GoToDefinition/Declaration commands for C-family

These are accessible through the :YcmCompleter command. The docs have more
information.

README.md

@@ -87,7 +87,7 @@ Command Line Tools (that you install from within Xcode).
 Install CMake. Preferably with [Homebrew][brew], but here's the [stand-alone
 CMake installer][cmake-download].
 
-_If_ you have installed a Homebrew Python and/or Homebrew MacVim, see the FAQ
+_If_ you have installed a Homebrew Python and/or Homebrew MacVim, see the _FAQ_
 for details.
 
 Compiling YCM **with** semantic support for C-family languages:
@@ -100,10 +100,10 @@ Compiling YCM **without** semantic support for C-family languages:
     cd ~/.vim/bundle/YouCompleteMe
     ./install.sh
 
-That's it. You're done. Refer to the User Guide section on how to use YCM. Don't
+That's it. You're done. Refer to the _User Guide_ section on how to use YCM.
-forget that if you want the C-family semantic completion engine to work, you
+Don't forget that if you want the C-family semantic completion engine to work,
-will need to provide the compilation flags for your project to YCM. It's all in
+you will need to provide the compilation flags for your project to YCM. It's all
-the User Guide.
+in the User Guide.
 
 YCM comes with sane defaults for its options, but you still may want to take a
 look at what's available for configuration. There are a few interesting options
@@ -139,10 +139,10 @@ Compiling YCM **without** semantic support for C-family languages:
     cd ~/.vim/bundle/YouCompleteMe
     ./install.sh
 
-That's it. You're done. Refer to the User Guide section on how to use YCM. Don't
+That's it. You're done. Refer to the _User Guide_ section on how to use YCM.
-forget that if you want the C-family semantic completion engine to work, you
+Don't forget that if you want the C-family semantic completion engine to work,
-will need to provide the compilation flags for your project to YCM. It's all in
+you will need to provide the compilation flags for your project to YCM. It's all
-the User Guide.
+in the User Guide.
 
 YCM comes with sane defaults for its options, but you still may want to take a
 look at what's available for configuration. There are a few interesting options
@@ -164,7 +164,7 @@ code is platform agnostic, so if everything is configured correctly, YCM
 _should_ work on Windows without issues (but as of writing, it's untested on
 that platform).
 
-See the FAQ if you have any issues.
+See the _FAQ_ if you have any issues.
 
 **Remember:** YCM is a plugin with a compiled component. If you **update** YCM
 using Vundle and the ycm_core library API has changed (happens rarely), YCM will
@@ -270,10 +270,10 @@ notify you to recompile it. You should then rerun the install process.
     version 3.2 into the `YouCompleteMe/python` folder then YCM _will not work_
     if you selected C-family support during YCM compilation.
 
-That's it. You're done. Refer to the User Guide section on how to use YCM. Don't
+That's it. You're done. Refer to the _User Guide_ section on how to use YCM.
-forget that if you want the C-family semantic completion engine to work, you
+Don't forget that if you want the C-family semantic completion engine to work,
-will need to provide the compilation flags for your project to YCM. It's all in
+you will need to provide the compilation flags for your project to YCM. It's all
-the User Guide.
+in the User Guide.
 
 YCM comes with sane defaults for its options, but you still may want to take a
 look at what's available for configuration. There are a few interesting options
@@ -294,7 +294,7 @@ User Guide
   through the completions. Use Shift-TAB to cycle backwards. Note that if you're
   using console Vim (that is, not Gvim or MacVim) then it's likely that the
   Shift-TAB binding will not work because the console will not pass it to Vim.
-  You can remap the keys; see the options section below.
+  You can remap the keys; see the _Options_ section below.
 
 ### Completion string ranking
 
@@ -328,7 +328,7 @@ compile the current file. You can also provide a path to a global
 `.ycm_extra_conf.py` file, which will be used as a fallback. To prevent the
 execution of malicious code from a file you didn't write YCM will ask you once
 per `.ycm_extra_conf.py` if it is safe to load. This can be disabled and you can
-white-/blacklist files. See the Options section for more details.
+white-/blacklist files. See the _Options_ section for more details.
 
