llvm-gcc treats a tentative definition with a previous
(or follow up) extern declaration with weak_import as
an actual definition. make clang follows this behavior.
// rdar://9538608
llvm-gcc treats an extern declaration with weak_import
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@133450 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/attr-weak-import.c b/test/CodeGen/attr-weak-import.c
new file mode 100644
index 0000000..f02d09e
--- /dev/null
+++ b/test/CodeGen/attr-weak-import.c
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 -triple x86_64-darwin-apple -emit-llvm -o - %s | FileCheck %s
+// rdar://9538608
+
+extern int A __attribute__((weak_import));
+int A;
+
+extern int B __attribute__((weak_import));
+extern int B;
+
+int C;
+extern int C __attribute__((weak_import));
+
+extern int D __attribute__((weak_import));
+extern int D __attribute__((weak_import));
+int D;
+
+extern int E __attribute__((weak_import));
+int E;
+extern int E __attribute__((weak_import));
+
+// CHECK: @A = global i32
+// CHECK-NOT: @B =
+// CHECK: @C = global i32
+// CHECK: @D = global i32
+// CHECK: @E = global i32
+