[modules] Stop trying to fake up a linear MacroDirective history.

Modules builds fundamentally have a non-linear macro history. In the interest
of better source fidelity, represent the macro definition information
faithfully: we have a linear macro directive history within each module, and at
any point we have a unique "latest" local macro directive and a collection of
visible imported directives. This also removes the attendent complexity of
attempting to create a correct MacroDirective history (which we got wrong
in the general case).

No functionality change intended.

llvm-svn: 236176

1 files changed, 5 insertions, 0 deletions

diff --git a/clang/lib/AST/NSAPI.cpp b/clang/lib/AST/NSAPI.cpp
index 033a87b8ae2..2749100e14a 100644
--- a/clang/lib/AST/NSAPI.cpp
+++ b/clang/lib/AST/NSAPI.cpp
@@ -505,6 +505,11 @@ StringRef NSAPI::GetNSIntegralKind(QualType T) const {
   return StringRef();
 }
 
+bool NSAPI::isMacroDefined(StringRef Id) const {
+  // FIXME: Check whether the relevant module macros are visible.
+  return Ctx.Idents.get(Id).hasMacroDefinition();
+}
+
 bool NSAPI::isObjCTypedef(QualType T,
                           StringRef name, IdentifierInfo *&II) const {
   if (!Ctx.getLangOpts().ObjC1)