fix(run): honor manifest launcher flags by ayagmar · Pull Request #2439 · jbangdev/jbang

ayagmar · 2026-03-27T22:16:26Z

JBang runs jars with -classpath ... Main instead of java -jar, so manifest launcher entries were being ignored. This change reads the relevant values from the primary jar manifest and passes the equivalent JVM flags when JBang launches the jar

That means:

Add-Opens -> --add-opens=...=ALL-UNNAMED
Add-Exports -> --add-exports=...=ALL-UNNAMED
Enable-Native-Access: ALL-UNNAMED -> --enable-native-access=ALL-UNNAMED

This also fixes a bug where Add-Opens was being read from the wrong manifest value.

Added regression tests for the Add-Opens and Enable-Native-Access cases.

Not included : the separate classpath duplication issue mentioned in #2438.

…butes Extends manifest attribute support for jars beyond PR jbangdev#2439 to handle Add-Reads module dependencies and SplashScreen-Image extraction. Changes: - Add Project.ATTR_ADD_READS and Project.ATTR_SPLASH_SCREEN_IMAGE constants - Import Add-Reads and SplashScreen-Image attributes from jar manifests - Process Add-Reads: converts to --add-reads JVM flags (Java 9+) - Process SplashScreen-Image: extracts image and passes -splash flag - Fix KeyValue.of() to support values containing '=' signs Add-Reads implementation: - Parses space-separated module dependencies (e.g., "mod1=mod2 mod3=mod4") - Generates --add-reads flags for each dependency pair - Version-gated for Java 9+ with runAsModule check SplashScreen-Image implementation: - Extracts splash image from jar to <jarPath>.splash.<ext> in cache - Smart caching: only re-extracts if jar is newer than cached image - Fails gracefully with warnings (never breaks the build) - Adds -splash:<path> flag before other JVM options KeyValue parser fix: - Changed split("=") to split("=", 2) to handle values with '=' - Enables manifest directives like //MANIFEST Add-Reads=mod1=mod2 This builds on PR jbangdev#2439's copyManifestAttribute() and addAllUnnamedManifestOptions() patterns. Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

… helper methods - Replace copyManifestAttribute() and addAllUnnamedManifestOptions() with inline code - These helper methods are from PR jbangdev#2439 which is not yet merged - Use the same pattern that exists in main branch - Add missing imports for JarOutputStream, Manifest, and assumeTrue in tests - Fix test code to use correct CmdGenerator.builder() pattern Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/main/java/dev/jbang/source/generators/JarCmdGenerator.java

maxandersen · 2026-03-28T07:23:38Z

src/main/java/dev/jbang/source/generators/JarCmdGenerator.java

-					optionalArgs.add("--add-opens=" + val + "=ALL-UNNAMED");
-				}
-			}
+		if (!runAsModule && jdk.majorVersion() >= 9) {


is not runAsModule a requirement here ? add-opens and add-exports still apply wether it is run as a module or not is it not?

Got example where this will be wrong/fail?

Sorry for that that's my mistake. I don’t really have a real case to justify the runAsModule guard, so I’ll remove it

src/main/java/dev/jbang/source/generators/JarCmdGenerator.java

maxandersen

overall direction is good!

But not following why run-as-module should affect these settings; if its related to module-info presence then I would like example/test of what breaks/fails

and jbang should not fail on attributes it does not know if java -jar would not fail so need that to be gracefully handled or shown case where -jar would fail

ayagmar · 2026-03-28T11:25:14Z

overall direction is good!

But not following why run-as-module should affect these settings; if its related to module-info presence then I would like example/test of what breaks/fails

and jbang should not fail on attributes it does not know if java -jar would not fail so need that to be gracefully handled or shown case where -jar would fail

Thanks for the review @maxandersen
The runAsModule restriction was my fault, I dropped that guard in the latest push since I don't have a reproducer or example
Regarding the java-jar failing I attached sources on the comment above

Changes: - Replace validation with pass-through for Enable-Native-Access - Let JVM validate values instead of JBang - Consistent with how we handle Add-Opens/Add-Exports - Simpler code, future-proof if spec changes - Add addManifestOptions() helper - Similar to addAllUnnamedManifestOptions but without =ALL-UNNAMED suffix - Used for Enable-Native-Access which passes values directly - Update tests: - Replace testRejectsInvalidEnableNativeAccess with testPassesThroughEnableNativeAccessModuleName - Add testReadingAddExportsWithHelper (using new createJar() helper) - Add edge case tests: * testEmptyManifestAttributeIgnored (whitespace-only values) * testMultipleSpacesBetweenValues (multiple spaces between values) * testMultipleModulesForEnableNativeAccess (space-separated module list) - Add documentation: - New "JAR Manifest Attributes" section in running.adoc - Documents Add-Opens, Add-Exports, Enable-Native-Access - Explains how values are passed to JVM - Links to JAR spec and JEP 472 - References issue jbangdev#2441 for --ignore-manifest flag Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

maxandersen

i changed to simple passthrough for now to let javac complain + added tests/docs

maxandersen · 2026-03-28T22:47:07Z

@all-contributors add @@ayagmar for code

allcontributors · 2026-03-28T22:47:11Z

@maxandersen

Could not find the user @ayagmar on github.

maxandersen · 2026-03-29T13:06:58Z

https://github.com/all-contributors add @ayagmar for code

maxandersen mentioned this pull request Mar 28, 2026

feat: add support for Add-Reads and SplashScreen-Image manifest attributes #2440

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maxandersen reviewed Mar 28, 2026

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fix(run): honor manifest launcher flags

52f14a2

ayagmar force-pushed the fix/2366-2438-manifest-attrs branch from 8ab21ec to b10580d Compare March 28, 2026 11:13

fix(run): remove module guard and match java -jar native-access errors

e35dd51

ayagmar force-pushed the fix/2366-2438-manifest-attrs branch from b10580d to e35dd51 Compare March 28, 2026 11:20

ayagmar requested a review from maxandersen March 28, 2026 11:20

maxandersen mentioned this pull request Mar 28, 2026

Add --ignore-manifest flag to skip problematic manifest attributes #2441

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maxandersen approved these changes Mar 28, 2026

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maxandersen merged commit 32568d1 into jbangdev:main Mar 29, 2026
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maxandersen mentioned this pull request Mar 30, 2026

jbang run <jarFile> ignores Add-Opens property in the MANIFEST.MF file #2438

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fix(run): honor manifest launcher flags#2439

fix(run): honor manifest launcher flags#2439
maxandersen merged 3 commits intojbangdev:mainfrom
ayagmar:fix/2366-2438-manifest-attrs

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