Support javac as a compiler for Tycho #3350

laeubi · 2024-01-11T12:20:59Z

Currently Tycho is strictly using ecj as a compiler but in general it might be there are situations one wants to use javac for compilation even though it might not has full features supported (e.g. package restrictions).

This is an attempt to make it possible to use javac at a very basic level.

mickaelistria · 2024-01-11T12:55:59Z

This is an interesting feature also for people who want to build/use plugins leveraging very new Java features which aren't yet supported by ECJ.

laeubi · 2024-01-11T13:31:31Z

/request-license-review

github-actions · 2024-01-11T13:32:07Z

/request-license-review

License review requests:

maven/mavencentral/org.codehaus.plexus/plexus-compiler-javac/2.14.2

After all reviews have concluded, re-run the license-vetting check from the Github Actions web-interface to update its status.

Workflow run (with attached summary files):
https://github.com/eclipse-tycho/tycho/actions/runs/7489496537

laeubi · 2024-01-11T13:33:18Z

I now made the (very simple) testcase pass by just omit any custom options Tycho adds if not ECJ is selected as compiler.

Currently Tycho is strictly using ecj as a compiler but in general it might be there are situations one wants to use javac for compilation even though it might not has full features supported (e.g. package restrictions). This is an attempt to make it possible to use javac at a very basic level.

szarnekow · 2024-01-11T14:23:59Z

tycho-compiler-plugin/src/main/java/org/eclipse/tycho/compiler/AbstractOsgiCompilerMojo.java

@@ -851,14 +855,22 @@ private void configureBootClassPath(CompilerConfiguration compilerConfiguration,
                if (includeParent != null) {
                    Xpp3Dom[] includes = includeParent.getChildren("include");
                    if (includes.length > 0) {
-                        compilerConfiguration.addCompilerCustomArgument("-bootclasspath", scanBootclasspath(
+                        addCompilerCustomArgument(compilerConfiguration, "-bootclasspath", scanBootclasspath(


Bootclasspath is a standard javac option. Skipping this might cause surprises.

It seems not to be a standard plexus compiler option so I'm not sure how to handle this gracefully...

szarnekow · 2024-01-11T14:24:35Z

tycho-compiler-plugin/src/main/java/org/eclipse/tycho/compiler/AbstractOsgiCompilerMojo.java

@@ -738,7 +742,7 @@ protected CompilerConfiguration getCompilerConfiguration(List<String> compileSou
                if (jreClasspathEntry.isModule()) {
                    Collection<String> modules = jreClasspathEntry.getLimitModules();
                    if (!modules.isEmpty()) {
-                        compilerConfiguration.addCompilerCustomArgument("--limit-modules", String.join(",", modules));
+                        addCompilerCustomArgument(compilerConfiguration, "--limit-modules", String.join(",", modules));


This is a standard javac option, too

It seems not to be a standard plexus compiler option so I'm not sure how to handle this gracefully...

szarnekow · 2024-01-11T14:26:36Z

tycho-compiler-plugin/src/main/java/org/eclipse/tycho/compiler/AbstractOsgiCompilerMojo.java

@@ -581,7 +582,7 @@ public List<String> getClasspathElements() throws MojoExecutionException {
                    .filter(AbstractOsgiCompilerMojo::isValidLocation).distinct();
            classpathLocations.forEach(location -> {
                String path = location.getAbsolutePath();
-                String entry = path + toString(cpe.getAccessRules());
+                String entry = path + toString(cpe.getAccessRules(), useAccessRules);
                if (seen.add(entry)) {


For all but the first entry seen.add(entry) will be false. The included paths and the classpath will miss entries. (with javac that is)

For all but the first entry seen.add(entry) will be false. The included paths and the classpath will miss entries. (with javac that is)

I'm not sure I understand what you want to suggest here, the whole "see" part is that a path could apear multiple times (e.g. with different environments) so it is to make the list not contain it more than once ...

szarnekow · 2024-01-11T14:28:47Z

tycho-compiler-plugin/src/main/java/org/eclipse/tycho/compiler/AbstractOsgiCompilerMojo.java

@@ -573,6 +573,7 @@ public List<String> getClasspathElements() throws MojoExecutionException {
        final List<String> classpath = new ArrayList<>();


@laeubi This class AbstractOsgiCompilerMojo does not contain any JavaDoc on the class declaration itself. It makes me wonder if it is even supposed to work with javac, given that the plain Java compiler does not have any understanding of OSGI semantics.

