Switch NamespaceDecl from its own hand-rolled redeclaration chain over
to Redeclarable<NamespaceDecl>, so that we benefit from the improveed
redeclaration deserialization and merging logic provided by
Redeclarable<T>. Otherwise, no functionality change.

As a drive-by fix, collapse the "inline" bit into the low bit of the
original namespace/anonymous namespace, saving 8 bytes per
NamespaceDecl on x86_64.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@147729 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Modules/Inputs/module.map b/test/Modules/Inputs/module.map
index 640aa3c..2819e62 100644
--- a/test/Modules/Inputs/module.map
+++ b/test/Modules/Inputs/module.map
@@ -63,3 +63,15 @@
   header "redecl-merge-bottom.h" 
   export *
 }
+module namespaces_top { 
+  header "namespaces-top.h"
+  export *
+}
+module namespaces_left { 
+  header "namespaces-left.h"
+  export *
+}
+module namespaces_right { 
+  header "namespaces-right.h"
+  export *
+}
diff --git a/test/Modules/Inputs/namespaces-left.h b/test/Modules/Inputs/namespaces-left.h
new file mode 100644
index 0000000..85e6d7d
--- /dev/null
+++ b/test/Modules/Inputs/namespaces-left.h
@@ -0,0 +1,11 @@
+@import namespaces_top;
+
+namespace N1 { }
+
+namespace N1 { 
+  float& f(float);
+}
+
+namespace N2 { 
+  float& f(float);
+}
diff --git a/test/Modules/Inputs/namespaces-right.h b/test/Modules/Inputs/namespaces-right.h
new file mode 100644
index 0000000..23c88bd
--- /dev/null
+++ b/test/Modules/Inputs/namespaces-right.h
@@ -0,0 +1,18 @@
+@import namespaces_top;
+
+namespace N2 { }
+
+namespace N2 { }
+
+namespace N2 { }
+
+namespace N2 { }
+
+namespace N2 { 
+  double& f(double);
+}
+
+namespace N3 { 
+  double& f(double);
+}
+
diff --git a/test/Modules/Inputs/namespaces-top.h b/test/Modules/Inputs/namespaces-top.h
new file mode 100644
index 0000000..a69f43f
--- /dev/null
+++ b/test/Modules/Inputs/namespaces-top.h
@@ -0,0 +1,11 @@
+namespace N1 { 
+  int& f(int);
+}
+
+namespace N2 { 
+  int& f(int);
+}
+
+namespace N3 { 
+  int& f(int);
+}
diff --git a/test/Modules/namespaces.cpp b/test/Modules/namespaces.cpp
new file mode 100644
index 0000000..75557ba
--- /dev/null
+++ b/test/Modules/namespaces.cpp
@@ -0,0 +1,15 @@
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -x objective-c++ -fmodules -fmodule-cache-path %t -I %S/Inputs %s -verify
+
+@import namespaces_left;
+@import namespaces_right;
+
+void test() {
+  int &ir1 = N1::f(1);
+  int &ir2 = N2::f(1);
+  int &ir3 = N3::f(1);
+  float &fr1 = N1::f(1.0f);
+  float &fr2 = N2::f(1.0f);
+  double &dr1 = N2::f(1.0);
+  double &dr2 = N3::f(1.0);
+}