Add a callback for `__has_include` and use it for dependency scanning.

This adds a preprocessor callback for the `__has_include` and
`__has_include_next` directives.

Successful checking for the presence of a header should add it to the list of
header dependencies so this overrides the callback in the dependency scanner.

Patch by Pete Cooper with some additions by me.

rdar://problem/39545636

Differential Revision: https://reviews.llvm.org/D30882

llvm-svn: 342517

1 files changed, 8 insertions, 0 deletions

diff --git a/clang/lib/Lex/PPMacroExpansion.cpp b/clang/lib/Lex/PPMacroExpansion.cpp
index 346dd947c02..ffc2ed8c933 100644
--- a/clang/lib/Lex/PPMacroExpansion.cpp
+++ b/clang/lib/Lex/PPMacroExpansion.cpp
@@ -23,6 +23,7 @@
 #include "clang/Lex/CodeCompletionHandler.h"
 #include "clang/Lex/DirectoryLookup.h"
 #include "clang/Lex/ExternalPreprocessorSource.h"
+#include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/LexDiagnostic.h"
 #include "clang/Lex/MacroArgs.h"
 #include "clang/Lex/MacroInfo.h"
@@ -1242,6 +1243,13 @@ static bool EvaluateHasIncludeCommon(Token &Tok,
       PP.LookupFile(FilenameLoc, Filename, isAngled, LookupFrom, LookupFromFile,
                     CurDir, nullptr, nullptr, nullptr, nullptr);
 
+  if (PPCallbacks *Callbacks = PP.getPPCallbacks()) {
+    SrcMgr::CharacteristicKind FileType = SrcMgr::C_User;
+    if (File)
+      FileType = PP.getHeaderSearchInfo().getFileDirFlavor(File);
+    Callbacks->HasInclude(FilenameLoc, Filename, isAngled, File, FileType);
+  }
+
   // Get the result value.  A result of true means the file exists.
   return File != nullptr;
 }