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

[Björn Bidar]

Po Lu <luangruo@yahoo.com> writes:

W> 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.

The reference to the autoconf manual makes me wonder what would be the
cutoff point for older systems to support. Some of these systems are
quite ancient.