Bug 276741

Summary: comparing identical value detection does not work for this
Product: [Eclipse Project] JDT Reporter: Dani Megert <daniel_megert>
Component: CoreAssignee: Srikanth Sankaran <srikanth_sankaran>
Status: VERIFIED FIXED QA Contact:
Severity: normal    
Priority: P3 CC: frederic_fusier, mhilpert, Olivier_Thomann, srikanth_sankaran
Version: 3.5   
Target Milestone: 3.6 M1   
Hardware: PC   
OS: Windows XP   
Whiteboard:

Description Dani Megert CLA 2009-05-18 12:03:35 EDT 
I20090515-1143.

Comparing identical value detection does not work for this, i.e.

if (this == this)

is not warned.
Comment 1 Srikanth Sankaran CLA 2009-05-19 03:01:50 EDT 
Will investigate this.
Comment 2 Srikanth Sankaran CLA 2009-05-25 07:48:16 EDT 
Proposed patch for bug #276740 should also fix this.
Comment 3 Srikanth Sankaran CLA 2009-06-17 02:45:04 EDT 
Released for 3.6M1
Comment 4 Frederic Fusier CLA 2009-06-22 11:46:14 EDT 
Srikanth,

Using nightly build leads to have 101 additional warnings in org.eclipse.jdt.core.tests.model project while building my workspace...

All these warnings are in ASTTest and ASTParserTest test suites, typically on following lines:
		assertTrue(ASTParser.K_EXPRESSION == 1);
		           ^^^^^^^^^^^^^^^^^^^^^^^^^^^

This sounds a valid test for me, unless I miss something? If so, then this option should be unset on this project to avoid all these noisy warnings...
Comment 5 Dani Megert CLA 2009-06-23 02:33:07 EDT 
>                assertTrue(ASTParser.K_EXPRESSION == 1);
>                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
>This sounds a valid test for me, unless I miss something?

What does the test do? Verify the value of constants? If so, it makes sense otherwise I don't see the value of such an assert.
Comment 6 Frederic Fusier CLA 2009-06-23 04:09:02 EDT 
(In reply to comment #5)
> >                assertTrue(ASTParser.K_EXPRESSION == 1);
> >                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
> >This sounds a valid test for me, unless I miss something?
> 
> What does the test do? Verify the value of constants? If so, it makes sense
> otherwise I don't see the value of such an assert.
> 
These are typically tests to verify that API constants value are not modified...
Comment 7 Srikanth Sankaran CLA 2009-06-23 05:28:24 EDT 
(In reply to comment #4)
> Srikanth,
> Using nightly build leads to have 101 additional warnings in
> org.eclipse.jdt.core.tests.model project while building my workspace...
> All these warnings are in ASTTest and ASTParserTest test suites, typically on
> following lines:
>                 assertTrue(ASTParser.K_EXPRESSION == 1);
>                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^
> This sounds a valid test for me, unless I miss something? 

I have verified that all the 101 additional warnings are correct
and intended to be produced.

For the org.eclipse.jdt.core.tests.model project alone, I am changing
the compiler setting so these warnings are not produced.

Changed project preferences released to HEAD.
Comment 8 MH CLA 2009-07-10 05:46:37 EDT 
In Eclipse 3.5 it's still not fixed:

java.lang.Double has a method:

    /**
     * Returns <code>true</code> if the specified number is a
     * Not-a-Number (NaN) value, <code>false</code> otherwise.
     *
     * @param   v   the value to be tested.
     * @return  <code>true</code> if the value of the argument is NaN;
     *          <code>false</code> otherwise.
     */
    static public boolean isNaN(double v) {
	return (v != v);
    }

The "v != v" is NOT marked! 

My custom code

   if (d != d) { //Double.isNaN()

is marked for "d != d" with "Comparing identical expressions"!
Comment 9 Frederic Fusier CLA 2009-07-10 06:25:57 EDT 
(In reply to comment #8)
> In Eclipse 3.5 it's still not fixed:
>
Yes, because this bug is targeted 3.6M1. Furthermore, it seems not to be so critical to be backported to 3.5.1 (no data loss, no exceptions), unless you give solid arguments to convince us...
Comment 10 Dani Megert CLA 2009-07-10 09:24:05 EDT 
This is definitely not 3.5.1 worthy.
Comment 11 Frederic Fusier CLA 2009-08-04 08:35:58 EDT 
Verified for 3.6M1 using build 20090802-2000.