Implement redeclaration merging for namespaces defined in distinct

modules. Teach name lookup into namespaces to search in each of the
merged DeclContexts as well as the (now-primary) DeclContext. This
supports the common case where two different modules put something
into the same namespace.

llvm-svn: 147778

3 files changed, 48 insertions, 0 deletions

diff --git a/clang/test/Modules/Inputs/namespaces-left.h b/clang/test/Modules/Inputs/namespaces-left.h
index 85e6d7dc607..6835cda0c4f 100644
--- a/clang/test/Modules/Inputs/namespaces-left.h
+++ b/clang/test/Modules/Inputs/namespaces-left.h
@@ -9,3 +9,19 @@ namespace N1 {
 namespace N2 { 
   float& f(float);
 }
+
+
+
+
+
+namespace N5 {
+  int &f(int);
+}
+
+namespace N6 {
+  int &f(int);
+}
+
+namespace N7 {
+  int &f(int);
+}
diff --git a/clang/test/Modules/Inputs/namespaces-right.h b/clang/test/Modules/Inputs/namespaces-right.h
index 23c88bdbe9b..0afef073c31 100644
--- a/clang/test/Modules/Inputs/namespaces-right.h
+++ b/clang/test/Modules/Inputs/namespaces-right.h
@@ -16,3 +16,14 @@ namespace N3 {
   double& f(double);
 }
 
+namespace N5 {
+  double &f(double);
+}
+
+namespace N6 {
+  double &f(double);
+}
+
+namespace N7 {
+  double &f(double);
+}
diff --git a/clang/test/Modules/namespaces.cpp b/clang/test/Modules/namespaces.cpp
index 75557ba4c14..e1a8d6e8b09 100644
--- a/clang/test/Modules/namespaces.cpp
+++ b/clang/test/Modules/namespaces.cpp
@@ -1,6 +1,10 @@
 // RUN: rm -rf %t
 // RUN: %clang_cc1 -x objective-c++ -fmodules -fmodule-cache-path %t -I %S/Inputs %s -verify
 
+namespace N6 {
+  char &f(char);
+}
+
 @import namespaces_left;
 @import namespaces_right;
 
@@ -13,3 +17,20 @@ void test() {
   double &dr1 = N2::f(1.0);
   double &dr2 = N3::f(1.0);
 }
+
+// Test namespaces merged without a common first declaration.
+namespace N5 {
+  char &f(char);
+}
+
+void testMerged() {
+  int &ir1 = N5::f(17);
+  int &ir2 = N6::f(17);
+  int &ir3 = N7::f(17);
+  double &fr1 = N5::f(1.0);
+  double &fr2 = N6::f(1.0);
+  double &fr3 = N7::f(1.0);
+  char &cr1 = N5::f('a');
+  char &cr2 = N6::f('b');
+}
+