[Modules] Cope better with top-level declarations loaded after being declared in the current translation unit <rdar://problem/13189985>.

These two related tweaks to keep the information associated with a
given identifier correct when the identifier has been given some
top-level information (say, a top-level declaration) and more
information is then loaded from a module. The first ensures that an
identifier that was "interesting" before being loaded from an AST is
considered to be different from its on-disk counterpart. Otherwise, we
lose such changes when writing the current translation unit as a
module.

Second, teach the code that injects AST-loaded names into the
identifier chain for name lookup to keep the most recent declaration,
so that we don't end up confusing our declaration chains by having a
different declaration in there.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174895 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 29 insertions, 0 deletions

diff --git a/test/Modules/Inputs/module.map b/test/Modules/Inputs/module.map
index 2e6ef088d4..eeb8d158e5 100644
--- a/test/Modules/Inputs/module.map
+++ b/test/Modules/Inputs/module.map
@@ -86,6 +86,10 @@ module redecl_merge_right {
   export *
 }
 module redecl_merge_bottom { 
+  explicit module prefix {
+    header "redecl-merge-bottom-prefix.h"
+  }
+
   header "redecl-merge-bottom.h" 
   export *
 }
diff --git a/test/Modules/Inputs/redecl-merge-bottom-prefix.h b/test/Modules/Inputs/redecl-merge-bottom-prefix.h
new file mode 100644
index 0000000000..6501e1b65b
--- /dev/null
+++ b/test/Modules/Inputs/redecl-merge-bottom-prefix.h
@@ -0,0 +1,4 @@
+// A class that is declared in the 'bottom' module, then loaded from
+// one of the modules it depends on. It needs to be visible when this
+// module is loaded.
+@class DeclaredThenLoaded;
diff --git a/test/Modules/Inputs/redecl-merge-bottom.h b/test/Modules/Inputs/redecl-merge-bottom.h
index 28ea20c55d..b8fb1794af 100644
--- a/test/Modules/Inputs/redecl-merge-bottom.h
+++ b/test/Modules/Inputs/redecl-merge-bottom.h
@@ -18,3 +18,8 @@ struct S3;
 
 void refers_to_C4(C4*);
 
+@interface UnrelatedToDeclaredThenLoaded
+- declaredThenLoadedMethod;
+@end
+
+@class DeclaredThenLoaded;
diff --git a/test/Modules/Inputs/redecl-merge-left.h b/test/Modules/Inputs/redecl-merge-left.h
index 973d594a30..cf07165a26 100644
--- a/test/Modules/Inputs/redecl-merge-left.h
+++ b/test/Modules/Inputs/redecl-merge-left.h
@@ -82,3 +82,11 @@ extern double var3;
 // top level.
 typedef void funcptr_with_id(int id);
 
+// A class that is declared in the 'bottom' module, then loaded from
+// one of the modules it depends on.
+@interface DeclaredThenLoaded
+- declaredThenLoadedMethod;
+@end
+
+@class DeclaredThenLoaded;
+
diff --git a/test/Modules/redecl-merge2.m b/test/Modules/redecl-merge2.m
new file mode 100644
index 0000000000..3431ecc90b
--- /dev/null
+++ b/test/Modules/redecl-merge2.m
@@ -0,0 +1,8 @@
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t -I %S/Inputs %s -verify -Wno-objc-root-class
+// expected-no-diagnostics
+
+@import redecl_merge_bottom.prefix;
+
+DeclaredThenLoaded *dtl;
+