Introduce separate ZEND_AST_CLASS_NAME AST node

Instead of representing this as a ZEND_AST_CLASS_CONST with a
"class" constant name.

Class constants and ::class are unrelated features that happen to
share syntax, so represent and handle them separately.

5 files changed, 85 insertions, 58 deletions

diff --git a/Zend/tests/class_name_of_var.phpt b/Zend/tests/class_name_of_var.phpt
new file mode 100644
index 0000000000..29f19e9fac
--- /dev/null
+++ b/Zend/tests/class_name_of_var.phpt
@@ -0,0 +1,11 @@
+--TEST--
+$var::class is not supported
+--FILE--
+<?php
+
+$obj = new stdClass;
+var_dump($obj::class);
+
+?>
+--EXPECTF--
+Fatal error: Cannot use ::class with dynamic class name in %s on line %d
diff --git a/Zend/zend_ast.c b/Zend/zend_ast.c
index 834696c2ca..b691dce0e0 100644
--- a/Zend/zend_ast.c
+++ b/Zend/zend_ast.c
@@ -102,6 +102,16 @@ ZEND_API zend_ast * ZEND_FASTCALL zend_ast_create_constant(zend_string *name, ze
 	return (zend_ast *) ast;
 }
 
+ZEND_API zend_ast * ZEND_FASTCALL zend_ast_create_class_const_or_name(zend_ast *class, zend_ast *name) {
+	zend_string *name_str = zend_ast_get_str(name);
+	if (zend_string_equals_literal_ci(name_str, "class")) {
+		zend_string_release(name_str);
+		return zend_ast_create(ZEND_AST_CLASS_NAME, class);
+	} else {
+		return zend_ast_create(ZEND_AST_CLASS_CONST, class, name);
+	}
+}
+
 ZEND_API zend_ast *zend_ast_create_decl(
 	zend_ast_kind kind, uint32_t flags, uint32_t start_lineno, zend_string *doc_comment,
 	zend_string *name, zend_ast *child0, zend_ast *child1, zend_ast *child2, zend_ast *child3
@@ -1606,6 +1616,10 @@ simple_list:
 			smart_str_appends(str, "::");
 			zend_ast_export_name(str, ast->child[1], 0, indent);
 			break;
+		case ZEND_AST_CLASS_NAME:
+			zend_ast_export_ns_name(str, ast->child[0], 0, indent);
+			smart_str_appends(str, "::class");
+			break;
 		case ZEND_AST_ASSIGN:            BINARY_OP(" = ",   90, 91, 90);
 		case ZEND_AST_ASSIGN_REF:        BINARY_OP(" =& ",  90, 91, 90);
 		case ZEND_AST_ASSIGN_OP:
diff --git a/Zend/zend_ast.h b/Zend/zend_ast.h
index db1f51b378..78d879a3c6 100644
--- a/Zend/zend_ast.h
+++ b/Zend/zend_ast.h
@@ -87,6 +87,7 @@ enum _zend_ast_kind {
 	ZEND_AST_POST_INC,
 	ZEND_AST_POST_DEC,
 	ZEND_AST_YIELD_FROM,
+	ZEND_AST_CLASS_NAME,
 
 	ZEND_AST_GLOBAL,
 	ZEND_AST_UNSET,
@@ -200,6 +201,7 @@ ZEND_API zend_ast * ZEND_FASTCALL zend_ast_create_zval_from_str(zend_string *str
 ZEND_API zend_ast * ZEND_FASTCALL zend_ast_create_zval_from_long(zend_long lval);
 
 ZEND_API zend_ast * ZEND_FASTCALL zend_ast_create_constant(zend_string *name, zend_ast_attr attr);
+ZEND_API zend_ast * ZEND_FASTCALL zend_ast_create_class_const_or_name(zend_ast *class, zend_ast *name);
 
 #if ZEND_AST_SPEC
 # define ZEND_AST_SPEC_CALL(name, ...) \
diff --git a/Zend/zend_compile.c b/Zend/zend_compile.c
index af6a3f1332..a12de01990 100644
--- a/Zend/zend_compile.c
+++ b/Zend/zend_compile.c
@@ -1366,21 +1366,12 @@ static void zend_ensure_valid_class_fetch_type(uint32_t fetch_type) /* {{{ */
 }
 /* }}} */
 
-static zend_bool zend_try_compile_const_expr_resolve_class_name(zval *zv, zend_ast *class_ast, zend_ast *name_ast, zend_bool constant) /* {{{ */
+static zend_bool zend_try_compile_const_expr_resolve_class_name(zval *zv, zend_ast *class_ast, zend_bool constant) /* {{{ */
 {
 	uint32_t fetch_type;
 
-	if (name_ast->kind != ZEND_AST_ZVAL) {
-		return 0;
-	}
-
-	if (!zend_string_equals_literal_ci(zend_ast_get_str(name_ast), "class")) {
-		return 0;
-	}
-
 	if (class_ast->kind != ZEND_AST_ZVAL) {
-		zend_error_noreturn(E_COMPILE_ERROR,
-			"Dynamic class names are not allowed in compile-time ::class fetch");
+		zend_error_noreturn(E_COMPILE_ERROR, "Cannot use ::class with dynamic class name");
 	}
 
 	fetch_type = zend_get_class_fetch_type(zend_ast_get_str(class_ast));
@@ -1390,10 +1381,9 @@ static zend_bool zend_try_compile_const_expr_resolve_class_name(zval *zv, zend_a
 		case ZEND_FETCH_CLASS_SELF:
 			if (CG(active_class_entry) && zend_is_scope_known()) {
 				ZVAL_STR_COPY(zv, CG(active_class_entry)->name);
-			} else {
-				ZVAL_NULL(zv);
+				return 1;
 			}
-			return 1;
+			return 0;
 		case ZEND_FETCH_CLASS_STATIC:
 		case ZEND_FETCH_CLASS_PARENT:
 			if (constant) {
@@ -1401,10 +1391,8 @@ static zend_bool zend_try_compile_const_expr_resolve_class_name(zval *zv, zend_a
 					"%s::class cannot be used for compile-time class name resolution",
 					fetch_type == ZEND_FETCH_CLASS_STATIC ? "static" : "parent"
 				);
-			} else {
-				ZVAL_NULL(zv);
 			}
-			return 1;
+			return 0;
 		case ZEND_FETCH_CLASS_DEFAULT:
 			ZVAL_STR(zv, zend_resolve_class_name_ast(class_ast));
 			return 1;
@@ -7689,16 +7677,6 @@ void zend_compile_class_const(znode *result, zend_ast *ast) /* {{{ */
 	znode class_node, const_node;
 	zend_op *opline;
 
-	if (zend_try_compile_const_expr_resolve_class_name(&result->u.constant, class_ast, const_ast, 0)) {
-		if (Z_TYPE(result->u.constant) == IS_NULL) {
-			zend_op *opline = zend_emit_op_tmp(result, ZEND_FETCH_CLASS_NAME, NULL, NULL);
-			opline->op1.num = zend_get_class_fetch_type(zend_ast_get_str(class_ast));
-		} else {
-			result->op_type = IS_CONST;
-		}
-		return;
-	}
-
 	zend_eval_const_expr(&ast->child[0]);
 	zend_eval_const_expr(&ast->child[1]);
 
@@ -7716,10 +7694,6 @@ void zend_compile_class_const(znode *result, zend_ast *ast) /* {{{ */
 		}
 		zend_string_release_ex(resolved_name, 0);
 	}
-	if (const_ast->kind == ZEND_AST_ZVAL && zend_string_equals_literal_ci(zend_ast_get_str(const_ast), "class")) {
-		zend_error_noreturn(E_COMPILE_ERROR,
-			"Dynamic class names are not allowed in compile-time ::class fetch");
-	}
 
 	zend_compile_class_ref(&class_node, class_ast, ZEND_FETCH_CLASS_EXCEPTION);
 
