Bug #21085: [BUG] Stack consistency error with -ne

• Status: Closed
• Assignee: prism
• Target version: -
• ruby -v: ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [arm64-darwin24]
• Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: REQUIRED

[segiddins (Samuel Giddins)]

Running the following crashes for me

echo '' | ruby -ne ''

Attached the diagnostic report as requested

[ufuk (Ufuk Kayserilioglu)]

This succeeds with the parse.y parser, so it seems to be a Prism compiler bug:

❯ echo '' | ruby --parser=parse.y -vne ''
ruby 3.4.1 (2024-12-25 revision 48d4efcb85) [arm64-darwin23]

❯ echo '' | ruby --parser=prism -vne ''
ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [arm64-darwin23]
-e:1: [BUG] Stack consistency error (sp: 7, bp: 6)
...

[segiddins (Samuel Giddins)]

Good catch.

❯ ruby --dump=insns -vne '' --parser=parse.y
ruby 3.4.1 (2024-12-25 revision 48d4efcb85) [arm64-darwin24]
== disasm: #<ISeq:<main>@-e:1 (1,0)-(1,0)>
0000 jump                                   4                         (   1)
0002 putnil
0003 pop
0004 putself
0005 getglobal                              :$/
0007 opt_send_without_block                 <calldata!mid:gets, argc:1, FCALL|ARGS_SIMPLE>
0009 branchif                               4
0011 putnil
0012 leave

❯ ruby --dump=insns -vne '' --parser=prism
ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [arm64-darwin24]
== disasm: #<ISeq:<main>@-e:1 (1,0)-(1,0)>
0000 jump                                   7                         (   1)[Li]
0002 putnil
0003 pop
0004 jump                                   7
0006 putnil
0007 putself
0008 getglobal                              :$/
0010 opt_send_without_block                 <calldata!mid:gets, argc:1, FCALL|ARGS_SIMPLE>
0012 branchif                               6
0014 putnil
0015 leave

[alanwu (Alan Wu)]

• Assignee set to prism

[kddnewton (Kevin Newton)]

• Backport changed from 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN to 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: REQUIRED

[kddnewton (Kevin Newton)]

• Status changed from Open to Closed

Applied in changeset git|241ada7b1ca4fd71dc47a83d912ee25162a555d9.

---

[ruby/prism] Do not put empty statements in while because of -n

Fixes [Bug #21085]

https://github.com/ruby/prism/commit/ebb9c36a10