Bug #14459: Unexpected compile error in 2.5.0

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-darwin17]
• Backport: 2.3: DONTNEED, 2.4: DONTNEED, 2.5: DONE

[jnchito (Junichi Ito)]

I created this script as test.rb.

h = { us: 'dollar', india: 'rupee' }
# 変数hのキーと値を**で展開させる
{ japan: 'yen', **h } #=> {:japan=>"yen", :us=>"dollar", :india=>"rupee"}

# **を付けない場合は構文エラーになる
# { japan: 'yen', h }
#=> SyntaxError: syntax error, unexpected '}', expecting =>
#   { japan: 'yen', h }
#                      ^

# ----------------------------------------

h = { us: 'dollar', india: 'rupee' }
{ japan: 'yen' }.merge(h) #=> {:japan=>"yen", :us=>"dollar", :india=>"rupee"}

In Ruby 2.4.3 it runs without errors, but in Ruby 2.5.0 it fails with compile error (SyntaxError).

➜  Desktop rbenv shell 2.4.3
➜  Desktop ruby -v
ruby 2.4.3p205 (2017-12-14 revision 61247) [x86_64-darwin17]
➜  Desktop ruby test.rb     
➜  Desktop rbenv shell 2.5.0
➜  Desktop ruby -v          
ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-darwin17]
➜  Desktop ruby test.rb     
-- raw disasm--------
 <L508596008>
 trace: 1
 0000 putobject            :us                                         (   1)
 0002 putstring            "dollar"                                    (   1)
 0004 putobject            :india                                      (   1)
 0006 putstring            "rupee"                                     (   1)
 0008 newhash              4                                           (   1)
 0010 setlocal_OP__WC__0   3                                           (   1)
 trace: 1
*0012 newhash              2                                           (   3)
 0014 getlocal_OP__WC__0   3                                           (   3)
 0016 pop                                                              (   3)
 trace: 1
 0017 putobject            :us                                         (  13)
 0019 putstring            "dollar"                                    (  13)
 0021 putobject            :india                                      (  13)
 0023 putstring            "rupee"                                     (  13)
 0025 newhash              4                                           (  13)
 0027 setlocal_OP__WC__0   3                                           (  13)
 trace: 1
 0029 putobject            :japan                                      (  14)
 0031 putstring            "yen"                                       (  14)
 0033 newhash              2                                           (  14)
 0035 getlocal_OP__WC__0   3                                           (  14)
 0037 opt_send_without_block <callinfo:merge, 1>, <call cache>         (  14)
 0040 leave                                                            (  14)
---------------------
test.rb:3: argument stack underflow (-1)
Traceback (most recent call last):
test.rb: compile error (SyntaxError)

I attached actual test.rb. I think it should run without errors in Ruby 2.5.0 too.

[wanabe (_ wanabe)]

git bisect tells that this is since r61329 [Bug #14201].

$ git checkout 5c3f9641c0475b6ec2e26c8e6df921abf47856ca~
Previous HEAD position was 5c3f9641c0... compile.c: side effect in splat
HEAD is now at 494b3aeaea... Use syswrite to avoid potential buffering in IO#select spec

$ make REVISION_FORCE=PHONY .revision.time miniruby >/dev/null 2>&1 && ./miniruby -ve 'h = { us: "dollar", india: "rupee" }; { japan: "yen", **h }; true'
ruby 2.5.0dev (2017-12-19 trunk 61327) [x86_64-linux]
-e:1: warning: possibly useless use of true in void context

$ git checkout 5c3f9641c0475b6ec2e26c8e6df921abf47856ca
Previous HEAD position was 494b3aeaea... Use syswrite to avoid potential buffering in IO#select spec
HEAD is now at 5c3f9641c0... compile.c: side effect in splat

$ make REVISION_FORCE=PHONY .revision.time miniruby >/dev/null 2>&1 && ./miniruby -ve 'h = { us: "dollar", india: "rupee" }; { japan: "yen", **h }; true'
ruby 2.5.0dev (2017-12-19 trunk 61329) [x86_64-linux]
-e:1: warning: possibly useless use of true in void context
-- raw disasm--------
 <L-35872528>
 trace: 1
 0000 putobject            :us                                         (   1)
 0002 putstring            "dollar"                                    (   1)
 0004 putobject            :india                                      (   1)
 0006 putstring            "rupee"                                     (   1)
 0008 newhash              4                                           (   1)
 0010 setlocal_OP__WC__0   3                                           (   1)
*0012 newhash              2                                           (   1)
 0014 putspecialobject     1                                           (   1)
 0016 swap                                                             (   1)
 0017 getlocal_OP__WC__0   3                                           (   1)
 0019 opt_send_without_block <callinfo:core#hash_merge_kwd, 2>, <call cache>(   1)
 0022 pop                                                              (   1)
 0023 putobject            true                                        (   1)
 0025 leave                                                            (   1)
---------------------
-e:1: argument stack underflow (-1)
Traceback (most recent call last):
-e: compile error (SyntaxError)

[wanabe (_ wanabe)]

• Related to Bug #14201: Regression due to over optimization of hash splat added

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

Applied in changeset trunk|r62333.

---

compile.c: popped hash

• compile.c (compile_array): skip creating new hash if preceeding
  elements are popped all. [ruby-core:85486] [Bug #14459]

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.3: UNKNOWN, 2.4: UNKNOWN, 2.5: UNKNOWN to 2.3: DONTNEED, 2.4: DONTNEED, 2.5: REQUIRED

[naruse (Yui NARUSE)]

• Backport changed from 2.3: DONTNEED, 2.4: DONTNEED, 2.5: REQUIRED to 2.3: DONTNEED, 2.4: DONTNEED, 2.5: DONE

ruby_2_5 r62527 merged revision(s) 62333.