@@ -7733,6 +7707,21 @@ void zend_compile_class_const(znode *result, zend_ast *ast) /* {{{ */
 }
 /* }}} */
 
+void zend_compile_class_name(znode *result, zend_ast *ast) /* {{{ */
+{
+	zend_ast *class_ast = ast->child[0];
+	zend_op *opline;
+
+	if (zend_try_compile_const_expr_resolve_class_name(&result->u.constant, class_ast, 0)) {
+		result->op_type = IS_CONST;
+		return;
+	}
+
+	opline = zend_emit_op_tmp(result, ZEND_FETCH_CLASS_NAME, NULL, NULL);
+	opline->op1.num = zend_get_class_fetch_type(zend_ast_get_str(class_ast));
+}
+/* }}} */
+
 void zend_compile_resolve_class_name(znode *result, zend_ast *ast) /* {{{ */
 {
 	zend_ast *name_ast = ast->child[0];
@@ -7924,6 +7913,7 @@ zend_bool zend_is_allowed_in_const_expr(zend_ast_kind kind) /* {{{ */
 		|| kind == ZEND_AST_CONDITIONAL || kind == ZEND_AST_DIM
 		|| kind == ZEND_AST_ARRAY || kind == ZEND_AST_ARRAY_ELEM
 		|| kind == ZEND_AST_CONST || kind == ZEND_AST_CLASS_CONST
+		|| kind == ZEND_AST_CLASS_NAME
 		|| kind == ZEND_AST_MAGIC_CONST || kind == ZEND_AST_COALESCE;
 }
 /* }}} */
@@ -7936,7 +7926,6 @@ void zend_compile_const_expr_class_const(zend_ast **ast_ptr) /* {{{ */
 	zend_string *class_name;
 	zend_string *const_name = zend_ast_get_str(const_ast);
 	zend_string *name;
-	zval result;
 	int fetch_type;
 
 	if (class_ast->kind != ZEND_AST_ZVAL) {
@@ -7944,11 +7933,6 @@ void zend_compile_const_expr_class_const(zend_ast **ast_ptr) /* {{{ */
 			"Dynamic class names are not allowed in compile-time class constant references");
 	}
 
-	if (zend_try_compile_const_expr_resolve_class_name(&result, class_ast, const_ast, 1)) {
-		*ast_ptr = zend_ast_create_zval(&result);
-		return;
-	}
-
 	class_name = zend_ast_get_str(class_ast);
 	fetch_type = zend_get_class_fetch_type(class_name);
 
@@ -7973,6 +7957,19 @@ void zend_compile_const_expr_class_const(zend_ast **ast_ptr) /* {{{ */
 }
 /* }}} */
 
+void zend_compile_const_expr_class_name(zend_ast **ast_ptr) /* {{{ */
+{
+	zend_ast *class_ast = (*ast_ptr)->child[0];
+	uint32_t fetch_type = zend_get_class_fetch_type(zend_ast_get_str(class_ast));
+
+	/* If we reach here, ::class should have either been constant evaluated or replaced
+	 * by a AST_MAGIC_CONST, so only the error case is left here. */
+	zend_error_noreturn(E_COMPILE_ERROR,
+		"%s::class cannot be used for compile-time class name resolution",
+		fetch_type == ZEND_FETCH_CLASS_STATIC ? "static" : "parent"
+	);
+}
+
 void zend_compile_const_expr_const(zend_ast **ast_ptr) /* {{{ */
 {
 	zend_ast *ast = *ast_ptr;
@@ -8024,6 +8021,9 @@ void zend_compile_const_expr(zend_ast **ast_ptr) /* {{{ */
 		case ZEND_AST_CLASS_CONST:
 			zend_compile_const_expr_class_const(ast_ptr);
 			break;
+		case ZEND_AST_CLASS_NAME:
+			zend_compile_const_expr_class_name(ast_ptr);
+			break;
 		case ZEND_AST_CONST:
 			zend_compile_const_expr_const(ast_ptr);
 			break;
@@ -8312,6 +8312,9 @@ void zend_compile_expr(znode *result, zend_ast *ast) /* {{{ */
 		case ZEND_AST_CLASS_CONST:
 			zend_compile_class_const(result, ast);
 			return;
+		case ZEND_AST_CLASS_NAME:
+			zend_compile_class_name(result, ast);
+			return;
 		case ZEND_AST_ENCAPS_LIST:
 			zend_compile_encaps_list(result, ast);
 			return;
@@ -8605,32 +8608,16 @@ void zend_eval_const_expr(zend_ast **ast_ptr) /* {{{ */
 		}
 		case ZEND_AST_CLASS_CONST:
 		{
-			zend_ast *class_ast = ast->child[0];
-			zend_ast *name_ast = ast->child[1];
+			zend_ast *class_ast;
+			zend_ast *name_ast;
 			zend_string *resolved_name;
 
