gcc/ChangeLog:
* doc/extend.texi (nonnull): List no-argument form. Reference
-fno-delete-null-pointer-checks and -fisolate-erroneous-paths-attribute.
===================================================================
@@ -3075,7 +3075,8 @@ including those that do not have an attribute suit
them individually. This attribute is supported mainly for the purpose
of testing the compiler.
-@item nonnull (@var{arg-index}, @dots{})
+@item nonnull
+@itemx nonnull (@var{arg-index}, @dots{})
@cindex @code{nonnull} function attribute
@cindex functions with non-null pointer arguments
The @code{nonnull} attribute specifies that some function parameters should
@@ -3092,10 +3093,15 @@ causes the compiler to check that, in calls to @co
arguments @var{dest} and @var{src} are non-null. If the compiler
determines that a null pointer is passed in an argument slot marked
as non-null, and the @option{-Wnonnull} option is enabled, a warning
-is issued. The compiler may also choose to make optimizations based
-on the knowledge that certain function arguments will never be null.
+is issued. @xref{Warning Options}. Unless disabled by
+the @option{-fno-delete-null-pointer-checks} option the compiler may
+also perform optimizations based on the knowledge that certain function
+arguments cannot be null. In addition,
+the @option{-fisolate-erroneous-paths-attribute} option can be specified
+to have GCC transform calls with null arguments to non-null functions
+into traps. @xref{Optimize Options}.
-If no argument index list is given to the @code{nonnull} attribute,
+If no @var{arg-index} is given to the @code{nonnull} attribute,
all pointer arguments are marked as non-null. To illustrate, the
following declaration is equivalent to the previous example: