fix(rt): repair closure callee setup for iter-eq repro (#957)

## Summary
- adds `iter-eq-copied-take-dereftruncate` as a regression
- fixes `setupCalleeClosure2` by initializing callee `_1` with the
closure env before tuple unpacking
- removes temporary show tracking after the repro reaches `#EndProgram`

## Why This Fix
- Red commit frontier: after `1947` steps the new repro stopped at:
- `#traverseProjection(toLocal(1), thunk(operandCopy(place(... local:
local(1) ...))))`
- Root cause: `setupCalleeClosure2` reserved `NEWLOCALS` and unpacked
the tuple argument into `_2..`, but never wrote the closure receiver/env
into `_1`. The std closure body later dereferenced `local(1)`, so
execution walked a bad projection path instead of the closure env.
- Fix: write `#incrementRef(getValue(LOCALS, CLOSURE))` into `local(1)`
before `#setTupleArgs(2, ...)`.
- Effect: the same repro moves from the stuck `1947`-step leaf to
`#EndProgram` after `5601` steps. The cleanup commit then deletes only
the temporary show artifact.

Author: Stevengre

kmir/src/kmir/kdist/mir-semantics/kmir.md

@@ -562,7 +562,8 @@ Therefore a heuristics is used here:
                 _SPAN
               )
          =>
-           #setTupleArgs(2, getValue(LOCALS, TUPLE)) ~> #execBlock(FIRST)
+           #setLocalValue(place(local(1), .ProjectionElems), #incrementRef(getValue(LOCALS, CLOSURE)))
+        ~> #setTupleArgs(2, getValue(LOCALS, TUPLE)) ~> #execBlock(FIRST)
           // arguments are tuple components, stored as _2 .. _n
          ...
        </k>

kmir/src/tests/integration/data/prove-rs/iter-eq-copied-take-dereftruncate.rs

@@ -0,0 +1,32 @@
+fn main() {
+    let _keep: fn() -> bool = repro;
+}
+
+#[inline(never)]
+#[no_mangle]
+pub fn repro() -> bool {
+    let k0 = Pubkey([1; 32]);
+    let k1 = Pubkey([2; 32]);
+    let k2 = Pubkey([3; 32]);
+    let n = 2usize;
+
+    let accounts = [
+        AccountInfo { key: &k0 },
+        AccountInfo { key: &k1 },
+        AccountInfo { key: &k2 },
+    ];
+    let signers = [k1, k2, k0];
+
+    accounts[1..]
+        .iter()
+        .map(|signer| *signer.key)
+        .eq(signers.iter().take(n).copied())
+}
+
+#[derive(Clone)]
+struct AccountInfo<'a> {
+    key: &'a Pubkey,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+struct Pubkey([u8; 32]);

kmir/src/tests/integration/test_integration.py

@@ -38,6 +38,7 @@
     'assume-cheatcode-conflict-fail': ['check_assume_conflict'],
     'transmute-bytes': ['bytes_to_u64', 'u64_to_bytes'],
     'test_offset_from-fail': ['testing'],
+    'iter-eq-copied-take-dereftruncate': ['repro'],
 }
 PROVE_RS_SHOW_SPECS = [
     'local-raw-fail',