RE: use of hyphen in recipes to ignore errors precludes using -- as comment character

[Cook, Malcolm]

>On 2021-02-19 21:12, Cook, Malcolm wrote:
>> Gnu manual reads:
>> 
>> To ignore errors in a recipe line, write a '-' at the beginning of
>> the line's text (after the initial tab)...
>> 
>> I think it would be good if the implementation changed to allow instead
>> 
>> To ignore errors in a recipe line, write a '-' as the first character
>> of the line's text (immediately after the initial tab with no other
>> preceding whitespace)...
>
>I don't see the difference. There isn't any whitespace allowed between 
>the
>tab and the minus.

Why do you say this? According to what?

>
>In any case, this is a POSIX feature:
>
>Makefile command lines can have one or more of the following
>prefixes: a <hyphen-minus> ( '-' ), an at-sign ( '@' ), or a
><plus-sign> ( '+' ). These shall modify the way in which make
>processes the command.
>
>- If the command prefix contains a <hyphen-minus>, or the -i
>option is present, or the special target .IGNORE has either
>the current target as a prerequisite or has no prerequisites,
>any error found while executing the command shall be ignored.
>
>@ If the command prefix contains an at-sign and the make
>utility command line -n option is not specified, or the -s
>option is present, or the special target .SILENT has either
>the current target as a prerequisite or has no prerequisites,
>the command shall not be written to standard output before it
>is executed.
>
>+ If the command prefix contains a <plus-sign>, this
>indicates a makefile command line that shall be executed even
>if -n, -q, or -t is specified.
>

I guess what is not clearly defined at least to me is what constitutes a 
"prefix".

Apparently whitespace gets ignored in looking for a prefix.  To me this is 
unfortunate and what I am suggesting might be changed.


>Experimenting with GNU Make, this succeeds for me, as expected,
>with a diagnostic about the error being ignored:
>
>.PHONY: all
>
>all:
>-false
>echo foo
>
>This, with an added space, fails:
>
>.PHONY: all
>
>all:
>- false
>echo foo
>
>
>> This would allow the use of '--' following an initial space after the
>> tab to serve its usual role introducing an SQL comment, allowing
>> commenting out selected lines of SQL statement within a HERE string.
>
>How are you embedding here strings into make recipes? That generally
>doesn't work very well, unless perhaps you are using the GNU Make
>extension which allows all of he lines of a recipe to be a single
>shell script, rather than individual scripts.

That is what I am doing, yes.

.ONESHELL

To me all this stuff about prefixes in the middle of a multiline recipe doesn't 
even make sense with .ONESHELL.

>