The problem is with #newTemp: used for binding a temporary in a block argument - [:foo <<< ] which increments the total number of temps in encoder (nTemps).. and as result, at the point where #fixTemp: is sent, the nTemps = 2, while actually should be = 1. resulting that error code temp having wrong index. and if you look later, the total number of temps in compiled method are not based on nTemps variable of encoder, but actually calculated from scratch: aCompiledMethodClass newBytes: blkSize trailerBytes: trailer nArgs: arguments size nTemps: (encoder supportsClosureOpcodes ifTrue: [| locals | locals := arguments, temporaries, (primErrNode ifNil: [#()] ifNotNil: [{primErrNode}]). encoder noteBlockExtent: block blockExtent hasLocals: locals. locals size] ifFalse: [encoder maxTemp]) here, locals size = 2, not 3 which means, that (storeIntoTemp: 2) won't work, because it lies outside of method's temps range. Here's even more crazy... if we compile code like that: badat: index <primitive: 60 error: x > [:foo | | xx y z | 5]. ^ x Bytecode: <primitive: 60 error: x> 17 <81 45> storeIntoTemp: 5 19 <8F 01 00 05> closureNumCopied: 0 numArgs: 1 bytes 23 to 27 23 <73> pushConstant: nil 24 <73> pushConstant: nil 25 <73> pushConstant: nil 26 <20> pushConstant: 5 27 <7D> blockReturn 28 <87> pop 29 <15> pushTemp: 5 30 <7C> returnTop -- Best regards, Igor Stasenko.

Igor, great catch. I prefer the attached. Strictly, the index needs to be fixed correctly before the node's size is determined, since it could change (not in this bytecode set, but in some future one it could). On Tue, Mar 20, 2012 at 8:38 AM, Igor Stasenko <siguctua@gmail.com> wrote:

Here the simple method:

at: index <primitive: 60 error: x > ^ x

And its bytecode:

<primitive: 60 error: x> 13 <81 41> storeIntoTemp: 1 15 <11> pushTemp: 1 16 <7C> returnTop

Now, if i add this:

at: index <primitive: 60 error: x > [:foo | 5]. ^ x

I get following bytecode:

<primitive: 60 error: x> 17 <81 42> storeIntoTemp: 2 19 <8F 01 00 02> closureNumCopied: 0 numArgs: 1 bytes 23 to 24 23 <20> pushConstant: 5 24 <7D> blockReturn 25 <87> pop 26 <12> pushTemp: 2 27 <7C> returnTop

so, if we ignore the block closure bytecodes, we have:

<primitive: 60 error: x> 17 <81 42> storeIntoTemp: 2 26 <12> pushTemp: 2 27 <7C> returnTop

The problem is that for method context there are only 2 temps (argument + error code) .. but not 3 (index is zero-based).

The fix should be simple.. in code which calculates the temp index for 'error code' temp.

-- Best regards, Igor Stasenko.

-- best, Eliot