 This system was designed this way so that the user can perform any arbitrary
 sequence of operations to produce a list of compilation flags YCM should hand
@@ -492,6 +492,50 @@ used.
 Call `YcmCompleter` without further arguments for information about the
 commands you can call for the selected completer.
 
+See the _YcmCompleter subcommands_ section for more information on the available
+subcommands.
+
+YcmCompleter subcommands
+------------------------
+
+[See the docs for the `YcmCompleter` command before tackling this section.]
+
+The invoked subcommand is automatically routed to the currently active semantic
+completer, so `:YcmCommand GoToDefinition` will invoke the `GoToDefinition`
+subcommand on the Python semantic completer if the currently active file is a
+Python one and on the Clang completer if the currently active file is a
+C/C++/Objective-C one.
+
+You may also want to map the subcommands to something less verbose; for
+instance, `nnoremap <leader>jd :YcmCommand GoToDefinitionElseDeclaration<CR>`
+maps the `<leader>jd` sequence to the longer subcommand invocation.
+
+### The `GoToDeclaration` subcommand
+
+Looks up the symbol under the cursor and jumps to its declaration.
+
+Supported in filetypes: `c, cpp, objc, objcpp`
+
+### The `GoToDefinition` subcommand
+
+Looks up the symbol under the cursor and jumps to its definition.
+
+NOTE: For C-family languages **this only works in certain situations**, namely when
+the definition of the symbol is in the current translation unit. A translation
+unit consists of the file you are editing and all the files you are including
+with `#include` directives (directly or indirectly) in that file.
+
+Supported in filetypes: `c, cpp, objc, objcpp`
+
+### The `GoToDefinitionElseDeclaration` subcommand
+
+Looks up the symbol under the cursor and jumps to its definition if possible; if
+the definition is not accessible from the current translation unit, jumps to the
+symbol's declaration.
+
+Supported in filetypes: `c, cpp, objc, objcpp`
+
+
 Options
 -------
 
@@ -904,7 +948,7 @@ This means that YCM tried to set up a key mapping but failed because you already
 had something mapped to that key combination. The `<blah>` part of the message
 will tell you what was the key combination that failed.
 
-Look in the options section and see if which of the default mappings conflict
+Look in the _Options_ section and see if which of the default mappings conflict
 with your own. Then change that option value to something else so that the
 conflict goes away.
 

cpp/ycm/ClangCompleter/ClangCompleter.cpp

@@ -262,6 +262,34 @@ ClangCompleter::CandidatesForQueryAndLocationInFileAsync(
 }
 
 
+Location ClangCompleter::GetDeclarationLocation(
+    const std::string &filename,
+    int line,
+    int column,
+    const std::vector< UnsavedFile > &unsaved_files,
+    const std::vector< std::string > &flags ) {
+  shared_ptr< TranslationUnit > unit = GetTranslationUnitForFile(
+                                         filename,
+                                         unsaved_files,
+                                         flags );
+  return unit->GetDeclarationLocation( line, column, unsaved_files );
+}
+
+
+Location ClangCompleter::GetDefinitionLocation(
+    const std::string &filename,
+    int line,
+    int column,
+    const std::vector< UnsavedFile > &unsaved_files,
+    const std::vector< std::string > &flags ) {
+  shared_ptr< TranslationUnit > unit = GetTranslationUnitForFile(
+                                         filename,
+                                         unsaved_files,
+                                         flags );
+  return unit->GetDefinitionLocation( line, column, unsaved_files );
+}
+
+
 void ClangCompleter::DeleteCachesForFileAsync( const std::string &filename ) {
   file_cache_delete_stack_.Push( filename );
 }

cpp/ycm/ClangCompleter/ClangCompleter.h

@@ -40,6 +40,7 @@ namespace YouCompleteMe {
 class CandidateRepository;
 class TranslationUnit;
 struct CompletionData;
+struct Location;
 
 typedef std::vector< CompletionData > CompletionDatas;
 
@@ -94,6 +95,20 @@ public:
     const std::vector< UnsavedFile > &unsaved_files,
     const std::vector< std::string > &flags );
 
