Built-in function power10 doesnt seem to exist

[hansonchar]

Describe the bug
Under List-of-Built-in-Functions:

pow10/0

But

$ jq -nc 'pow10'
jq: error (at <unknown>): Error: pow10/0 not found at build time

Furthermore, under Math, pow10 is listed as a one-input C-math function, but

$ jq -nc 'pow10(1)'
jq: error: pow10/1 is not defined at <top-level>, line 1:
pow10(1)
jq: 1 compile error

Environment (please complete the following information):

$ uname -a
Darwin ... 21.6.0 Darwin Kernel Version 21.6.0: Mon Dec 19 20:44:01 PST 2022; root:xnu-8020.240.18~2/RELEASE_X86_64 x86_64

$ jq --version
jq-1.6

[emanuele6]

Furthermore, under Math, pow10 is listed as a one-input C-math function, but

Exactly, it only has one input, so you use it as 2|pow10, not as pow10(2) just like the sine function is used as 2|sin.

---

Note that a pow10/0 function does in fact exist in your jq, otherwise the script would not compile at all, and note that jq only errors when pow10 is run:

~ $ jq -n '2|try pow10'
~ $ jq -n '2|try pow10a'
jq: error: pow10a/0 is not defined at <top-level>, line 1:
2|try pow10a
jq: 1 compile error
~ $ jq -n '2|select(false)|pow10'
~ $ jq -n '2|select(true)|pow10'
jq: error (at <unknown>): Error: pow10/0 not found at build time

Your jq does have pow10/0, but it is implemented effectively as:

def pow10:
    error("Error: pow10/0 not found");

Support of libc math functions depends on the underlying libc since those jq functions are just wrappers around them.
If libc doesn't provide one of those functions, jq still provides the jq wrapper as a function that error when it is used, so that scripts that use it still compile.

Your system's libc does not support pow10, like most other modern systems don't; pow10 is not defined by the C standard and is an old extension.

This is a duplicate of #2456. You can also read that for more details.

[hansonchar]

Interesting!