[Tooling][libclang] Remove unused CompilationDatabase::MappedSources

Summary:
This field is never assigned to and it's only ever read from libclang.
This patch removes it and adapts libclang to return constants.

Reviewers: klimek, bkramer

Reviewed By: klimek

Subscribers: cfe-commits, klimek

Differential Revision: https://reviews.llvm.org/D32351

llvm-svn: 303635
diff --git a/clang/tools/libclang/CXCompilationDatabase.cpp b/clang/tools/libclang/CXCompilationDatabase.cpp
index c122ec8..2ca5326 100644
--- a/clang/tools/libclang/CXCompilationDatabase.cpp
+++ b/clang/tools/libclang/CXCompilationDatabase.cpp
@@ -145,36 +145,23 @@
 unsigned
 clang_CompileCommand_getNumMappedSources(CXCompileCommand CCmd)
 {
-  if (!CCmd)
-    return 0;
-
-  return static_cast<CompileCommand *>(CCmd)->MappedSources.size();
+  // Left here for backward compatibility. No mapped sources exists in the C++
+  // backend anymore.
+  return 0;
 }
 
 CXString
 clang_CompileCommand_getMappedSourcePath(CXCompileCommand CCmd, unsigned I)
 {
-  if (!CCmd)
-    return cxstring::createNull();
-
-  CompileCommand *Cmd = static_cast<CompileCommand *>(CCmd);
-
-  if (I >= Cmd->MappedSources.size())
-    return cxstring::createNull();
-
-  return cxstring::createRef(Cmd->MappedSources[I].first.c_str());
+  // Left here for backward compatibility. No mapped sources exists in the C++
+  // backend anymore.
+  return cxstring::createNull();
 }
 
 CXString
 clang_CompileCommand_getMappedSourceContent(CXCompileCommand CCmd, unsigned I)
 {
-  if (!CCmd)
-    return cxstring::createNull();
-
-  CompileCommand *Cmd = static_cast<CompileCommand *>(CCmd);
-
-  if (I >= Cmd->MappedSources.size())
-    return cxstring::createNull();
-
-  return cxstring::createRef(Cmd->MappedSources[I].second.c_str());
+  // Left here for backward compatibility. No mapped sources exists in the C++
+  // backend anymore.
+  return cxstring::createNull();
 }