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Bug 474038

Summary:	Wrongly reports addition of first type parameter to a generic method
Product:	[Eclipse Project] PDE	Reporter:	Markus Keller <markus.kell.r>
Component:	API Tools	Assignee:	Markus Keller <markus.kell.r>
Status:	VERIFIED FIXED	QA Contact:
Severity:	normal
Priority:	P3	CC:	daniel_megert, Lars.Vogel, markus.kell.r, Vikas.Chandra
Version:	4.6	Flags:	Vikas.Chandra: review+
Target Milestone:	4.6 M2
Hardware:	All
OS:	All
See Also:	https://git.eclipse.org/r/52960 https://git.eclipse.org/c/pde/eclipse.pde.ui.git/commit/?id=4f5169287422584658daa624ce779ba77b45c5c7
Whiteboard:
Bug Depends on:
Bug Blocks:	465292

Description Markus Keller

2015-07-31 09:49:18 EDT

Bug 465292 revealed an example of a binary-compatible, but source-incompatible API change.

Example:

public interface Test {
	public void move(Number n, List<Number> l);
}

Change to:

public interface Test {
	public <T extends Number> void move(T n, List<T> l);
}

Since the erasure didn't change, this is a binary-compatible change. However, an implementation or extension of the interface that already used the List<Number> parameter type won't compile any more after the change. (If it used the raw type List, then would still compile.)

Since API Tools are only concerned about binary-incompatible changes, this change should not result in an error.

Fix follows.

Comment 1 Eclipse Genie

2015-07-31 09:51:24 EDT

New Gerrit change created: https://git.eclipse.org/r/52960

Comment 2 Markus Keller

2015-07-31 10:35:15 EDT

The main fix is in ClassFileComparator line 676, where the compatible IDelta.TYPE_PARAMETERS flag is used instead of IDelta.TYPE_PARAMETER. The latter is correctly reported as error in DeltaProcessor#isMethodCompatible(IDelta).

The other changes in ClassFileComparator fix the IDelta#getKey() for methods. element1.getName() is not a correct key, which resulted in problem markers with wrong source ranges ([-1, 1]) for the errors in bug 465292. To see this part of the fix in action, e.g. apply this incompatible addition of a second type parameter to  org.eclipse.e4.ui.workbench.modeling.EModelService:

Old:
	public <T> List<T> findElements(MUIElement searchRoot,
			String id, Class<T> clazz, List<String> tagsToMatch);

New:
	public <T, M extends MUIElement> List<T> findElements(M searchRoot,
			String id, Class<T> clazz, List<String> tagsToMatch);

Comment 3 Vikas Chandra

2015-09-11 07:40:20 EDT

Fix works fine and all test case passes. Can you update the license year before committing.

Comment 4 Eclipse Genie

2015-09-11 10:38:42 EDT

Gerrit change https://git.eclipse.org/r/52960 was merged to [master].
Commit: http://git.eclipse.org/c/pde/eclipse.pde.ui.git/commit/?id=4f5169287422584658daa624ce779ba77b45c5c7

Comment 5 Lars Vogel

2015-09-11 10:40:02 EDT

Thanks Markus. @Vikas, I updated the copyright headers for Markus.

Comment 6 Vikas Chandra

2015-09-15 04:46:48 EDT

verified in 
Version: Neon (4.6)
Build id: I20150914-2000