Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -7194,8 +7194,9 @@
 def err_dynamic_var_init : Error<
     "dynamic initialization is not supported for "
     "__device__, __constant__, and __shared__ variables.">;
-def err_shared_var_init : Error<
-    "initialization is not supported for __shared__ variables.">;
+def warn_shared_var_init : Warning<
+    "initialization is not supported for __shared__ variables.">,
+    InGroup<DiagGroup<"cuda-shared-init">>, DefaultError;
 def err_device_static_local_var : Error<
     "within a %select{__device__|__global__|__host__|__host__ __device__}0 "
     "function, only __shared__ variables or const variables without device "
Index: lib/Sema/SemaCUDA.cpp
===================================================================
--- lib/Sema/SemaCUDA.cpp
+++ lib/Sema/SemaCUDA.cpp
@@ -499,7 +499,7 @@
 
     if (!AllowedInit) {
       Diag(VD->getLocation(), VD->hasAttr<CUDASharedAttr>()
-                                  ? diag::err_shared_var_init
+                                  ? diag::warn_shared_var_init
                                   : diag::err_dynamic_var_init)
           << Init->getSourceRange();
       VD->setInvalidDecl();