2 files changed, 23 insertions, 36 deletions
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index a119ad3..8c29e24 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -7138,11 +7138,9 @@ The @code{aligned} attribute can also be used for functions
 @cindex @code{counted_by} variable attribute
 @item counted_by (@var{count})
 The @code{counted_by} attribute may be attached to the C99 flexible array
-member, or a pointer field of a structure.  It indicates that the number
-of the elements of the array that is held by the flexible array member
-field, or is pointed to by the pointer field, is given by the field
-"@var{count}" in the same structure as the flexible array member or the
-pointer field.
+member of a structure.  It indicates that the number of the elements of the
+array is given by the field "@var{count}" in the same structure as the
+flexible array member.
 
 This attribute is available only in C for now.
 In C++ this attribute is ignored.
@@ -7163,22 +7161,8 @@ struct P @{
 @end smallexample
 
 @noindent
-specifies that the @code{array} is a flexible array member whose number
-of elements is given by the field @code{count} in the same structure.
-
-@smallexample
-struct PP @{
-  size_t count2;
-  char other1;
-  char *array2 __attribute__ ((counted_by (count2)));
-  int other2;
-@} *pp;
-@end smallexample
-
-@noindent
-specifies that the @code{array2} is an array that is pointed by the
-pointer field, and its number of elements is given by the field
-@code{count2} in the same structure.
+specifies that the @code{array} is a flexible array member whose number of
+elements is given by the field @code{count} in the same structure.
 
 The field that represents the number of the elements should have an
 integer type.  Otherwise, the compiler reports an error and ignores
@@ -7187,12 +7171,6 @@ the attribute.
 When the field that represents the number of the elements is assigned a
 negative integer value, the compiler treats the value as zero.
 
-The @code{counted_by} attribute is not allowed for a pointer to @code{void},
-a pointer to function, or a pointer to a structure or union that includes
-a flexible array member.  However, it is allowed for a pointer to
-non-void incomplete structure or union types, as long as the type could
-be completed before the first reference to the pointer.
-
 An explicit @code{counted_by} annotation defines a relationship between
 two objects, @code{p->array} and @code{p->count}, and there are the
 following requirements on the relationship between this pair:
@@ -7208,13 +7186,6 @@ available all the time.  This relationship must hold even after any of
 these related objects are updated during the program.
 @end itemize
 
-In addition to the above requirements, there is one more requirement
-between this pair if and only if @code{p->array} is an array that is
-pointed by the pointer field:
-
-@code{p->array} and @code{p->count} can only be changed by changing the
-whole structure at the same time.
-
 It's the programmer's responsibility to make sure the above requirements to
 be kept all the time.  Otherwise the compiler reports warnings and
 the results of the array bound sanitizer and the
@@ -7236,8 +7207,6 @@ In the above, @code{ref1} uses @code{val1} as the number of the elements in
 @code{p->array}, and @code{ref2} uses @code{val2} as the number of elements
 in @code{p->array}.
 
-Note, however, the above feature is not valid for the pointer field.
-
 @cindex @code{alloc_size} variable attribute
 @item alloc_size (@var{position})
 @itemx alloc_size (@var{position-1}, @var{position-2})
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 7640e7d..74f5ee2 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -3816,6 +3816,23 @@ Warn when a type with an ABI tag is used in a context that does not
 have that ABI tag.  See @ref{C++ Attributes} for more information
 about ABI tags.
 
+@opindex Wabbreviated-auto-in-template-arg
+@opindex Wno-abbreviated-auto-in-template-arg
+@item -Wno-abbreviated-auto-in-template-arg
+Disable the error for an @code{auto} placeholder type used within a
+template argument list to declare a C++20 abbreviated function
+template, e.g.
+
+@smallexample
+void f(S<auto>);
+@end smallexample
+
+This feature was proposed in the Concepts TS, but was not adopted into
+C++20; in the standard, a placeholder in a parameter declaration must
+appear as a decl-specifier.  The error can also be reduced to a
+warning by @option{-fpermissive} or
+@option{-Wno-error=abbreviated-auto-in-template-arg}.
+
 @opindex Wcomma-subscript
 @opindex Wno-comma-subscript
 @item -Wcomma-subscript @r{(C++ and Objective-C++ only)}
@@ -6443,6 +6460,7 @@ only by this flag, but it also downgrades some C and C++ diagnostics
 that have their own flag:
 
 @gccoptlist{
+-Wabbreviated-auto-in-template-arg @r{(C++ and Objective-C++ only)}
 -Wdeclaration-missing-parameter-type @r{(C and Objective-C only)}
 -Wimplicit-function-declaration @r{(C and Objective-C only)}
 -Wimplicit-int @r{(C and Objective-C only)}