Allow arbitrary const expressions in backed enums

Closes GH-7821
Closes GH-8190
Closes GH-8418

Author: iluuu1994

NEWS

@@ -7,6 +7,8 @@ PHP                                                                        NEWS
     references). (Nicolas Grekas)
   . Fixed bug GH-8661 (Nullsafe in coalesce triggers undefined variable
     warning). (ilutov)
+  . Fixed bug GH-7821 and GH-8418 (Allow arbitrary const expressions in backed
+    enums). (ilutov)
 
 - MBString:
   . Backwards-compatible mappings for 0x5C/0x7E in Shift-JIS are restored,

Zend/tests/enum/backed-duplicate-int.phpt

@@ -8,6 +8,33 @@ enum Foo: int {
     case Baz = 0;
 }
 
+try {
+    var_dump(Foo::Bar);
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+try {
+    var_dump(Foo::Bar);
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+try {
+    var_dump(Foo::from(42));
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+try {
+    var_dump(Foo::tryFrom('bar'));
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
 ?>
---EXPECTF--
-Fatal error: Duplicate value in enum Foo for cases Bar and Baz in %s on line %s
+--EXPECT--
+Duplicate value in enum Foo for cases Bar and Baz
+Duplicate value in enum Foo for cases Bar and Baz
+Duplicate value in enum Foo for cases Bar and Baz
+Foo::tryFrom(): Argument #1 ($value) must be of type int, string given

Zend/tests/enum/backed-duplicate-string.phpt

@@ -10,6 +10,33 @@ enum Suit: string {
     case Spades = 'H';
 }
 
+try {
+    var_dump(Suit::Hearts);
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+try {
+    var_dump(Suit::Hearts);
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+try {
+    var_dump(Suit::from(42));
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+try {
+    var_dump(Suit::tryFrom('bar'));
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
 ?>
---EXPECTF--
-Fatal error: Duplicate value in enum Suit for cases Hearts and Spades in %s on line %s
+--EXPECT--
+Duplicate value in enum Suit for cases Hearts and Spades
+Duplicate value in enum Suit for cases Hearts and Spades
+Duplicate value in enum Suit for cases Hearts and Spades
+Duplicate value in enum Suit for cases Hearts and Spades

Zend/tests/enum/backed-int-const-invalid-expr.phpt

@@ -11,4 +11,4 @@ var_dump(Foo::Bar->value);
 
 ?>
 --EXPECTF--
-Fatal error: Enum case value must be compile-time evaluatable in %s on line %d
+Fatal error: Constant expression contains invalid operations in %s on line %d

Zend/tests/enum/backed-mismatch.phpt

@@ -7,6 +7,33 @@ enum Foo: int {
     case Bar = 'bar';
 }
 
+try {
+    var_dump(Foo::Bar);
+} catch (Error $e) {
+    echo get_class($e), ': ', $e->getMessage(), "\n";
+}
+
+try {
+    var_dump(Foo::Bar);
+} catch (Error $e) {
+    echo get_class($e), ': ', $e->getMessage(), "\n";
+}
+
+try {
+    var_dump(Foo::from(42));
+} catch (Error $e) {
+    echo get_class($e), ': ', $e->getMessage(), "\n";
+}
+
+try {
+    var_dump(Foo::from('bar'));
+} catch (Error $e) {
+    echo get_class($e), ': ', $e->getMessage(), "\n";
+}
+
 ?>
---EXPECTF--
-Fatal error: Enum case type string does not match enum backing type int in %s on line %d
+--EXPECT--
+TypeError: Enum case type string does not match enum backing type int
+TypeError: Enum case type string does not match enum backing type int
+TypeError: Enum case type string does not match enum backing type int
+TypeError: Foo::from(): Argument #1 ($value) must be of type int, string given

Zend/tests/enum/gh7821.phpt

@@ -0,0 +1,26 @@
+--TEST--
+GH-7821: Can't use arbitrary constant expressions in enum cases
+--FILE--
+<?php
+
+interface I {
+    public const A = 'A';
+    public const B = 'B';
+}
+
+enum B: string implements I {
+    case C = I::A;
+    case D = self::B;
+}
+
+var_dump(B::A);
+var_dump(B::B);
+var_dump(B::C->value);
+var_dump(B::D->value);
+
+?>
+--EXPECT--
+string(1) "A"
+string(1) "B"
+string(1) "A"
+string(1) "B"

Zend/tests/enum/gh8418.phpt

@@ -0,0 +1,20 @@
+--TEST--
+GH-8418: Enum constant expression evaluation doesn't work with warmed cache
+--FILE--
+<?php
+
+class ExampleClass
+{
+    public const EXAMPLE_CONST = 42;
+}
+
+enum ExampleEnum: int
+{
+    case ENUM_CASE = ExampleClass::EXAMPLE_CONST;
+}
+
+var_dump(ExampleEnum::ENUM_CASE->value);
+
+?>
+--EXPECT--
+int(42)

Zend/tests/enum/non-backed-enum-with-expr-value.phpt

@@ -9,4 +9,4 @@ enum Foo {
 
 ?>
 --EXPECTF--
-Fatal error: Case Bar of non-backed enum Foo must not have a value, try adding ": int" to the enum declaration in %s on line %d
+Fatal error: Case Bar of non-backed enum Foo must not have a value in %s on line %d

Zend/tests/enum/non-backed-enum-with-int-value.phpt

@@ -9,4 +9,4 @@ enum Foo {
 
 ?>
 --EXPECTF--
-Fatal error: Case Bar of non-backed enum Foo must not have a value, try adding ": int" to the enum declaration in %s on line %d
+Fatal error: Case Bar of non-backed enum Foo must not have a value in %s on line %d

Zend/tests/enum/non-backed-enum-with-string-value.phpt

@@ -9,4 +9,4 @@ enum Foo {
 
 ?>
 --EXPECTF--
-Fatal error: Case Bar of non-backed enum Foo must not have a value, try adding ": string" to the enum declaration in %s on line %d
+Fatal error: Case Bar of non-backed enum Foo must not have a value in %s on line %d