JDK-8325189: Enable this-escape javac warning in java.base #17692

jddarcy · 2024-02-02T23:36:41Z

After the "this-escape" lint warning was added to javac (JDK-8015831), the base module was not updated to be able to compile with this warning enabled. This PR makes the necessary changes to allow the base module to build with the warning enabled.

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Issue

JDK-8325189: Enable this-escape javac warning in java.base (Enhancement - P3)

Reviewers

Alan Bateman (@AlanBateman - Reviewer)
Erik Joelsson (@erikj79 - Reviewer)
Naoto Sato (@naotoj - Reviewer)
Stuart Marks (@stuart-marks - Reviewer)
Magnus Ihse Bursie (@magicus - Reviewer)
Joe Wang (@JoeWang-Java - Reviewer)
Lance Andersen (@LanceAndersen - Reviewer)
Weijun Wang (@wangweij - Reviewer)

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Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/17692/head:pull/17692
$ git checkout pull/17692

Update a local copy of the PR:
$ git checkout pull/17692
$ git pull https://git.openjdk.org/jdk.git pull/17692/head

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$ git pr checkout 17692

View PR using the GUI difftool:
$ git pr show -t 17692

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https://git.openjdk.org/jdk/pull/17692.diff

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bridgekeeper · 2024-02-02T23:37:11Z

👋 Welcome back darcy! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2024-02-02T23:38:02Z

@jddarcy The following labels will be automatically applied to this pull request:

build
core-libs
i18n
net
nio
security

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jddarcy · 2024-02-02T23:38:41Z

In its initial form, the changes are tested on Linux. Later on, I'll do cross-platform builds to make sure there aren't any, say, windows-specific changes that are needed as well.

I can file a follow-up umbrella bug with the original list of ~200 warnings so the constructors and initializers in question can be examined to see if they should be updated.

mlbridge · 2024-02-02T23:41:10Z

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jddarcy · 2024-02-03T01:34:52Z

In its initial form, the changes are tested on Linux. Later on, I'll do cross-platform builds to make sure there aren't any, say, windows-specific changes that are needed as well.

PS Builds pass on all platforms (linux, mac, and windows) on Oracle's internal build system.

AlanBateman

I skimmed through the use sites and don't see any issues. There is one bucket of escaping "this" that will go away once the support for running with the SM goes away.

openjdk · 2024-02-04T06:56:25Z

@jddarcy This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8325189: Enable this-escape javac warning in java.base

Reviewed-by: alanb, erikj, naoto, smarks, ihse, joehw, lancea, weijun

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At the time when this comment was updated there had been no new commits pushed to the master branch. If another commit should be pushed before you perform the /integrate command, your PR will be automatically rebased. If you prefer to avoid any potential automatic rebasing, please check the documentation for the /integrate command for further details.

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jddarcy · 2024-02-05T20:35:15Z

In its initial form, the changes are tested on Linux. Later on, I'll do cross-platform builds to make sure there aren't any, say, windows-specific changes that are needed as well.

I can file a follow-up umbrella bug with the original list of ~200 warnings so the constructors and initializers in question can be examined to see if they should be updated.

Filed JDK-8325263 .

stuart-marks

Changes in java.util and java.util.concurrent look fine.

There are a startling number of places where this is potentially leaked to a subclass. It would be interesting to analyze the pathologies and have a discussion of potential fixes. There may also be compatibility issues with potential fixes (nothing in this PR that I can see) because the behavior can change from the point of view of subclasses.

magicus

Build changes look fine, but there is really a lot of places where the warning is individually disabled. This indicates either that the warning is too broad, or that the code base is potentially very buggy; neither of which sounds very good. :(

dfuch

I looked at the modifications in java.net / sun.net. Looks generally good though I have some comments.

dfuch · 2024-02-06T14:28:15Z

src/java.base/share/classes/java/net/Socket.java

@@ -319,6 +320,7 @@ private static Void checkPermission(SocketImpl impl) {
     * @see        java.net.SocketImpl
     * @see        SecurityManager#checkConnect
     */
+    @SuppressWarnings("this-escape")


This is a weird one. I guess the issue here is that the escape happens in the chained constructor, and is propagated recursively up the constructor chain. Is the suppress warning here still needed after disabling this-escape warning at line 358?

Actually - these are all weird since the only place where the escape happens is in the private constructor at line 548 - and it doesn't even get flagged there (presumably because it's a private constructor?)

I guess that the rationale is that subclasses cannot override the private constructor (where the escape happen), but can override the public constructor that calls the private constructor where the escape happen. I can't help feeling that the warning would be better placed on the private constructor though. Seeing it here confused me a lot.

dfuch · 2024-02-06T14:35:52Z

src/java.base/share/classes/sun/net/www/MessageHeader.java

@@ -50,6 +50,7 @@ public MessageHeader () {
        grow();
    }

+    @SuppressWarnings("this-escape")


An alternative here could be to make the class final. AFAICS it's not subclassed anywhere. If you'd prefer not to do this here then maybe a followup issue could be logged?

I'd prefer if that kind of change were done as a subtask of

JDK-8325263: Address this-escape lint warnings java.base (umbrella)

Thanks Joe. I logged JDK-8325361: Make sun.net.www.MessageHeader final

jddarcy · 2024-02-06T17:41:35Z

Build changes look fine, but there is really a lot of places where the warning is individually disabled. This indicates either that the warning is too broad, or that the code base is potentially very buggy; neither of which sounds very good. :(

I deliberately choose to suppress the warning at each constructor location rather than at the class level so there are more SuppressWarnings annotations than strictly needed to get the build to be clean. However, I thought limiting the scope of the annotations was preferable for several reasons, including more precisely indicating where any code updates are needed.

This is a new warning run over old code, in some cases very old code. I don't find it surprising that there were several hundred instances of this warning in java.base given the amount of code there.

JoeWang-Java

The two XML changes look good to me. There would be a lot of warnings in the java.xml module as well, if we had to do it in the future.

wangweij

Security changes look fine. Although I don't know how to remove those annotations later. A lot of compatibility impact.

jddarcy · 2024-02-07T20:04:10Z

Thanks all for the reviews. Will integrate now after a sync with mainline and successful cross-platform build run.

jddarcy · 2024-02-07T20:04:22Z

/integrate

openjdk · 2024-02-07T20:05:12Z

Going to push as commit fbd15b2.

openjdk · 2024-02-07T20:05:18Z

@jddarcy Pushed as commit fbd15b2.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

jddarcy · 2024-02-07T20:38:31Z

Security changes look fine. Although I don't know how to remove those annotations later. A lot of compatibility impact.

In case you didn't see it, the warning message are listed in an attachment on JDK-8325263.

JDK-8325189: Enable this-escape javac warning in java.base

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Merge branch 'master' into JDK-8325189

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Merge branch 'master' into JDK-8325189

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jddarcy deleted the JDK-8325189 branch October 17, 2024 16:48

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JDK-8325189: Enable this-escape javac warning in java.base #17692

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