Add an environment variable that makes libclang use chaining for PCH.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@110414 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/ASTUnit.cpp b/lib/Frontend/ASTUnit.cpp
index 7c15d82..88c55a8 100644
--- a/lib/Frontend/ASTUnit.cpp
+++ b/lib/Frontend/ASTUnit.cpp
@@ -848,7 +848,9 @@
// Tell the compiler invocation to generate a temporary precompiled header.
FrontendOpts.ProgramAction = frontend::GeneratePCH;
- // FIXME: Set ChainedPCH, once it is ready.
+ // FIXME: Set ChainedPCH unconditionally, once it is ready.
+ if (::getenv("LIBCLANG_CHAINING"))
+ FrontendOpts.ChainedPCH = true;
// FIXME: Generate the precompiled header into memory?
FrontendOpts.OutputFile = GetPreamblePCHPath();