Fix T_NUM_STRING negation

T_NUM_STRING follows the rules of symtable numeric string
conversion. If the offset isn't an integer under those rules, it
is treated as a string. This should apply to negated T_NUM_STRINGs
as well.

Author: nikic

Zend/tests/neg_num_string.phpt

@@ -0,0 +1,47 @@
+--TEST--
+Test edge-cases for negative num strings in interpolated string offsets
+--FILE--
+<?php
+
+$a = [
+    "0" => 1,
+    "-0" => 2,
+    "1" => 3,
+    "-1" => 4,
+    "0x0" => 5,
+    "-0x0" => 6,
+    "00" => 7,
+    "-00" => 8,
+    "9223372036854775808" => 9,
+    "-9223372036854775808" => 10,
+    "2147483648" => 11,
+    "-2147483648" => 12,
+];
+
+var_dump("$a[0]");
+var_dump("$a[-0]");
+var_dump("$a[1]");
+var_dump("$a[-1]");
+var_dump("$a[0x0]");
+var_dump("$a[-0x0]");
+var_dump("$a[00]");
+var_dump("$a[-00]");
+var_dump("$a[9223372036854775808]");
+var_dump("$a[-9223372036854775808]");
+var_dump("$a[2147483648]");
+var_dump("$a[-2147483648]");
+
+?>
+--EXPECT--
+string(1) "1"
+string(1) "2"
+string(1) "3"
+string(1) "4"
+string(1) "5"
+string(1) "6"
+string(1) "7"
+string(1) "8"
+string(1) "9"
+string(2) "10"
+string(2) "11"
+string(2) "12"

Zend/zend_compile.c

@@ -1830,6 +1830,28 @@ zend_ast *zend_ast_append_str(zend_ast *left_ast, zend_ast *right_ast) /* {{{ */
 }
 /* }}} */
 
+zend_ast *zend_negate_num_string(zend_ast *ast) /* {{{ */
+{
+	zval *zv = zend_ast_get_zval(ast);
+	if (Z_TYPE_P(zv) == IS_LONG) {
+		if (Z_LVAL_P(zv) == 0) {
+			ZVAL_NEW_STR(zv, zend_string_init("-0", sizeof("-0")-1, 0));
+		} else {
+			ZEND_ASSERT(Z_LVAL_P(zv) > 0);
+			Z_LVAL_P(zv) *= -1;
+		}
+	} else if (Z_TYPE_P(zv) == IS_STRING) {
+		size_t orig_len = Z_STRLEN_P(zv);
+		zend_string_extend(Z_STR_P(zv), orig_len + 1, 0);
+		memmove(Z_STRVAL_P(zv) + 1, Z_STRVAL_P(zv), orig_len + 1);
+		Z_STRVAL_P(zv)[0] = '-';
+	} else {
+		ZEND_ASSERT(0);
+	}
+	return ast;
+}
+/* }}} */
+
 void zend_verify_namespace(void) /* {{{ */
 {
 	if (FC(has_bracketed_namespaces) && !FC(in_namespace)) {

Zend/zend_compile.h

@@ -726,7 +726,10 @@ ZEND_API binary_op_type get_binary_op(int opcode);
 
 void zend_stop_lexing(void);
 void zend_emit_final_return(int return_one);
+
+/* Used during AST construction */
 zend_ast *zend_ast_append_str(zend_ast *left, zend_ast *right);
+zend_ast *zend_negate_num_string(zend_ast *ast);
 uint32_t zend_add_class_modifier(uint32_t flags, uint32_t new_flag);
 uint32_t zend_add_member_modifier(uint32_t flags, uint32_t new_flag);
 void zend_handle_encoding_declaration(zend_ast *ast);

Zend/zend_language_parser.y

@@ -1247,10 +1247,10 @@ encaps_var:
 ;
 
 encaps_var_offset:
-		T_STRING		{ $$ = $1; }
-	|	T_NUM_STRING	{ $$ = $1; }
-	|	'-' T_NUM_STRING { $$ = zend_ast_create(ZEND_AST_UNARY_MINUS, $2); }
-	|	T_VARIABLE		{ $$ = zend_ast_create(ZEND_AST_VAR, $1); }
+		T_STRING			{ $$ = $1; }
+	|	T_NUM_STRING		{ $$ = $1; }
+	|	'-' T_NUM_STRING 	{ $$ = zend_negate_num_string($2); }
+	|	T_VARIABLE			{ $$ = zend_ast_create(ZEND_AST_VAR, $1); }
 ;