coalesce.diff

diff --git a/Zend/zend_ast.h b/Zend/zend_ast.h
index 2a1582c..b571ee1 100644
--- a/Zend/zend_ast.h
+++ b/Zend/zend_ast.h
@@ -115,6 +115,7 @@ enum _zend_ast_kind {
 	ZEND_AST_NEW,
 	ZEND_AST_INSTANCEOF,
 	ZEND_AST_YIELD,
+	ZEND_AST_COALESCE,
 
 	ZEND_AST_STATIC,
 	ZEND_AST_WHILE,
diff --git a/Zend/zend_compile.c b/Zend/zend_compile.c
index 0f91a81..2ecadb6 100644
--- a/Zend/zend_compile.c
+++ b/Zend/zend_compile.c
@@ -6922,6 +6922,30 @@ void zend_compile_conditional(znode *result, zend_ast *ast TSRMLS_DC) /* {{{ */
 }
 /* }}} */
 
+void zend_compile_coalesce(znode *result, zend_ast *ast TSRMLS_DC) /* {{{ */
+{
+	zend_ast *expr_ast = ast->child[0];
+	zend_ast *default_ast = ast->child[1];
+
+	znode expr_node, default_node;
+	zend_op *opline;
+	uint32_t opnum;
+
+	zend_compile_var(&expr_node, expr_ast, BP_VAR_IS TSRMLS_CC);
+
+	opnum = get_next_op_number(CG(active_op_array));
+	zend_emit_op(result, ZEND_COALESCE, &expr_node, NULL TSRMLS_CC);
+
+	zend_compile_expr(&default_node, default_ast TSRMLS_CC);
+
+	opline = zend_emit_op(NULL, ZEND_QM_ASSIGN, &default_node, NULL TSRMLS_CC);
+	SET_NODE(opline->result, result);
+
+	opline = &CG(active_op_array)->opcodes[opnum];
+	opline->op2.opline_num = get_next_op_number(CG(active_op_array));
+}
+/* }}} */
+
 void zend_compile_print(znode *result, zend_ast *ast TSRMLS_DC) /* {{{ */
 {
 	zend_ast *expr_ast = ast->child[0];
@@ -7759,6 +7783,9 @@ void zend_compile_expr(znode *result, zend_ast *ast TSRMLS_DC) /* {{{ */
 		case ZEND_AST_CONDITIONAL:
 			zend_compile_conditional(result, ast TSRMLS_CC);
 			return;
+		case ZEND_AST_COALESCE:
+			zend_compile_coalesce(result, ast TSRMLS_CC);
+			return;
 		case ZEND_AST_PRINT:
 			zend_compile_print(result, ast TSRMLS_CC);
 			return;
diff --git a/Zend/zend_language_parser.y b/Zend/zend_language_parser.y
index 6bfef22..97fc4de 100644
--- a/Zend/zend_language_parser.y
+++ b/Zend/zend_language_parser.y
@@ -67,6 +67,7 @@ static YYSIZE_T zend_yytnamerr(char*, const char*);
 %right T_YIELD
 %left '=' T_PLUS_EQUAL T_MINUS_EQUAL T_MUL_EQUAL T_DIV_EQUAL T_CONCAT_EQUAL T_MOD_EQUAL T_AND_EQUAL T_OR_EQUAL T_XOR_EQUAL T_SL_EQUAL T_SR_EQUAL T_POW_EQUAL
 %left '?' ':'
+%right T_COALESCE
 %left T_BOOLEAN_OR
 %left T_BOOLEAN_AND 
 %left '|'
@@ -221,6 +222,7 @@ static YYSIZE_T zend_yytnamerr(char*, const char*);
 %token T_NS_C            "__NAMESPACE__ (T_NS_C)"
 %token T_NS_SEPARATOR    "\\ (T_NS_SEPARATOR)"
 %token T_ELLIPSIS        "... (T_ELLIPSIS)"
+%token T_COALESCE        "?? (T_COALESCE)"
 %token T_POW             "** (T_POW)"
 %token T_POW_EQUAL       "**= (T_POW_EQUAL)"
 
