nested lua expansions not supported

Description of problem:

Nested lua expansions in an RPM spec file don't appear to work. From what I can tell (also by peeking at the RPM sources) the print buffer for lua expansions is not preserved between nested lua invocations.

Version-Release number of selected component (if applicable):

rpm-4.6.0-1.fc10.x86_64 (also affects F9 rpm)

How reproducible:

Always (see attach spec)

Steps to Reproduce:
1. download the attached spec file
2. rpmbuild --nodeps -bs *.spec
3. rpm -qp --requires *.src.rpm

Actual results:

Expected results:

Additional info:

I guess the workaround is to never nest lua expansions, but it can be tricky if other rpm macros are defined in terms of them...

Created attachment 335592
spec file with lua scripts

(aside)
Nested lua expansions actually "work" @rpm5.org.

Here's your foo.spec with %trace added:
  0< # this statement stumbles (print buffer is mis-directed)
  1> %{expand:%{lua:
  foo = rpm.expand("%__foo")
  print("BuildRequires: " .. foo .. "-devel" .. "\n")
}}^
  2> %{lua:
  foo = rpm.expand("%__foo")
  print("BuildRequires: " .. foo .. "-devel" .. "\n")
}^
  1> %__foo^
  2> %{lua:
  print("foo")
}^
  1< foo
  0< foo
  1< BuildRequires: foo-devel
  1< BuildRequires: foo-devel
  0< BuildRequires: foo-devel

But the fundamental issue for RPM is
    Is there any need for multiple nested lua invocations in RPM
    coordinated through a print buffer?

E.g. the embedded lua interpreter is (by intent) persistent so that
variables can be shared between invocations.

OTOH, the expectation here is that the print buffer be specifcally tied
to each nested invocation, i.e. unshared. That isn't a suprising expectation,
just not what was/is implemented with embedded lua.

Its conceivable to have lua invocations behave either with globally
shared state, or with independent nested invocations, dependent
on how invoked. The analogue in shell is {} vs () nesting, commands within
{} are executed by the current interpreter, () nests an interpreter when needed.

But that just brings me full circle to
    Is there really any need for this level of complexity to generate
        BuildRequires: foo-devel

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FWIW, support for nested Lua macros has now been added upstream.

Nested lua macros are supported in rpm >= 4.9.1, in rawhide now.