258039 – [1.5][compiler] Misleading error message for "instanceof List<Object>"

Bug 258039 - [1.5][compiler] Misleading error message for "instanceof List<Object>"

Summary: [1.5][compiler] Misleading error message for "instanceof List<Object>"

Status:	VERIFIED FIXED

Alias:	None

Product:	JDT
Classification:	Eclipse Project
Component:	Core (show other bugs)
Version:	3.4
Hardware:	PC Windows XP

Importance:	P3 normal (vote)
Target Milestone:	3.5 M4
Assignee:	Philipe Mulet
QA Contact:

URL:
Whiteboard:
Keywords:

Depends on:
Blocks:

Reported:	2008-12-09 05:02 EST by Jerome Lanneluc
Modified:	2008-12-11 11:17 EST (History)
CC List:	1 user (show)

See Also:

Attachments
Proposed patch (7.16 KB, patch) 2008-12-09 07:59 EST, Philipe Mulet	no flags	Details \| Diff
Better patch (19.38 KB, patch) 2008-12-09 09:21 EST, Philipe Mulet	no flags	Details \| Diff
Show Obsolete (1) View All Add an attachment (proposed patch, testcase, etc.)

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Description Jerome Lanneluc

2008-12-09 05:02:01 EST

I20081209-0100

import java.util.List;
public class X {
  boolean foo() {
    return null instanceof List<Object>; 
  }
}

This reports: "Cannot perform instanceof check against parameterized type List<Object>. Use instead its raw form List since generic type information will be erased at runtime"

It should not suggests to us a raw type since it will trigger a warning (see bug 252120). It should suggests to use List<?> instead.

Comment 1 Philipe Mulet

2008-12-09 07:29:48 EST

True, but note that quickfix caused a compile error to be raised, which is bad when attempting to fix a warning... they should het a bug opened as well.

Comment 2 Jerome Lanneluc

2008-12-09 07:38:41 EST

(In reply to comment #1)
> True, but note that quickfix caused a compile error to be raised, which is bad
> when attempting to fix a warning... they should het a bug opened as well.
Entered bug 258059 against JDT/UI

Comment 3 Philipe Mulet

2008-12-09 07:55:55 EST

Note also, that our message wasn't good for instanceof T (type param). 

e.g.
import java.util.*;
public class X {
	<T extends List<Object>> boolean foo2() {
		return null instanceof T;
	}
}

--> Cannot perform instanceof check against type parameter T. Use instead its erasure List<E> since generic type information will be erased at runtime

Will fix it as well.

Comment 4 Philipe Mulet

2008-12-09 07:57:44 EST

Added GenericTypeTest#test1426

Comment 5 Philipe Mulet

2008-12-09 07:59:07 EST

Created attachment 119898 [details]
Proposed patch

Comment 6 Philipe Mulet

2008-12-09 09:21:39 EST

Created attachment 119906 [details]
Better patch

Comment 7 Philipe Mulet

2008-12-10 12:43:28 EST

Released for 3.5M4

Comment 8 Philipe Mulet

2008-12-10 12:44:23 EST

Fixed

Comment 9 Jerome Lanneluc

2008-12-11 11:17:54 EST

Verified for 3.5M4 using I20081211-0100