Switch to more explicit <- returns, allow omitting <- for terminating blocks

Author: iluuu1994

Zend/Optimizer/dce.c

@@ -154,6 +154,7 @@ static inline bool may_have_side_effects(
 		case ZEND_INCLUDE_OR_EVAL:
 		case ZEND_THROW:
 		case ZEND_MATCH_ERROR:
+		case ZEND_MATCH_BLOCK_NO_VALUE_ERROR:
 		case ZEND_EXT_STMT:
 		case ZEND_EXT_FCALL_BEGIN:
 		case ZEND_EXT_FCALL_END:

Zend/tests/match/block_arg_return.phpt

@@ -3,7 +3,7 @@ Match expression block must not use return
 --FILE--
 <?php
 foo(match (1) {
-    1 => { return; null }
+    1 => { return; }
 });
 ?>
 --EXPECTF--

Zend/tests/match/block_basic.phpt

@@ -12,11 +12,14 @@ function bar() {
 
 function test($value) {
     var_dump(match ($value) {
-        1 => { 1 },
-        2 => { $x = 2; $x },
+        1 => { <- 1; },
+        2 => {
+            $x = 2;
+            <- $x;
+        },
         3 => {
             foo();
-            bar()
+            <- bar();
         },
     });
 }

Zend/tests/match/block_expr_break_escape.phpt

@@ -3,7 +3,7 @@ Match expression block must not use break
 --FILE--
 <?php
 var_dump(match ($value) {
-    1 => { break; [] },
+    1 => { break; },
 });
 ?>
 --EXPECTF--

Zend/tests/match/block_expr_break_no_escape.phpt

@@ -8,7 +8,7 @@ var_dump(match (1) {
             echo $value, "\n";
             break;
         }
-        42
+        <- 42;
     },
 });
 ?>

Zend/tests/match/block_expr_goto_escape.phpt

@@ -5,7 +5,6 @@ Match expression block must not use goto
 var_dump(match (1) {
     1 => {
         goto after;
-        42
     },
 });
 after:

Zend/tests/match/block_expr_goto_into.phpt

@@ -6,7 +6,7 @@ goto in;
 var_dump(match (1) {
     1 => {
 in:
-        42
+        <- 42;
     },
 });
 ?>

Zend/tests/match/block_expr_no_result.phpt

@@ -2,11 +2,19 @@
 Match expression block must return a value
 --FILE--
 <?php
-var_dump(match (1) {
-    1 => {
-        echo "Not returning anything\n";
-    },
-});
+function test() {
+    var_dump(match (1) {
+        1 => {
+            echo "Not returning anything\n";
+        },
+    });
+}
+try {
+    test();
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
 ?>
---EXPECTF--
-Fatal error: Blocks of match expression with used result must return a value. Did you mean to omit the last semicolon? in %s on line %d
+--EXPECT--
+Not returning anything
+Match expected a value from block but none was returned

Zend/tests/match/block_expr_return.phpt

@@ -3,7 +3,7 @@ Match expression block must not use return
 --FILE--
 <?php
 var_dump(match ($value) {
-    1 => { return; [] },
+    1 => { return; },
 });
 ?>
 --EXPECTF--

Zend/tests/match/block_expr_throw.phpt

@@ -5,7 +5,7 @@ Throwing match expression block must clean up live-vars
 
 function throw_($value) {
     var_dump([new \stdClass] + match ($value) {
-        1 => { throw new Exception('Exception with live var'); [] },
+        1 => { throw new Exception('Exception with live var'); },
     });
 }
 

Zend/tests/match/block_stmt_with_result.phpt

@@ -3,7 +3,7 @@ Match statement block must not return a value
 --FILE--
 <?php
 match (1) {
-    1 => { 42 },
+    1 => { <- 42; },
 };
 ?>
 --EXPECTF--

Zend/zend_compile.c

@@ -6058,13 +6058,15 @@ static void zend_compile_match(znode *result, zend_ast *ast)
 			CG(context).in_block_expr = true;
 			zend_compile_stmt_list(body_ast->child[0]);
 			zend_ast *result_expr_ast = body_ast->child[1];
-			if (result && !result_expr_ast) {
-				zend_error_noreturn(E_COMPILE_ERROR, "Blocks of match expression with used result must return a value. Did you mean to omit the last semicolon?");
-			} else if (!result && result_expr_ast) {
+			if (!result && result_expr_ast) {
 				zend_error_noreturn(E_COMPILE_ERROR, "Blocks of match expression with unused result must not return a value");
 			}
 			if (result_expr_ast) {
 				zend_compile_expr(&body_node, result_expr_ast);
+			} else if (result) {
+				zend_emit_op(NULL, ZEND_MATCH_BLOCK_NO_VALUE_ERROR, NULL, NULL);
+				body_node.op_type = IS_CONST;
+				ZVAL_NULL(&body_node.u.constant);
 			}
 			CG(context).in_block_expr = prev_in_block_expr;
 		} else {

