| Message ID | 1445576998-2921-24-git-send-email-eblake@redhat.com |
|---|---|
| State | New |
| Headers | show |
Eric Blake <eblake@redhat.com> writes: > 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. Suggest to add something like: Therefore, we only reserve it as a struct type member name. > And it is still okay to use it as a > branch name within a union, although not worth adding a > positive test to qapi-schema-test for this corner case. Not sure this sentence is needed. > Signed-off-by: Eric Blake <eblake@redhat.com> > > --- > v10: new patch, split from 1/17 and 3/17; by deferring this until > after the rename was complete, it reduces churn due to the new feature > --- > scripts/qapi.py | 2 +- > tests/Makefile | 1 + > tests/qapi-schema/struct-member-u.err | 1 + > tests/qapi-schema/struct-member-u.exit | 1 + > tests/qapi-schema/struct-member-u.json | 7 +++++++ > tests/qapi-schema/struct-member-u.out | 0 > 6 files changed, 11 insertions(+), 1 deletion(-) > create mode 100644 tests/qapi-schema/struct-member-u.err > create mode 100644 tests/qapi-schema/struct-member-u.exit > create mode 100644 tests/qapi-schema/struct-member-u.json > create mode 100644 tests/qapi-schema/struct-member-u.out > > diff --git a/scripts/qapi.py b/scripts/qapi.py > index 8b9f5f7..b941ccf 100644 > --- a/scripts/qapi.py > +++ b/scripts/qapi.py > @@ -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).startswith('has_'): > + if key == 'u' or c_name(key).startswith('has_'): Perhaps c_name(key) == 'u' would be very slightly cleaner. No difference in practice, of course. > raise QAPIExprError(expr_info, > "Member of %s uses reserved name '%s'" > % (source, key)) > diff --git a/tests/Makefile b/tests/Makefile > index 9194264..8c239f8 100644 > --- a/tests/Makefile > +++ b/tests/Makefile > @@ -326,6 +326,7 @@ qapi-schema += struct-base-clash-deep.json > qapi-schema += struct-base-clash.json > qapi-schema += struct-data-invalid.json > qapi-schema += struct-member-invalid.json > +qapi-schema += struct-member-u.json The closely related test for the reserved 'has_' prefix is called args-has-clash.json. More losely related tests for other reserved names are called reserved-command.json, reserved-member.json. Should these all be called like reserved-WHATEVER-WHERE.json? > qapi-schema += struct-name-list.json > qapi-schema += trailing-comma-list.json > qapi-schema += trailing-comma-object.json > diff --git a/tests/qapi-schema/struct-member-u.err b/tests/qapi-schema/struct-member-u.err > new file mode 100644 > index 0000000..0dc354c > --- /dev/null > +++ b/tests/qapi-schema/struct-member-u.err > @@ -0,0 +1 @@ > +tests/qapi-schema/struct-member-u.json:7: Member of 'data' for struct 'Oops' uses reserved name 'u' > diff --git a/tests/qapi-schema/struct-member-u.exit b/tests/qapi-schema/struct-member-u.exit > new file mode 100644 > index 0000000..d00491f > --- /dev/null > +++ b/tests/qapi-schema/struct-member-u.exit > @@ -0,0 +1 @@ > +1 > diff --git a/tests/qapi-schema/struct-member-u.json b/tests/qapi-schema/struct-member-u.json > new file mode 100644 > index 0000000..1eaf0f3 > --- /dev/null > +++ b/tests/qapi-schema/struct-member-u.json > @@ -0,0 +1,7 @@ > +# 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' } } > diff --git a/tests/qapi-schema/struct-member-u.out b/tests/qapi-schema/struct-member-u.out > new file mode 100644 > index 0000000..e69de29
diff --git a/scripts/qapi.py b/scripts/qapi.py index 8b9f5f7..b941ccf 100644 --- a/scripts/qapi.py +++ b/scripts/qapi.py @@ -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).startswith('has_'): + if key == 'u' or c_name(key).startswith('has_'): raise QAPIExprError(expr_info, "Member of %s uses reserved name '%s'" % (source, key)) diff --git a/tests/Makefile b/tests/Makefile index 9194264..8c239f8 100644 --- a/tests/Makefile +++ b/tests/Makefile @@ -326,6 +326,7 @@ qapi-schema += struct-base-clash-deep.json qapi-schema += struct-base-clash.json qapi-schema += struct-data-invalid.json qapi-schema += struct-member-invalid.json +qapi-schema += struct-member-u.json qapi-schema += struct-name-list.json qapi-schema += trailing-comma-list.json qapi-schema += trailing-comma-object.json diff --git a/tests/qapi-schema/struct-member-u.err b/tests/qapi-schema/struct-member-u.err new file mode 100644 index 0000000..0dc354c --- /dev/null +++ b/tests/qapi-schema/struct-member-u.err @@ -0,0 +1 @@ +tests/qapi-schema/struct-member-u.json:7: Member of 'data' for struct 'Oops' uses reserved name 'u' diff --git a/tests/qapi-schema/struct-member-u.exit b/tests/qapi-schema/struct-member-u.exit new file mode 100644 index 0000000..d00491f --- /dev/null +++ b/tests/qapi-schema/struct-member-u.exit @@ -0,0 +1 @@ +1 diff --git a/tests/qapi-schema/struct-member-u.json b/tests/qapi-schema/struct-member-u.json new file mode 100644 index 0000000..1eaf0f3 --- /dev/null +++ b/tests/qapi-schema/struct-member-u.json @@ -0,0 +1,7 @@ +# 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' } }
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. And it is still okay to use it as a branch name within a union, although not worth adding a positive test to qapi-schema-test for this corner case. Signed-off-by: Eric Blake <eblake@redhat.com> --- v10: new patch, split from 1/17 and 3/17; by deferring this until after the rename was complete, it reduces churn due to the new feature --- scripts/qapi.py | 2 +- tests/Makefile | 1 + tests/qapi-schema/struct-member-u.err | 1 + tests/qapi-schema/struct-member-u.exit | 1 + tests/qapi-schema/struct-member-u.json | 7 +++++++ tests/qapi-schema/struct-member-u.out | 0 6 files changed, 11 insertions(+), 1 deletion(-) create mode 100644 tests/qapi-schema/struct-member-u.err create mode 100644 tests/qapi-schema/struct-member-u.exit create mode 100644 tests/qapi-schema/struct-member-u.json create mode 100644 tests/qapi-schema/struct-member-u.out diff --git a/tests/qapi-schema/struct-member-u.out b/tests/qapi-schema/struct-member-u.out new file mode 100644 index 0000000..e69de29