clang-tidy: Enable bugprone-forward-declaration-namespace check

This checks if an unused forward declaration is in a wrong
namespace. The check inspects all unused forward declarations and
checks if there is any declaration/definition with the same name
existing, which could indicate that the forward declaration is in
a potentially wrong namespace.

Change-Id: Ie75495d7b054245d6328e7f946775d72220cbe1e
Signed-off-by: Pavithra Barithaya <pavithrabarithaya07@gmail.com>
diff --git a/.clang-tidy b/.clang-tidy
index 03942b9..e1143dd 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -8,6 +8,7 @@
 bugprone-dangling-handle,
 bugprone-dynamic-static-initializers,
 bugprone-fold-init-type,
+bugprone-forward-declaration-namespace,
 bugprone-forwarding-reference-overload,
 bugprone-implicit-widening-of-multiplication-result,
 bugprone-inaccurate-erase,
diff --git a/scheduled_host_transition.hpp b/scheduled_host_transition.hpp
index 9b7c53f..530031f 100644
--- a/scheduled_host_transition.hpp
+++ b/scheduled_host_transition.hpp
@@ -8,8 +8,6 @@
 #include <xyz/openbmc_project/State/Host/server.hpp>
 #include <xyz/openbmc_project/State/ScheduledHostTransition/server.hpp>
 
-class TestScheduledHostTransition;
-
 namespace phosphor
 {
 namespace state
@@ -17,6 +15,8 @@
 namespace manager
 {
 
+class TestScheduledHostTransition;
+
 using Transition =
     sdbusplus::server::xyz::openbmc_project::state::Host::Transition;
 using ScheduledHostTransitionInherit = sdbusplus::server::object_t<