Give eval an independent return boundary and result

engine/vm.c

@@ -992,6 +992,7 @@ static sxi32 VmOverloadDominates(ph7_vm *pVm, ph7_value *aArg, ph7_vm_func *pFir
 /* Forward declaration */
 #define VM_EXEC_INCLUDE 2
 #define VM_EXEC_HANDLER 4
+#define VM_EXEC_EVAL 8
 #define VM_INCLUDE_RETURN 3
 #define VM_INCLUDE_JUMP 4
 #define VM_INCLUDE_EXCEPTION 5
@@ -2854,7 +2855,7 @@ static sxi32 VmByteCodeExec(
 	ph7_value *pStack,   /* Operand stack */
 	int nTos,            /* Top entry in the operand stack (usually -1) */
 	ph7_value *pResult,  /* Store program return value here. NULL otherwise */
-	int iExecFlags       /* Callback (1), included statements or exception handler */
+	int iExecFlags       /* Callback (1), included statements, handler or eval */
 ) {
 	VmInstr *pInstr;
 	ph7_value *pTos;
@@ -6170,6 +6171,7 @@ Resume:
 						/* Release the call context */
 						VmReleaseCallContext(&sCtx);
 						if(rc == PH7_ABORT) {
+							PH7_MemObjRelease(&sRet);
 							goto Abort;
 						}
 						if(pInstr->iP1 > 0) {
@@ -6179,6 +6181,15 @@ Resume:
 						/* Save foreign function return value */
 						PH7_MemObjStore(&sRet, pTos);
 						PH7_MemObjRelease(&sRet);
+						if(rc == PH7_EXCEPTION) {
+							PH7_MemObjStore(pTos, &sTransfer);
+							/* Keep a NULL result if an uncaught handler resumes this
+							 * expression. Region unwind still discards interrupted operands. */
+							PH7_MemObjRelease(pTos);
+							iTransfer = VM_TRANSFER_THROW;
+							nTarget = pc + 1;
+							goto Unwind;
+						}
 					}
 					break;
 				}
@@ -6306,7 +6317,7 @@ Unwind:
 		goto Resume;
 	}
 	if(iTransfer == VM_TRANSFER_THROW) {
-		if(SySetUsed(&pVm->aException) == 0 && (iExecFlags & (VM_EXEC_HANDLER | VM_EXEC_INCLUDE)) == 0) {
+		if(SySetUsed(&pVm->aException) == 0 && (iExecFlags & (VM_EXEC_HANDLER | VM_EXEC_INCLUDE | VM_EXEC_EVAL)) == 0) {
 			/* A nonfatal handler resumes this iteration with its bindings intact. */
 			rc = VmUncaughtException(pVm, (sTransfer.nType & MEMOBJ_OBJ) ? (ph7_class_instance *)sTransfer.x.pOther : 0);
 			if(rc == PH7_ABORT) {
@@ -6325,9 +6336,10 @@ Unwind:
 	/* Only the selected explicit value is checked against the return contract.
 	 * A bare return keeps NULL. An include directly borrowing the active method
 	 * frame has no enclosing region left to override its result; otherwise it
-	 * defers this check to the owner, just like a handler. */
+	 * defers this check to the owner, just like a handler. Eval has its own
+	 * dynamic return contract, even when borrowing an active owner frame. */
 	if(bReturnValue && (pEntryFrame->iFlags & VM_FRAME_ACTIVE) &&
-		(iExecFlags & VM_EXEC_HANDLER) == 0) {
+		(iExecFlags & (VM_EXEC_HANDLER | VM_EXEC_EVAL)) == 0) {
 		ph7_vm_func *pFunc = (ph7_vm_func *)pEntryFrame->pUserData;
 		if(pFunc->nType & MEMOBJ_NAMED) {
 			PH7_VmTypeClass(pVm, pFunc->nType, TRUE);
@@ -10162,13 +10174,22 @@ static sxi32 VmEvalChunk(
 	/* Assume a boolean true return value */
 	PH7_MemObjInitFromBool(pVm, &sResult, 1);
 	/* Execute the compiled chunk */
-	if(bInclude) {
+	if(bInclude || iFlags == PH7_AERSCRIPT_CHNK) {
 		ph7_value *pStack = VmNewOperandStack(pVm, SySetUsed(&aByteCode));
 		if(pStack == 0) {
 			rc = SXERR_MEM;
 		} else {
+			/* A nested call must return its exception here before the caller's
+			 * regions (or uncaught handler) consume it. */
+			ph7_exception *pBoundary = 0;
+			if(!bInclude && SySetPut(&pVm->aException, &pBoundary) != SXRET_OK) {
+				PH7_VmMemoryError(pVm);
+			}
 			rc = VmByteCodeExec(pVm, (VmInstr *)SySetBasePtr(&aByteCode), pStack, -1,
-				&sResult, VM_EXEC_INCLUDE);
+				&sResult, bInclude ? VM_EXEC_INCLUDE : VM_EXEC_EVAL);
+			if(!bInclude) {
+				SySetPop(&pVm->aException);
+			}
 			SyMemBackendFree(&pVm->sAllocator, pStack);
 			if((rc == VM_INCLUDE_RETURN || rc == VM_RETURN_VOID || rc == VM_INCLUDE_JUMP || rc == VM_INCLUDE_EXCEPTION) && pResult) {
 				PH7_MemObjStore(&sResult, pResult);
@@ -10189,7 +10210,7 @@ Cleanup:
 	/* Cleanup the mess left behind */
 	pVm->pByteContainer = pByteCode;
 	SySetRelease(&aByteCode);
-	return bRequire || bInclude ? rc : SXRET_OK;
+	return bRequire || bInclude || rc == PH7_EXCEPTION || rc == PH7_ABORT ? rc : SXRET_OK;
 }
 /*
  * value eval(string $code)
@@ -10197,9 +10218,8 @@ Cleanup:
  * Parameter
  *  code: PHP code to evaluate.
  * Return
- *  eval() returns NULL unless return is called in the evaluated code, in which case
- *  the value passed to return is returned. If there is a parse error in the evaluated
- *  code, eval() returns FALSE and execution of the following code continues normally.
+ *  eval() returns TRUE unless return is called in the evaluated code, in which case
+ *  the value passed to return is returned. Missing or empty input returns NULL.
  */
 static int vm_builtin_eval(ph7_context *pCtx, int nArg, ph7_value **apArg) {
 	SyString sChunk;    /* Chunk to evaluate */
@@ -10216,8 +10236,7 @@ static int vm_builtin_eval(ph7_context *pCtx, int nArg, ph7_value **apArg) {
 		return SXRET_OK;
 	}
 	/* Eval the chunk */
-	VmEvalChunk(pCtx->pVm, &(*pCtx), &sChunk, PH7_AERSCRIPT_CHNK, 0, 0);
-	return SXRET_OK;
+	return VmEvalChunk(pCtx->pVm, &(*pCtx), &sChunk, PH7_AERSCRIPT_CHNK, 0, 0);
 }
 /*
  * Check if a file path is already included.