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

3 files changed, 27 insertions, 0 deletions

diff --git a/clang/test/Modules/Inputs/macros_left.h b/clang/test/Modules/Inputs/macros_left.h
index dfe56052bfc..919dc20ebc9 100644
--- a/clang/test/Modules/Inputs/macros_left.h
+++ b/clang/test/Modules/Inputs/macros_left.h
@@ -3,3 +3,10 @@
 
 #undef TOP_LEFT_UNDEF
 
+
+
+
+#define LEFT_RIGHT_IDENTICAL int
+#define LEFT_RIGHT_DIFFERENT float
+#define LEFT_RIGHT_DIFFERENT2 float
+#define LEFT_RIGHT_DIFFERENT3 float
diff --git a/clang/test/Modules/Inputs/macros_right.h b/clang/test/Modules/Inputs/macros_right.h
index 3351e9796c4..8e9688223bc 100644
--- a/clang/test/Modules/Inputs/macros_right.h
+++ b/clang/test/Modules/Inputs/macros_right.h
@@ -4,3 +4,12 @@
 #undef TOP_RIGHT_REDEF
 #define TOP_RIGHT_REDEF float
 
+
+
+
+
+#define LEFT_RIGHT_IDENTICAL int
+#define LEFT_RIGHT_DIFFERENT int
+#define LEFT_RIGHT_DIFFERENT2 int
+#define LEFT_RIGHT_DIFFERENT3 int
+
diff --git a/clang/test/Modules/Inputs/module.map b/clang/test/Modules/Inputs/module.map
index 9044922799a..b26234382b1 100644
--- a/clang/test/Modules/Inputs/module.map
+++ b/clang/test/Modules/Inputs/module.map
@@ -18,6 +18,17 @@ module lookup_left_cxx { header "lookup_left.hpp" }
 module lookup_right_cxx { header "lookup_right.hpp" }
 module module_private_left { header "module_private_left.h" }
 module module_private_right { header "module_private_right.h" }
+module macros_top { 
+  header "macros_top.h" 
+}
+module macros_left { 
+  header "macros_left.h" 
+  export *
+}
+module macros_right { 
+  header "macros_right.h" 
+  export *
+}
 module macros { header "macros.h" }
 module category_top { header "category_top.h" }
 module category_left {