How to figure out which Xlint option corresponds to a compiler warning?

问题

My software builds use -Xlint -Werror so I routinely run across compiler warnings that break my build. Every once in a while I run across a warning that I need to suppress, but it's always difficult to figure out which Xlint option suppresses the warning I am seeing.

I'll give you a concrete example. I recently ran across:

[WARNING] module-info.java:[16,106] module not found: 
    org.bitbucket.cowwoc.requirements.guava

I searched the JDK 11 source-code and discovered this warning message declared at /src/jdk.compiler/share/classes/com/sun/tools/javac/resources/compiler.properties as:

# 0: symbol
compiler.err.module.not.found=\
    module not found: {0}

Now, it turns out that this is suppressed by -Xlint:-module but that's not obvious from the documentation. -Xlint:-export could made sense as well. I've also run across warnings in the past that couldn't be suppressed at all (these were subsequently fixed).

Instead of resorting to trial and error, is there a deterministic way to figure out which Xlint option corresponds to each warning message? Is there some sort of mapping file somewhere in the JDK source codes?

UPDATE: I am using Maven 3.6.0, maven-compiler-plugin 3.8.0, JDK 11.0.1

回答1:

One way to do that, if somehow you're not able to access the online documentation could be using the command

javac --help-extra

This would list out the possible warnings that you could enable/disable. For example from javac 12-ea :

回答2:

Alan Bateman pointed me in the right direction. It seems that the maven-compiler-plugin suppressing vital information. Here is the output from javac 11.0.1:

C:\Users\Gili\Documents\requirements\java\src\main\java\module-info.java:16: warning: [module] module not found: org.bitbucket.cowwoc.requirements.guava
        exports org.bitbucket.cowwoc.requirements.java.internal.impl to org.bitbucket.cowwoc.requirements.guava;

Here is the corresponding output from maven-compiler-plugin:

[WARNING] /C:/Users/Gili/Documents/requirements/java/src/main/java/module-info.java:[16,106] module not found: org.bitbucket.cowwoc.requirements.guava

javac mentions [module] at the beginning of the warning, indicating that -Xlint:-module will suppress this warning.

I filed a bug report here: https://issues.apache.org/jira/browse/MCOMPILER-367

来源：https://stackoverflow.com/questions/53676235/how-to-figure-out-which-xlint-option-corresponds-to-a-compiler-warning

标签

java

maven

compiler-warnings

lint

java-11