Re: reduce forks during autoconf

[Eric Blake]

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According to Bruno Haible on 5/13/2008 8:10 PM:
| Eric Blake wrote:
|> | +   echo "  m4_ifval([${macro_prefix_arg}_LIBSOURCES_LIST], ["
|>
|> This needs to be m4_ifset, not m4_ifval.  As written, you are checking
|> that *_LIBSOURCES_LIST is not the empty string (it's not)
|
| Oops. I actually want to use m4_ifval, not m4_ifset, because it's a simple
| binary test, not forcing me to think about the distinction between undefined
| and empty value.

m4_ifset does not care about undefined vs. empty; it is also a simple
binary test.  In general, expanding a macro that is used to hold arbitrary
text is dangerous if the text might contain m4-active characters (such as
, or []); but for this particular usage, I don't think we will ever use
AC_REPLACE_FUNC with a file name that falls in this category.

- --
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden
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