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Re: Force -O0 flags, inhibit the default -O2 flags

From: Harald Dunkel
Subject: Re: Force -O0 flags, inhibit the default -O2 flags
Date: Thu, 29 Sep 2005 10:44:48 +0200
User-agent: Debian Thunderbird 1.0.2 (X11/20050402)

Sander Niemeijer wrote:
> On woensdag, sep 28, 2005, at 17:04 Europe/Amsterdam, Harald Dunkel wrote:
>>> autoconf sets CFLAGS/CXXFLAGS to "reasonable defaults", that's all. If
>>> these defaults cause problems on your platforms, you have to override
>>> them.
>> They cannot be called "defaults", if they get a higher priority
>> than the flags set in my And I do not think that
>> setting CXXFLAGS='-g -O2' is a reasonable default, unless autoconf/
>> automake's assumption is that the user is supposed to debug the
>> developer's code.
>> IMHO the priorities for setting build flags should be (highest
>> first):
>>     1)    user
>>     2)    developer
>>     3)    autoconf/automake
>> Surely it is OK that autoconf/automake can provide default build
>> flags somehow, but the flags set by the developer (e.g. AM_CXXFLAGS)
>> should get a higher priority, if they are set. And automake/autoconf
>> should provide just the bare minimum.
> As a developer you have full control over both AM_xxxFLAGS and xxxFLAGS
> variables. There is no ownership difference between these two types of
> flags from a developer/autoconf point of view. If you don't like the
> default for CXXFLAGS that autoconf choses then just replace it in the
> way Ralph explained:
> CXXFLAGS=${CXXFLAGS-"<your other settings>"}

Sorry, but you missed one point: Autconf/automake _should_ provide
default build flags, but with a lower priority then the flags set
by the developer. It should be possible for a developer to set in

        AM_CXXFLAGS = -Wall

if he wants to extend Automake's default (-g -O2), or

        AM_AM_CXXFLAGS =
        AM_CXXFLAGS = -O3 -Wall

if he wants to ignore it. Just as an example.

Important is that control about the defaults provided by autoconf/
automake is moved to the developer, if he is interested. The user
should keep the final saying. I guess we all agree here.



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