[Picolibc] meson and ninja

[Larry Doolittle]

Keith -

Thanks for the prompt response!  Maybe we're in the same time zone.  ;-)

On Tue, Apr 28, 2020 at 01:57:10PM -0700, Keith Packard wrote:
> The meson.build file says >= 0.50. Meson *should* complain about having
> the wrong version when you try to run it, but ...

Maybe meson-0.49.2 crashed before it got to the version test.
I get a python stack dump starting with
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/mesonbuild/mesonmain.py", line 112, in run
    return options.run_func(options)
proceeding through about 37 intermediate entries to
  File "/usr/lib/python3/dist-packages/mesonbuild/mparser.py", line 405, in __init__
    self.subdir = token.subdir
AttributeError: 'TernaryNode' object has no attribute 'subdir'

> You can build for a single architecture, but there's no current way to
> specify a shorter list of architectures. So, if you only need these two,
> you could just build both of them separately. I've included a shell
> script and cross compile configuration file that builds for rv32imac;
> feel free to edit this as you like.

Nice, that's a big help.  The key entry is -Dmultilib=false.

The cross-foo.txt file you posted defines
  cpu_family = 'riscv'
That triggers a warning from meson
  Unknown CPU family riscv, please report this at https://github.com/mesonbuild/meson/issues/new
which seemed odd to me.
Referring to meson github issue #5950, I changed it to riscv32.
But that broke the picolibc ninja build!
  [930/1037] Linking target test/printf/scanf
  FAILED: test/printf/scanf 
followed by a large number of
  ... undefined reference to `__iob'
error messages.

Is this easily explainable?
I can restore build success by adding riscv32 entries to
the five meson.build files that have riscv entries.
Plus cp test-riscv.ld test-riscv32.ld (?).

> If you think it would be useful, I could add a way to specify a subset
> of the desired architectures.

That could come in handy, and I do see that in git master now.

  - Larry