[OpenJDK 2D-Dev] JDK 9 RFR of JDK-8066621: Suppress deprecation warnings in java.desktop module

joe darcy joe.darcy at oracle.com
Sat Dec 13 01:35:17 UTC 2014

Hi Phil,

On 12/12/2014 12:46 PM, Phil Race wrote:
> Hi,
> You did not provide a direct reference to the set of warnings that 
> were generated.
> fortunately I found it here :- 
> https://bugs.openjdk.java.net/browse/JDK-8066622

Each "Suppress deprecations warnings in foo" bug is linked to a "Fix 
deprecation warnings in foo" bug which lists the exact warnings.

> A couple of things I find 'unfortunate' are
> 1) In order to avoid a deprecation warning on one call/line of a 100 
> line method,
> the entire method is subject to the annotation. Eg :-
> dev/jdk/src/java.desktop/share/classes/javax/print/ServiceUI.java:226: 
> warning: [deprecation] show() in Dialog has been deprecated
> Other deprecated uses could silently creep into such a body of code.

That is true, but today deprecations warnings can (and do) creep into 
the entirely of the JDK without notice. Turning on the deprecation lint 
warning in the build will prevent that for the vast majority of code, 
which is why I want to get the remaining warning suppression bugs 
quickly pushed into JDK 9 so the build warning can be enabled. (This 
suppression effort was on hold until a small language change was 
recently implemented in JDK 9 to eliminate deprecation warnings just for 
importing a deprecated type.)

For the "fix the warning" companion bug to this bug, I would recommend 
factoring out the deprecated method call into its own private method to 
limit the scope of the @SuppressWarning annotation. For this changeset, 
I didn't want to actually modify the contents or structure of any 
methods I so didn't undertake that kind of transformation.

> 2) Some significant fraction of all the warnings are for getPeer() :-
> dev/jdk/src/java.desktop/share/classes/java/awt/Container.java:821: 
> warning: [deprecation] getPeer() in Component has been deprecated

Yes, I also noticed that a sizeable percentage of the warnings were for 
uses of that one method.

> The issue here is that the deprecation javadoc tag is unable to 
> distinguish deprecated for
> external usage vs legitimate internal usage.

FYI, Stuart Mark / Dr. Deprecator gave an interesting talk at JavaOne 
this year covering the nuances of deprecation in the JDK:


> There is no problem with code inside the desktop module
> calling getPeer() which is defined in this same module.  There may not 
> be many other APIs that
> have this similar issue, but if there are it might be better to find 
> some way to make it clear
> that we aren't suppressing warnings until we fix the code : rather we 
> really should not be
> receiving a warning here anyway since there is nothing to fix.

Well, the @SuppressWarnings annotation can be used to convey that 
information, perhaps supplemented by a comment or a wrapper method 
around getPeer; something like

   * Package-access method somewhere in java.awt
static java.awt Component privilegeOfPeerage(java.awt Component c) {
     return c.getPeer();

> Perhaps "Component. getPeer()"
> could acquire an annotation  like "module-nodeprecation" which 
> automatically suppresses the
> annotation processor  warnings for all such cases. If javac doesn't 
> know about modules perhaps
> we could utilise a javac flag that's used only by the JDK build to 
> indicate that an annotation
> like that should apply.

At this point, I think that level of solution would be overkill 
(especially given the JDK's historical lack of discipline around 
deprecation warnings).

> Regarding the show() case above I came across a puzzle.
> show() is first defined on Component, as is its 'replacement' 
> setVisible(boolean).
> It turns out that what we have in Component is
> public void setVisible(boolean b) {
>    show(b);
> }
> @Deprecated
> public void show(boolean b) {
>    if (b) {
>       show();
>   } else {
>       hide();
> }
> @Deprecated
> public void show() {
>  ...
> }
> So I am puzzled why those uses within Component aren't suppressed in 
> your webrev ?
> Is there some automatic suppression of the warnings within the class 
> that does
> the deprecation ? 

Yes, quoting from the JLS:

"A Java compiler must produce a deprecation warning when a type, method, 
field, or constructor whose declaration is annotated with |@Deprecated| 
is used (overridden, invoked, or referenced by name) in a construct 
which is explicitly or implicitly declared, unless:
     * [...]
     * The use and declaration are both within the same outermost class. "


Thanks for the review,


> If so then perhaps the module idea above can be considered
> an extension of this. If that isn't what's happening, then what is ?
> -phil.
> On 12/9/2014 4:41 PM, joe darcy wrote:
>> Hello,
>> In support of JEP 212: Resolve Lint and Doclint Warnings 
>> (http://openjdk.java.net/jeps/212), which is targeted to JDK 9, 
>> please review the large but straightforward set of changes in the 
>> webrev:
>>     http://cr.openjdk.java.net/~darcy/8066621.0/
>> Some background of the approach being taken to address this part of 
>> JEP 212 was discussed on core-libs:
>> http://mail.openjdk.java.net/pipermail/core-libs-dev/2014-December/030085.html 
>> Briefly, to allow the deprecation warnings to be dealt with and that 
>> sole remaining lint warning category enabled in the build, a two-step 
>> approach is being taken. The first step is to suppress the 
>> deprecation warnings and the second step is for area-experts to 
>> examine the specific uses of deprecated APIs in their code. This 
>> webrev only attempts to cover the first step.
>> The webrev is based off of the JDK 9 "dev" forest rather than the 
>> "client" forest. Since the change only involves copyright updates and 
>> adding annotations, there would be no functional modification in the 
>> changeset. Therefore, I would strongly prefer to push these changes 
>> directly to dev rather than pushing them to client and waiting for 
>> them to propagate to dev to expedite the time when the build warning 
>> can be enabled. (If a warning is not enabled in the build, new 
>> instances of the warning tend to creep into the code base.)
>> Thanks,
>> -Joe

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