Re: [PATCH bpf-next v1 3/4] selftests/bpf: Test btf_dump rendering of decl_tags

[Ihor Solodrai <ihor.solodrai@linux.dev>]

On 9/17/26 3:30 AM, Alan Maguire wrote:
> On 17/09/2026 02:20, Ihor Solodrai wrote:
>> Cover the decl tag rendering the previous patch added. One subtest
>> builds a BTF with every shape that renders, plus two that must not:
>>
>>  - a named record with both forms of tag
>>  - a typedef'd anonymous record, whose attribute precedes the declarator
>>  - a union
>>  - a record that also carries the derived packed attribute
>>  - an anonymous record inlined at a member
>>  - two records whose tags are added in reverse target order, which is
>>    what pins the sort: without it the earlier record loses its attribute
>>  - attributes on a var and on a func, which btf_dump never declares
>>
>> A second subtest appends types and attributes to a dumper that has
>> already run. Its last phase adds an attribute for a record emitted two
>> dumps earlier and checks nothing is rendered for it: an attribute is
>> part of the type, and btf_dump emits each definition once.
>>
>> A third covers members. A member attribute and a record one share a key
>> in the index, so it checks they do not leak into each other's position,
>> over a function pointer, an array and a bit-field - declarators the
>> attribute has to follow rather than precede.
>>
>> A fourth covers typedefs, including a typedef of an anonymous record
>> carrying three groups at once, binding to the member, the record and
>> the typedef.
>>
>> Switch test_ctx__dump_and_compare() to compare_text_to_expected()
>> while we are here.
>>
>> Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
> 
> Small suggestion; while this test is great at exercising the btf dump
> internals, adding a bpftool btf dump test to prog_tests/bpftool_btf_dump.c
> might help illustrate the change end-to-end (if you're planning this
> as part of the work to eliminate the push/pop attributes feel free to
> ignore). Thanks!

Hi Alan. Thanks for taking a look.

Yes, that's exactly the plan. btf_dump.c contains tests for libbpf btf_dump
primitives, and bpftool_btf_dump.c is for bpftool format c.

So more tests coming soon, no worries.

> 
> 
>> ---
>>  .../selftests/bpf/prog_tests/btf_dump.c       | 343 +++++++++++++++++-
>>  1 file changed, 342 insertions(+), 1 deletion(-)
>>
>> [...]
>>  
>