Bug with nested path and variable-style parameters
thaliaarchi opened this issue · 2 comments
thaliaarchi commented
I wanted to do performance and feature-coverage comparisons between jq and gojq using my wsjq Whitespace interpreter, which is considerably complex for a jq program (and overcomes the limitations of your jq Brainfuck interpreter). However, in the process, I uncovered a bug in gojq. Here's an example, reduced from various instructions in interpret_step:
def assert($cond; msg): if $cond then . else msg | halt_error end;
def at($n): assert(.stack|length > $n; "stack underflow") | .stack[-$n-1];
def top: at(0);
{ stack: [1, 2, 3] } |
top += top$ jq -ncf minimal.jq
{"stack":[1,2,6]}
$ gojq -nf minimal.jq
gojq: invalid path against: object ({"stack":[1,2,3]})If any of one these changes are made to the example program, it will run without error:
- Change the parameter from a filter to a variable:
$cond->cond - Desugar the parameter filter:
def assert(cond; msg): cond as $cond | …(the jq docs imply that this is equivalent) - Inline the call to
assert/2inat/1 - Use bare array instead of in an object:
{ stack: [1, 2, 3] }and.stack->[1, 2, 3]and.
So, the problem appears to be caused by a nested path generated by a filter that uses variable-style parameters.
wader commented
Spent some time trying to undersand what is going on. I think triggering the error can be minimize to:
{} | path(def f($_): .; f(.s)).
This might be a hint, def f($_) vs def f(c): c as $_. I would have expect them to be very similar? the expbegin difference looks suspicous?
$ GOJQ_DEBUG=1 go run -tags gojq_debug cmd/gojq/main.go -n '{} | path(def f($_): .; f(.s))'
0 scope [1,2,0]
1 store [1,0] ## $ARGS
2 const {} ## {}
3 pathbegin null
4 store [1,1]
5 jump 26
6 scope [2,1,0] ## lambda:6
7 jump 17
8 scope [3,3,1] ## f
9 store [3,0]
10 store [3,1] ## _
11 load [3,0]
12 load [3,1]
13 callpc null
14 store [3,2] ## $_
15 load [3,0]
16 ret null ## end of f
17 store [2,0]
18 jump 22
19 scope [4,0,0] ## lambda:19
20 index "s" ## .s
21 ret null ## end of lambda:19
22 pushpc 19
23 load [2,0]
24 call 8 ## call f
25 ret null ## end of lambda:6
26 load [1,1]
27 pushpc 6
28 callpc null
29 load [1,1]
30 pathend null
31 ret null
----------------------------------------+
0 scope [1,2,0] | null {"named":{},"positional":[]}
1 store [1,0] | null {"named":{},"positional":[]} ## $ARGS
2 const {} | null ## {}
3 pathbegin null | {}
4 store [1,1] | {}
5 jump 26 |
26 load [1,1] |
27 pushpc 6 | {}
28 callpc null | {} [6,0]
6 scope [2,1,0] | {} ## lambda:6
7 jump 17 | {}
17 store [2,0] | {}
18 jump 22 |
22 pushpc 19 |
23 load [2,0] | [19,1]
24 call 8 | [19,1] {} ## call f
8 scope [3,3,1] | [19,1] {} ## f
9 store [3,0] | [19,1] {}
10 store [3,1] | [19,1] ## _
11 load [3,0] |
12 load [3,1] | {}
13 callpc null | {} [19,1]
19 scope [4,0,0] | {} ## lambda:19
20 index "s" | {} ## .s
21 ret null | null ## end of lambda:19
14 store [3,2] | null ## $_
15 load [3,0] |
16 ret null | {} ## end of f
25 ret null | {} ## end of lambda:6
29 load [1,1] | {}
30 pathend null | {} {}
gojq: invalid path against: object ({})
exit status 5
$ GOJQ_DEBUG=1 go run -tags gojq_debug cmd/gojq/main.go -n '{} | path(def f(c): c as $_ | .; f(.s))'
0 scope [1,2,0]
1 store [1,0] ## $ARGS
2 const {} ## {}
3 pathbegin null
4 store [1,1]
5 jump 28
6 scope [2,1,0] ## lambda:6
7 jump 19
8 scope [3,3,1] ## f
9 store [3,0]
10 store [3,1] ## c
11 load [3,0]
12 dup null
13 expbegin null
14 load [3,1]
15 callpc null
16 store [3,2] ## $_
17 expend null
18 ret null ## end of f
19 store [2,0]
20 jump 24
21 scope [4,0,0] ## lambda:21
22 index "s" ## .s
23 ret null ## end of lambda:21
24 pushpc 21
25 load [2,0]
26 call 8 ## call f
27 ret null ## end of lambda:6
28 load [1,1]
29 pushpc 6
30 callpc null
31 load [1,1]
32 pathend null
33 ret null
----------------------------------------+
0 scope [1,2,0] | null {"named":{},"positional":[]}
1 store [1,0] | null {"named":{},"positional":[]} ## $ARGS
2 const {} | null ## {}
3 pathbegin null | {}
4 store [1,1] | {}
5 jump 28 |
28 load [1,1] |
29 pushpc 6 | {}
30 callpc null | {} [6,0]
6 scope [2,1,0] | {} ## lambda:6
7 jump 19 | {}
19 store [2,0] | {}
20 jump 24 |
24 pushpc 21 |
25 load [2,0] | [21,1]
26 call 8 | [21,1] {} ## call f
8 scope [3,3,1] | [21,1] {} ## f
9 store [3,0] | [21,1] {}
10 store [3,1] | [21,1] ## c
11 load [3,0] |
12 dup null | {}
13 expbegin null | {} {}
14 load [3,1] | {} {}
15 callpc null | {} {} [21,1]
21 scope [4,0,0] | {} {} ## lambda:21
22 index "s" | {} {} ## .s
23 ret null | {} null ## end of lambda:21
16 store [3,2] | {} null ## $_
17 expend null | {}
18 ret null | {} ## end of f
27 ret null | {} ## end of lambda:6
31 load [1,1] | {}
32 pathend null | {} {}
33 ret null | []
[]
33 ret <backtrack> null |
itchyny commented
Thank you for reporting. I fixed the bug.