[POC] Support calling functions from constant expressions

Zend/tests/call_in_const/backticks_forbidden.phpt

@@ -0,0 +1,12 @@
+--TEST--
+Cannot use backtick shorthand for shell_exec in constant expressions
+--FILE--
+<?php
+// Make sure that this is not accidentally allowed by future changes to PHP.
+// During compilation, this gets converted to a regular function call opcode.
+class Example {
+    const TEST_CONST = [`echo test`];
+}
+?>
+--EXPECTF--
+Fatal error: Constant expression contains invalid operations in %s on line 5

Zend/tests/call_in_const/class_const01.phpt

@@ -0,0 +1,15 @@
+--TEST--
+Can call internal functions from class constants
+--FILE--
+<?php
+class Example {
+    const X = cos(0);
+
+    public static function main() {
+        echo "X is " . self::X . "\n";
+    }
+}
+Example::main();
+?>
+--EXPECT--
+X is 1

Zend/tests/call_in_const/class_const02.phpt

@@ -0,0 +1,27 @@
+--TEST--
+Can call internal functions from class constants
+--FILE--
+<?php
+class Example {
+    const X = [
+        'key1' => 'value1',
+        'key2' => 'value2',
+    ];
+    const Y = array_flip(self::X);
+    const Z = array_flip(self::Y);
+}
+var_export(Example::Z);
+var_export(Example::Z);
+var_export(Example::Y);
+?>
+--EXPECT--
+array (
+  'key1' => 'value1',
+  'key2' => 'value2',
+)array (
+  'key1' => 'value1',
+  'key2' => 'value2',
+)array (
+  'value1' => 'key1',
+  'value2' => 'key2',
+)

Zend/tests/call_in_const/class_const03.phpt

@@ -0,0 +1,24 @@
+--TEST--
+Cannot call functions accessing the variable scope in class constants
+--FILE--
+<?php
+class Example {
+    const X = func_get_args();
+
+    public static function main($value) {
+        try {
+            var_export(self::X);
+        } catch (Error $e) {
+            printf("Caught %s on line %d\n", $e->getMessage(), $e->getLine());
+        }
+        try {
+            var_export(self::X);
+        } catch (Error $e) {
+            printf("Caught %s on line %d\n", $e->getMessage(), $e->getLine());
+        }
+    }
+}
+Example::main('test');
+?>
+--EXPECTF--
+Fatal error: Constant expression uses function func_get_args() which is not in get_const_expr_functions() in %s on line 3

Zend/tests/call_in_const/class_const04.phpt

@@ -0,0 +1,29 @@
+--TEST--
+Handling call_user_func and static in class constants.
+--FILE--
+<?php
+class MyClass {
+    // There's only one constant declaration that gets shared by all of the classes.
+    // So act as though the class scope is MyClass no matter where it gets called.
+    const X = call_user_func('static::example');
+
+    public static function example() {
+        return static::class;
+    }
+    public static function main() {
+        echo static::X . "\n";
+    }
+}
+class SubClass extends MyClass {
+    public static function example() {
+        return "Other\n";
+    }
+}
+// This wouldn't work without further updates to the implementation.
+echo MyClass::X;
+SubClass::main();
+MyClass::main();
+
+?>
+--EXPECTF--
+Fatal error: Constant expression uses function call_user_func() which is not in get_const_expr_functions() in %s on line 5

Zend/tests/call_in_const/global_const01.phpt

@@ -0,0 +1,11 @@
+--TEST--
+Can call internal functions from global constants
+--FILE--
+<?php
+const VALUES = RANGE(1, 100);
+const SUM = array_sum(VALUES);
+
+echo "SUM is " . SUM . "\n";
+?>
+--EXPECT--
+SUM is 5050

Zend/tests/call_in_const/global_const02.phpt

@@ -0,0 +1,11 @@
+--TEST--
+Cannot declare constants with function calls that contain objects
+--FILE--
+<?php
+function make_object_array() {
+    return [new stdClass()];
+}
+const OBJECT_VALUES = make_object_array();
+?>
+--EXPECTF--
+Fatal error: Constant expression uses function make_object_array() which is not in get_const_expr_functions() in %s on line 5

