Merge pull request #1401 from jbj/tostring-performance-1.22

C++: Move `Element.toString` performance change note to 1.22 file

Author: geoffw0

change-notes/1.21/analysis-cpp.md

@@ -39,5 +39,4 @@
     - The taint tracking library now includes taint-specific edges for functions modeled in `semmle.code.cpp.models.interfaces.DataFlow`.
     - The taint tracking library adds flow through library functions that are modeled in `semmle.code.cpp.models.interfaces.Taint`. Queries can add subclasses of `TaintFunction` to specify additional flow.
 - There is a new `FoldExpr` class, representing C++17 fold expressions.
-- The member predicates `DeclarationEntry.getUnspecifiedType`, `Expr.getUnspecifiedType`, and `Variable.getUnspecifiedType` have been added. These should be preferred over the existing `getUnderlyingType` predicates.
-- The predicate `TypeMention.toString()` has been simplified to always return the string "`type mention`".  This may improve performance when using `Element.toString()` or its descendants.
+- The member predicates `DeclarationEntry.getUnspecifiedType`, `Expr.getUnspecifiedType`, and `Variable.getUnspecifiedType` have been added. These should be preferred over the existing `getUnderlyingType` predicates.

change-notes/1.22/analysis-cpp.md

@@ -0,0 +1,17 @@
+# Improvements to C/C++ analysis
+
+## General improvements
+
+## New queries
+
+| **Query**                   | **Tags**  | **Purpose**                                                        |
+|-----------------------------|-----------|--------------------------------------------------------------------|
+
+## Changes to existing queries
+
+| **Query**                  | **Expected impact**    | **Change**                                                       |
+|----------------------------|------------------------|------------------------------------------------------------------|
+
+## Changes to QL libraries
+
+- The predicate `TypeMention.toString()` has been simplified to always return the string "`type mention`".  This may improve performance when using `Element.toString()` or its descendants.