> From: Paul Smith <psm...@gnu.org>
> Cc: bug-make@gnu.org
> Date: Sun, 28 Apr 2013 15:15:09 -0400
>
> The goal of this code in the if-statement is to implement a special case
> allowing ONESHELL to be easier to add in the case where you DO have a
> standard shell. In that case, and ONLY in that case, we remove the
> internal @-+ characters. This allows you to have something like:
>
> foo:
> @echo hi
> @echo there
> @echo how are you
>
> And have it continue to work if you add ONESHELL (for performance
> reasons) without rewriting all the recipes.
I understand that much.
> However, if you do NOT have a POSIX shell, then we do NOT remove these
> internal characters: we simply provide the script as-is and only the
> first line is checked for special characters. This lets you use
> something like Perl, where @ is a special character, for example:
>
> SHELL = /usr/bin/perl
> foo:
> @print "hi";
> @array = qw(there how are you);
> print "@array\n";
This is not yet supported on MS-Windows. We currently only support
either a Bourne-compatible shell or the stock Windows shells,
command.com and cmd.exe. And the Windows shells don't need these
characters, so it is OK to remove them as in the case of a Posix
shell.
> I think the implementation you have is not quite right. I think the
> parsing of the @-+ stuff is common across all platforms if we have a
> shell, so you don't need the "else /* non-posix shell */".
I do need a separate code, because it doesn't just remove the @-+
stuff, it also removes escaped newlines, so that this:
foo && \
bar && \
baz
is transformed into a single line
foo && bar && baz
That's because stock Windows shells don't know about escaped
newlines. I also remove leading whitespace from each logical line,
while at that, because I don't want to rely on Windows shells too much
(some of their internal commands are quite weird).
> I think it pseudo-code it would look something like this:
>
> if (posix-shell)
> {
> ...strip out @-+ from LINE...
> }
> #ifdef WINDOWS32
> if (need a batch file)
> {
> ...write LINE to the batch file & setup new_argv for batch...
> }
> else
> #endif
> {
> ...chop LINE up into new_argv...
> }
> return new_argv;
>
> Or something.
I will take a look.
> Also, I'm not sure about adding things like @echo off to the batch
> file. That assumes that we'll always be using command.com to run
> the batch file, but what if the user specified C:/perl/bin/perl.exe
> or something as their SHELL?
This is not supported yet; if the user tries that, @echo off will be
the least of their problems ;-)
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