Anyone help me with a stack dump?

[Cecil Ward]

On Monday, 31 July 2023 at 14:38:52 UTC, ryuukk_ wrote:
> Your problem lies at line 1541
>
> You can use `ddemangle` executable to make mangled names 
> readable, i don't know if it comes with the compiler
>
> ```
> _platform_memmove
> pure nothrow ref @trusted wchar[] 
> core.internal.array.appending._d_arrayappendT!(wchar[], 
> char)._d_arrayappendT(scope return ref wchar[], scope wchar[])
> void 
> asm_parse.AsmTransformTemplate!(wchar).__unittest_L1541_C1_1()
> asm_parse.__unittest
> asm_parse.__unittest
> asm_parse.__unittest
> asm_parse.__unittest
> int 
> core.runtime.runModuleUnitTests().__foreachbody6(object.ModuleInfo*)
> int rt.minfo.moduleinfos_apply(scope int 
> delegate(immutable(object.ModuleInfo*))).__foreachbody2(ref 
> rt.sections_elf_shared.DSO)
> int rt.sections_elf_shared.DSO.opApply(scope int delegate(ref 
> rt.sections_elf_shared.DSO))
> int rt.minfo.moduleinfos_apply(scope int 
> delegate(immutable(object.ModuleInfo*)))
> int object.ModuleInfo.opApply(scope int 
> delegate(object.ModuleInfo*))
> runModuleUnitTests
> void rt.dmain2._d_run_main2(char[][], ulong, extern (C) int 
> function(char[][])*).runAll()
> _d_run_main2
> _d_run_main
> start
> ```

Thank you all for your help. In the real code I have a struct 
(object) in the heap but in the unittests I first of all had it 
in place in the stack, then tried changing to the heap to see if 
that would fix the problem. That didn’t work. I first ran the 
struct initialisation routine in each one of the unittests, but I 
still suspect that the thing is not completely initialised. Maybe 
I forgot to set something in the init routine and it gets set to 
a sensible value in subsequent code, but all that code is not 
running in the unittests. An uninitialised field would be my best 
guess. I can see the AAarch64 instruction that it dies on and my 
AAarch64 is non-existent but I’ve done so much asm over the years 
that I can hazard a guess. It is doing something like p->field 
and it looks like a read instruction but I’m not sure about the 
operand ordering as we probably have the stupid ATT asm to deal 
with. Of course a write instruction is more likely to cause a 
crash. I could try and work out how to see all the relevant 
registers, could be p is a null pointer or perhaps just out of 
range.

Really annoying as that code seems to work perfectly in normal 
use, and disabling that unittest block restores sanity. I really 
am going to have to go off and do a lot of reading.