Represent ?? as BINARY_OP

Author: nikic

README.md

@@ -263,6 +263,7 @@ ast\flags\BINARY_IS_SMALLER_OR_EQUAL
 ast\flags\BINARY_IS_GREATER          // since version 20
 ast\flags\BINARY_IS_GREATER_OR_EQUAL // since version 20
 ast\flags\BINARY_SPACESHIP
+ast\flags\BINARY_COALESCE            // since version 40
 
 // Used by ast\AST_ASSIGN_OP in versions before 20 (exclusive)
 ast\flags\ASSIGN_BITWISE_OR
@@ -308,7 +309,7 @@ This section lists the AST node kinds that are supported and the names of their
 version >= 30).
 
 ```
-AST_AND:              left, right            // prior to version 10
+AST_AND:              left, right            // prior to version 20
 AST_ARRAY_ELEM:       value, key
 AST_ASSIGN:           var, expr
 AST_ASSIGN_OP:        var, expr
@@ -323,7 +324,7 @@ AST_CLASS_CONST:      class, const
 AST_CLONE:            expr
 AST_CLOSURE:          params, uses, stmts, returnType
 AST_CLOSURE_VAR:      name
-AST_COALESCE:         left, right
+AST_COALESCE:         left, right            // prior to version 40
 AST_CONDITIONAL:      cond, true, false
 AST_CONST:            name
 AST_CONST_ELEM:       name, value
@@ -413,6 +414,10 @@ ZEND_AST_USE
 Version changelog
 -----------------
 
+### 40 (in development)
+
+* `AST_COALESCE` is now represented as an `AST_BINARY_OP` with flag `BINARY_COALESCE`.
+
 ### 30 (current)
 
 Supported since 2015-03-10.

ast.c

@@ -35,6 +35,7 @@
 #define AST_BINARY_IS_GREATER_OR_EQUAL 257
 #define AST_BINARY_BOOL_OR 258
 #define AST_BINARY_BOOL_AND 259
+#define AST_BINARY_COALESCE 260
 
 /* Flags for UNARY_OP to use instead of AST_SILENCE, AST_UNARY_PLUS, AST_UNARY_MINUS */
 #define AST_SILENCE 260
@@ -274,6 +275,12 @@ static void ast_to_zval(zval *zv, zend_ast *ast, zend_long version) {
 				ast->kind = ZEND_AST_BINARY_OP;
 				ast->attr = AST_BINARY_BOOL_AND;
 				break;
+			case ZEND_AST_COALESCE:
+				if (version >= 40) {
+					ast->kind = ZEND_AST_BINARY_OP;
+					ast->attr = AST_BINARY_COALESCE;
+				}
+				break;
 			case ZEND_AST_SILENCE:
 				ast->kind = ZEND_AST_UNARY_OP;
 				ast->attr = AST_SILENCE;
@@ -362,7 +369,7 @@ static void ast_to_zval(zval *zv, zend_ast *ast, zend_long version) {
 	ast_fill_children_ht(Z_ARRVAL(tmp_zv), ast, version);
 }
 
-static const zend_long versions[] = {10, 15, 20, 30};
+static const zend_long versions[] = {10, 15, 20, 30, 40};
 static const size_t versions_count = sizeof(versions)/sizeof(versions[0]);
 
 static zend_string *ast_version_info() {
@@ -621,6 +628,7 @@ PHP_MINIT_FUNCTION(ast) {
 	ast_register_flag_constant("BINARY_IS_GREATER", AST_BINARY_IS_GREATER);
 	ast_register_flag_constant("BINARY_IS_GREATER_OR_EQUAL", AST_BINARY_IS_GREATER_OR_EQUAL);
 	ast_register_flag_constant("BINARY_SPACESHIP", ZEND_SPACESHIP);
+	ast_register_flag_constant("BINARY_COALESCE", AST_BINARY_COALESCE);
 
 	ast_register_flag_constant("ASSIGN_BITWISE_OR", ZEND_ASSIGN_BW_OR);
 	ast_register_flag_constant("ASSIGN_BITWISE_AND", ZEND_ASSIGN_BW_AND);

tests/coalesce.phpt

@@ -0,0 +1,30 @@
+--TEST--
+Null-coalesce operator
+--FILE--
+<?php
+
+require __DIR__ . '/../util.php';
+
+$code = <<<'PHP'
+<?php
+$a ?? $b;
+PHP;
+
+echo ast_dump(ast\parse_code($code, $version=30)), "\n";
+echo ast_dump(ast\parse_code($code, $version=40)), "\n";
+
+?>
+--EXPECT--
+AST_STMT_LIST
+    0: AST_COALESCE
+        left: AST_VAR
+            name: "a"
+        right: AST_VAR
+            name: "b"
+AST_STMT_LIST
+    0: AST_BINARY_OP
+        flags: BINARY_COALESCE (260)
+        left: AST_VAR
+            name: "a"
+        right: AST_VAR
+            name: "b"

util.php

@@ -88,6 +88,7 @@ function get_flag_info() : array {
             flags\BINARY_IS_GREATER => 'BINARY_IS_GREATER',
             flags\BINARY_IS_GREATER_OR_EQUAL => 'BINARY_IS_GREATER_OR_EQUAL',
             flags\BINARY_SPACESHIP => 'BINARY_SPACESHIP',
+            flags\BINARY_COALESCE => 'BINARY_COALESCE',
         ],
         ast\AST_ASSIGN_OP => $sharedBinaryOps + [
             // Old version 10 flags