-			if (zend_try_compile_const_expr_resolve_class_name(&result, class_ast, name_ast, 0)) {
-				if (Z_TYPE(result) == IS_NULL) {
-					if (zend_get_class_fetch_type(zend_ast_get_str(class_ast)) == ZEND_FETCH_CLASS_SELF) {
-						zend_ast_destroy(ast);
-						*ast_ptr = zend_ast_create_ex(ZEND_AST_MAGIC_CONST, T_CLASS_C);
-					}
-					return;
-				}
-				break;
-			}
-
 			zend_eval_const_expr(&ast->child[0]);
 			zend_eval_const_expr(&ast->child[1]);
 
 			class_ast = ast->child[0];
 			name_ast = ast->child[1];
 
-			if (name_ast->kind == ZEND_AST_ZVAL && zend_string_equals_literal_ci(zend_ast_get_str(name_ast), "class")) {
-				zend_error_noreturn(E_COMPILE_ERROR,
-					"Dynamic class names are not allowed in compile-time ::class fetch");
-			}
-
 			if (class_ast->kind != ZEND_AST_ZVAL || name_ast->kind != ZEND_AST_ZVAL) {
 				return;
 			}
@@ -8645,7 +8632,20 @@ void zend_eval_const_expr(zend_ast **ast_ptr) /* {{{ */
 			zend_string_release_ex(resolved_name, 0);
 			break;
 		}
-
+		case ZEND_AST_CLASS_NAME:
+		{
+			zend_ast *class_ast = ast->child[0];
+			if (zend_try_compile_const_expr_resolve_class_name(&result, class_ast, 0)) {
+				break;
+			}
+			/* TODO We should not use AST_MAGIC_CONST for this, because the semantics are slightly
+			 * different. */
+			if (zend_get_class_fetch_type(zend_ast_get_str(class_ast)) == ZEND_FETCH_CLASS_SELF) {
+				zend_ast_destroy(ast);
+				*ast_ptr = zend_ast_create_ex(ZEND_AST_MAGIC_CONST, T_CLASS_C);
+			}
+			return;
+		}
 		default:
 			return;
 	}
diff --git a/Zend/zend_language_parser.y b/Zend/zend_language_parser.y
index cf6f066260..ec9ba82193 100644
--- a/Zend/zend_language_parser.y
+++ b/Zend/zend_language_parser.y
@@ -1095,9 +1095,9 @@ scalar:
 constant:
 		name { $$ = zend_ast_create(ZEND_AST_CONST, $1); }
 	|	class_name T_PAAMAYIM_NEKUDOTAYIM identifier
-			{ $$ = zend_ast_create(ZEND_AST_CLASS_CONST, $1, $3); }
+			{ $$ = zend_ast_create_class_const_or_name($1, $3); }
 	|	variable_class_name T_PAAMAYIM_NEKUDOTAYIM identifier
-			{ $$ = zend_ast_create(ZEND_AST_CLASS_CONST, $1, $3); }
+			{ $$ = zend_ast_create_class_const_or_name($1, $3); }
 ;
 
 optional_expr: