Rust: improve performance of Crate::toString

Author: aibaars

rust/ql/lib/codeql/rust/elements/internal/CrateImpl.qll

@@ -12,8 +12,18 @@ private import codeql.rust.elements.internal.generated.Crate
  */
 module Impl {
   class Crate extends Generated::Crate {
-    override string toString() {
-      result = "Crate(" + this.getName() + "@" + concat(this.getVersion()) + ")"
+    override string toString() { result = strictconcat(int i | | this.toStringPart(i) order by i) }
+
+    private string toStringPart(int i) {
+      i = 0 and result = "Crate("
+      or
+      i = 1 and result = this.getName()
+      or
+      i = 2 and result = "@"
+      or
+      i = 3 and result = this.getVersion()
+      or
+      i = 4 and result = ")"
     }
   }
 }