Bug #20701
closedHash argument passed as keyword splat can be mutated inside method
Description
If you call a method with a splatted kwargs that also uses a splatted array followed by at least one positional argument, the called method can mutate the splatted kwargs.
def foo(a, h)
h[:splat_modified] = true
end
a = []
b = {splat_modified: false}
foo(*a, :x, **b)
b[:splat_modified] # Should be 'false' but is 'true'
# It makes no difference if the called method expects a kwargs
def foo2(a, **h)
h[:splat_modified] = true
end
b[:splat_modified] = false
foo2(*a, :x, **b)
b[:splat_modified] # Should be 'false' but is 'true'
# The case when a block is also pass is broken too
c = proc { }
b[:splat_modified] = false
foo(*a, :x, **b, &c)
b[:splat_modified] # Should be 'false' but is 'true'
# When the extra positional argument after the array splat is removed the correct behavior is restored
b[:splat_modified] = false
foo(*a, **b)
foo(*a, :x, **b, &c)
b[:splat_modified] # Is 'false'
Apparently, this problem is due to the KW_SPLAT_MUT
flag being set at the method's call site:
ruby --dump=insns,-optimize -e 'a, b, c = [4,6,4],{a: 3},:ds; foo(*a,9,**c)
outputs
0000 duparray [4, 6, 4] ( 1)[Li]
0002 duphash {:a=>3}
0004 putobject :ds
0006 setlocal c@2, 0
0009 setlocal b@1, 0
0012 setlocal a@0, 0
0015 putself
0016 getlocal a@0, 0
0019 splatarray true
0021 putobject 9
0023 pushtoarray 1
0025 getlocal c@2, 0
0028 send <calldata!mid:foo, argc:2, ARGS_SPLAT|ARGS_SPLAT_MUT|FCALL|KW_SPLAT|KW_SPLAT_MUT>, nil
0031 leave
The error is present in both 3.3 and 3.4:
- ruby 3.4.0dev (2024-08-27T00:39:24Z master e5295644c9) [x86_64-linux]
- ruby 3.3.4 (2024-07-09 revision be1089c8ec) [x86_64-linux]
PR for test: https://github.com/ruby/ruby/pull/11467
Updated by jeremyevans0 (Jeremy Evans) about 2 months ago
Thanks for the report. Looks like a regression in e87d0882910001ef3b0c2ccd43bf00cee8c34a0c. I submitted a pull request to fix this: https://github.com/ruby/ruby/pull/11468
Updated by jeremyevans (Jeremy Evans) about 2 months ago
- Status changed from Open to Closed
Applied in changeset git|a3562c2a0abf1c2bdd1d50377b4f929580782594.
Remove incorrect setting of KW_SPLAT_MUT flag
Fixes [Bug #20701]
Co-authored-by: Pablo Herrero pablodherrero@gmail.com
Updated by jeremyevans0 (Jeremy Evans) about 2 months ago
- Backport changed from 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN to 3.1: DONTNEED, 3.2: DONTNEED, 3.3: REQUIRED
Updated by k0kubun (Takashi Kokubun) about 1 month ago
- Backport changed from 3.1: DONTNEED, 3.2: DONTNEED, 3.3: REQUIRED to 3.1: DONTNEED, 3.2: DONTNEED, 3.3: DONE
ruby_3_3 cf9a6c2b63e6337a3f6ce76527446739e5aceb67 merged revision(s) a3562c2a0abf1c2bdd1d50377b4f929580782594.