[Preamble] Empty preamble is not an error.

hokein · hokein · commit 70560ba8db05 · 2018-08-17T14:25:10.000Z
Summary: Empty preamble is valid for source file which doesn't have any preprocessor and #includes. This patch makes clang treat an empty preamble as a normal preamble. Check: ninja check-clang A testcase is added in https://reviews.llvm.org/D50627. Reviewers: ilya-biryukov Subscribers: cfe-commits Differential Revision: https://reviews.llvm.org/D50628 llvm-svn: 340029
diff --git a/clang/include/clang/Frontend/PrecompiledPreamble.h b/clang/include/clang/Frontend/PrecompiledPreamble.h
@@ -286,8 +286,7 @@ class PreambleCallbacks {
 };
 
 enum class BuildPreambleError {
-  PreambleIsEmpty = 1,
-  CouldntCreateTempFile,
+  CouldntCreateTempFile = 1,
   CouldntCreateTargetInfo,
   BeginSourceFileFailed,
   CouldntEmitPCH
diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
@@ -1363,7 +1363,6 @@ ASTUnit::getMainBufferWithPrecompiledPreamble(
     } else {
       switch (static_cast<BuildPreambleError>(NewPreamble.getError().value())) {
       case BuildPreambleError::CouldntCreateTempFile:
-      case BuildPreambleError::PreambleIsEmpty:
         // Try again next time.
         PreambleRebuildCounter = 1;
         return nullptr;
diff --git a/clang/lib/Frontend/PrecompiledPreamble.cpp b/clang/lib/Frontend/PrecompiledPreamble.cpp
@@ -237,9 +237,6 @@ llvm::ErrorOr<PrecompiledPreamble> PrecompiledPreamble::Build(
     PreambleCallbacks &Callbacks) {
   assert(VFS && "VFS is null");
 
-  if (!Bounds.Size)
-    return BuildPreambleError::PreambleIsEmpty;
-
   auto PreambleInvocation = std::make_shared<CompilerInvocation>(Invocation);
   FrontendOptions &FrontendOpts = PreambleInvocation->getFrontendOpts();
   PreprocessorOptions &PreprocessorOpts =
@@ -423,9 +420,6 @@ bool PrecompiledPreamble::CanReuse(const CompilerInvocation &Invocation,
   PreprocessorOptions &PreprocessorOpts =
       PreambleInvocation->getPreprocessorOpts();
 
-  if (!Bounds.Size)
-    return false;
-
   // We've previously computed a preamble. Check whether we have the same
   // preamble now that we did before, and that there's enough space in
   // the main-file buffer within the precompiled preamble to fit the
@@ -758,8 +752,6 @@ const char *BuildPreambleErrorCategory::name() const noexcept {
 
 std::string BuildPreambleErrorCategory::message(int condition) const {
   switch (static_cast<BuildPreambleError>(condition)) {
-  case BuildPreambleError::PreambleIsEmpty:
-    return "Preamble is empty";
   case BuildPreambleError::CouldntCreateTempFile:
     return "Could not create temporary file for PCH";
   case BuildPreambleError::CouldntCreateTargetInfo:
