[Bug-mit-scheme] [bug #40150] mit-scheme-c-9.1.1 overrides user supplied optimization CFLAGS

[George Skabinsky]

URL:
  <http://savannah.gnu.org/bugs/?40150>

                 Summary: mit-scheme-c-9.1.1 overrides user supplied
optimization CFLAGS
                 Project: MIT/GNU Scheme
            Submitted by: gska
            Submitted on: Mon 30 Sep 2013 09:35:12 PM GMT
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: None
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                Keywords: 

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Details:

by default, autoconf'd programs set "-O2 -g" as default CFLAGS.
however they're only used when the user does *not* pass custom CFLAGS.

so the code there is equivalent to
[ -z $CFLAGS ] && CFLAGS="-O2 -g"

mit scheme otoh has the following:
CFLAGS="$CFLAGS -O3"

thus, -O3 is always added to the *end* of the CFLAGS, which takes precedence.
so the user has no way to override the hardcore -O3 optimization, which takes
5-10 times as long (and much more RAM) to build than -O0.

if otoh the statement would look like this:
CFLAGS="-O3 $CFLAGS"
the user could still override the optimization level since his own CFLAGS come
last.

however the best approach is the one taken by vanilla autoconf (first code
example).




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