Autocompletion doesn't work well within lambda expressions

[bitray]

Issue Type: Bug

[Error - 7:12:19 PM] Feb 17, 2022, 7:12:19 PM Problems occurred when invoking code from plug-in: "org.eclipse.core.resources".

java.lang.IllegalArgumentException:
at org.eclipse.core.runtime.Assert.isLegal(Assert.java:66)
at org.eclipse.core.runtime.Assert.isLegal(Assert.java:50)
at org.eclipse.core.internal.jobs.JobManager.setRule(JobManager.java:1400)
at org.eclipse.core.internal.jobs.InternalJob.setRule(InternalJob.java:486)
at org.eclipse.core.runtime.jobs.Job.setRule(Job.java:771)
at org.eclipse.jdt.ls.core.internal.handlers.BaseDocumentLifeCycleHandler.triggerValidation(BaseDocumentLifeCycleHandler.java:154)
at org.eclipse.jdt.ls.core.internal.handlers.BaseDocumentLifeCycleHandler.triggerValidation(BaseDocumentLifeCycleHandler.java:138)
at org.eclipse.jdt.ls.core.internal.handlers.WorkspaceDiagnosticsHandler.visit(WorkspaceDiagnosticsHandler.java:180)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:67)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:77)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:77)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:77)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:77)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:77)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:77)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:77)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:77)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:77)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:51)
at org.eclipse.jdt.ls.core.internal.handlers.WorkspaceDiagnosticsHandler.resourceChanged(WorkspaceDiagnosticsHandler.java:103)
at org.eclipse.core.internal.events.NotificationManager$1.run(NotificationManager.java:305)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
at org.eclipse.core.internal.events.NotificationManager.notify(NotificationManager.java:295)
at org.eclipse.core.internal.events.NotificationManager.broadcastChanges(NotificationManager.java:158)
at org.eclipse.core.internal.resources.Workspace.broadcastPostChange(Workspace.java:381)
at org.eclipse.core.internal.resources.Workspace.endOperation(Workspace.java:1503)
at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:2327)
at org.eclipse.core.internal.events.NotificationManager$NotifyJob.run(NotificationManager.java:44)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)

Extension version: 1.3.0
VS Code version: Code 1.64.2 (f80445acd5a3dadef24aa209168452a3d97cc326, 2022-02-09T22:02:28.252Z)
OS version: Windows_NT x64 10.0.19042
Restricted Mode: No

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-10610U CPU @ 1.80GHz (8 x 2304)
GPU Status	2d_canvas: unavailable_software gpu_compositing: disabled_software multiple_raster_threads: enabled_on oop_rasterization: disabled_off opengl: disabled_off rasterization: disabled_software skia_renderer: enabled_on video_decode: disabled_software vulkan: disabled_off webgl: unavailable_software webgl2: unavailable_software
Load (avg)	undefined
Memory (System)	31.73GB (16.09GB free)
Process Argv	--disable-gpu --disable-gpu-compositing --log error
Screen Reader	no
VM	0%

[rgrunber]

Are you able to provide a sample snippet of code (or even the project & file) on which the issue is reproducible ?

[bitray]

@rgrunber Hello, Rgrunber. seems the issue is no more coming up.
At that time , all the auto completion operations are invalid . Hence I finished the code by feature of VScode editor.
After that , seems everything recovers...

Hence , i can not provide sample snippet .. Sorry for that ...

But I found something about stream api. Auto-completion works fine when i type map() method. But it doesn't work if I didn't finish the code in {}.. It means I can not use . to complete collect(Collectors.toList()); section.. Errors can block auto-completion...Probably it is not issue , but a little strange, because it can work fine by using IDEA.
List<XxDTO> returnList = data.stream().map(x -> { ResposeDTO element = new ResposeDTO (); return BeanUtil.fillBeanWithMap(x, element, false); }).collect(Collectors.toList());

[rgrunber]

I'm able to reproduce as well, even on upstream Eclipse, so this is a JDT Core problem. Completions dealing with lambdas not working under certain conditions are a known issue.

(cursor at | and error meant to be a non-existent token)

List<Integer> returnList = Arrays.asList(1, 2, 3, 4, 5)
                .stream().map(t -> {
                    return error;
                }).|

Completion fails to be triggered.

My guess is the completion relies on being able to resolve the signature of the lambda, which likely breaks completion when the body has compilation errors.

[rgrunber]

Looking through :

https://stackoverflow.com/questions/33305414/eclipse-java-8-auto-completion-for-lambda-expressions
https://bugs.eclipse.org/bugs/show_bug.cgi?id=460921
https://bugs.eclipse.org/bugs/show_bug.cgi?id=551391
https://bugs.eclipse.org/bugs/show_bug.cgi?id=561100

this appears to be a common issue with lambdas.

[juhaku]

I can also confirm the issue arises within lambda bodies that cannot match to the required method signature immediately. Like Java Consumer does work ok, however Supplier or Function at the other hand does not. See the details here: eclipse-jdtls/eclipse.jdt.ls#2237 (comment)

[fbricon]

another case where completion fails:

 List.of("a", "b").stream().map(n -> n != null? n.|);