Zend/zend_execute.c

@@ -887,6 +887,11 @@ ZEND_COLD void zend_match_unhandled_error(const zval *value)
 	smart_str_free(&msg);
 }
 
+ZEND_COLD void zend_match_block_no_value_error(void)
+{
+	zend_throw_exception_ex(zend_ce_unhandled_match_error, 0, "Match expected a value from block but none was returned");
+}
+
 ZEND_API ZEND_COLD void ZEND_FASTCALL zend_readonly_property_modification_error(
 		const zend_property_info *info) {
 	zend_throw_error(NULL, "Cannot modify readonly property %s::$%s",

Zend/zend_language_parser.y

@@ -70,7 +70,7 @@ static YYSIZE_T zend_yytnamerr(char*, const char*);
 %left '^'
 %left T_AMPERSAND_NOT_FOLLOWED_BY_VAR_OR_VARARG T_AMPERSAND_FOLLOWED_BY_VAR_OR_VARARG
 %nonassoc T_IS_EQUAL T_IS_NOT_EQUAL T_IS_IDENTICAL T_IS_NOT_IDENTICAL T_SPACESHIP
-%nonassoc '<' T_IS_SMALLER_OR_EQUAL '>' T_IS_GREATER_OR_EQUAL
+%nonassoc '<' T_IS_SMALLER_OR_EQUAL '>' T_IS_GREATER_OR_EQUAL T_THIN_ARROW_LEFT
 %left '.'
 %left T_SL T_SR
 %left '+' '-'
@@ -216,6 +216,7 @@ static YYSIZE_T zend_yytnamerr(char*, const char*);
 %token T_OBJECT_OPERATOR "'->'"
 %token T_NULLSAFE_OBJECT_OPERATOR "'?->'"
 %token T_DOUBLE_ARROW    "'=>'"
+%token T_THIN_ARROW_LEFT "'<-'"
 %token T_COMMENT         "comment"
 %token T_DOC_COMMENT     "doc comment"
 %token T_OPEN_TAG        "open tag"
@@ -739,7 +740,8 @@ match_arm_cond_list:
 
 match_arm_body:
 		expr { $$ = $1; }
-	|	'{' inner_statement_list optional_expr '}' { $$ = zend_ast_create(ZEND_AST_MATCH_ARM_BLOCK, $2, $3); }
+	|	'{' inner_statement_list '}' { $$ = zend_ast_create(ZEND_AST_MATCH_ARM_BLOCK, $2, NULL); }
+	|	'{' inner_statement_list T_THIN_ARROW_LEFT optional_expr ';' '}' { $$ = zend_ast_create(ZEND_AST_MATCH_ARM_BLOCK, $2, $4); }
 ;
 
 while_statement:
@@ -1215,6 +1217,9 @@ expr:
 			{ $$ = zend_ast_create_binary_op(ZEND_IS_NOT_EQUAL, $1, $3); }
 	|	expr '<' expr
 			{ $$ = zend_ast_create_binary_op(ZEND_IS_SMALLER, $1, $3); }
+	/* BC for $foo<-$bar */
+	|	expr T_THIN_ARROW_LEFT expr
+			{ $$ = zend_ast_create_binary_op(ZEND_IS_SMALLER, $1, zend_ast_create(ZEND_AST_UNARY_MINUS, $3)); }
 	|	expr T_IS_SMALLER_OR_EQUAL expr
 			{ $$ = zend_ast_create_binary_op(ZEND_IS_SMALLER_OR_EQUAL, $1, $3); }
 	|	expr '>' expr

Zend/zend_language_scanner.l

@@ -1603,6 +1603,10 @@ OPTIONAL_WHITESPACE_OR_COMMENTS ({WHITESPACE}|{MULTI_LINE_COMMENT}|{SINGLE_LINE_
 	goto restart;
 }
 
+<ST_IN_SCRIPTING>"<-" {
+	RETURN_TOKEN(T_THIN_ARROW_LEFT);
+}
+
 <ST_IN_SCRIPTING>"::" {
 	RETURN_TOKEN(T_PAAMAYIM_NEKUDOTAYIM);
 }

Zend/zend_vm_def.h

@@ -9217,6 +9217,13 @@ ZEND_VM_COLD_CONST_HANDLER(197, ZEND_MATCH_ERROR, CONST|TMPVARCV, UNUSED)
 	HANDLE_EXCEPTION();
 }
 
+ZEND_VM_COLD_CONST_HANDLER(204, ZEND_MATCH_BLOCK_NO_VALUE_ERROR, UNUSED, UNUSED)
+{
+	SAVE_OPLINE();
+	zend_match_block_no_value_error();
+	HANDLE_EXCEPTION();
+}
+
 ZEND_VM_COLD_CONSTCONST_HANDLER(189, ZEND_IN_ARRAY, CONST|TMP|VAR|CV, CONST, NUM)
 {
 	USE_OPLINE