Zend/tests/call_in_const/methods_forbidden.phpt

@@ -0,0 +1,19 @@
+--TEST--
+Cannot call methods in constant expressions
+--FILE--
+<?php
+// Currently, php will evaluate all of the instance property defaults at once and cache them
+// the first time a class gets instantiated, in _object_and_properties_init.
+//
+// Authors of future RFCs may wish to change PHP
+// to allow `count()` or `generate_unique_id()` or `public $fields = new stdClass();`
+// as the defaults of instance properties.
+class MyClass {
+    public static function example() {
+        return 'value';
+    }
+    const X = 'MyClass::example'();
+}
+?>
+--EXPECTF--
+Fatal error: Constant expression contains invalid name for function call in %s on line 12

Zend/tests/call_in_const/param_defaults01.phpt

@@ -0,0 +1,17 @@
+--TEST--
+Can call internal functions from parameter default
+--FILE--
+<?php
+namespace NS;
+use function max;
+function test_default($x = max(1, 3, 2)) {
+    echo "x is $x\n";
+}
+test_default();
+test_default(2);
+test_default();
+?>
+--EXPECT--
+x is 3
+x is 2
+x is 3

Zend/tests/call_in_const/param_defaults02.phpt

@@ -0,0 +1,26 @@
+--TEST--
+Cannot access variable scope in parameter defaults
+--FILE--
+<?php
+
+namespace NS;
+
+use Error;
+
+function test_default($x = func_get_args()) {
+    var_dump($x);
+}
+try {
+    test_default();
+} catch (Error $e) {
+    printf("Caught %s on line %d\n", $e->getMessage(), $e->getLine());
+}
+test_default('overriding the default');
+try {
+    test_default();
+} catch (Error $e) {
+    printf("Caught %s on line %d\n", $e->getMessage(), $e->getLine());
+}
+?>
+--EXPECTF--
+Fatal error: Constant expression uses function NS\func_get_args() which is not in get_const_expr_functions() in %s on line 7

Zend/tests/call_in_const/param_defaults03.phpt

@@ -0,0 +1,20 @@
+--TEST--
+User-defined functions are evaluated every time in param defaults (not callable)
+--FILE--
+<?php
+
+function generate_new_id() : int {
+    static $id = 100;
+    ++$id;
+    return $id;
+}
+
+function test_id(int $id = generate_new_id()) {
+    echo "id is $id\n";
+}
+test_id();
+test_id(-1);
+test_id();
+?>
+--EXPECTF--
+Fatal error: Constant expression uses function generate_new_id() which is not in get_const_expr_functions() in %s on line 9

Zend/tests/call_in_const/param_defaults04.phpt

@@ -0,0 +1,14 @@
+--TEST--
+Functions must be unambiguously in the whitelist
+--FILE--
+<?php
+namespace NS;
+function test_default($x = max(1, 3, 2)) {
+    echo "x is $x\n";
+}
+test_default();
+test_default(2);
+test_default();
+?>
+--EXPECTF--
+Fatal error: Constant expression uses function NS\max() which is not in get_const_expr_functions() in %s on line 3

Zend/tests/call_in_const/param_ref.phpt

@@ -0,0 +1,20 @@
+--TEST--
+Warn when calling function expecting a reference as an argument
+--INI--
+error_reporting=E_ALL
+--FILE--
+<?php
+class Example {
+    const VALUES = [];
+    const IS_MATCH = preg_match('/test/', 'testing');
+    const IS_MATCH_V2 = preg_match('/test/', 'testing', self::VALUES);
+
+    public static function main() {
+        echo "X is " . self::X . "\n";
+    }
+}
+var_dump(Example::IS_MATCH);
+var_dump(Example::IS_MATCH_V2);
+var_dump(Example::VALUES);
+--EXPECTF--
+Fatal error: Constant expression uses function preg_match() which is not in get_const_expr_functions() in %s on line 4

Zend/tests/call_in_const/property_default01.phpt

@@ -0,0 +1,22 @@
+--TEST--
+Can call user-defined functions from defaults of static properties
+--FILE--
+<?php
+namespace NS;
+function log_call($arg) {
+    echo "log_call(" . var_export($arg, true) . ")\n";
+    return $arg;
+}
+class MyClass {
+    public static $DEBUG = log_call(true);
+    public static $DEBUG2 = namespace\log_call(range(1,2));
+}
+echo "Start\n";
+var_export(MyClass::$DEBUG); echo "\n";
+var_export(MyClass::$DEBUG2); echo "\n";
+var_export(MyClass::$DEBUG); echo "\n";
+MyClass::$DEBUG = "New value";
+echo MyClass::$DEBUG . "\n";
+?>
+--EXPECTF--
+Fatal error: Constant expression uses function NS\log_call() which is not in get_const_expr_functions() in %s on line 8

