<rdar://problem/10796651> Introduce configuration macros into module maps.

Configuration macros are macros that are intended to alter how a
module works, such that we need to build different module variants
for different values of these macros. A module can declare its
configuration macros, in which case we will complain if the definition
of a configation macro on the command line (or lack thereof) differs
from the current preprocessor state at the point where the module is
imported. This should eliminate some surprises when enabling modules,
because "#define CONFIG_MACRO ..." followed by "#include
<module/header.h>" would silently ignore the CONFIG_MACRO setting. At
least it will no longer be silent about it.

Configuration macros are eventually intended to help reduce the number
of module variants that need to be built. When the list of
configuration macros for a module is exhaustive, we only need to
consider the settings for those macros when building/finding the
module, which can help isolate modules for various project-specific -D
flags that should never affect how modules are build (but currently do).



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177466 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 3 insertions, 1 deletions

diff --git a/include/clang/Serialization/ASTBitCodes.h b/include/clang/Serialization/ASTBitCodes.h
index 93c5c073d5..2669d8e6d7 100644
--- a/include/clang/Serialization/ASTBitCodes.h
+++ b/include/clang/Serialization/ASTBitCodes.h
@@ -609,7 +609,9 @@ namespace clang {
       /// from this submodule.
       SUBMODULE_EXCLUDED_HEADER = 9,
       /// \brief Specifies a library or framework to link against.
-      SUBMODULE_LINK_LIBRARY = 10
+      SUBMODULE_LINK_LIBRARY = 10,
+      /// \brief Specifies a configuration macro for this module.
+      SUBMODULE_CONFIG_MACRO = 11
     };
 
     /// \brief Record types used within a comments block.