Maven compiler creates ghost classes when invoked with a compilerId of 'eclipse'
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Key: MCOMPILER-43
URL: http://jira.codehaus.org/browse/MCOMPILER-43
Project: Maven 2.x Compiler Plugin
Issue Type: Bug
Affects Versions: 2.0.1
Environment: Windows XP, java 5 and java 1.4 with maven 2.0.4
Reporter: Binyan
Priority: Critical
Attachments: compiler-test.zip
The maven-compiler-plugin, along with the plexus-eclipse-compiler component, is
generating ghost classes (i.e. java source files that compile, but don't
generate a .class file). If I put a deliberate error into the Logger.java file
then the compilers, javac and eclipse, both catch it. However, only javac when
invoked through maven will create a .class files for the 2 java files in the
example project. I'm using the following pom definition:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0";
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
http://maven.apache.org/maven-v4_0_0.xsd";>
<modelVersion>4.0.0</modelVersion>
<groupId>com.abc.logging</groupId>
<artifactId>abc-logging</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<name>ABC Logging</name>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.4</source>
<target>1.4</target>
<verbose>true</verbose>
<fork>false</fork>
<compilerId>eclipse</compilerId>
</configuration>
<dependencies>
<dependency>
<groupId>org.codehaus.plexus</groupId>
<artifactId>plexus-compiler-eclipse</artifactId>
<version>1.5.1</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
</project>
If you execute "mvn clean compile" then there will only be 1 class file,
Foo.class, in the target/classes/com/abc/logging directory. However if you
change the pom's <compilerId> element to be javac then 3 classes are now in the
target folder. This would indicate an eclipse compiler bug, but wait there's
more. The plexus-eclipse-compiler component uses the
org.eclipse.jdt.core:core:3.1.0 repo artifact for compiling. So if you run the
batch compiler in the core-3.1.0 jar like
java -jar <repo path>/org/eclipse/jdt/core/3.1.0/core-3.1.0.jar -verbose -d
target/classes src/main/java
then you will get the following output indicating all 3 classes were created.
E:\dev\workspace-eclipse\compiler-test>java -jar "C:\Documents and
Settings\wbeckwit\.m2\repository\org\eclipse\jdt\core\3.1.0\core-3.1.0.jar"
-verbose -d target/classes -verbose src/main/java
Collecting source files inside
E:\dev\workspace-eclipse\compiler-test\src\main\java
Collecting source files inside
E:\dev\workspace-eclipse\compiler-test\src\main\resources
[parsing
E:\dev\workspace-eclipse\compiler-test\src\main\java\com\abc\logging\Foo.java -
#1/2]
[parsing
E:\dev\workspace-eclipse\compiler-test\src\main\java\com\abc\logging\Logger.java
- #2/2]
[reading java/lang/Object.class]
[analyzing
E:\dev\workspace-eclipse\compiler-test\src\main\java\com\abc\logging\Foo.java -
#1/2]
[writing com\abc\logging\Foo.class - #1]
[completed
E:\dev\workspace-eclipse\compiler-test\src\main\java\com\abc\logging\Foo.java -
#1/2]
[analyzing
E:\dev\workspace-eclipse\compiler-test\src\main\java\com\abc\logging\Logger.java
- #2/2]
[reading java/util/Map.class]
[reading java/util/HashMap.class]
[reading java/lang/Class.class]
[reading java/lang/String.class]
[reading java/lang/Throwable.class]
[reading java/io/Serializable.class]
[reading java/lang/Cloneable.class]
[reading java/util/AbstractMap.class]
[writing com\abc\logging\Logger$Bar.class - #2]
[writing com\abc\logging\Logger.class - #3]
[completed
E:\dev\workspace-eclipse\compiler-test\src\main\java\com\abc\logging\Logger.java
- #2/2]
[2 units compiled]
[3 .class files generated]
----------
1. WARNING in
E:\dev\workspace-eclipse\compiler-test\src\main\java\com\abc\logging\Logger.java
(at line 8)
private boolean debug; // *** comment this invocation out and the
class file will be generated
^^^^^
The field Logger.debug is never read locally
----------
1 problem (1 warning)
E:\dev\workspace-eclipse\compiler-test>
Also if you use the lastest 3.2 eclipse compiler available here,
http://download.eclipse.org/eclipse/downloads/drops/R-3.2-200606291905/download.php?dropFile=ecj.jar,
then you still get 3 classes compiled.
Therefore this indicates a maven bug, but wait there's even more. The
Logger.java file has 2 "// ***" comments in it. If you comment out the boolean
declaration then the eclipse compiler, when invoked through maven, will create
the 3 class files. Howeve if you also comment out the marked method invocation
then the we're back to getting only 1 class file generated. WTF!? Again javac
invoked via maven and the eclipse core-3.1.0 compiler always generates 3 class
files. Can someone help the universe make sense again?
Setting the <fork> element to true has no affect on the results seen.
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