Rust: Add QLDoc to the AST consistency rules and make their output more consistent.

Author: geoffw0

rust/ql/lib/codeql/rust/AstConsistency.qll

@@ -5,20 +5,32 @@
 private import rust
 private import codeql.rust.elements.internal.generated.ParentChild
 
-query predicate multipleToString(Element e, string s) {
-  s = strictconcat(e.toString(), ",") and
+/**
+ * Holds if `e` has more than one `toString()` result.
+ */
+query predicate multipleToStrings(Element e, string s) {
+  s = strictconcat(e.toString(), ", ") and
   strictcount(e.toString()) > 1
 }
 
+/**
+ * Holds if `e` has more than one `Location`.
+ */
 query predicate multipleLocations(Locatable e) { strictcount(e.getLocation()) > 1 }
 
+/**
+ * Holds if `e` has more than one `getPrimaryQlClasses()` result.
+ */
 query predicate multiplePrimaryQlClasses(Element e, string s) {
-  s = e.getPrimaryQlClasses() and
+  s = strictconcat(e.getPrimaryQlClasses(), ", ") and
   strictcount(e.getAPrimaryQlClass()) > 1
 }
 
 private Element getParent(Element child) { child = getChildAndAccessor(result, _, _) }
 
+/**
+ * Holds if `child` has more than one AST parent.
+ */
 query predicate multipleParents(Element child, Element parent) {
   parent = getParent(child) and
   strictcount(getParent(child)) > 1