@@ -827,6 +829,8 @@ expr_without_variable:
 			{ $$ = zend_ast_create(ZEND_AST_CONDITIONAL, $1, $3, $5); }
 	|	expr '?' ':' expr
 			{ $$ = zend_ast_create(ZEND_AST_CONDITIONAL, $1, NULL, $4); }
+	|	expr T_COALESCE expr
+			{ $$ = zend_ast_create(ZEND_AST_COALESCE, $1, $3); }
 	|	internal_functions_in_yacc { $$ = $1; }
 	|	T_INT_CAST expr		{ $$ = zend_ast_create_cast(IS_LONG, $2); }
 	|	T_DOUBLE_CAST expr	{ $$ = zend_ast_create_cast(IS_DOUBLE, $2); }
diff --git a/Zend/zend_language_scanner.l b/Zend/zend_language_scanner.l
index bcc341e..3da8406 100644
--- a/Zend/zend_language_scanner.l
+++ b/Zend/zend_language_scanner.l
@@ -1202,6 +1202,10 @@ NEWLINE ("\r"|"\n"|"\r\n")
 	return T_ELLIPSIS;
 }
 
+<ST_IN_SCRIPTING>"??" {
+	return T_COALESCE;
+}
+
 <ST_IN_SCRIPTING>"new" {
 	return T_NEW;
 }
diff --git a/Zend/zend_opcode.c b/Zend/zend_opcode.c
index d57721e..8c294f1 100644
--- a/Zend/zend_opcode.c
+++ b/Zend/zend_opcode.c
@@ -738,6 +738,7 @@ ZEND_API int pass_two(zend_op_array *op_array TSRMLS_DC)
 			case ZEND_JMPZ_EX:
 			case ZEND_JMPNZ_EX:
 			case ZEND_JMP_SET:
+			case ZEND_COALESCE:
 			case ZEND_NEW:
 			case ZEND_FE_RESET:
 			case ZEND_FE_FETCH:
diff --git a/Zend/zend_vm_def.h b/Zend/zend_vm_def.h
index a3ae246..d28227e 100644
--- a/Zend/zend_vm_def.h
+++ b/Zend/zend_vm_def.h
@@ -5238,6 +5238,41 @@ ZEND_VM_HANDLER(152, ZEND_JMP_SET, CONST|TMP|VAR|CV, ANY)
 	ZEND_VM_NEXT_OPCODE();
 }
 
+ZEND_VM_HANDLER(169, ZEND_COALESCE, CONST|TMP|VAR|CV, ANY)
+{
+	USE_OPLINE
+	zend_free_op free_op1;
+	zval *value;
+	int is_ref = 0;
+
+	SAVE_OPLINE();
+	value = GET_OP1_ZVAL_PTR(BP_VAR_IS);
+
+	if ((OP1_TYPE == IS_VAR || OP1_TYPE == IS_CV) && Z_ISREF_P(value)) {
+		is_ref = 1;
+		value = Z_REFVAL_P(value);
+	}
+
+	if (Z_TYPE_P(value) > IS_NULL) {
+		ZVAL_COPY_VALUE(EX_VAR(opline->result.var), value);
+		if (OP1_TYPE == IS_CONST) {
+			if (UNEXPECTED(Z_OPT_COPYABLE_P(value))) {
+				zval_copy_ctor_func(EX_VAR(opline->result.var));
+			}
+		} else if (OP1_TYPE == IS_CV) {
+			if (Z_OPT_REFCOUNTED_P(value)) Z_ADDREF_P(value);
+		} else if (OP1_TYPE == IS_VAR && is_ref) {
+			if (Z_OPT_REFCOUNTED_P(value)) Z_ADDREF_P(value);
+			FREE_OP1();
+		}
+		ZEND_VM_JMP(opline->op2.jmp_addr);
+	}
+
+	FREE_OP1();
+	CHECK_EXCEPTION();
+	ZEND_VM_NEXT_OPCODE();
+}
+
 ZEND_VM_HANDLER(22, ZEND_QM_ASSIGN, CONST|TMP|VAR|CV, ANY)
 {
 	USE_OPLINE