Warnings: Precision

[maenu]

Show warning only if:

• return is assigned
• if not null checked

[maenu]

Try to use JDT null analysis, plug in annotation in AST.

[lukaszbinden]

first attempt of AST rewriting:

package test1; public class X { public void foo() { String s = "sdf"; IntStream @Nullable, chars = s.chars(); } }

[lukaszbinden]

AST rewrite works. But document remains unsaved. Need to figure out a way to do the rewrite before the save operation.

possible solution: A save action is a special clean up that perform the requested modifications on save automatically. http://help.eclipse.org/mars/index.jsp?topic=%2Forg.eclipse.jdt.doc.isv%2Fguide%2Fjdt_api_contributing_a_cleanup.htm

[lukaszbinden]

changes in commit:

• compiler.annotation.nullanalysis=enabled
• implement a ICleanUp extension point as a SaveAction to rewrite AST in order to add Nullable annotations -> only proof of concept/prototyp yet next steps:
• complete SaveAction: return ICleanUpFix (Cursor after save operation at top
• Nullability check for any API methods, currently only for file Isa.java... chars()
• refactor source

[lukaszbinden]

https://www.eclipse.org/forums/index.php/t/202641/

org.eclipse.jdt.internal.compiler.classfmt.MethodInfoWithTypeAnnotations

[lukaszbinden]

evtl. OSGI Hook Configurator to hook into the class loading process and then supplement API classes with Nullable information: osgi.hook.configurators.include

https://wiki.eclipse.org/Adaptor_Hooks

[lukaszbinden]

ok does not seem to work easily, especially with a plugin based attempt:

java.lang.ClassNotFoundException: ch.unibe.scg.methodnullabilityplugin.MyClassLoaderHookConfigurator at java.net.URLClassLoader.findClass(URLClassLoader.java:381) at java.lang.ClassLoader.loadClass(ClassLoader.java:424) at java.lang.ClassLoader.loadClass(ClassLoader.java:357) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:264) at org.eclipse.osgi.internal.hookregistry.HookRegistry.loadConfigurators(HookRegistry.java:185) at org.eclipse.osgi.internal.hookregistry.HookRegistry.initialize(HookRegistry.java:106) at org.eclipse.osgi.internal.framework.EquinoxContainer.(EquinoxContainer.java:64) at org.eclipse.osgi.launch.Equinox.(Equinox.java:31) at org.eclipse.core.runtime.adaptor.EclipseStarter.startup(EclipseStarter.java:303) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:239) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:673) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:610) at org.eclipse.equinox.launcher.Main.run(Main.java:1519) at org.eclipse.equinox.launcher.Main.main(Main.java:1492)

[lukaszbinden]

it seems that OSGi HookRegistry is too global to serve for our plugin

[lukaszbinden]

cannot find hook/listener in org.eclipse.jdt.internal.compiler.lookup.LookupEnvironment

extension point: CompilationParticipant. reconcile hook delivers a jdt.core.ICompilationUnit.

Potential approach: AnnotationUtils of org.eclipse.jst.ws.annotations.core.utils (only provisional API)

[lukaszbinden]

manually inserting an annotation into IMethod/BinaryMethod/ResolvedBinaryMethod or MethodBinding. Could potentially work but have not found a way to hook into creation of those objects.

[lukaszbinden]

NB: Bean Validation API (e.g. @Null) is part of Java EE (since v6) and not SE

[lukaszbinden]

another approach: use javassist to dynamically add Nullable annotation to e.g. IMethod instances

http://stackoverflow.com/questions/2944896/dynamically-add-annotation-to-an-existing-class

[lukaszbinden]

Managed to "inject" a Nullable annotation in the form of AnnotationBinding into a BinaryTypeBinding (return type of respective nullable method), but it would not show the warning.

This stackoverflow post suggests that the idea is practically infeasible (no extension points or alike available for such a kind of thing):

http://stackoverflow.com/questions/14867657/custom-compile-time-class-loading-in-eclipse

[lukaszbinden]

Idea below of @Nullable injection via reflection does not work as the underlying models are different between methods that have this annotation in the class file (cf. MethodInfoWithTypeAnnotations) and methods that don't (cf. MethodInfo, and MethodInfo.createMethod)

`

                           IMethodBinding methodBinding = node.resolveMethodBinding();
            IJavaElement javaElement = methodBinding.getJavaElement();
            ITypeBinding tb = methodBinding.getReturnType();                             
                            Field binding = tb.getClass().getDeclaredField("binding");
            binding.setAccessible(true);
            BinaryTypeBinding compilerMethodBinding = (BinaryTypeBinding) binding.get(tb);
            AnnotationBinding[] typeAnnotations = compilerMethodBinding.getTypeAnnotations();
            if (methodBinding.getName().equals("yesIAmNullable")) {
                boolean containsIt = false;
                for (AnnotationBinding ab : typeAnnotations) {
                    nullableAnnotation = ab;
                }
                yesIAmNullable = methodBinding;

            } else if (methodBinding.getName().equals("noIAmNotNullable")) {
                if (nullableAnnotation != null) {
                    AnnotationBinding[] newAb = new AnnotationBinding[1];
                    newAb[0] = nullableAnnotation;
                    compilerMethodBinding.setTypeAnnotations(newAb, true);
                    noIAmNotNullable = methodBinding;

                }
            }`

[lukaszbinden]

Last attempt: byte code injection via AspectJ or Javassist

[maenu]

Insert nullable annotation into sources, IR does not work. Assignments missing.

[maenu]

Annotate types in declarations for local variables (prio 1), fields (prio 2), parameters (prio 2)