Specify safe values for bool

Author: dkorpel

spec/declaration.dd

@@ -652,8 +652,9 @@ $(GNAME VoidInitializer):
         $(GLINK Initializer) or are set to the default value for the
         type of the variable. If the $(I Initializer) is $(D void),
         however, the variable is not initialized.
-        Void initializers for objects that contain indirections is not
-        allowed in `@safe` code.
+        Void initializers for variables with a type that may contain
+        $(DDSUBLINK spec/function, safe-values, unsafe values) (such as types with pointers)
+        are not allowed in `@safe` code.
         )
 
         $(IMPLEMENTATION_DEFINED If a void initialized variable's value is

spec/function.dd

@@ -3966,7 +3966,9 @@ $(H3 $(LNAME2 safe-interfaces, Safe Interfaces))
 
 $(H3 $(LNAME2 safe-values, Safe Values))
 
-        $(P For $(DDSUBLINK spec/type, basic-data-types, basic data types), all
+        $(P For a `bool`, only 0 and 1 are safe values.)
+
+        $(P For all other $(DDSUBLINK spec/type, basic-data-types, basic data types), all
         possible bit patterns are safe.)
 
         $(P A pointer is a safe value when it is one of:)
@@ -4006,6 +4008,8 @@ $(H3 $(LNAME2 safe-values, Safe Values))
         ---
         int[] f() @system
         {
+            bool b = true; /* b is initialized safe */
+            *(cast(ubyte*) &b) = 0xAA; /* b is now unsafe because it's not 0 or 1 */
             int[3] a;
             int[] d1 = a[0 .. 2]; /* d1 is safe. */
             int[] d2 = a.ptr[0 .. 3]; /* d2 is unsafe because it goes beyond a's