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Re: reduce forks during autoconf
From: |
Eric Blake |
Subject: |
Re: reduce forks during autoconf |
Date: |
Tue, 13 May 2008 20:17:20 -0600 |
User-agent: |
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.14) Gecko/20080421 Thunderbird/2.0.0.14 Mnenhy/0.7.5.666 |
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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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