Re: master a89c86888c4 1/3: Detect developer builds in git worktrees as well

[Po Lu]

Mattias Engdegård <mattias.engdegard@gmail.com> writes:

> 30 sep. 2023 kl. 13.33 skrev Po Lu <luangruo@yahoo.com>:
>
>> test -o is equally non-portable.  I will fix that on master.
>
> The Solaris man page suggested that -o would work. Is it in error, or did I 
> misread it?
>
> https://docs.oracle.com/cd/E86824_01/html/E54763/test-1.html

It functions on Solaris, but not under other POSIX systems.
(autoconf)Limitations of Builtins mentions:

‘test’
     The ‘test’ program is the way to perform many file and string
     tests.  It is often invoked by the alternate name ‘[’, but using
     that name in Autoconf code is asking for trouble since it is an M4
     quote character.

     The ‘-a’, ‘-o’, ‘(’, and ‘)’ operands are not present in all
     implementations, and have been marked obsolete by Posix 2008.  This
     is because there are inherent ambiguities in using them.  For
     example, ‘test "$1" -a "$2"’ looks like a binary operator to check
     whether two strings are both non-empty, but if ‘$1’ is the literal
     ‘!’, then some implementations of ‘test’ treat it as a negation of
     the unary operator ‘-a’.

     Thus, portable uses of ‘test’ should never have more than four
     arguments, and scripts should use shell constructs like ‘&&’ and
     ‘||’ instead.  If you combine ‘&&’ and ‘||’ in the same statement,
     keep in mind that they have equal precedence, so it is often better
     to parenthesize even when this is redundant.  For example:

          # Not portable:
          test "X$a" = "X$b" -a \
            '(' "X$c" != "X$d" -o "X$e" = "X$f" ')'

          # Portable:
          test "X$a" = "X$b" &&
            { test "X$c" != "X$d" || test "X$e" = "X$f"; }

     ‘test’ does not process options like most other commands do; for
     example, it does not recognize the ‘--’ argument as marking the end
     of options.

     It is safe to use ‘!’ as a ‘test’ operator.  For example, ‘if test
     ! -d foo; ...’ is portable even though ‘if ! test -d foo; ...’ is
     not.