Fix smithyFormat classpath serialization error#161
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When smithyFormat fails on invalid syntax, the ModelSyntaxException thrown inside the isolated URLClassLoader cannot be serialized by Gradle's daemon (ShapeId is not visible to the daemon classloader). Strip the cause chain at the worker boundary and rethrow as a plain GradleException with only the root cause message.
JordonPhillips
approved these changes
Feb 19, 2026
| .buildAndFail(); | ||
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| // The real error from the Smithy formatter must be present. | ||
| Assertions.assertTrue( |
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Using assertThat with containsString from hamcrest will give better errors
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Yep, can do it as follow up.
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Background
Root Cause
SmithyUtils.RunCliexecutes the Smithy CLI inside a customURLClassLoaderisolated from Gradle's daemon classloader. When the CLI throwsModelSyntaxException, the original catch block preserved the full cause chain viathrow new RuntimeException(e). Gradle's daemon serializer (ExceptionPlaceholder) then tries to introspect the exception's fields -- butModelSyntaxExceptionandShapeIdwere loaded by the isolated classloader, not the daemon's. Java class identity is per classloader instance, so the lookup fails even thoughsmithy-modelis already a plugin dependency.Fix
In
SmithyUtils.RunCli.execute(), unwrap the cause chain to the root, extract only the message string (falling back to the class name if the message is null), and throw a plainGradleExceptionwith no cause attached, so the daemon serializer never encounters the isolated types. Users still see the real error (e.g."Cannot format invalid models: Syntax error at line 105, column 8").An alternative is to add
smithy-modelto the daemon classpath.smithy-modelis already a plugin dependency, so it is present in the daemon's classpath. This still does not work as theModelSyntaxExceptioninstance was created by the isolatedURLClassLoader, and Java's class identity check requires the same classloader instance, not just the same JAR. Fixing this would require removing the classloader isolation entirely, which reintroducesZipException: invalid LOC headererrors from stale cached JARs that required us to isolate the Smithy CLI classloader in the first place.Testing
Added a regression test.
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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.