[RFC] Implement block expressions - alternative implementation

Zend/tests/block_expr/001.phpt

@@ -0,0 +1,32 @@
+--TEST--
+Test basic basic block expression
+--FILE--
+<?php
+
+echo {
+    echo "a\n";
+    echo "b\n";
+    "c\n"
+};
+
+echo { "d\n" };
+
+echo 'e' . { "f\n" };
+
+echo { 'g' } . "h\n";
+
+echo {
+    echo "i\n";
+    { "j\n" }
+};
+
+?>
+--EXPECT--
+a
+b
+c
+d
+ef
+gh
+i
+j

Zend/tests/block_expr/002.phpt

@@ -0,0 +1,43 @@
+--TEST--
+Test block expression in arrow functions
+--FILE--
+<?php
+
+$a = 'a';
+
+var_dump((fn() => {
+    var_dump('b');
+    var_dump('c');
+    $a
+})());
+
+var_dump((fn() => {
+    var_dump('d');
+    var_dump('e');
+    return 'f';
+})());
+
+var_dump((fn() => {
+    var_dump('g');
+    var_dump('h');
+})());
+
+var_dump((fn() => {})());
+
+var_dump((fn() => {
+    'i'
+})());
+
+?>
+--EXPECT--
+string(1) "b"
+string(1) "c"
+string(1) "a"
+string(1) "d"
+string(1) "e"
+string(1) "f"
+string(1) "g"
+string(1) "h"
+NULL
+NULL
+string(1) "i"

Zend/tests/block_expr/003.phpt

@@ -0,0 +1,43 @@
+--TEST--
+Test block expression pretty printing
+--FILE--
+<?php
+
+assert((function () {
+    return {
+        echo 'Foo' . PHP_EOL;
+        {
+            echo 'Bar' . PHP_EOL;
+        }
+        false
+    };
+})());
+
+assert(10 + {
+    echo 'Foo';
+    -10
+});
+
+assert({ false });
+
+?>
+--EXPECTF--
+Foo
+Bar
+
+Warning: assert(): assert(function () {
+    return {
+        echo 'Foo' . PHP_EOL;
+        echo 'Bar' . PHP_EOL;
+        false
+    };
+}()) failed in %s on line %d
+Foo
+Warning: assert(): assert(10 + {
+    echo 'Foo';
+    -10
+}) failed in %s on line %d
+
+Warning: assert(): assert({
+    false
+}) failed in %s on line %d

Zend/tests/block_expr/004.phpt

@@ -0,0 +1,10 @@
+--TEST--
+Parse error when expression in block expression is missing
+--FILE--
+<?php
+
+$a = {};
+
+?>
+--EXPECTF--
+Parse error: syntax error, unexpected '}' in %s on line %d

Zend/tests/block_expr/005.phpt

@@ -0,0 +1,26 @@
+--TEST--
+Test exceptions in block expression
+--SKIPIF--
+<?php
+die("skip this test because it leaks memory");
+?>
+--FILE--
+<?php
+
+try {
+    $ary = [];
+    ($ary + [1]) + { throw new Exception('a'); null };
+} catch (Throwable $e) {
+    var_dump($e->getMessage());
+}
+
+try {
+    throw new Exception({ throw new Exception('b'); null });
+} catch (Throwable $e) {
+    var_dump($e->getMessage());
+}
+
+?>
+--EXPECT--
+string(1) "a"
+string(1) "b"

Zend/tests/block_expr/006.phpt

@@ -0,0 +1,16 @@
+--TEST--
+Parse error when semicolon after block expression is missing
+--FILE--
+<?php
+
+function foo() {
+    {
+        echo "Foo\n";
+        echo "Bar\n";
+        'Baz'
+    }
+}
+
+?>
+--EXPECTF--
+Parse error: syntax error, unexpected '}' in %s on line %d

