c-family/
	* c.opt (Wimplicit-fallthrough=): Default to 1.

gcc/
	* common.opt (Wimplicit-fallthrough=): Default to 1.
	* doc/invoke.texi (-Wextra, -Wimplicit-fallthrough): Adjust
	documentation.

testsuite/
	* c-c++-comon/Wimplicit-fallthrough-1.c: Specify level for
	-Wimplicit-fallthrough
	* c-c++-comon/Wimplicit-fallthrough-10.c: Likewise.
	* c-c++-comon/Wimplicit-fallthrough-12.c: Likewise.
	* c-c++-comon/Wimplicit-fallthrough-16.c: Likewise.
	* c-c++-comon/Wimplicit-fallthrough-19.c: Likewise.
	* c-c++-comon/Wimplicit-fallthrough-2.c: Likewise.
	* c-c++-comon/Wimplicit-fallthrough-22.c: Likewise.
	* c-c++-comon/Wimplicit-fallthrough-25.c: Likewise.
	* c-c++-comon/Wimplicit-fallthrough-26.c: Likewise.
	* c-c++-comon/Wimplicit-fallthrough-3.c: Likewise.
	* c-c++-comon/Wimplicit-fallthrough-4.c: Likewise.
	* c-c++-comon/Wimplicit-fallthrough-5.c: Likewise.
	* c-c++-comon/Wimplicit-fallthrough-7.c: Likewise.
	* c-c++-comon/Wimplicit-fallthrough-8.c: Likewise.
	* c-c++-comon/attr-fallthrough-1.c: Likewise.
	* g++.dg/cpp0x/fallthrough1.C: Likewise.
	* objc.dg/Wimplicit-fallthrough-1.m: Likewise.

Index: gcc/c-family/c.opt
===================================================================
--- gcc/c-family/c.opt	(revision 241233)
+++ gcc/c-family/c.opt	(working copy)
@@ -541,7 +541,7 @@ C ObjC Var(warn_implicit) Warning LangEn
 Warn about implicit declarations.
 
 Wimplicit-fallthrough=
-LangEnabledBy(C ObjC C++ ObjC++,Wextra,3,0)
+LangEnabledBy(C ObjC C++ ObjC++,Wextra,1,0)
 ; in common.opt
 
 Wdouble-promotion
Index: gcc/common.opt
===================================================================
--- gcc/common.opt	(revision 241233)
+++ gcc/common.opt	(working copy)
@@ -602,7 +602,7 @@ Common Var(warn_hsa) Init(1) Warning
 Warn when a function cannot be expanded to HSAIL.
 
 Wimplicit-fallthrough
-Common Alias(Wimplicit-fallthrough=,3,0) Warning
+Common Alias(Wimplicit-fallthrough=,1,0) Warning
 
 Wimplicit-fallthrough=
 Common Var(warn_implicit_fallthrough) RejectNegative Joined UInteger Warning
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi	(revision 241233)
+++ gcc/doc/invoke.texi	(working copy)
@@ -3735,7 +3735,7 @@ name is still supported, but the newer n
 @gccoptlist{-Wclobbered  @gol
 -Wempty-body  @gol
 -Wignored-qualifiers @gol
--Wimplicit-fallthrough=3 @gol
+-Wimplicit-fallthrough=1 @gol
 -Wmissing-field-initializers  @gol
 -Wmissing-parameter-type @r{(C only)}  @gol
 -Wold-style-declaration @r{(C only)}  @gol
@@ -4107,7 +4107,7 @@ This warning is enabled by @option{-Wall
 @item -Wimplicit-fallthrough
 @opindex Wimplicit-fallthrough
 @opindex Wno-implicit-fallthrough
-@option{-Wimplicit-fallthrough} is the same as @option{-Wimplicit-fallthrough=3}
+@option{-Wimplicit-fallthrough} is the same as @option{-Wimplicit-fallthrough=1}
 and @option{-Wno-implicit-fallthrough} is the same as
 @option{-Wimplicit-fallthrough=0}.
 
