report done

report.tex

@@ -390,23 +390,61 @@ void translateWhole(final @MinLen(1) CharSequence input, final Writer writer) th
     final String quoteless = input.subSequence(1, lastIndex).toString();
 \end{minted}
 
+This assertion is one good example of CheckerFramework's limitations in
+verifying transitively true properties due to the lack of deductive verification
+capabilities. All assertions added in the project are trivial in this way to
+some degree.
+
 \section{Conclusions}
 
 As evidenced by the Apache Common Text test suite and the previous section of
-this report, no changes in the implementation behaviour are introduced in the
+this report, no changes in the implementation behaviour were introduced in the
 code by the refactor. Only extended type annotations and assertions (that hold
-when executing the test suite) are added to the code.
+when executing the test suite) were added to the code.
 
-{\color{red}
+No implementaton-derived bugs were discovered during refactoring, altough the
-Did using the checker help you find any bugs or other questionable design and implementation choices?
+introduction of additional method preconditions via extended type annotations
+was sometimes needed. Some questionable design choices were found in the
+library, namely the \textit{CharSequenceTranslator} template method hierarchy
+with \mintinline{java}{public} implementors and the inversion of abstration by
+refused bequest in the \textit{SinglePassTranslator} partial implementation,
+however I managed to introduce correct extended types without drastic
+alterations (which may have broken clients of the library).
 
-> no bugs found, couple of design choices
+It was quite easy to introduce the CheckerFramework index checker to the Maven
+build toolchain of the project. However, compiling the project after this was
+significantly slower than before and lots of spurious warnings (i.e. false
+positives) were produced by the tool due to its lack of deductive verification
+capabilities. Some benefits were gained by using the tool, namely being able to
+better refine the precondition of the methods in the library by documenting them
+in an automatedly parsable fashion. However, the sheer number of trivially true
+assertions introduced to silence some warnings is a significant downside to
+consider when using the index checker.
 
-How complex was it to apply the checker, and what benefits did you gain in return?
+The CheckerFramework extended type checker has a cost and complexity of usage
+greater than the Infer static analysis tool and lower than the Dafny deductive
+verifier. However, with respect to my experience with all the tools in carrying
+out the assignment, this is the tool that has shown to be the less useful. 
 
-> not so complex, lots of false positives
+The less powerful Infer static analyzer, even with a great number of false
+positives, was able to highlight some bugs in the project I have chosen for that
+assignment (Apache Commons Lang). As all Apache Commons libraries are quite
+mature and well-maintained it is expected that both tools find relatively few
+things to flag in them. However, no noteworthy errors were found by
+CheckerFramework in this project other than some small imprecisions in the 
+precondition specification of some methods. 
 
-Compare the checker’s trade-off between complexity of usage and analysis power to that of other software analysis techniques you’re familiar with (in particular, those used in previous assignments).
+When compared to Dafny and deductive verifiers in general, clearly both Infer
-}
+and CheckerFramework pale in comparison in terms of capabilities. However, the
+increased cost of adoption and of the tool's execution make it suitable only to
+critical portions of project codebases.
+
+Finally, I would like to mention the
+\href{https://github.com/JetBrains/java-annotations}{Jetbrains Java Annotations}
+as a much less powerful but effective extended type checking mechanism to handle
+nullable an non-null values in plain Java. Even if its scope of analysis is
+rather narrow and warnings an the type checking process is proprietary (as only
+Jetbrains IDEs interpret the annotations) I have found it an effective
+development aid in my university and work experience.
 \end{document}