Fix byref capture in GenStructStateMachine and Env stack tracking

T-Gro · Copilot · T-Gro · commit f29ffbb91bd8 · 2026-02-26T16:18:25.000+01:00
- GenStructStateMachine: use GenGetFreeVarForClosure (like all other
  closure paths) to properly dereference byrefs when initializing
  captured variables in struct state machine closures.
- GenGetStorageAndSequel Env case: use ilField.ActualType instead of
  ilTy for the Push annotation so the stack tracking matches the
  actual type loaded by ldfld (important when byref is stripped by
  capturedTypeForFreeVar).

Co-authored-by: Copilot &lt;223556219+Copilot@users.noreply.github.com&gt;
diff --git a/src/Compiler/CodeGen/IlxGen.fs b/src/Compiler/CodeGen/IlxGen.fs
@@ -6352,7 +6352,7 @@ and GenStructStateMachine cenv cgbuf eenvouter (res: LoweredStateMachine) sequel
             else
                 // initialize the captured var
                 CG.EmitInstr cgbuf (pop 0) (Push [ ilMachineAddrTy ]) (I_ldloc(uint16 locIdx2))
-                GenGetLocalVal cenv cgbuf eenvouter m fv None
+                GenGetFreeVarForClosure cenv cgbuf eenvouter m fv
                 CG.EmitInstr cgbuf (pop 2) (Push []) (mkNormalStfld (mkILFieldSpecInTy (ilCloTy, ilv.fvName, ilv.fvType)))
 
         // Generate the start expression
@@ -9876,7 +9876,7 @@ and GenGetStorageAndSequel (cenv: cenv) cgbuf eenv m (ty, ilTy) storage storeSeq
         CommitGetStorageSequel cenv cgbuf eenv m ty None storeSequel
 
     | Env(_, ilField, localCloInfo) ->
-        CG.EmitInstrs cgbuf (pop 0) (Push [ ilTy ]) [ mkLdarg0; mkNormalLdfld ilField ]
+        CG.EmitInstrs cgbuf (pop 0) (Push [ ilField.ActualType ]) [ mkLdarg0; mkNormalLdfld ilField ]
         CommitGetStorageSequel cenv cgbuf eenv m ty localCloInfo storeSequel
 
 /// Load free variables for closure capture, dereferencing byrefs.