Index: gcc/testsuite/c-c++-common/Wimplicit-fallthrough-1.c
===================================================================
--- gcc/testsuite/c-c++-common/Wimplicit-fallthrough-1.c	(revision 241233)
+++ gcc/testsuite/c-c++-common/Wimplicit-fallthrough-1.c	(working copy)
@@ -1,6 +1,6 @@
 /* PR c/7652 */
 /* { dg-do compile } */
-/* { dg-options "-Wimplicit-fallthrough" } */
+/* { dg-options "-Wimplicit-fallthrough=3" } */
 /* Test taken from
    <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0188r0.pdf>.  */
 
Index: gcc/testsuite/c-c++-common/Wimplicit-fallthrough-10.c
===================================================================
--- gcc/testsuite/c-c++-common/Wimplicit-fallthrough-10.c	(revision 241233)
+++ gcc/testsuite/c-c++-common/Wimplicit-fallthrough-10.c	(working copy)
@@ -1,6 +1,6 @@
 /* PR c/7652 */
 /* { dg-do compile } */
-/* { dg-options "-Wimplicit-fallthrough" } */
+/* { dg-options "-Wimplicit-fallthrough=3" } */
 
 extern void bar (int);
 
Index: gcc/testsuite/c-c++-common/Wimplicit-fallthrough-12.c
===================================================================
--- gcc/testsuite/c-c++-common/Wimplicit-fallthrough-12.c	(revision 241233)
+++ gcc/testsuite/c-c++-common/Wimplicit-fallthrough-12.c	(working copy)
@@ -1,6 +1,6 @@
 /* PR c/7652 */
 /* { dg-do compile } */
-/* { dg-options "-Wimplicit-fallthrough -O2" } */
+/* { dg-options "-Wimplicit-fallthrough=3 -O2" } */
 
 /* Don't let optimizations preclude the warning.  */
 
Index: gcc/testsuite/c-c++-common/Wimplicit-fallthrough-16.c
===================================================================
--- gcc/testsuite/c-c++-common/Wimplicit-fallthrough-16.c	(revision 241233)
+++ gcc/testsuite/c-c++-common/Wimplicit-fallthrough-16.c	(working copy)
@@ -1,6 +1,6 @@
 /* PR c/7652 */
 /* { dg-do compile } */
-/* { dg-options "-Wimplicit-fallthrough" } */
+/* { dg-options "-Wimplicit-fallthrough=3" } */
 
 /* Another nested switch, and with an initialization on top.  Check that
    we do warn here.  */
Index: gcc/testsuite/c-c++-common/Wimplicit-fallthrough-19.c
===================================================================
--- gcc/testsuite/c-c++-common/Wimplicit-fallthrough-19.c	(revision 241233)
+++ gcc/testsuite/c-c++-common/Wimplicit-fallthrough-19.c	(working copy)
@@ -1,6 +1,6 @@
 /* PR c/7652 */
 /* { dg-do compile } */
-/* { dg-options "-Wimplicit-fallthrough" } */
+/* { dg-options "-Wimplicit-fallthrough=3" } */
 
 /* Testing non-case labels.  */
 
Index: gcc/testsuite/c-c++-common/Wimplicit-fallthrough-2.c
===================================================================
--- gcc/testsuite/c-c++-common/Wimplicit-fallthrough-2.c	(revision 241233)
+++ gcc/testsuite/c-c++-common/Wimplicit-fallthrough-2.c	(working copy)
@@ -1,6 +1,6 @@
 /* PR c/7652 */
 /* { dg-do compile } */
-/* { dg-options "-Wimplicit-fallthrough" } */
+/* { dg-options "-Wimplicit-fallthrough=3" } */
 
 extern void bar (int);
 
Index: gcc/testsuite/c-c++-common/Wimplicit-fallthrough-22.c
===================================================================
--- gcc/testsuite/c-c++-common/Wimplicit-fallthrough-22.c	(revision 241233)
+++ gcc/testsuite/c-c++-common/Wimplicit-fallthrough-22.c	(working copy)
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-Wimplicit-fallthrough" } */
+/* { dg-options "-Wimplicit-fallthrough=3" } */
 
 void bar (int);
 
Index: gcc/testsuite/c-c++-common/Wimplicit-fallthrough-25.c
===================================================================
--- gcc/testsuite/c-c++-common/Wimplicit-fallthrough-25.c	(revision 241233)
+++ gcc/testsuite/c-c++-common/Wimplicit-fallthrough-25.c	(working copy)
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-Wextra" } */
+/* { dg-options "-Wimplicit-fallthrough=3" } */
 
 void bar (int);
 
Index: gcc/testsuite/c-c++-common/Wimplicit-fallthrough-26.c
===================================================================
--- gcc/testsuite/c-c++-common/Wimplicit-fallthrough-26.c	(revision 241233)
+++ gcc/testsuite/c-c++-common/Wimplicit-fallthrough-26.c	(working copy)
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-Wimplicit-fallthrough" } */
+/* { dg-options "-Wimplicit-fallthrough=3" } */
 
 void bar (int);
 
