"for arg do" is reported as syntax error despite being valid

[cdown]

The shorthand for for arg in "$@"; do, for arg do (note: without the requirement of a semicolon), is reported as a violation of SC107{3,2}, but it is explicitly permitted by POSIX, and in fact is more portable than for arg; do (with semicolon).

A script that triggers this:

for arg do
    echo "$arg"
done

[cdown]

Duplicate of #44.