behavior.union.test.reinterpret packed union fails on big endian targets

[alexrp]

Zig Version

9ef16b3

Steps to Reproduce and Observed Behavior

Run e.g. zig test -target mips-linux-none test/behavior/union.zig --test-cmd qemu-mips --test-cmd-bin.

error: 'behavior.union.test.reinterpret packed union' failed: expected 42, found 187
/home/alexrp/Source/zig/lib/std/testing.zig:97:17: 0x2dc983 in expectEqualInner__anon_30353 (test)
                return error.TestExpectedEqual;
                ^
/home/alexrp/Source/zig/test/behavior/union.zig:1860:17: 0x42b067 in doTheTest (test)
                try expectEqual(@as(u8, 0x2a), u.foo);
                ^
/home/alexrp/Source/zig/test/behavior/union.zig:1908:5: 0x42b903 in test.reinterpret packed union (test)
    try S.doTheTest();
    ^

Notably, the test does not fail for mipsel-linux-*.

Expected Behavior

No failure.

[alexrp]

This also fails on big endian PowerPC, but not little endian, just like MIPS. I'm convinced it's an endianness bug at this point.

[nektro]

this also fails on s390x which is also a big endian architecture