Do not show signature help at the end of an invocation

[jdneo]

for example, when it's foo(), we should not show the signature help.

Signed-off-by: sheche sheche@microsoft.com

[jdneo]

New behavior

Old behavior (The staging bits)

[rgrunber]

The change works well for me. I just noticed some exceptions thrown when we get into some really weird cases like :

(cursor at |)
System.out.println()|()

SEVERE: Internal error: java.lang.IndexOutOfBoundsException: Index -1 out of bounds for length 0
java.util.concurrent.CompletionException: java.lang.IndexOutOfBoundsException: Index -1 out of bounds for length 0
	at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(Unknown Source)
	at java.base/java.util.concurrent.CompletableFuture.completeThrowable(Unknown Source)
	at java.base/java.util.concurrent.CompletableFuture$UniApply.tryFire(Unknown Source)
	at java.base/java.util.concurrent.CompletableFuture$Completion.exec(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinPool.scan(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(Unknown Source)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(Unknown Source)
Caused by: java.lang.IndexOutOfBoundsException: Index -1 out of bounds for length 0
	at java.base/jdk.internal.util.Preconditions.outOfBounds(Unknown Source)
	at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Unknown Source)
	at java.base/jdk.internal.util.Preconditions.checkIndex(Unknown Source)
	at java.base/java.util.Objects.checkIndex(Unknown Source)
	at java.base/java.util.ArrayList.get(Unknown Source)
	at org.eclipse.jdt.ls.core.internal.handlers.SignatureHelpUtils.getSignatureHelpFromASTNode(SignatureHelpUtils.java:65)
	at org.eclipse.jdt.ls.core.internal.handlers.SignatureHelpHandler.signatureHelp(SignatureHelpHandler.java:76)
	at org.eclipse.jdt.ls.core.internal.handlers.JDTLanguageServer.lambda$8(JDTLanguageServer.java:590)
	at org.eclipse.jdt.ls.core.internal.BaseJDTLanguageServer.lambda$0(BaseJDTLanguageServer.java:75)
	... 7 more

context.arguments() - [$missing$()]
context.argumentRanges() - []

I was wondering why the logic in the first if statement isn't just used to cover the else. Either way, I would probably just try to avoid hitting the error.

[jdneo]

Didn't know why I could not reproduce the error

But anyway, it makes sense to add more checks to avoid those unexpected errors. So I added some checks in the if-else block.

[rgrunber]

Did you try without breakpoints? There's a cancellation check for the monitor if you look at SignatureHelpContext#resolve(..). In many cases dealing with popups in the UI, simply switching away from the UI being tested is enough to trigger the cancellation. If you set your breakpoint after the cancellation checks, maybe you'll run into the issue ?

Change looks good to me.