On Tue, Mar 15, 2016 at 7:51 PM, Jason Merrill <ja...@redhat.com> wrote: > On 03/15/2016 08:25 PM, Joseph Myers wrote: >> >> On Tue, 15 Mar 2016, H.J. Lu wrote: >> >>> On Tue, Mar 15, 2016 at 3:34 PM, Joseph Myers <jos...@codesourcery.com> >>> wrote: >>>> >>>> On Tue, 15 Mar 2016, H.J. Lu wrote: >>>> >>>>> On Tue, Mar 15, 2016 at 2:39 PM, Joseph Myers <jos...@codesourcery.com> >>>>> wrote: >>>>>> >>>>>> I'm not sure if the zero-size arrays (a GNU extension) are considered >>>>>> to >>>>>> make a struct non-empty, but in any case I think the tests should >>>>>> cover >>>>>> such arrays as elements of structs. >>>>> >>>>> >>>>> There are couple tests for structs with members of array >>>>> of empty types. testsuite/g++.dg/abi/empty14.h has >>>> >>>> >>>> My concern is the other way round - structs with elements such as >>>> "int a[0];", an array [0] of a nonempty type. My reading of the >>>> subobject >>>> definition is that such an array should not cause the struct to be >>>> considered nonempty (it doesn't result in any int subobjects). >>> >>> >>> This is a test for struct with zero-size array, which isn't treated >>> as empty type. C++ and C are compatible in its passing. >> >> >> Where is the current definition of empty types you're proposing for use in >> GCC? Is the behavior of this case clear from that definition? > > > "An empty type is a type where it and all of its subobjects (recursively) > are of structure, union, or array type. No memory slot nor register should > be used to pass or return an object of empty type." > > It seems to me that such a struct should be considered an empty type under > this definition, since a zero-length array has no subobjects. >
Since zero-size array is GCC extension, we can change it. Do we want to change its passing for C? -- H.J.
