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Bug 425170

Summary:

ClassCastException in CommandContext when an expression returns an empty set

Product:

[Modeling] Sirius

Reporter:

Stephane Begaudeau <stephane.begaudeau>

Component:

Core

Assignee:

Pierre-Charles David <pierre-charles.david>

Status:

CLOSED FIXED

QA Contact:

Julien Dupont <julien.dupont>

Severity:

major

Priority:

CC:

alex.lagarde, florian.barbin, julien.dupont, pierre-charles.david

Version:

1.0.0

Keywords:

triaged

Target Milestone:

1.0.0M7

Hardware:

All

OS:

All

Whiteboard:

Attachments:

Description	Flags
Use case to reproduce Class Cast Exception	none

Description Stephane Begaudeau

2014-01-09 05:43:02 EST

In org.eclipse.sirius.tools.api.command.CommandContext#getContextTargets(...)

http://git.eclipse.org/c/sirius/org.eclipse.sirius.git/tree/plugins/org.eclipse.sirius/src/org/eclipse/sirius/tools/api/command/CommandContext.java

Line 170/171
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
} else if (result instanceof Collection) {
   contextTargets = (List<Object>) result; // BUG!
} else {
   contextTargets = Lists.newArrayList(result);
}
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

There are other kinds of collections in Java :)

The whole "if" part could be replaced by something like this:
if (result == null) {
   contextTargets = Lists.newArrayList();
} else {
   contextTargets = Lists.newArrayList(result);
}

Since if it's a collection, Guava can create a new ArrayList from it anyway.

Comment 1 Alex Lagarde

2014-01-09 07:49:47 EST

Hi Stephane, could you please join steps to reproduce the issue?

Comment 2 Stephane Begaudeau

2014-01-09 08:09:57 EST

(In reply to Alex Lagarde from comment #1)
> Hi Stephane, could you please join steps to reproduce the issue?

Ask Julien :)

It was an Acceleo expression involving eInverse() which must have returned an empty set.

Comment 3 Julien Dupont

2014-01-13 05:35:01 EST

Created attachment 238906 [details]
Use case to reproduce Class Cast Exception

To reproduce:
Open the use case representation Diagram and select node named Class1. Try to remove. Does Nothing, open the view "Error Log". The Class Cast Exeption appears.
This problem is in the VSM on remove tool, with this expression: "[oclAsType(ecore::EReference).eInverse()/]" that return an empty list.

Comment 4 Pierre-Charles David

2014-01-15 10:10:09 EST

I renamed the ticket for more clarity, so here is the actual exception (which was used as a title previously):

Caused by: java.lang.ClassCastException: java.util.Collections$EmptySet cannot be cast to java.util.List

Comment 5 Pierre-Charles David

2014-04-22 08:20:25 EDT

See https://git.eclipse.org/r/#/c/25343/.

Note that the suggestion for further simplification in #c1 would not work: result is statically known as a raw Object, so even if it is actually a collection, Lists.newArrayList(result) would call the Lists.newArrayList(E... elements) variant, which would result in a list with a single element (which would happen to be a collection).

Comment 6 Pierre-Charles David

2014-04-25 11:09:17 EDT

Fixed by 3d05b28b007ea955c7ad566a6a13d1577c00e364.

Comment 7 Pierre-Charles David

2014-05-12 03:45:31 EDT

Available in Sirius 1.0.0M7 (see https://wiki.eclipse.org/Sirius/1.0.0M7 & http://git.eclipse.org/c/sirius/org.eclipse.sirius.git/tag/?id=v1.0.0M7).