Compilation actually do not require much of OSGi, ECJ supports "restrictions" on classpath entries but javac not as far as I know so thats the main difference here, also the target and source levels are derived from the manifest if possible.

laeubi · 2024-01-11T15:02:59Z

@szarnekow the javac support is really basic, I think the best would be to merge this first (I already tested it with a smaller Tycho project) and enhance it afterwards by e.g. adding another testcase that makes use of some of the yet not supported option.

Another open issue is that we should upgrade to catch up with the latest changes from the maven-compiler-plugin here:

[tycho-compiler-plugin] sync with recent maven changes #3351

github-actions · 2024-01-11T15:59:31Z

Test Results

579 files +3 579 suites +3 3h 53m 45s ⏱️ - 2m 35s
382 tests +1 374 ✅ +1 7 💤 ±0 1 ❌ ±0
1 146 runs +3 1 123 ✅ +3 22 💤 ±0 1 ❌ ±0

For more details on these failures, see this check.

Results for commit 7cc26f2. ± Comparison against base commit 36fd6a9.

github-actions · 2024-01-11T16:09:51Z

💔 All backports failed

Status	Branch	Result
❌	tycho-4.0.x	Backport failed because of merge conflicts You might need to backport the following PRs to tycho-4.0.x: - Add support for API Tools Annotations to Tycho

Manual backport

To create the backport manually run:

backport --pr 3350

Questions ?

Please refer to the Backport tool documentation and see the Github Action logs for details

laeubi mentioned this pull request Jan 11, 2024

EXPERIMENT: JDT using Javac instead of ECJ eclipse-jdt/eclipse.jdt.core#1827

Open

laeubi force-pushed the javac branch from 19975b8 to 508feae Compare January 11, 2024 12:32

laeubi force-pushed the javac branch from 508feae to 73c53cd Compare January 11, 2024 13:32

laeubi marked this pull request as ready for review January 11, 2024 13:32

laeubi added the backport-to-tycho-4.0.x Can be added to a PR to trigger an automatic backport of the change label Jan 11, 2024

laeubi force-pushed the javac branch from 73c53cd to 7cc26f2 Compare January 11, 2024 14:09

szarnekow reviewed Jan 11, 2024

View reviewed changes

laeubi merged commit 7d9df57 into eclipse-tycho:main Jan 11, 2024
8 of 10 checks passed

github-actions bot mentioned this pull request Jan 22, 2024

Add support to specify target locations in the pom configuration #3396

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github-actions bot mentioned this pull request Feb 15, 2024

Add p2-aware model converter for CycloneDX SBOM generation #3258

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eclipse-tycho-bot mentioned this pull request Aug 4, 2024

Add support for bumping maven-target locations #4078

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eclipse-tycho-bot mentioned this pull request Oct 19, 2024

Support version-ranges and no-version for units in IU target locations #4361

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eclipse-tycho-bot mentioned this pull request Dec 16, 2024

Add support for TargetDefinition#implicitDependencies #4528

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Support javac as a compiler for Tycho #3350

Support javac as a compiler for Tycho #3350

laeubi commented Jan 11, 2024

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laeubi commented Jan 11, 2024

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szarnekow Jan 11, 2024 •

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		@@ -573,6 +573,7 @@ public List<String> getClasspathElements() throws MojoExecutionException {
		final List<String> classpath = new ArrayList<>();

Support javac as a compiler for Tycho #3350

Support javac as a compiler for Tycho #3350

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laeubi commented Jan 11, 2024

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Test Results

github-actions bot commented Jan 11, 2024

💔 All backports failed

Manual backport

Questions ?

szarnekow Jan 11, 2024 •

edited

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