Code size report:

  mpy-cross:    +0 +0.000% 
   bare-arm:    +0 +0.000% 
minimal x86:    +0 +0.000% 
   unix x64:    +0 +0.000% standard
      stm32:    +0 +0.000% PYBV10
     mimxrt:    +0 +0.000% TEENSY40
        rp2:    +0 +0.000% RPI_PICO_W
       samd:    +0 +0.000% ADAFRUIT_ITSYBITSY_M4_EXPRESS
  qemu rv32:    +0 +0.000% VIRT_RV32

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.39%. Comparing base (35d07df) to head (08219b5).

@@           Coverage Diff           @@
##           master   #18194   +/-   ##
=======================================
  Coverage   98.39%   98.39%           
=======================================
  Files         171      171           
  Lines       22276    22276           
=======================================
  Hits        21918    21918           
  Misses        358      358           

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Thanks for the contribution.

This check seems quite specific to m68k. Can it be done in a more general way?

Yes, -malign-int is a specific GCC option for m68k targets only. I updated the code to use MICROPY_OBJ_BASE_ALIGNMENT macro in a more general way.

Updated changes:

Add a compile-time static assertion to ensure uPy objects are aligned to at least a 4-byte boundary.

Change the MICROPY_OBJ_BASE_ALIGNMENT macro to a numeric value, making it easier to define via CFLAGS in Makefiles.

I didn't expect that all MSVC builds failed due to the new added static assert.
Interesting...

I didn't expect that all MSVC builds failed due to the new added static assert.

That might be fixed by #18145

I didn't expect that all MSVC builds failed due to the new added static assert. Interesting...

I'm not surprised --- there's actually like a dozen cases you need to cover if you want anything to do with alignment in C to be totally portable across all the compilers MicroPython targets.

I have a PR that adds proper portable macros for alignment, though, that I proposed a few days ago:

• py/misc: Add MP_ALIGNAS and MP_ALIGNOF macros. #18148

Changing MICROPY_OBJ_BASE_ALIGNMENT to just be a number rather than an attribute sounds like a good idea to me, though --- I'd suggest rebasing downstream of that and changing the declaration in obj.h to use the MP_ALIGNAS macro it defines.

I'd suggest rebasing downstream of that and changing the declaration in obj.h to use the MP_ALIGNAS macro it defines.

Sure! I will update the code when PR #18145 and your PR #18148 get merged. Thanks for pointing this out!