--- gcc/gcc/doc/invoke.texi

+++ gcc/gcc/doc/invoke.texi

@@ -13880,6 +13880,12 @@ exits.  Only variables that are actually allocated on the stack are

 considered, optimized away variables or variables allocated in registers

 don't count.

+NOTE: In ALT gcc 4.1.1-alt9 and later versions up to 8.3.1-alt2 this option

+was enabled by default for C, C++, ObjC, ObjC++ if none of

+@option{-fno-stack-protector}, @option{-fstack-protector-all},

+@option{-fstack-protector-strong}, @option{-nostdlib},

+nor @option{-ffreestanding} was specified.

+

 @item -fstack-protector-all

 @opindex fstack-protector-all

 Like @option{-fstack-protector} except that all functions are protected.

@@ -13892,6 +13898,12 @@ references to local frame addresses.  Only variables that are actually

 allocated on the stack are considered, optimized away variables or variables

 allocated in registers don't count.

+NOTE: In ALT gcc 8.3.1-alt3 and later versions this option is enabled by

+default for C, C++, ObjC, ObjC++ if none of @option{-fno-stack-protector},

+@option{-fstack-protector}, @option{-fstack-protector-all},

+@option{-fstack-protector-explicit}, @option{-nostdlib},

+nor @option{-ffreestanding} are specified.

+

 @item -fstack-protector-explicit

 @opindex fstack-protector-explicit

 Like @option{-fstack-protector} but only protects those functions which

--- gcc/gcc/gcc.c

+++ gcc/gcc/gcc.c

@@ -1144,6 +1144,7 @@ static const char *cpp_debug_options = "%{d*}";

 /* NB: This is shared amongst all front-ends, except for Ada.  */

 static const char *cc1_options =

 "%{pg:%{fomit-frame-pointer:%e-pg and -fomit-frame-pointer are incompatible}}\

+ %{!fno-stack-protector:%{!fstack-protector:%{!fstack-protector-strong:%{!fstack-protector-all:%{!fstack-protector-explicit:%{!ffreestanding:%{!nostdlib:-fstack-protector-strong}}}}}}}\

  %{!iplugindir*:%{fplugin*:%:find-plugindir()}}\

  %1 %{!Q:-quiet} %{!dumpbase:-dumpbase %B} %{d*} %{m*} %{aux-info*}\

  %{fcompare-debug-second:%:compare-debug-auxbase-opt(%b)} \