+  Location GetDeclarationLocation(
+    const std::string &filename,
+    int line,
+    int column,
+    const std::vector< UnsavedFile > &unsaved_files,
+    const std::vector< std::string > &flags );
+
+  Location GetDefinitionLocation(
+    const std::string &filename,
+    int line,
+    int column,
+    const std::vector< UnsavedFile > &unsaved_files,
+    const std::vector< std::string > &flags );
+
   void DeleteCachesForFileAsync( const std::string &filename );
 
 private:

cpp/ycm/ClangCompleter/ClangUtils.cpp

@@ -188,7 +188,7 @@ Diagnostic DiagnosticWrapToDiagnostic( DiagnosticWrap diagnostic_wrap ) {
                              &diagnostic.column_number_,
                              &unused_offset );
 
-  diagnostic.filename_ = CXStringToString( clang_getFileName( file ) );
+  diagnostic.filename_ = CXFileToFilepath( file );
   diagnostic.text_ = CXStringToString(
                        clang_getDiagnosticSpelling( diagnostic_wrap.get() ) );
   diagnostic.long_formatted_text_ = FullDiagnosticText( diagnostic_wrap.get() );
@@ -196,6 +196,23 @@ Diagnostic DiagnosticWrapToDiagnostic( DiagnosticWrap diagnostic_wrap ) {
   return diagnostic;
 }
 
+bool CursorIsValid( CXCursor cursor ) {
+  return !clang_Cursor_isNull( cursor ) &&
+         !clang_isInvalid( clang_getCursorKind( cursor ) );
+}
+
+bool CursorIsReference( CXCursor cursor ) {
+  return clang_isReference( clang_getCursorKind( cursor ) );
+}
+
+bool CursorIsDeclaration( CXCursor cursor ) {
+  return clang_isDeclaration( clang_getCursorKind( cursor ) );
+}
+
+std::string CXFileToFilepath( CXFile file ) {
+  return CXStringToString( clang_getFileName( file ) );
+}
+
 std::string ClangVersion() {
   return CXStringToString( clang_getClangVersion() );
 }

cpp/ycm/ClangCompleter/ClangUtils.h

@@ -42,6 +42,14 @@ std::vector< CXUnsavedFile > ToCXUnsavedFiles(
 
 Diagnostic DiagnosticWrapToDiagnostic( DiagnosticWrap diagnostic_wrap );
 
+bool CursorIsValid( CXCursor cursor );
+
+bool CursorIsReference( CXCursor cursor );
+
+bool CursorIsDeclaration( CXCursor cursor );
+
+std::string CXFileToFilepath( CXFile file );
+
 std::string ClangVersion();
 
 } // namespace YouCompleteMe

cpp/ycm/ClangCompleter/Location.h

@@ -0,0 +1,59 @@
+// Copyright (C) 2011, 2012  Strahinja Val Markovic  <val@markovic.io>
+//
+// This file is part of YouCompleteMe.
+//
+// YouCompleteMe is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// YouCompleteMe is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with YouCompleteMe.  If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef LOCATION_H_6TLFQH4I
+#define LOCATION_H_6TLFQH4I
+
+#include "standard.h"
+#include <string>
+#include <clang-c/Index.h>
+
+namespace YouCompleteMe {
+
+struct Location {
+  // Creates an invalid location
+  Location()
+    : line_number_( 0 ),
+      column_number_( 0 ),
+      filename_( "" ) {}
+
+  Location( const std::string &filename, uint line, uint column )
+    : line_number_( line ),
+      column_number_( column ),
+      filename_( filename ) {}
+
+  bool operator== ( const Location &other ) const {
+    return
+      line_number_ == other.line_number_ &&
+      column_number_ == other.column_number_ &&
+      filename_ == other.filename_;
+  }
+
+  bool IsValid() {
+    return !filename_.empty();
+  }
+
+  uint line_number_;
+  uint column_number_;
+
+  // The full, absolute path
+  std::string filename_;
+};
+
+} // namespace YouCompleteMe
+
+#endif /* end of include guard: LOCATION_H_6TLFQH4I */

cpp/ycm/ClangCompleter/TranslationUnit.cpp

@@ -21,7 +21,6 @@
 #include "exceptions.h"
 #include "ClangUtils.h"
 
-#include <clang-c/Index.h>
 #include <boost/shared_ptr.hpp>
 #include <boost/type_traits/remove_pointer.hpp>
 
