Python: Delete some misleading qhelp and rename a couple of queries.

python/ql/src/analysis/ImportFailure.ql

@@ -68,4 +68,4 @@ where not ie.refersTo(_) and
               guard.controls(ie.getAFlowNode().getBasicBlock(), true)
       )
 
-select ie, "Unable to resolve import of '" + ie.getImportedModuleName() + "'."
+select ie, "Unable to resolve import of '" + ie.getImportedModuleName() + "'."

python/ql/src/analysis/KeyPointsToFailure.qhelp

@@ -1,11 +0,0 @@
-<!DOCTYPE qhelp PUBLIC
-  "-//Semmle//qhelp//EN"
-  "qhelp.dtd">
-<qhelp>
-<overview>
-<p>Points-to analysis underpins type inference and thus most of Semmle's Python analysis.
-Failures in points-to undermines type inference and reduces the coverage and also accuracy of many queries.
-</p>
-
-</overview>
-</qhelp>

python/ql/src/analysis/KeyPointsToFailure.ql

@@ -1,9 +1,10 @@
 /**
- * @name Key "points-to" fails for expression.
+ * @name Key points-to fails for expression.
  * @description Expression does not "point-to" an object which prevents further points-to analysis.
  * @kind problem
  * @problem.severity info
  * @id py/key-points-to-failure
+ * @deprecated
  */
 
 import python

python/ql/src/analysis/PointsToFailure.qhelp

@@ -1,11 +0,0 @@
-<!DOCTYPE qhelp PUBLIC
-  "-//Semmle//qhelp//EN"
-  "qhelp.dtd">
-<qhelp>
-<overview>
-<p>Points-to analysis underpins type inference and thus most of Semmle's Python analysis.
-Failures in points-to undermines type inference and reduces the coverage and also accuracy of many queries.
-</p>
-
-</overview>
-</qhelp>

python/ql/src/analysis/PointsToFailure.ql

@@ -1,10 +1,11 @@
 /**
- * @name "points-to" fails for expression.
+ * @name points-to fails for expression.
  * @description Expression does not "point-to" an object which prevents type inference.
  * @kind problem
  * @id py/points-to-failure
  * @problem.severity info
- * @tags reliability
+ * @tags debug
+ * @deprecated
  */
 
 import python

python/ql/src/analysis/TypeHierarchyFailure.qhelp

@@ -4,11 +4,12 @@
 <qhelp>
 <overview>
 <p>In order to analyse uses of a class, all its attributes need to be known. Without the full inheritance hierarchy this is impossible.
-This is an informational query only. 
+This query finds classes where type inference fails and gives some indication as to why that failure occurred.
 </p>
 
 <p>
 This is an informational query only, this query depends on points-to and type inference.
+Unlike normal queries it does not indicate any problem with the program being analyzed.
 </p>
 
 </overview>

python/ql/src/analysis/TypeHierarchyFailure.ql

@@ -1,16 +1,16 @@
 /**
  * @name Inheritance hierarchy cannot be inferred for class
- * @description Inability to infer inheritance hierarchy cannot be inferred for class will impair analysis
+ * @description Inability to infer the inheritance hierarchy for a class will impair analysis.
  * @id py/failed-inheritance-inference
  * @kind problem
  * @problem.severity info
+ * @tags debug
  */
- 
+
 import python
 
 
-from Class cls
-where not exists(ClassObject c | c.getPyClass() = cls)
-or
-exists(ClassObject c | c.getPyClass() = cls | c.failedInference())
-select cls, "Inference of class hierarchy failed for class."
+from Class cls, string reason
+where
+exists(ClassObject c | c.getPyClass() = cls | c.failedInference(reason))
+select cls, "Inference of class hierarchy failed for class '" + cls.getName() + "': " + reason + "."

python/ql/src/analysis/TypeInferenceFailure.qhelp

@@ -1,13 +0,0 @@
-<!DOCTYPE qhelp PUBLIC
-  "-//Semmle//qhelp//EN"
-  "qhelp.dtd">
-<qhelp>
-
-<overview>
-<p>
-Type inference is the key part of Semmle's Python analysis.
-Failures in type inference and reduces the coverage and also accuracy of many queries.
-</p>
-
-</overview>
-</qhelp>

python/ql/src/analysis/TypeInferenceFailure.ql

@@ -4,11 +4,12 @@
  * @kind problem
  * @problem.severity info
  * @id py/type-inference-failure
+ * @deprecated
  */
 import python
 
 
-from ControlFlowNode f, Object o 
+from ControlFlowNode f, Object o
 where f.refersTo(o) and 
 not exists(ClassObject c | f.refersTo(o, c, _))
 select o, "Type inference fails for 'object'."