Index: gcc/testsuite/c-c++-common/Wimplicit-fallthrough-3.c
===================================================================
--- gcc/testsuite/c-c++-common/Wimplicit-fallthrough-3.c	(revision 241233)
+++ gcc/testsuite/c-c++-common/Wimplicit-fallthrough-3.c	(working copy)
@@ -1,6 +1,6 @@
 /* PR c/7652 */
 /* { dg-do compile } */
-/* { dg-options "-Wimplicit-fallthrough" } */
+/* { dg-options "-Wimplicit-fallthrough=3" } */
 
 extern void bar (int);
 
Index: gcc/testsuite/c-c++-common/Wimplicit-fallthrough-4.c
===================================================================
--- gcc/testsuite/c-c++-common/Wimplicit-fallthrough-4.c	(revision 241233)
+++ gcc/testsuite/c-c++-common/Wimplicit-fallthrough-4.c	(working copy)
@@ -1,6 +1,6 @@
 /* PR c/7652 */
 /* { dg-do compile } */
-/* { dg-options "-Wimplicit-fallthrough" } */
+/* { dg-options "-Wimplicit-fallthrough=3" } */
 
 extern void bar (int);
 
Index: gcc/testsuite/c-c++-common/Wimplicit-fallthrough-5.c
===================================================================
--- gcc/testsuite/c-c++-common/Wimplicit-fallthrough-5.c	(revision 241233)
+++ gcc/testsuite/c-c++-common/Wimplicit-fallthrough-5.c	(working copy)
@@ -1,6 +1,6 @@
 /* PR c/7652 */
 /* { dg-do compile } */
-/* { dg-options "-Wimplicit-fallthrough" } */
+/* { dg-options "-Wimplicit-fallthrough=2" } */
 
 extern void bar (int);
 extern void die (void) __attribute__((noreturn));
Index: gcc/testsuite/c-c++-common/Wimplicit-fallthrough-7.c
===================================================================
--- gcc/testsuite/c-c++-common/Wimplicit-fallthrough-7.c	(revision 241233)
+++ gcc/testsuite/c-c++-common/Wimplicit-fallthrough-7.c	(working copy)
@@ -1,6 +1,6 @@
 /* PR c/7652 */
 /* { dg-do compile } */
-/* { dg-options "-Wimplicit-fallthrough" } */
+/* { dg-options "-Wimplicit-fallthrough=3" } */
 
 extern void bar (int);
 extern int bar2 (void);
Index: gcc/testsuite/c-c++-common/Wimplicit-fallthrough-8.c
===================================================================
--- gcc/testsuite/c-c++-common/Wimplicit-fallthrough-8.c	(revision 241233)
+++ gcc/testsuite/c-c++-common/Wimplicit-fallthrough-8.c	(working copy)
@@ -1,6 +1,6 @@
 /* PR c/7652 */
 /* { dg-do compile } */
-/* { dg-options "-Wimplicit-fallthrough" } */
+/* { dg-options "-Wimplicit-fallthrough=3" } */
 
 extern void grace (int);
 
Index: gcc/testsuite/c-c++-common/attr-fallthrough-1.c
===================================================================
--- gcc/testsuite/c-c++-common/attr-fallthrough-1.c	(revision 241233)
+++ gcc/testsuite/c-c++-common/attr-fallthrough-1.c	(working copy)
@@ -1,6 +1,6 @@
 /* PR c/7652 */
 /* { dg-do compile } */
-/* { dg-options "-Wall -Wextra -Wpedantic" } */
+/* { dg-options "-Wall -Wimplicit-fallthrough=3 -Wpedantic" } */
 
 extern void bar (int);
 void
Index: gcc/testsuite/g++.dg/cpp0x/fallthrough1.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/fallthrough1.C	(revision 241233)
+++ gcc/testsuite/g++.dg/cpp0x/fallthrough1.C	(working copy)
@@ -1,6 +1,6 @@
 // PR c/7652
 // { dg-do compile { target c++11 } }
-// { dg-options "-Wextra -Wall -Wpedantic" }
+// { dg-options "-Wimplicit-fallthrough=3 -Wall -Wpedantic" }
 
 extern void bar (int);
 void
Index: gcc/testsuite/objc.dg/Wimplicit-fallthrough-1.m
===================================================================
--- gcc/testsuite/objc.dg/Wimplicit-fallthrough-1.m	(revision 241233)
+++ gcc/testsuite/objc.dg/Wimplicit-fallthrough-1.m	(working copy)
@@ -1,6 +1,6 @@
 /* PR c/7652 */
 /* { dg-do compile } */
-/* { dg-options "-Wimplicit-fallthrough" } */
+/* { dg-options "-Wimplicit-fallthrough=3" } */
 /* Test taken from
    <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0188r0.pdf>.  */
 