@@ -133,6 +132,17 @@ void TranslationUnit::Reparse(
 }
 
 
+void TranslationUnit::ReparseForIndexing(
+  const std::vector< UnsavedFile > &unsaved_files ) {
+  std::vector< CXUnsavedFile > cxunsaved_files =
+      ToCXUnsavedFiles( unsaved_files );
+
+  Reparse( cxunsaved_files,
+           CXTranslationUnit_PrecompiledPreamble |
+           CXTranslationUnit_SkipFunctionBodies );
+}
+
+
 std::vector< CompletionData > TranslationUnit::CandidatesForLocation(
   int line,
   int column,
@@ -170,22 +180,74 @@ std::vector< CompletionData > TranslationUnit::CandidatesForLocation(
   return candidates;
 }
 
+Location TranslationUnit::GetDeclarationLocation(
+    int line,
+    int column,
+    const std::vector< UnsavedFile > &unsaved_files ) {
+  ReparseForIndexing( unsaved_files );
+  unique_lock< mutex > lock( clang_access_mutex_ );
+
+  if ( !clang_translation_unit_ )
+    return Location();
+
+  CXCursor cursor = GetCursor( line, column );
+  if ( !CursorIsValid( cursor ) )
+    return Location();
+
+  CXCursor referenced_cursor = clang_getCursorReferenced( cursor );
+  if ( !CursorIsValid( referenced_cursor ) )
+    return Location();
+
+  return LocationFromSourceLocation(
+      clang_getCursorLocation( referenced_cursor ) );
+}
+
+Location TranslationUnit::GetDefinitionLocation(
+    int line,
+    int column,
+    const std::vector< UnsavedFile > &unsaved_files ) {
+  ReparseForIndexing( unsaved_files );
+  unique_lock< mutex > lock( clang_access_mutex_ );
+
+  if ( !clang_translation_unit_ )
+    return Location();
+
+  CXCursor cursor = GetCursor( line, column );
+  if ( !CursorIsValid( cursor ) )
+    return Location();
+
+  CXCursor definition_cursor = clang_getCursorDefinition( cursor );
+  if ( !CursorIsValid( definition_cursor ) )
+    return Location();
+
+  return LocationFromSourceLocation(
+      clang_getCursorLocation( definition_cursor ) );
+}
+
 
 // Argument taken as non-const ref because we need to be able to pass a
 // non-const pointer to clang. This function (and clang too) will not modify the
 // param though.
 void TranslationUnit::Reparse(
   std::vector< CXUnsavedFile > &unsaved_files ) {
+  Reparse( unsaved_files, clang_defaultEditingTranslationUnitOptions() );
+}
+
+
+// Argument taken as non-const ref because we need to be able to pass a
+// non-const pointer to clang. This function (and clang too) will not modify the
+// param though.
+void TranslationUnit::Reparse( std::vector< CXUnsavedFile > &unsaved_files,
+                               uint parse_options ) {
   unique_lock< mutex > lock( clang_access_mutex_ );
 
   if ( !clang_translation_unit_ )
     return;
 
-  int failure = clang_reparseTranslationUnit(
+  int failure = clang_reparseTranslationUnit( clang_translation_unit_,
-                  clang_translation_unit_,
+                                              unsaved_files.size(),
-                  unsaved_files.size(),
+                                              &unsaved_files[ 0 ],
-                  &unsaved_files[ 0 ],
+                                              parse_options );
-                  clang_defaultEditingTranslationUnitOptions() );
 
   if ( failure ) {
     Destroy();
@@ -215,4 +277,33 @@ void TranslationUnit::UpdateLatestDiagnostics() {
   }
 }
 
+CXCursor TranslationUnit::GetCursor( int line, int column ) {
+  // ASSUMES A LOCK IS ALREADY HELD ON clang_access_mutex_!
+  if ( !clang_translation_unit_ )
+    return clang_getNullCursor();
+
+  CXFile file = clang_getFile( clang_translation_unit_, filename_.c_str() );
+  CXSourceLocation source_location = clang_getLocation(
+      clang_translation_unit_,
+      file,
+      line,
+      column );
+
+  return clang_getCursor( clang_translation_unit_, source_location );
+}
+
+Location TranslationUnit::LocationFromSourceLocation(
+    CXSourceLocation source_location ) {
+  // ASSUMES A LOCK IS ALREADY HELD ON clang_access_mutex_!
+  if ( !clang_translation_unit_ )
+    return Location();
+
+  CXFile file;
+  uint line;
+  uint column;
+  uint offset;
+  clang_getExpansionLocation( source_location, &file, &line, &column, &offset );
+  return Location( CXFileToFilepath( file ), line, column );
+}
+
 } // namespace YouCompleteMe

cpp/ycm/ClangCompleter/TranslationUnit.h

@@ -22,17 +22,15 @@
 #include "Future.h"
 #include "UnsavedFile.h"
 #include "Diagnostic.h"
+#include "Location.h"
 