Zend/zend_ast.c

@@ -1501,6 +1501,15 @@ static ZEND_COLD void zend_ast_export_ex(smart_str *str, zend_ast *ast, int prio
 		case ZEND_AST_TRAIT_ADAPTATIONS:
 			zend_ast_export_stmt(str, ast, indent);
 			break;
+		case ZEND_AST_BLOCK_EXPR:
+			smart_str_appends(str, "{\n");
+			zend_ast_export_stmt(str, ast->child[0], indent + 1);
+			zend_ast_export_indent(str, indent + 1);
+			zend_ast_export_ex(str, ast->child[1], 0, indent + 1);
+			smart_str_appendc(str, '\n');
+			zend_ast_export_indent(str, indent);
+			smart_str_appendc(str, '}');
+			break;
 		case ZEND_AST_IF:
 			zend_ast_export_if_stmt(str, (zend_ast_list*)ast, indent);
 			break;

Zend/zend_ast.h

@@ -123,6 +123,7 @@ enum _zend_ast_kind {
 	ZEND_AST_YIELD,
 	ZEND_AST_COALESCE,
 	ZEND_AST_ASSIGN_COALESCE,
+	ZEND_AST_BLOCK_EXPR,
 
 	ZEND_AST_STATIC,
 	ZEND_AST_WHILE,

Zend/zend_compile.c

@@ -8334,6 +8334,16 @@ void zend_compile_class_name(znode *result, zend_ast *ast) /* {{{ */
 }
 /* }}} */
 
+void zend_compile_block_expr(znode *result, zend_ast *ast) /* {{{ */
+{
+	zend_ast *statement_list = ast->child[0];
+	zend_ast *expr_ast = ast->child[1];
+
+	zend_compile_stmt(statement_list);
+	zend_compile_expr(result, expr_ast);
+}
+/* }}} */
+
 static zend_op *zend_compile_rope_add_ex(zend_op *opline, znode *result, uint32_t num, znode *elem_node) /* {{{ */
 {
 	if (num == 0) {
@@ -8954,6 +8964,9 @@ void zend_compile_expr(znode *result, zend_ast *ast) /* {{{ */
 		case ZEND_AST_ARROW_FUNC:
 			zend_compile_func_decl(result, ast, 0);
 			return;
+		case ZEND_AST_BLOCK_EXPR:
+			zend_compile_block_expr(result, ast);
+			return;
 		default:
 			ZEND_ASSERT(0 /* not supported */);
 	}

Zend/zend_language_parser.y

@@ -1021,6 +1021,7 @@ expr:
 	|	T_YIELD_FROM expr { $$ = zend_ast_create(ZEND_AST_YIELD_FROM, $2); CG(extra_fn_flags) |= ZEND_ACC_GENERATOR; }
 	|	inline_function { $$ = $1; }
 	|	T_STATIC inline_function { $$ = $2; ((zend_ast_decl *) $$)->flags |= ZEND_ACC_STATIC; }
+	|	'{' inner_statement_list expr '}' { $$ = zend_ast_create(ZEND_AST_BLOCK_EXPR, $2, $3); }
 ;
 
 
@@ -1036,6 +1037,15 @@ inline_function:
 				  zend_ast_create(ZEND_AST_RETURN, $11), $6);
 				  ((zend_ast_decl *) $$)->lex_pos = $10;
 				  CG(extra_fn_flags) = $9; }
+	|	fn returns_ref '(' parameter_list ')' return_type backup_doc_comment T_DOUBLE_ARROW backup_fn_flags backup_lex_pos '{' inner_statement_list '}' backup_fn_flags {
+			zval zv; ZVAL_NULL(&zv);
+			zend_ast *null_ast = zend_ast_create_zval(&zv);
+			$$ = zend_ast_create_decl(ZEND_AST_ARROW_FUNC, $2 | $14, $1, $7,
+				zend_string_init("{closure}", sizeof("{closure}") - 1, 0), $4, NULL,
+				zend_ast_create(ZEND_AST_RETURN, zend_ast_create(ZEND_AST_BLOCK_EXPR, $12, null_ast)), $6);
+			((zend_ast_decl *) $$)->lex_pos = $10;
+			CG(extra_fn_flags) = $9;
+		}
 ;
 
 fn: