Re: How to properly make an enable debugging option in configure

[Thomas Dickey]

On Sat, Feb 13, 2016 at 12:31:51AM +0000, Andy Falanga (afalanga) wrote:
> I would like to know the "proper" method for adding an "--enable-debug" 
> option to my build using autotools.  Perhaps what I should call this is 
> a "best-practice" or something similar.  So, some googling and Autotools 
> Mythbusters suggests it should be AC_ARG_ENABLE.  So, I put this into my 
> configure.ac file:
> 
> AC_ARG_ENABLE([debug],
>       AC_HELP_STRING([--enable-debug],
>                      [Additional output from binary and turns off 
> optimizations]),
>       [CXXCPP="${CXXCPP} -DDEBUG"

CXXCPP doesn't appear to be set at this point, since it does not contribute
to the "checking" message below.

>        CXXFLAGS="${CXXFLAGS} -O0 -ggdb"],
>       [CXXCPP=${CXXCPP}
>        CXXFLAGS="${CXXFLAGS} -O2 -g"])

By the way, it's a common convention to put preprocessor options in
the CPPFLAGS variable, leaving CXXFLAGS for compiler options.
 
> However, when I run configure, I get this:
> 
> checking how to run the C++ preprocessor...  -DDEBUG
> configure: error: in `/home/afalanga/devel/o2archanges':
> configure: error: C++ preprocessor " -DDEBUG" fails sanity check
> See `config.log' for more details
> 
> So, I look in config.log but this doesn't really help.  Is there a 
> better way?  Should I instead make it add "#define DEBUG" in config.h if 
> "--enable-debug" is provided?  Did I make an incorrect assumption in the 
> actions arguments to AC_ARG_ENABLE()?  Any help is greatly appreciated.
> 
> Andy

-- 
Thomas E. Dickey <address@hidden>
http://invisible-island.net
ftp://invisible-island.net

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