Implement const array/string dereference

RFC:https://wiki.php.net/rfc/constdereference

Author: laruence

NEWS

@@ -6,6 +6,7 @@ PHP                                                                        NEWS
   . Drop Windows XP and 2003 support. (Pierre)
   . World domination
   . Improve set_exception_handler while doing reset.(Laruence)
+  . Support constant array/string dereferencing. (Laruence)
 
 - Core:
   . Implemented FR #60738 (Allow 'set_error_handler' to handle NULL).

UPGRADING

@@ -26,6 +26,8 @@ PHP X.Y UPGRADE NOTES
 2. New Features
 ========================================
 
+- Support constant array/string dereferencing. (Laruence)
+  (https://wiki.php.net/rfc/constdereference)
 
 ========================================
 2. Changes in SAPI modules

Zend/tests/const_dereference_001.phpt

@@ -0,0 +1,21 @@
+--TEST--
+Const array deference
+--FILE--
+<?php
+error_reporting(E_ALL);
+
+var_dump(array(1, 2, 3, 4,) [3]);
+var_dump(array(1, 2, 3, 4,) ['foo']);
+var_dump(array(array(1,2,3), array(4, 5, 6))[1][2]);
+
+foreach (array(array(1, 2, 3))[0] as $var) {
+     echo $var;
+}
+?>
+--EXPECTF--
+int(4)
+
+Notice: Undefined index: foo in %sconst_dereference_001.php on line %d
+NULL
+int(6)
+123

Zend/tests/const_dereference_002.phpt

@@ -0,0 +1,18 @@
+--TEST--
+Const string dereference
+--FILE--
+<?php
+error_reporting(E_ALL);
+
+var_dump("foobar"[3]);
+var_dump("foobar"[2][0]);
+var_dump("foobar"["foo"]["bar"]);
+
+--EXPECTF--
+string(1) "b"
+string(1) "o"
+
+Warning: Illegal string offset 'foo' in %sconst_dereference_002.php on line %d
+
+Warning: Illegal string offset 'bar' in %sconst_dereference_002.php on line %d
+string(1) "f"

Zend/tests/const_dereference_003.phpt

@@ -0,0 +1,21 @@
+--TEST--
+Const array deference
+--FILE--
+<?php
+error_reporting(E_ALL);
+
+var_dump([1, 2, 3, 4,][3]);
+var_dump([1, 2, 3, 4]['foo']);
+var_dump([array(1,2,3), [4, 5, 6]][1][2]);
+
+foreach (array([1, 2, 3])[0] as $var) {
+     echo $var;
+}
+?>
+--EXPECTF--
+int(4)
+
+Notice: Undefined index: foo in %sconst_dereference_003.php on line %d
+NULL
+int(6)
+123

Zend/zend_language_parser.y

@@ -789,8 +789,8 @@ expr_without_variable:
 	|	T_EXIT exit_expr	{ zend_do_exit(&$$, &$2 TSRMLS_CC); }
 	|	'@' { zend_do_begin_silence(&$1 TSRMLS_CC); } expr { zend_do_end_silence(&$1 TSRMLS_CC); $$ = $3; }
 	|	scalar				{ $$ = $1; }
-	|	T_ARRAY '(' array_pair_list ')' { $$ = $3; }
- 	|	'[' array_pair_list ']' { $$ = $2; }
+	|	combined_scalar_offset { zend_do_end_variable_parse(&$1, BP_VAR_R, 0 TSRMLS_CC); }
+	|	combined_scalar { $$ = $1; }
 	|	'`' backticks_expr '`' { zend_do_shell_exec(&$$, &$2 TSRMLS_CC); }
 	|	T_PRINT expr  { zend_do_print(&$$, &$2 TSRMLS_CC); }
 	|	function is_reference '(' { zend_do_begin_lambda_function_declaration(&$$, &$1, $2.op_type, 0 TSRMLS_CC); }
@@ -799,6 +799,15 @@ expr_without_variable:
 			parameter_list ')' lexical_vars '{' inner_statement_list '}' {  zend_do_end_function_declaration(&$2 TSRMLS_CC); $$ = $5; }
 ;
 
+combined_scalar_offset:
+	  combined_scalar '[' dim_offset ']' { zend_do_begin_variable_parse(TSRMLS_C); fetch_array_dim(&$$, &$1, &$3 TSRMLS_CC); }
+	| combined_scalar_offset '[' dim_offset ']' { fetch_array_dim(&$$, &$1, &$3 TSRMLS_CC); }
+    | T_CONSTANT_ENCAPSED_STRING '[' dim_offset ']' { zend_do_begin_variable_parse(TSRMLS_C); fetch_array_dim(&$$, &$1, &$3 TSRMLS_CC); }
+
+combined_scalar:
+      T_ARRAY '(' array_pair_list ')' { $$ = $3; }
+    | '[' array_pair_list ']' { $$ = $2; }
+
 function:
 	T_FUNCTION { $$.u.op.opline_num = CG(zend_lineno); }
 ;

Zend/zend_vm_def.h

@@ -1174,7 +1174,7 @@ ZEND_VM_HANDLER(89, ZEND_FETCH_IS, CONST|TMP|VAR|CV, UNUSED|CONST|VAR)
 	ZEND_VM_DISPATCH_TO_HELPER_EX(zend_fetch_var_address_helper, type, BP_VAR_IS);
 }
 
-ZEND_VM_HANDLER(81, ZEND_FETCH_DIM_R, VAR|CV, CONST|TMP|VAR|CV)
+ZEND_VM_HANDLER(81, ZEND_FETCH_DIM_R, CONST|TMP|VAR|CV, CONST|TMP|VAR|CV)
 {
 	USE_OPLINE
 	zend_free_op free_op1, free_op2;
@@ -1187,10 +1187,19 @@ ZEND_VM_HANDLER(81, ZEND_FETCH_DIM_R, VAR|CV, CONST|TMP|VAR|CV)
 	    EX_T(opline->op1.var).var.ptr_ptr) {
 		PZVAL_LOCK(*EX_T(opline->op1.var).var.ptr_ptr);
 	}
-	container = GET_OP1_ZVAL_PTR_PTR(BP_VAR_R);
-	zend_fetch_dimension_address_read(&EX_T(opline->result.var), container, GET_OP2_ZVAL_PTR(BP_VAR_R), OP2_TYPE, BP_VAR_R TSRMLS_CC);
-	FREE_OP2();
-	FREE_OP1_VAR_PTR();
+    
+    if (OP1_TYPE == IS_TMP_VAR || OP1_TYPE == IS_CONST) {
+        zval *container = GET_OP1_ZVAL_PTR(BP_VAR_R);
+        zend_fetch_dimension_address_read(&EX_T(opline->result.var), &container, GET_OP2_ZVAL_PTR(BP_VAR_R), OP2_TYPE, BP_VAR_R TSRMLS_CC);
+        FREE_OP2();
+        FREE_OP1();
+    } else {
+        container = GET_OP1_ZVAL_PTR_PTR(BP_VAR_R);
+        zend_fetch_dimension_address_read(&EX_T(opline->result.var), container, GET_OP2_ZVAL_PTR(BP_VAR_R), OP2_TYPE, BP_VAR_R TSRMLS_CC);
+        FREE_OP2();
+        FREE_OP1_VAR_PTR();
+    }
+
 	CHECK_EXCEPTION();
 	ZEND_VM_NEXT_OPCODE();
 }