jamesfredley opened a new issue, #16126:
URL: https://github.com/apache/grails-core/issues/16126
### Summary
A Grails 7 plugin whose AST transformation populates a **private trait
method** on the annotated class silently produces a class that is missing that
method under Grails 8 / Groovy 5. Compilation succeeds, the plugin loads, and
the failure only appears at runtime as a `MissingPropertyException` naming an
internal member the user never wrote.
Found while auditing released Grails 7 plugins against `8.0.0-M5`, using
`org.grails.plugins:i18n-enums:7.0.1` (latest release, catalog constraint
`7.0.0 > *`).
This is **not** #16123. That issue is about a *generic trait with fields*
failing with `MalformedParameterizedTypeException` through
`$Trait$FieldHelper`. The trait here is not generic, declares no fields, and
ships **no** `$Trait$FieldHelper` at all. The mechanism and the symptom are
different, so I am filing it separately rather than commenting there.
### Grails Version
8.0.0-M5 (Groovy 5.0.8, Spring Boot 4.1.0, JDK 21.0.11)
### Steps to Reproduce
In a stock `create-app --profile=web` application on 8.0.0-M5:
```groovy
implementation "org.grails.plugins:i18n-enums:7.0.1"
```
```groovy
package i18nenums
import grails.plugins.i18nEnums.annotations.I18nEnum
@I18nEnum
enum DeliveryStatus {
SHIPPED
}
```
with `i18nenums.DeliveryStatus.SHIPPED=Shipped` in `messages.properties`,
then resolve it through the documented public API:
```groovy
messageSource.getMessage(DeliveryStatus.SHIPPED, Locale.ENGLISH)
```
### Actual Behaviour
Compilation succeeds and the plugin loads (`i18nEnums (7.0.1)` appears in
the load order). The failure happens at runtime:
```text
groovy.lang.MissingPropertyException: No such property: i18nEnumASTConfig
for class: i18nenums.DeliveryStatus
at
grails.plugins.i18nEnums.traits.I18nEnumTrait$Trait$Helper.getConfigProperty(I18nEnumTrait.groovy:72)
at
grails.plugins.i18nEnums.traits.I18nEnumTrait$Trait$Helper.getCodes(I18nEnumTrait.groovy:18)
at
org.springframework.context.support.AbstractMessageSource.getMessage(AbstractMessageSource.java:168)
```
No Grails-owned frame appears; the frames are plugin-owned and Spring-owned.
### Root Cause
The plugin's `I18nEnumTransformation` does not add a new field. It **looks
up an existing method on the annotated class and replaces its body**:
```text
private static void addi18nEnumASTConfig(ClassNode, AnnotationNode);
...
25: aload_0
26: ldc // String getI18nEnumASTConfig
32: invokevirtual ClassNode.getMethod:(String, Parameter[]) -> MethodNode
...
85: invokevirtual MethodNode.setCode:(Statement) // installs the config
map as the method body
```
That method is declared **private in the trait**, so it exists only as a
helper static:
```text
grails.plugins.i18nEnums.traits.I18nEnumTrait$Trait$Helper
private static java.util.Map
getI18nEnumASTConfig(java.lang.Class<I18nEnumTrait>);
private static <T> T getConfigProperty(java.lang.Class<I18nEnumTrait>,
java.lang.String, java.lang.Class<T>, T);
```
The compiled application enum on Grails 8 receives the trait's **public**
members but **not** the private one:
```text
$ javap -p build/classes/groovy/main/i18nenums/DeliveryStatus.class
public final class i18nenums.DeliveryStatus extends
java.lang.Enum<i18nenums.DeliveryStatus>
implements grails.plugins.i18nEnums.traits.I18nEnumTrait,
groovy.lang.GroovyObject {
public java.lang.Object[] getArguments();
public java.lang.String[] getCodes();
public java.lang.String getDefaultMessage();
public java.lang.String getName();
...
}
```
`getI18nEnumASTConfig` is absent from the emitted class, so the runtime
property lookup for `i18nEnumASTConfig` finds nothing and every message
resolution through the plugin fails.
Notably the transformation did **not** fail: `MethodNode.setCode` is invoked
unconditionally on the result of `getMethod(...)`, so a `null` lookup would
have produced a `NullPointerException` during compilation. Compilation was
clean, which means the method node was visible to the transform at AST time but
is not present in the class that is finally emitted.
### Expected Behaviour
Either the private trait method remains reachable on the implementing class
the way it was under the Groovy 4 line, or the mismatch surfaces at **compile**
time rather than as a runtime `MissingPropertyException` that names an internal
member.
### Why this is worth tracking here
The user-visible failure gives no indication of the real problem. `No such
property: i18nEnumASTConfig` names a member the application author never wrote,
on a class they declared with a single annotation, and it appears only when the
message is resolved - potentially far from the annotated enum.
Alongside #16122, #16123, #16124, and #16125, this is a fourth distinct way
a released Grails 7 plugin breaks on Grails 8, and the second traced to a
Groovy 4 -> 5 trait ABI change. Even if the fix belongs in the plugin, the
diagnosis cost here is high and a compile-time signal (or an upgrade-guide note
about private trait members and AST transformations) would remove most of it.
### Notes
Part of a compatibility sweep of released Grails 7 plugins against 8.0.0-M5.
In the same sweep, `greenmail:7.0.1`, `markdown:4.0.0`, `rendering:7.0.1`,
`x-frame-options:2.0.0`, `grails-csrf:2.0.0`, `joda-time:3.0.0`,
`taggable:7.0.0`, `cascade-validation:7.0.1`, `grails-cache-guava:7.0.0`, and
`grails-postgresql-extensions:8.0.0` all passed verification against their
documented public APIs.
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