Index: gcc/testsuite/gcc.dg/plugin/selfassign.c
===================================================================
--- gcc/testsuite/gcc.dg/plugin/selfassign.c	(revision 162051)
+++ gcc/testsuite/gcc.dg/plugin/selfassign.c	(working copy)
@@ -14,6 +14,7 @@
 #include "tree-pass.h"
 #include "intl.h"
 #include "plugin-version.h"
+#include "diagnostic.h"
 
 int plugin_is_GPL_compatible;
 
Index: gcc/testsuite/gcc.dg/plugin/ggcplug.c
===================================================================
--- gcc/testsuite/gcc.dg/plugin/ggcplug.c	(revision 162051)
+++ gcc/testsuite/gcc.dg/plugin/ggcplug.c	(working copy)
@@ -13,6 +13,7 @@
 #include "intl.h"
 #include "gcc-plugin.h"
 #include "plugin-version.h"
+#include "diagnostic.h"
 
 int plugin_is_GPL_compatible;
 
Index: gcc/testsuite/g++.dg/plugin/selfassign.c
===================================================================
--- gcc/testsuite/g++.dg/plugin/selfassign.c	(revision 162051)
+++ gcc/testsuite/g++.dg/plugin/selfassign.c	(working copy)
@@ -14,6 +14,7 @@
 #include "tree-pass.h"
 #include "intl.h"
 #include "plugin-version.h"
+#include "diagnostic.h"
 
 int plugin_is_GPL_compatible;
 
Index: gcc/testsuite/g++.dg/plugin/attribute_plugin.c
===================================================================
--- gcc/testsuite/g++.dg/plugin/attribute_plugin.c	(revision 162051)
+++ gcc/testsuite/g++.dg/plugin/attribute_plugin.c	(working copy)
@@ -10,6 +10,7 @@
 #include "intl.h"
 #include "toplev.h"
 #include "plugin.h"
+#include "diagnostic.h"
 
 int plugin_is_GPL_compatible;
 
Index: gcc/testsuite/g++.dg/plugin/dumb_plugin.c
===================================================================
--- gcc/testsuite/g++.dg/plugin/dumb_plugin.c	(revision 162051)
+++ gcc/testsuite/g++.dg/plugin/dumb_plugin.c	(working copy)
@@ -10,6 +10,7 @@
 #include "tree-pass.h"
 #include "intl.h"
 #include "toplev.h"
+#include "diagnostic.h"
 
 int plugin_is_GPL_compatible;
 
Index: gcc/testsuite/g++.dg/plugin/pragma_plugin.c
===================================================================
--- gcc/testsuite/g++.dg/plugin/pragma_plugin.c	(revision 162051)
+++ gcc/testsuite/g++.dg/plugin/pragma_plugin.c	(working copy)
@@ -14,6 +14,7 @@
 #include "tree-pass.h"
 #include "intl.h"
 #include "toplev.h"
+#include "diagnostic.h"
 
 int plugin_is_GPL_compatible;
 
Index: gcc/Makefile.in
===================================================================
--- gcc/Makefile.in	(revision 162051)
+++ gcc/Makefile.in	(working copy)
@@ -330,12 +330,15 @@
 LTO_BINARY_READER = @LTO_BINARY_READER@
 LTO_USE_LIBELF = @LTO_USE_LIBELF@
 
-# Compiler needed for plugin support
-PLUGINCC = $(COMPILER)
+# Compiler and flags needed for plugin support
+ifneq ($(ENABLE_BUILD_WITH_CXX),yes)
+PLUGINCC = $(CC)
+PLUGINCFLAGS = $(CFLAGS)
+else
+PLUGINCC = $(CXX)
+PLUGINCFLAGS = $(CXXFLAGS)
+endif
 
-# Flags needed for plugin support
-PLUGINCFLAGS = $(COMPILER_FLAGS)
-
 # Libs and linker options needed for plugin support
 PLUGINLIBS = @pluginlibs@