[PATCH, M2] introduction of --enable-libm2 in top level directory

[Joseph S. Myers]

On Tue, 19 Nov 2013, Gaius Mulley wrote:

> Below are two patches for configure.ac and Makefile.def which provide
> rules for building libm2 and checking gm2.  Tested on trunk and no new
> regressions have occurred when building with --enable-languages=all
> on x86_64 Debian Wheezy.

We don't use --enable-<library> options like that.  Instead:

(a) The front end's config-lang.in file sets target_libs, thereby causing 
the library to be disabled if the language is.  Of course this means you 
don't actually add the library before the front end - but these build 
rules are harmless in the absence of the library directory.  (In some 
cases, additional toplevel logic is needed - see how libitm etc. are 
disabled when C++ isn't built - but that shouldn't be relevant here.)

(b) Toplevel configure automatically supports --disable-<subdirectory> 
options to disable building a directory that would otherwise be built by 
default; they don't need adding explicitly.

> I presume the person committing the patches also regenerates configure
> and Makefile.in ?

Yes - and applies the patches to all three relevant repositories (GCC, 
binutils-gdb, src) or asks for help if they don't have access to them all.  
Unfortunately it seems some recent patches haven't gone in src (which is 
still used for newlib).

-- 
Joseph S. Myers
joseph@codesourcery.com