Hi,
On 13/08/2021 19:20, Roberto A. Foglietta wrote:
At the moment when $LINENO is printed by a function the number displayed
is the lines from the start of the function.
Unfortunately, this information is useless because we do not have $FUNCNAME.
Even if we have $FUNCNAME having always an absolute $LINENO will be more
easier.
I'm the one who implemented LINENO handling in dash, which is what
busybox's is based on. LINENO in functions being relative to the start
of the function was very much intentional: it is required by POSIX. I
think just dropping that entirely is wrong. However, at the same time, I
no longer believe POSIX requires LINENO in functions to _always_ be
relative to the start of the function.
Here's what POSIX says:
LINENO
Set by the shell to a decimal number representing the current
sequential line number (numbered starting with 1) within a script or
function before it executes each command. If the user unsets or
resets LINENO, the variable may lose its special meaning for the
life of the shell. If the shell is not currently executing a script
or function, the value of LINENO is unspecified. This volume of
POSIX.1-2017 specifies the effects of the variable only for systems
supporting the User Portability Utilities option.
What POSIX fails to specify is what happens when a function is defined
in a script. In that case, the line number can be either relative to the
start of the script, or to the start of the function, there is no text
here to specify which takes precedence. I agree that relative to the
start of the script is more intuitive, and as this is what other shells
already did, I believe that a reading of POSIX that disallows that
traditional behaviour, including my original reading, must be an
incorrect reading.
However, for functions defined outside of a script, the only way to
interpret the requirements is for LINENO to remain relative to the start
of the function as it is now.
I am maintaining my own fork of dash nowadays, and in that I modified it
to behave like ksh like so:
<https://github.com/hvdijk/gwsh/commit/2d4e35cdb4728cfa6de1b8a297ecbd7143fb2d08>.
The commit message shows the effects of the commit, and I think that
matches what you would like to see. If this commit is of interest to
busybox, feel free to use it.
Cheers,
Harald van Dijk
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