Re: [EXTERNAL] Re: Compiling GCC 11 for Windows targeting ARM on Linux

[Xi Ruoyao <xry111@mengyan1223.wang>]

On Tue, 2022-01-11 at 03:44 +0000, Thomas Sobczynski wrote:
> Update: I kept peering at the configure scripts and their embedded
> comments, and concluded that it's at least worth trying to add "--
> with-newlib" to the configure script parameters. That may not be the
> right move, but it did get me further into the build process. However,
> although its configure script finished, the GCC build seems unable to
> compile libstdc++ (tail end of output below). 
> 
> Am I barking up the wrong tree with "--with-newlib"? 

I think --with-newlib is needed, as it's the de-facto C library on bare
metal ARM.  But you need to install newlib for the target before
building libstdc++, because libstdc++ needs a C library.

And your configuration may trigger
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100017, which is fixed in
GCC 11 branch recently.  You may need to "git pull" your GCC 11 branch
to overcome it.

Maybe you can add --disable-libstdcxx and build a GCC without libstdc++,
reboot into Windows, and then compile newlib & libstdc++ for target with
the toolchain just built.

However, honestly I don't do any serious development on Windows...

> Does it make sense that the build is supplying include search
> directories from the GCC v11 build tree (compiler being compiled) to
> the native cross compiler which is GCC v9.x? I already misunderstood
> the build/host/target config earlier. Is it perhaps not_a_ GCC cross
> toolchain that I need, but perhaps I need to build _the_ compiler
> (v11) and then turn around and use it to build for the non-native
> Host?

"__has_builtin" is introduced in GCC 10, so GCC 9 can't recognize it. 
IIRC libstdc++ from a specific GCC version is only expected to be built
with GCC with the same version.

Jonathan?

-- 
Xi Ruoyao <xry111@mengyan1223.wang>
School of Aerospace Science and Technology, Xidian University