Hint to add : type to enum decl

when adding a backed value to a case without adding a backing type to the
enum.

Author: iluuu1994

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

@@ -0,0 +1,12 @@
+--TEST--
+Non-scalar enum errors when case has int value
+--FILE--
+<?php
+
+enum Foo {
+    case Bar = 1;
+}
+
+?>
+--EXPECTF--
+Fatal error: Case Bar of non-scalar enum Foo must not have a value, try adding ": int" to the enum declaration in %s on line %d

Zend/tests/enum/non-scalar-enum-with-value.phpt renamed to Zend/tests/enum/non-scalar-enum-with-invalid-value.phpt

@@ -1,10 +1,10 @@
 --TEST--
-Non-scalar enum errors when case has value
+Non-scalar enum errors when case has invalid value
 --FILE--
 <?php
 
 enum Foo {
-    case Bar = 1;
+    case Bar = 3.141;
 }
 
 ?>

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

@@ -0,0 +1,12 @@
+--TEST--
+Non-scalar enum errors when case has string value
+--FILE--
+<?php
+
+enum Foo {
+    case Bar = 'Bar';
+}
+
+?>
+--EXPECTF--
+Fatal error: Case Bar of non-scalar enum Foo must not have a value, try adding ": string" to the enum declaration in %s on line %d

Zend/zend_compile.c

@@ -7699,9 +7699,18 @@ static void zend_compile_enum_case(zend_ast *ast)
 	}
 	if (case_value_ast != NULL) {
 		if (enum_class->enum_scalar_type == IS_UNDEF) {
-			zend_error_noreturn(E_COMPILE_ERROR, "Case %s of non-scalar enum %s must not have a value",
-				ZSTR_VAL(enum_case_name),
-				ZSTR_VAL(enum_class_name));
+			zval case_value_zv;
+			ZVAL_COPY(&case_value_zv, zend_ast_get_zval(case_value_ast));
+			if (Z_TYPE(case_value_zv) == IS_LONG || Z_TYPE(case_value_zv) == IS_STRING) {
+				zend_error_noreturn(E_COMPILE_ERROR, "Case %s of non-scalar enum %s must not have a value, try adding \": %s\" to the enum declaration",
+					ZSTR_VAL(enum_case_name),
+					ZSTR_VAL(enum_class_name),
+					zend_zval_type_name(&case_value_zv));
+			} else {
+				zend_error_noreturn(E_COMPILE_ERROR, "Case %s of non-scalar enum %s must not have a value",
+					ZSTR_VAL(enum_case_name),
+					ZSTR_VAL(enum_class_name));
+			}
 		}
 
 		zend_eval_const_expr(&ast->child[1]);