseError( CXErrorCodeToString( code ) ) {
+};
+
 } // namespace YouCompleteMe

cpp/ycm/ClangCompleter/ClangUtils.h

@@ -19,6 +19,7 @@
 #define CLANGUTILS_H_9MVHQLJS
 
 #include <clang-c/Index.h>
+#include <stdexcept>
 #include <string>
 
 namespace YouCompleteMe {
@@ -37,6 +38,16 @@ std::string CXFileToFilepath( CXFile file );
 
 std::string ClangVersion();
 
+const char *CXErrorCodeToString( CXErrorCode code );
+
+/**
+ * Thrown when libclang fails to parse (or reparse) the translation unit.
+ */
+struct YCM_EXPORT ClangParseError : std::runtime_error {
+  ClangParseError( const char *what_arg );
+  ClangParseError( CXErrorCode code );
+};
+
 } // namespace YouCompleteMe
 
 #endif /* end of include guard: CLANGUTILS_H_9MVHQLJS */

cpp/ycm/ClangCompleter/TranslationUnit.cpp

@@ -17,7 +17,6 @@
 
 #include "TranslationUnit.h"
 #include "CompletionData.h"
-#include "exceptions.h"
 #include "ClangUtils.h"
 #include "ClangHelpers.h"
 
@@ -95,18 +94,17 @@ TranslationUnit::TranslationUnit(
                                  ? &cxunsaved_files[ 0 ] : nullptr;
 
   // Actually parse the translation unit.
-  CXErrorCode result = clang_parseTranslationUnit2FullArgv(
-                         clang_index,
-                         filename.c_str(),
-                         &pointer_flags[ 0 ],
-                         pointer_flags.size(),
-                         const_cast<CXUnsavedFile *>( unsaved ),
-                         cxunsaved_files.size(),
-                         EditingOptions(),
-                         &clang_translation_unit_ );
-
-  if ( result != CXError_Success ) {
-    throw( ClangParseError() );
+  CXErrorCode failure = clang_parseTranslationUnit2FullArgv(
+                          clang_index,
+                          filename.c_str(),
+                          &pointer_flags[ 0 ],
+                          pointer_flags.size(),
+                          const_cast<CXUnsavedFile *>( unsaved ),
+                          cxunsaved_files.size(),
+                          EditingOptions(),
+                          &clang_translation_unit_ );
+  if ( failure != CXError_Success ) {
+    throw ClangParseError( failure );
   }
 }
 
@@ -374,7 +372,7 @@ void TranslationUnit::Reparse(
 // param though.
 void TranslationUnit::Reparse( std::vector< CXUnsavedFile > &unsaved_files,
                                size_t parse_options ) {
-  int failure = 0;
+  CXErrorCode failure;
   {
     unique_lock< mutex > lock( clang_access_mutex_ );
 
@@ -385,15 +383,18 @@ void TranslationUnit::Reparse( std::vector< CXUnsavedFile > &unsaved_files,
     CXUnsavedFile *unsaved = unsaved_files.size() > 0
                              ? &unsaved_files[ 0 ] : nullptr;
 
-    failure = clang_reparseTranslationUnit( clang_translation_unit_,
-                                            unsaved_files.size(),
-                                            unsaved,
-                                            parse_options );
+    // This function should technically return a CXErrorCode enum but return an
+    // int instead.
+    failure = static_cast< CXErrorCode >(
+      clang_reparseTranslationUnit( clang_translation_unit_,
+                                    unsaved_files.size(),
+                                    unsaved,
+                                    parse_options ) );
   }
 
-  if ( failure ) {
+  if ( failure != CXError_Success ) {
     Destroy();
-    throw( ClangParseError() );
+    throw ClangParseError( failure );
   }
 
   UpdateLatestDiagnostics();

cpp/ycm/ClangCompleter/TranslationUnit.h

@@ -55,7 +55,7 @@ class TranslationUnit {
 
   YCM_EXPORT bool IsCurrentlyUpdating() const;
 
-  std::vector< Diagnostic > Reparse(
+  YCM_EXPORT std::vector< Diagnostic > Reparse(
     const std::vector< UnsavedFile > &unsaved_files );
 
   YCM_EXPORT std::vector< CompletionData > CandidatesForLocation(

cpp/ycm/ClangCompleter/TranslationUnitStore.cpp

@@ -18,7 +18,6 @@
 #include "TranslationUnitStore.h"
 #include "TranslationUnit.h"
 #include "Utils.h"
-#include "exceptions.h"
 
 #include <functional>
 
@@ -106,9 +105,9 @@ shared_ptr< TranslationUnit > TranslationUnitStore::GetOrCreate(
                                            unsaved_files,
                                            flags,
                                            clang_index_ );
-  } catch ( ClangParseError & ) {
+  } catch ( const ClangParseError & ) {
     Remove( filename );
-    return unit;
+    throw;
   }
 
   {

cpp/ycm/PythonSupport.h

@@ -39,6 +39,42 @@ YCM_EXPORT boost::python::list FilterAndSortCandidates(
 /// a string. Supports newstr and newbytes from python-future on Python 2.
 std::string GetUtf8String( const boost::python::object &value );
 
+/// Expose the C++ exception |CppException| as a Python exception inheriting
+/// from the base exception |base_exception| (default being Exception) with the
+/// fully qualified name <module>.|name| where <module> is the current
+/// Boost.Python module. |CppException| must define a what() method (easiest way
+/// is to derive it from std::runtime_error). This templated class should be
+/// instantiated inside the BOOST_PYTHON_MODULE macro.
+template< typename CppException >
+class PythonException {
+public:
+
+  PythonException( const char* name,
+                   PyObject* base_exception = PyExc_Exception ) {
+    std::string module_name = boost::python::extract< std::string >(
+        boost::python::scope().attr( "__name__" ) );
+    std::string fully_qualified_name = module_name + "." + name;
+    // PyErr_NewException does not modify the exception name so it's safe to
+    // cast away constness.
+    char *raw_name = const_cast< char * >( fully_qualified_name.c_str() );
+    python_exception_ = PyErr_NewException( raw_name, base_exception, NULL );
+
+    // Add the Python exception to the current Boost.Python module.
+    boost::python::scope().attr( name ) = boost::python::handle<>(
+      python_exception_ );
+
+    boost::python::register_exception_translator< CppException >( *this );
+  };
+
+  void operator() ( const CppException &cpp_exception ) const {
+    PyErr_SetString( python_exception_, cpp_exception.what() );
+  }
+
+private:
+  PyObject* python_exception_;
+
+};
+
 } // namespace YouCompleteMe
 
 #endif /* end of include guard: PYTHONSUPPORT_H_KWGFEX0V */

cpp/ycm/Utils.cpp

@@ -40,12 +40,4 @@ std::string ReadUtf8File( const fs::path &filepath ) {
   return std::string();
 }
 
-
-void WriteUtf8File( const fs::path &filepath, const std::string &contents ) {
-  fs::ofstream file;
-  file.open( filepath );
-  file << contents;
-  file.close();
-}
-
 } // namespace YouCompleteMe

cpp/ycm/Utils.h

@@ -149,11 +149,6 @@ YCM_EXPORT inline std::string SwapCase( const std::string &text ) {
 // an exception is thrown.
 std::string ReadUtf8File( const fs::path &filepath );
 
-// Writes the entire contents of the specified file. If the file does not exist,
-// an exception is thrown.
-YCM_EXPORT void WriteUtf8File( const fs::path &filepath,
-                                   const std::string &contents );
-
 template <class Container, class Key>
 typename Container::mapped_type &
 GetValueElseInsert( Container &container,