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Date: Fri, 23 Oct 2015 06:53:29 +0200
From: Denys Vlasenko <>
To: musl <>
Subject: Re: Having hard time adding to CFLAGS

On Fri, Oct 23, 2015 at 6:09 AM, Rich Felker <> wrote:
> On Thu, Oct 22, 2015 at 11:02:36PM -0400, Rich Felker wrote:
>> > the attached patch makes this work, but i
>> > consider -Os to be not part of 'needed'
>> > diff --git a/Makefile b/Makefile
>> > index 844a017..f713286 100644
>> > --- a/Makefile
>> > +++ b/Makefile
>> > @@ -94,22 +94,22 @@ crt/crt1.o crt/Scrt1.o crt/rcrt1.o src/ldso/dlstart.lo: $(wildcard arch/$(ARCH)/
>> >
>> >  crt/rcrt1.o: src/ldso/dlstart.c
>> >
>> > -crt/Scrt1.o crt/rcrt1.o: CFLAGS += -fPIC
>> > +crt/Scrt1.o crt/rcrt1.o: CFLAGS_ALL += -fPIC
>> This is the correct fix. I was not aware that make variables set from
>> the make command line would take precedence over the target-specific
>> += concatenations. The intent has always been that editing CFLAGS
>> should not break the build (unless you put really inapproriate stuff
>> there, of course).
> I've committed this with one change (omitting the -O3 thing that's
> really optional) and another related fix.
> Note however that overriding CFLAGS at make time is still a bad idea.
> It will suppress all the warning options configure detected and other
> useful but non-essential things like -fno-unwind-tables and
> -fno-asynchronous-unwind-tables. We should probably discuss whether
> this behavior is desirable. We could factor out all of the stuff
> configure detects into a CFLAGS_AUTO and leave CFLAGS just containing
> the user-provided options. Opinions?

Make configure --help warn/explain what would happen if
make CFLAGS=foo is run.

Currently, it is confusing. See for yourself:

Usage: $0 [OPTION]... [VAR=VALUE]... [TARGET]

To assign environment variables (e.g., CC, CFLAGS...), specify them as
VAR=VALUE.  See below for descriptions of some of the useful variables.
("ok, I got it. CFLAGS should go to configure's command line!")
Some influential environment variables:
  CC                      C compiler command [detected]
  CFLAGS                  C compiler flags [-Os -pipe ...]
  CROSS_COMPILE           prefix for cross compiler and tools [none]
  LIBCC                   compiler runtime library [detected]

Use these variables to override the choices made by configure.

("What? You just said that CFLAGS should be on command line!
Now you are saying it should be in the environment!
What it is?")

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