Zend/tests/call_in_const/property_default02.phpt

@@ -0,0 +1,16 @@
+--TEST--
+Cannot call functions from defaults of instance properties
+--FILE--
+<?php
+// Currently, php will evaluate all of the instance property defaults at once and cache them
+// the first time a class gets instantiated, in _object_and_properties_init.
+//
+// Authors of future RFCs may wish to change PHP
+// to allow `count()` or `generate_unique_id()` or `public $fields = new stdClass();`
+// as the defaults of instance properties.
+class MyClass {
+    public $v1 = count([]);
+}
+?>
+--EXPECTF--
+Fatal error: Default value for instance property MyClass::$v1 cannot contain function calls in %s on line 9

Zend/tests/call_in_const/recursion.phpt

@@ -0,0 +1,35 @@
+--TEST--
+Recursion in calls in class constants causes an error
+--FILE--
+<?php
+function x_plus_1() {
+    echo "Computing X + 1\n";
+    return Recursion::X + 1;
+}
+class Recursion {
+    const X = x_plus_1();
+    const MISSING = MISSING_GLOBAL + 1;
+}
+try {
+    echo "Recursion::X=" . Recursion::X . "\n";
+} catch (Error $e) {
+    printf("Caught %s: %s\n", get_class($e), $e->getMessage());
+}
+try {
+    echo "Recursion::X=" . Recursion::X . "\n";
+} catch (Error $e) {
+    printf("Second call caught %s: %s\n", get_class($e), $e->getMessage());
+}
+try {
+    echo "Recursion::MISSING=" . Recursion::MISSING;
+} catch (Error $e) {
+    printf("Caught %s: %s\n", get_class($e), $e->getMessage());
+}
+try {
+    echo "Recursion::MISSING=" . Recursion::MISSING;
+} catch (Error $e) {
+    printf("Second call caught %s: %s\n", get_class($e), $e->getMessage());
+}
+?>
+--EXPECTF--
+Fatal error: Constant expression uses function x_plus_1() which is not in get_const_expr_functions() in %s on line 7

Zend/tests/call_in_const/static_default01.phpt

@@ -0,0 +1,14 @@
+--TEST--
+Can call internal functions from defaults of static variables
+--FILE--
+<?php
+function main() {
+    static $call = SPRINTF("%s!", sprintf("Hello, %s", "World"));
+    echo "$call\n";
+}
+main();
+main();
+// Note: It may be possible to allowing literally any call or value in static variables, but this is outside of the scope of this RFC.
+?>
+--EXPECTF--
+Fatal error: Constant expression uses function SPRINTF() which is not in get_const_expr_functions() in %s on line 3

Zend/tests/call_in_const/static_default02.phpt

@@ -0,0 +1,18 @@
+--TEST--
+Cannot call user-defined functions from defaults of static variables
+--FILE--
+<?php
+function log_call(string $arg) {
+    echo "log_call('$arg')\n";
+    return $arg;
+}
+
+$f = function () {
+    static $call = log_call(sprintf("Hello, %s", "World"));
+    echo "$call\n";
+};
+$f();
+$f();
+?>
+--EXPECTF--
+Fatal error: Constant expression uses function log_call() which is not in get_const_expr_functions() in %s on line 8

Zend/tests/call_in_const/static_default03.phpt

@@ -0,0 +1,18 @@
+--TEST--
+Can call internal functions from defaults of static variables
+--FILE--
+<?php
+function main() {
+    static $call = missing_sprintf("%s!", sprintf("Hello, %s", "World"));
+    echo "$call\n";
+}
+for ($i = 0; $i < 2; $i++) {
+    try {
+        main();
+    } catch (Error $e) {
+        printf("Caught %s: %s at line %d\n", get_class($e), $e->getMessage(), $e->getLine());
+    }
+}
+?>
+--EXPECTF--
+Fatal error: Constant expression uses function missing_sprintf() which is not in get_const_expr_functions() in %s on line 3