Strangely formatted Java file stalls prettier-java

[leonardehrenfried]

Someone on our team reported a strange issue where the prettier-java maven plugin would hang indefinitely.

We traced it down to a malformed Java file. After fixing up the invalid Java, prettier worked as expected.

Reproduction case

It's actually quite simple to reproduce this. All you need to do is to create a Java file with the follwoing content

public {

}

This is of course very much invalid, but prettier should complain rather than hang forever.

If this doesn't give you enough to work with I can also provide a full reproduction repo.

Tested with prettier-java 1.6.8 and 1.7.1.

@testower @miklcct

[jtkiesel]

Thanks for reporting this issue! To confirm, were the versions you tested with 2.6.8 and 2.7.1? Not 1.6.8 and 1.7.1?

I expected this to be a bug in our parser, but creating a single Java file with only the contents you provided and running Prettier on it (with the latest version of it and prettier-plugin-java) responded with a parsing error pretty quickly (within a couple seconds). However, when testing with the prettier-maven-plugin, I reproduced it easily. The smallest file I've reproduced this with is a file containing a single alpha character, such as a.

This could simply be a bug in prettier-maven-plugin, but I'll try to see if I can confirm that. So far it doesn't appear to be an issue with prettier-plugin-java (every file I've reproduced this issue with has immediately returned a parsing error when running prettier directly).

[jtkiesel]

With a Maven project containing a single Java file with the contents a, running mvn -X prettier:write hangs after logging something similar to the following:

[DEBUG] Running prettier with args: /root/.m2/repository/com/hubspot/maven/plugins/prettier-maven-plugin/0.22/node-v16.13.2-linux-x64/bin/node /root/.m2/repository/com/hubspot/maven/plugins/prettier-maven-plugin/0.22/prettier-java-2.7.1/node_modules/prettier/bin/prettier.cjs --plugin=/root/.m2/repository/com/hubspot/maven/plugins/prettier-maven-plugin/0.22/prettier-java-2.7.1/node_modules/prettier-plugin-java/dist/index.js --color --write src/main/java/**/*.java

If I execute the exact command that prettier-maven-plugin claims it is executing, i.e.:

/root/.m2/repository/com/hubspot/maven/plugins/prettier-maven-plugin/0.22/node-v16.13.2-linux-x64/bin/node /root/.m2/repository/com/hubspot/maven/plugins/prettier-maven-plugin/0.22/prettier-java-2.7.1/node_modules/prettier/bin/prettier.cjs --plugin=/root/.m2/repository/com/hubspot/maven/plugins/prettier-maven-plugin/0.22/prettier-java-2.7.1/node_modules/prettier-plugin-java/dist/index.js --color --write src/main/java/**/*.java

Then it exits within a couple of seconds with a stack trace indicating the parsing error.

I would recommend creating an issue against the HubSpot/prettier-maven-plugin, as this appears to be an issue with its handling of this error. Perhaps the output from the error is too long, and the plugin isn't able to handle it?

[jtkiesel]

For what it's worth, I went ahead and tested the latest versions of prettier and prettier-plugin-java with the Spotless Maven plugin and it worked as expected (didn't hang, and exited with a parsing error). That could be an alternative now/long term, though it does require you to manage your own Node.js installation (prettier-maven-plugin installs it for you behind the scenes).

[leonardehrenfried]

Thanks for all of this. I can confirm that I meant 2.6.8 and 2.7.1.

I will open a ticket at HubSpot/prettier-maven-plugin.

[jtkiesel]

Closing now that this issue has been moved to prettier-maven-plugin. Can reopen if there somehow turns out to be something that needs to be done on our end to facilitate the fix.