Why Tycho cannot resolve this simple dependency to SWT? - eclipse

Question

I thought to have studied enough Maven + Tycho to configure at least a minimal target environment for a headless build, but still I am unable to make this small example work. I have three projects:
test, that contains
sub.ui and
sub.target
The test project has just a pom.xml that builds the two subprojects and whose only interesting part is the <pluginManagement> section:
...
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.eclipse.m2e</groupId>
<artifactId>lifecycle-mapping</artifactId>
<version>1.0.0</version>
<configuration>
<lifecycleMappingMetadata>
<pluginExecutions>
<pluginExecution>
<pluginExecutionFilter>
<groupId>org.eclipse.tycho</groupId>
<artifactId>target-platform-configuration</artifactId>
<versionRange>[1.0.0,)</versionRange>
<goals>
<goal>target-platform</goal>
</goals>
</pluginExecutionFilter>
<action>
<ignore />
</action>
</pluginExecution>
</pluginExecutions>
</lifecycleMappingMetadata>
</configuration>
</plugin>
<plugin>
<groupId>org.eclipse.tycho</groupId>
<artifactId>tycho-maven-plugin</artifactId>
<version>${tycho.version}</version>
<extensions>true</extensions>
</plugin>
<plugin>
<groupId>org.eclipse.tycho</groupId>
<artifactId>target-platform-configuration</artifactId>
<version>${tycho.version}</version>
<configuration>
<pomDependencies>wrapAsBundle</pomDependencies>
<target>
<artifact>
<groupId>${project.groupId}</groupId>
<artifactId>sub.target</artifactId>
<version>0.0.1-SNAPSHOT</version>
</artifact>
</target>
<environments>
<environment>
<os>linux</os>
<ws>gtk</ws>
<arch>x86</arch>
</environment>
<environment>
<os>linux</os>
<ws>gtk</ws>
<arch>x86_64</arch>
</environment>
<environment>
<os>win32</os>
<ws>win32</ws>
<arch>x86</arch>
</environment>
<environment>
<os>win32</os>
<ws>win32</ws>
<arch>x86_64</arch>
</environment>
<environment>
<os>macosx</os>
<ws>cocoa</ws>
<arch>x86_64</arch>
</environment>
</environments>
</configuration>
</plugin>
</plugins>
</pluginManagement>
</build>
...
verbose but quite straightforward (except perhaps for the lifecycle-mapping plugin, that however impacts only when building under Eclipse, and I want to build outside Eclipse). The sub.target project has a canonical pom.xml with just:
...
<build>
<plugins>
<plugin>
<groupId>org.eclipse.tycho</groupId>
<artifactId>tycho-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.eclipse.tycho</groupId>
<artifactId>target-platform-configuration</artifactId>
</plugin>
</plugins>
</build>
...
and a brief sub.target.target file:
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<?pde version="3.8"?>
<target includeMode="feature" name="Test" sequenceNumber="1">
<locations>
<location includeAllPlatforms="false" includeConfigurePhase="true" includeMode="planner" includeSource="true" type="InstallableUnit">
<repository location="https://download.eclipse.org/releases/latest/"/>
<unit id="org.eclipse.equinox.p2.user.ui.feature.group" version="0.0.0"/>
</location>
</locations>
<targetJRE path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-11"/>
</target>
The sub.ui project is a small plugin project with a silly main that uses a SWT class:
package foo;
import org.eclipse.swt.widgets.Label;
public class Main {
public static void main(String[] args) {
Label l = new Label(null, 0);
}
}
and a MANIFEST.MF:
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: Test UI
Bundle-SymbolicName: sub.ui;singleton:=true
Bundle-Version: 0.0.1.qualifier
Automatic-Module-Name: sub.ui
Bundle-RequiredExecutionEnvironment: JavaSE-11
Require-Bundle: org.eclipse.swt
Now, if I open a console and I mvn clear compile, Maven fails while building the Test UI plugin, and displays the errors:
[ERROR] Failed to execute goal org.eclipse.tycho:tycho-compiler-plugin:2.4.0:compile (default-compile) on project sub.ui: Compilation failure: Compilation failure:
[ERROR] /.../sub.ui/src/foo/Main.java:[3]
[ERROR] import org.eclipse.swt.widgets.Label;
[ERROR] ^^^^^^^^^^^
[ERROR] The import org.eclipse cannot be resolved
[ERROR] /.../sub.ui/src/foo/Main.java:[8]
[ERROR] Label l = new Label(null, 0);
[ERROR] ^^^^^
[ERROR] Label cannot be resolved to a type
[ERROR] /.../sub.ui/src/foo/Main.java:[8]
[ERROR] Label l = new Label(null, 0);
[ERROR] ^^^^^
[ERROR] Label cannot be resolved to a type
[ERROR] 3 problems (3 errors)
Apparently the build process does not link my code with the SWT version for my macos+cocoa platform, that is nevertheless listed among the plugins in the org.eclipse.equinox.p2.user.ui.feature.group. Strangely, if I launch Maven from Eclipse every now and then it links the right SWT library and completes the build process. What am I missing? How do I convince Tycho to use the information about my platform to consistently select the macos+cocoa SWT jar and link it to my code? I can share the complete example project on GitHub upon request if you cannot spot the mistake in the above code. Thank you for your patience.

Answer 1

Problem solved. Apparently the x86 platforms are no longer supported (the project I am working on is quite old). If we remove all the x86 <environment>s from the <pluginManagement> section of the main pom.xml file and leave only the x86_64 ones, everything works.