[include-cleaner] Avoid a caching issue when running --edit mode on m…

…ultiple files.

Snapshot all analysing files before running the tool, this makes sure
that we analyse all files statelessly and avoid the FileManager caching issue
when running `-edit` on multiple files.

Differential Revision: https://reviews.llvm.org/D155195

clang-tools-extra/include-cleaner/tool/IncludeCleaner.cpp

@@ -19,6 +19,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/FormatVariadic.h"
+#include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Regex.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/raw_ostream.h"
@@ -270,12 +271,24 @@ int main(int argc, const char **argv) {
       }
     }
   }
+
+  clang::tooling::ClangTool Tool(OptionsParser->getCompilations(),
+                                 OptionsParser->getSourcePathList());
+  std::vector<std::unique_ptr<llvm::MemoryBuffer>> Buffers;
+  for (const auto &File : OptionsParser->getSourcePathList()) {
+    auto Content = llvm::MemoryBuffer::getFile(File);
+    if (!Content) {
+      llvm::errs() << "Error: can't read file '" << File
+                   << "': " << Content.getError().message() << "\n";
+      return 1;
+    }
+    Buffers.push_back(std::move(Content.get()));
+    Tool.mapVirtualFile(File, Buffers.back()->getBuffer());
+  }
+
   auto HeaderFilter = headerFilter();
   if (!HeaderFilter)
     return 1; // error already reported.
   ActionFactory Factory(HeaderFilter);
-  return clang::tooling::ClangTool(OptionsParser->getCompilations(),
-                                   OptionsParser->getSourcePathList())
-             .run(&Factory) ||
-         Errors != 0;
+  return Tool.run(&Factory) || Errors != 0;
 }