tree cea015c280d1666e0a42bdb2f208d8829a5f4cc9
parent 8b03277b0bc18ab73be11b6067474d515fdad271
author Douglas Gregor <dgregor@apple.com> 1349916409 +0000
committer Douglas Gregor <dgregor@apple.com> 1349916409 +0000

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.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@165682 91177308-0d34-0410-b5e6-96231b3b80d8