Deserialize macro history when we deserialize an identifier that has

macro history.

When deserializing macro history, we arrange history such that the
macros that have definitions (that haven't been #undef'd) and are
visible come at the beginning of the list, which is what the
preprocessor and other clients of Preprocessor::getMacroInfo()
expect. If additional macro definitions become visible later, they'll
be moved toward the front of the list. Note that it's possible to have
ambiguities, but we don't diagnose them yet.

There is a partially-implemented design decision here that, if a
particular identifier has been defined or #undef'd within the
translation unit, that definition (or #undef) hides any macro
definitions that come from imported modules. There's still a little
work to do to ensure that the right #undef'ing happens.

Additionally, we'll need to scope the update records for #undefs, so
they only kick in when the submodule containing that update record
becomes visible.

llvm-svn: 165682

1 files changed, 4 insertions, 2 deletions

diff --git a/clang/lib/Lex/MacroInfo.cpp b/clang/lib/Lex/MacroInfo.cpp
index ffe31f24d35..7e538fabf4e 100644
--- a/clang/lib/Lex/MacroInfo.cpp
+++ b/clang/lib/Lex/MacroInfo.cpp
@@ -31,7 +31,8 @@ MacroInfo::MacroInfo(SourceLocation DefLoc)
     IsUsed(false),
     IsAllowRedefinitionsWithoutWarning(false),
     IsWarnIfUnused(false),
-    IsPublic(true) {
+    IsPublic(true),
+    IsHidden(false) {
 }
 
 MacroInfo::MacroInfo(const MacroInfo &MI, llvm::BumpPtrAllocator &PPAllocator)
@@ -54,7 +55,8 @@ MacroInfo::MacroInfo(const MacroInfo &MI, llvm::BumpPtrAllocator &PPAllocator)
     IsUsed(MI.IsUsed),
     IsAllowRedefinitionsWithoutWarning(MI.IsAllowRedefinitionsWithoutWarning),
     IsWarnIfUnused(MI.IsWarnIfUnused),
-    IsPublic(MI.IsPublic) {
+    IsPublic(MI.IsPublic),
+    IsHidden(MI.IsHidden) {
   setArgumentList(MI.ArgumentList, MI.NumArguments, PPAllocator);
 }