Changed formatting of array index calculation in 3.13.0: intended or not?

[uusijani]

With the same arguments given, output differs between 3.12.0 and 3.13.0, as demonstrated in the example below. I didn't see this mentioned directly in the release notes, so I was wondering if this is an intentional change or a bug. I don't mind the change per se, but just wanted to be sure that it's permanent before I adjust all my existing scripts to conform to the newer way shfmt prefers this.

$ cat asdf
#!/bin/bash

array=(
    "a"
    "b"
    "c"
)

value="${array[${#array[@]} - 1]}"

printf "%s\n" "${value}"

$ /usr/local/bin/archive/shfmt/shfmt_v3.12.0_linux_amd64 -i 4 -ci -l -d asdf # no output

$ /usr/local/bin/archive/shfmt/shfmt_v3.13.0_linux_amd64 -i 4 -ci -l -d asdf
asdf
diff asdf.orig asdf
--- asdf.orig
+++ asdf
@@ -6,6 +6,6 @@
     "c"
 )
 
-value="${array[${#array[@]} - 1]}"
+value="${array[${#array[@]}-1]}"
 
 printf "%s\n" "${value}"

[uusijani]

I noticed that for the specific case of picking an element from the end using just the size of the array itself, the above is a somewhat contrived example; a plain -1 would work just as well. But I can change the example script as below, and the difference between outputs still holds:

#!/bin/bash

array=(
    "a"
    "b"
    "c"
)

i=3

value="${array[i - 1]}"

printf "%s\n" "${value}"

[LangLangBart]

output differs between 3.12.0 and 3.13.0

see #1314

[mvdan]

Apologies that I missed this, @uusijani. Someone else reported the same and it's already fixed at master, as the change in formatting was unintentional as part of the Zsh work. I'll release v3.13.1 shortly with the revert.

[uusijani]

No worries, thanks for the fix!