Tool modules can be created via `jmod --main-class` option such that `ModuleMainClass` attribute will be added in `module-info.class` and the module's main class can be launched via `java -m <module-name>` without specifying the name of the main class.
In addition, for modules with `ModuleMainClass` attribute, jlink will pre-resolve the module graph such that when such module is launched at runtime (without `--add-modules` or `--limit-modules` option), the runtime can skip the module resolution and speed up the startup time. This PR extends the build system to allow a module to specify the main class under `make/modules/$MODULE/Jmod.gmk` file. Also JDK tools with a single entry point (or a primary entry point) are candidates to add `ModuleMainClass` attribute in `module-info.class` to benefit from the jlink optimization. For example, `java -m jdk.jpackage` will be launched using the pre-resolved module graph. ------------- Commit messages: - 8317620: Build JDK tools with ModuleMainClass attribute Changes: https://git.openjdk.org/jdk/pull/16463/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16463&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8317620 Stats: 18 lines in 9 files changed: 6 ins; 0 del; 12 mod Patch: https://git.openjdk.org/jdk/pull/16463.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/16463/head:pull/16463 PR: https://git.openjdk.org/jdk/pull/16463