+#include <clang-c/Index.h>
 #include <boost/utility.hpp>
 #include <boost/thread/mutex.hpp>
 
 #include <string>
 #include <vector>
 
-typedef void *CXIndex;
-typedef struct CXTranslationUnitImpl *CXTranslationUnit;
-struct CXUnsavedFile;
-
 namespace YouCompleteMe {
 
 struct CompletionData;
@@ -62,17 +60,35 @@ public:
 
   void Reparse( const std::vector< UnsavedFile > &unsaved_files );
 
+  void ReparseForIndexing( const std::vector< UnsavedFile > &unsaved_files );
+
   std::vector< CompletionData > CandidatesForLocation(
     int line,
     int column,
     const std::vector< UnsavedFile > &unsaved_files );
 
-private:
+  Location GetDeclarationLocation(
+    int line,
+    int column,
+    const std::vector< UnsavedFile > &unsaved_files );
 
+  Location GetDefinitionLocation(
+    int line,
+    int column,
+    const std::vector< UnsavedFile > &unsaved_files );
+
+private:
   void Reparse( std::vector< CXUnsavedFile > &unsaved_files );
 
+  void Reparse( std::vector< CXUnsavedFile > &unsaved_files,
+                uint parse_options );
+
   void UpdateLatestDiagnostics();
 
+  CXCursor GetCursor( int line, int column );
+
+  Location LocationFromSourceLocation( CXSourceLocation source_location );
+
   /////////////////////////////
   // PRIVATE MEMBER VARIABLES
   /////////////////////////////

cpp/ycm/tests/ClangCompleter/TranslationUnit_test.cpp

@@ -21,6 +21,8 @@
 #include <gtest/gtest.h>
 #include <gmock/gmock.h>
 
+#include <clang-c/Index.h>
+
 #include <boost/filesystem.hpp>
 namespace fs = boost::filesystem;
 
@@ -29,7 +31,21 @@ using ::testing::WhenSorted;
 
 namespace YouCompleteMe {
 
-TEST( TranslationUnitTest, ExceptionThrownOnParseFailure ) {
+class TranslationUnitTest : public ::testing::Test {
+protected:
+  virtual void SetUp() {
+    clang_index_ = clang_createIndex( 0, 0 );
+  }
+
+  virtual void TearDown() {
+    clang_disposeIndex( clang_index_ );
+  }
+
+  CXIndex clang_index_;
+};
+
+
+TEST_F( TranslationUnitTest, ExceptionThrownOnParseFailure ) {
   fs::path test_file = fs::temp_directory_path() / fs::unique_path();
   std::string junk = "#&9112(^(^#>@(^@!@(&#@a}}}}{nthoeu\n&&^^&^&!#%%@@!aeu";
   WriteUtf8File( test_file, junk );
@@ -44,5 +60,59 @@ TEST( TranslationUnitTest, ExceptionThrownOnParseFailure ) {
                 ClangParseError );
 }
 
