Commit 5e59baf9 authored by Eric Blake's avatar Eric Blake Committed by Markus Armbruster
Browse files

qapi: Reserve 'u' member name 



Now that we have separated union tag values from colliding with
non-variant C names, by naming the union 'u', we should reserve
this name for our use.  Note that we want to forbid 'u' even in
a struct with no variants, because it is possible for a future
qemu release to extend QMP in a backwards-compatible manner while
converting from a struct to a flat union.  Fortunately, no
existing clients were using this member name.  If we ever find
the need for QMP to have a member 'u', we could at that time
relax things, perhaps by having c_name() munge the QMP member to
'q_u'.

Note that we cannot forbid 'u' everywhere (by adding the
rejection code to check_name()), because the existing QKeyCode
enum already uses it; therefore we only reserve it as a struct
type member name.

Signed-off-by: default avatarEric Blake <eblake@redhat.com>
Message-Id: <1445898903-12082-24-git-send-email-eblake@redhat.com>
Signed-off-by: default avatarMarkus Armbruster <armbru@redhat.com>
parent e4ba22b3

scripts/qapi.py

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@@ -490,7 +490,7 @@ def check_type(expr_info, source, value, allow_array=False, 
    for (key, arg) in value.items():

        check_name(expr_info, "Member of %s" % source, key,

                   allow_optional=allow_optional)

        if c_name(key, False).startswith('has_'):

        if c_name(key, False) == 'u' or c_name(key, False).startswith('has_'):

            raise QAPIExprError(expr_info,

                                "Member of %s uses reserved name '%s'"

                                % (source, key))

tests/Makefile

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@@ -318,6 +318,7 @@ qapi-schema += redefined-type.json 
qapi-schema += reserved-command-q.json

qapi-schema += reserved-member-has.json

qapi-schema += reserved-member-q.json

qapi-schema += reserved-member-u.json

qapi-schema += reserved-type-kind.json

qapi-schema += reserved-type-list.json

qapi-schema += returns-alternate.json

tests/qapi-schema/reserved-member-u.err

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tests/qapi-schema/reserved-member-u.json:7: Member of 'data' for struct 'Oops' uses reserved name 'u'

tests/qapi-schema/reserved-member-u.exit

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1

tests/qapi-schema/reserved-member-u.json

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# Potential C member name collision

# We reject use of 'u' as a member name, to allow it for internal use in

# putting union branch members in a separate namespace from QMP members.

# This is true even for non-unions, because it is possible to convert a

# struct to flat union while remaining backwards compatible in QMP.

# TODO - we could munge the member name to 'q_u' to avoid the collision

{ 'struct': 'Oops', 'data': { 'u': 'str' } }