Hi Boris,

in trunk Squeak 6.1 alpha, VM Open Smalltalk Cog[Spur] VM [CoInterpreterPrimitives VMMaker.oscog-eem.3256] 5.20221022.0042, I get the debugger both ways. Both routes, testDirect & testIndirect result in a notifier failing in primitives 83, 84 & 100. The failure code for #100, Object>>#perform:withArguments:inSuperclass:, infers that the number of arguments is incorrect.

When I modify the source of these methods to include the primitive error code then in each failure the VM correctly supplies the #'bad number of arguments' error code.

So I see a correct system. I'm not seeing what you're seeing.

On Fri, Oct 21, 2022 at 6:54 AM Boris Shingarov <boris@shingarov.com> wrote:

Dear fellow VM hackers:
There is something about the #perform: prims I do not understand.

If I send #perform: not giving it enough arguments, I would expect the
primitive to fail through to the Smalltalk code in
Object>>perform:withArguments:inSuperclass:.

But, sometimes it's indeed what happens and sometimes it's not what
happens. In the attached test , if you run testDirect (in this
morning's Squeak6) you will end up in the debugger (expected), but if
you wrap in an extra send such as testIndirect, the prim will pass nil
for the missing argument (to me this is unexpected). I also tested in
last night's build of Cuis, and in Pharo8 (in the latter, the behavior
is even weirder: if you replace the fail code to answer #somethingElse,
you get #(somethingElse false false) instead of the #(false false false)
in Squeak).

Anyone has any thoughts on this?