These rules are already enforced (ref squizlabs#750)

src/Standards/PSR12/ruleset.xml

@@ -106,8 +106,8 @@
     <!-- checked by PSR12.Namespaces.CompoundNamespaceDepth -->
 
     <!-- When wishing to declare strict types in files containing markup outside PHP opening and closing tags, the declaration MUST be on the first line of the file and include an opening PHP tag, the strict types declaration and closing tag. -->
-
     <!-- Declare statements MUST contain no spaces and MUST be exactly declare(strict_types=1) (with an optional semi-colon terminator). -->
+    <!-- checked by PSR12.Files.DeclareStatement -->
 
     <!-- Block declare statements are allowed and MUST be formatted as below. -->