In the past, the Lock_Free aspect of a protected type (including an
anonymous type) defaulted to False. In the case where an explicit
"Lock_Free => True" aspect specification would be legal, the aspect now
defaults to True (which means that a lock-free implementation is used to
implement the type's protected operations); this is like the previous
behavior of the compiler with the -gnatd9 switch specified. Support for
the Lock_Free attribute (which should not be confused with the Lock_Free
aspect) is removed.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

        * debug.adb: Remove comment regarding the -gnatd9 switch.
        * doc/gnat_rm/implementation_defined_attributes.rst: Remove all
        mention of the Lock_Free attribute.
        * gnat_rm.texi, gnat_ugn.texi: Regenerate.
        * exp_attr.adb, sem_attr.adb: Remove all mention of the former
        Attribute_Lock_Free enumeration element of the Attribute_Id type.
        * sem_ch9.adb
        (Allows_Lock_Free_Implementation): Remove the Debug_Flag_9 test.
        Return False in the case of a protected function whose result type
        requires use of the secondary stack.
        (Satisfies_Lock_Free_Requirements): This functions checks for
        certain constructs and returns False if one is found. In the case
        of a protected function, there is no need to check to see if the
        protected object is being modified. So it is ok to omit *some*
        checks in the case of a protected function. But other checks which
        are required (e.g., the test for a reference to a variable that is
        not part of the protected object) were being incorrectly omitted.
        This could result in accepting "Lock_Free => True" aspect
        specifications that should be rejected.
        * snames.adb-tmpl: Name_Lock_Free no longer requires special
        treatment in Get_Pragma_Id or Is_Pragma_Name (because it is no
        longer an attribute name).
        * snames.ads-tmpl: Move the declaration of Name_Lock_Free to
        reflect the fact that it is no longer the name of an attribute.
        Delete Attribute_Lock_Free from the Attribute_Id enumeration type.

Attachment: patch.diff.gz
Description: application/gzip

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