+TEST_F( TranslationUnitTest, GoToDefinitionWorks ) {
+  fs::path path_to_testdata = fs::current_path() / fs::path( "testdata" );
+  fs::path test_file = path_to_testdata / fs::path( "goto.cpp" );
+
+  TranslationUnit unit( test_file.string(),
+                        std::vector< UnsavedFile >(),
+                        std::vector< std::string >(),
+                        clang_index_ );
+
+  Location location = unit.GetDefinitionLocation(
+      15,
+      3,
+      std::vector< UnsavedFile >() );
+
+  EXPECT_EQ( 1, location.line_number_ );
+  EXPECT_EQ( 8, location.column_number_ );
+  EXPECT_TRUE( !location.filename_.empty() );
+}
+
+TEST_F( TranslationUnitTest, GoToDefinitionFails ) {
+  fs::path path_to_testdata = fs::current_path() / fs::path( "testdata" );
+  fs::path test_file = path_to_testdata / fs::path( "goto.cpp" );
+
+  TranslationUnit unit( test_file.string(),
+                        std::vector< UnsavedFile >(),
+                        std::vector< std::string >(),
+                        clang_index_ );
+
+  Location location = unit.GetDefinitionLocation(
+      17,
+      3,
+      std::vector< UnsavedFile >() );
+
+  EXPECT_FALSE( location.IsValid() );
+}
+
+TEST_F( TranslationUnitTest, GoToDeclarationWorks ) {
+  fs::path path_to_testdata = fs::current_path() / fs::path( "testdata" );
+  fs::path test_file = path_to_testdata / fs::path( "goto.cpp" );
+
+  TranslationUnit unit( test_file.string(),
+                        std::vector< UnsavedFile >(),
+                        std::vector< std::string >(),
+                        clang_index_ );
+
+  Location location = unit.GetDeclarationLocation(
+      17,
+      3,
+      std::vector< UnsavedFile >() );
+
+  EXPECT_EQ( 12, location.line_number_ );
+  EXPECT_EQ( 8, location.column_number_ );
+  EXPECT_TRUE( !location.filename_.empty() );
+}
 
 } // namespace YouCompleteMe

cpp/ycm/tests/testdata/goto.cpp

@@ -0,0 +1,18 @@
+struct Foo {
+  int bar;
+  int zoo;
+};
+
+struct Bar {
+  int foo;
+  int zoo;
+};
+
+struct Foo;
+struct Zoo;
+
+void func() {
+  Foo foo;
+  foo.bar = 5;
+  Zoo *zoo = 0;
+}

cpp/ycm/ycm_core.cpp

@@ -24,6 +24,7 @@
 #  include "ClangUtils.h"
 #  include "CompletionData.h"
 #  include "Diagnostic.h"
+#  include "Location.h"
 #  include "UnsavedFile.h"
 #  include "CompilationDatabase.h"
 #endif // USE_CLANG_COMPLETER
@@ -45,7 +46,7 @@ int YcmCoreVersion()
 {
   // We increment this every time when we want to force users to recompile
   // ycm_core.
-  return 2;
+  return 3;
 }
 
 
@@ -115,6 +116,8 @@ BOOST_PYTHON_MODULE(ycm_core)
   class_< ClangCompleter, boost::noncopyable >( "ClangCompleter" )
     .def( "EnableThreading", &ClangCompleter::EnableThreading )
     .def( "DiagnosticsForFile", &ClangCompleter::DiagnosticsForFile )
+    .def( "GetDeclarationLocation", &ClangCompleter::GetDeclarationLocation )
+    .def( "GetDefinitionLocation", &ClangCompleter::GetDefinitionLocation )
     .def( "DeleteCachesForFileAsync",
           &ClangCompleter::DeleteCachesForFileAsync )
     .def( "UpdatingTranslationUnit", &ClangCompleter::UpdatingTranslationUnit )
@@ -144,6 +147,12 @@ BOOST_PYTHON_MODULE(ycm_core)
     .def_readonly( "text_", &Diagnostic::text_ )
     .def_readonly( "long_formatted_text_", &Diagnostic::long_formatted_text_ );
 
+  class_< Location >( "Location" )
+    .def_readonly( "line_number_", &Location::line_number_ )
+    .def_readonly( "column_number_", &Location::column_number_ )
+    .def_readonly( "filename_", &Location::filename_ )
+    .def( "IsValid", &Location::IsValid );
+
   class_< std::vector< Diagnostic > >( "DiagnosticVec" )
     .def( vector_indexing_suite< std::vector< Diagnostic > >() );
 

python/completers/cpp/clang_completer.py

@@ -27,6 +27,12 @@ from flags import Flags
 CLANG_FILETYPES = set( [ 'c', 'cpp', 'objc', 'objcpp' ] )
 MAX_DIAGNOSTICS_TO_DISPLAY = int( vimsupport.GetVariableValue(
   "g:ycm_max_diagnostics_to_display" ) )
+USER_COMMANDS_HELP_MESSAGE = """
+Supported commands are:
+  GoToDefinition
+  GoToDeclaration
+  GoToDefinitionElseDeclaration
+See the docs for information on what they do."""
 
