Bug 490740 - nested lua expansions not supported
Summary: nested lua expansions not supported
Alias: None
Product: Fedora
Classification: Fedora
Component: rpm
Version: rawhide
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Panu Matilainen
QA Contact: Fedora Extras Quality Assurance
Depends On:
TreeView+ depends on / blocked
Reported: 2009-03-17 19:22 UTC by Carl Roth
Modified: 2011-07-19 09:05 UTC (History)
6 users (show)

Fixed In Version:
Doc Type: Enhancement
Doc Text:
Clone Of:
Last Closed: 2011-07-19 09:05:01 UTC
Type: ---

Attachments (Terms of Use)
spec file with lua scripts (551 bytes, text/plain)
2009-03-17 19:23 UTC, Carl Roth
no flags Details

Description Carl Roth 2009-03-17 19:22:27 UTC
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...

Comment 1 Carl Roth 2009-03-17 19:23:29 UTC
Created attachment 335592 [details]
spec file with lua scripts

Comment 2 Jeff Johnson 2009-09-21 13:35:04 UTC
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:
  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

Comment 3 Bug Zapper 2009-11-18 11:32:45 UTC
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Comment 4 Panu Matilainen 2011-05-24 17:49:57 UTC
FWIW, support for nested Lua macros has now been added upstream.

Comment 5 Panu Matilainen 2011-07-19 09:05:01 UTC
Nested lua macros are supported in rpm >= 4.9.1, in rawhide now.

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