 
 class ClangCompleter( Completer ):
@@ -124,6 +130,78 @@ class ClangCompleter( Completer ):
     return results
 
 
+  def OnUserCommand( self, arguments ):
+    if not arguments:
+      vimsupport.EchoText( USER_COMMANDS_HELP_MESSAGE )
+      return
+
+    command = arguments[ 0 ]
+    if command == 'GoToDefinition':
+      self._GoToDefinition()
+    elif command == 'GoToDeclaration':
+      self._GoToDeclaration()
+    elif command == 'GoToDefinitionElseDeclaration':
+      self._GoToDefinitionElseDeclaration()
+
+
+  def _LocationForGoTo( self, goto_function ):
+    filename = vim.current.buffer.name
+    if not filename:
+      return None
+
+    flags = self.flags.FlagsForFile( filename )
+    if not flags:
+      vimsupport.PostVimMessage( 'Still no compile flags, can\'t compile.' )
+      return None
+
+    files = self.GetUnsavedFilesVector()
+    line, column = vimsupport.CurrentLineAndColumn()
+    # Making the line & column 1-based instead of 0-based
+    line += 1
+    column += 1
+    return getattr( self.completer, goto_function )(
+        filename,
+        line,
+        column,
+        files,
+        flags )
+
+
+  def _GoToDefinition( self ):
+    location = self._LocationForGoTo( 'GetDefinitionLocation' )
+    if not location.IsValid():
+      vimsupport.PostVimMessage( 'Can\'t jump to definition.' )
+      return
+
+    vimsupport.JumpToLocation( location.filename_,
+                               location.line_number_,
+                               location.column_number_ )
+
+
+  def _GoToDeclaration( self ):
+    location = self._LocationForGoTo( 'GetDeclarationLocation' )
+    if not location.IsValid():
+      vimsupport.PostVimMessage( 'Can\'t jump to declaration.' )
+      return
+
+    vimsupport.JumpToLocation( location.filename_,
+                               location.line_number_,
+                               location.column_number_ )
+
+
+  def _GoToDefinitionElseDeclaration( self ):
+    location = self._LocationForGoTo( 'GetDefinitionLocation' )
+    if not location.IsValid():
+      location = self._LocationForGoTo( 'GetDeclarationLocation' )
+    if not location.IsValid():
+      vimsupport.PostVimMessage( 'Can\'t jump to definition or declaration.' )
+      return
+
+    vimsupport.JumpToLocation( location.filename_,
+                               location.line_number_,
+                               location.column_number_ )
+
+
   def OnFileReadyToParse( self ):
     if vimsupport.NumLinesInBuffer( vim.current.buffer ) < 5:
       self.parse_future = None

python/vimsupport.py

@@ -49,6 +49,25 @@ def GetUnsavedBuffers():
   return ( x for x in vim.buffers if BufferModified( x.number ) )
 
 
+# Both |line| and |column| need to be 1-based
+def JumpToLocation( filename, line, column ):
+  # Add an entry to the jumplist
+  vim.command( "normal m'" )
+
+  if filename != vim.current.buffer.name:
+    # We prefix the command with 'keepjumps' so that opening the file is not
+    # recorded in the jumplist. So when we open the file and move the cursor to
+    # a location in it, the user can use CTRL-O to jump back to the original
+    # location, not to the start of the newly opened file.
+    # Sadly this fails on random occasions and the undesired jump remains in the
+    # jumplist.
+    vim.command( 'keepjumps edit {0}'.format( filename ) )
+  vim.current.window.cursor = ( line, column - 1 )
+
+  # Center the screen on the jumped-to location
+  vim.command( 'normal! zz' )
+
+
 def NumLinesInBuffer( buffer ):
   # This is actually less than obvious, that's why it's wrapped in a function
   return len( buffer )

python/ycm.py

@@ -257,7 +257,7 @@ def CurrentIdentifierFinished():
     return line[ : current_column ].isspace()
 
 
-COMPATIBLE_WITH_CORE_VERSION = 2
+COMPATIBLE_WITH_CORE_VERSION = 3
 
 def CompatibleWithYcmCore():
   try: