XenoAmess opened a new pull request, #1820:
URL: https://github.com/apache/commons-lang/pull/1820
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## Summary
Fix a regression introduced by #1548 (LANG-1749), released in Commons Lang
3.21.0: `TypeUtils.isAssignable` rejects legal assignments such as
`Class<Integer>` to `Class<?>` because the `java.lang.Class` check requires
exact type-argument equality, including when the target argument is a wildcard.
## Reproducer
```java
import java.lang.reflect.Type;
import org.apache.commons.lang3.reflect.TypeUtils;
class Reproducer {
public static void main(String[] args) {
final Type from = TypeUtils.parameterize(Class.class, Integer.class);
final Type to = TypeUtils.parameterize(Class.class,
TypeUtils.wildcardType().build());
System.out.println(TypeUtils.isAssignable(from, to));
}
}
```
Output:
| Version | Result |
| --- | --- |
| 3.20.0 | `true` |
| 3.21.0 | `false` |
| With this fix | `true` |
The corresponding assignment is accepted by `javac`:
```java
Class<Integer> source = Integer.class;
Class<?> target = source;
```
## Downstream evidence: EvoSuite
This regression caused a real downstream build failure when EvoSuite
upgraded Commons Lang:
1. **Dependency-update PR:**
[XenoAmess/evosuite#363](https://github.com/XenoAmess/evosuite/pull/363),
upgrading `org.apache.commons:commons-lang3` from 3.20.0 to 3.21.0.
2. **Failing Java CI:** [Ubuntu / Java 21
build](https://github.com/XenoAmess/evosuite/actions/runs/37233026734/job/111526535103),
at the dependency-update commit `8cc82c7ebe4c22952e4bbab46401ba0ceccc4e78`.
The affected downstream test is `TestGenericClassImpl.testAssignableClass`.
3. **Downstream workaround:** [EvoSuite commit
`6fd000e4a2934afa91397306f80f8101e33d8741`](https://github.com/XenoAmess/evosuite/commit/6fd000e4a2934afa91397306f80f8101e33d8741),
which adds a fallback to `GenericClassUtils.isAssignable` for parameterized
`Class` types. For example, when Commons Lang rejects `Class<Integer>` to
`Class<?>`, the workaround checks the target wildcard's bounds explicitly
instead of requiring exact argument equality.
4. **Java CI after the workaround:** [Successful run at
`6fd000e4a`](https://github.com/XenoAmess/evosuite/actions/runs/38734916786),
with both Ubuntu and Windows Java 21 builds passing.
## Implementation
- Allow a target `Class` wildcard argument when the source argument
satisfies its bounds, using the existing wildcard assignability logic. This
also handles wildcard source arguments such as `Class<? extends Integer>` to
`Class<? extends Number>`.
- Preserve an unresolved source type variable for the wildcard check instead
of losing it during variable-assignment unrolling. This allows `Class<T>` to
`Class<?>` when `T` is declared by another class.
- Continue rejecting raw generic source arguments against parameterized
upper bounds, since unchecked conversion does not apply inside a type argument.
The three regression tests introduced by #1548 continue to pass.
- Check lower bounds in the correct direction, including the legal
assignment from `Class<List>` to `Class<? super List<String>>`.
## Validation
- Added five regression test methods covering unbounded, upper-bounded,
lower-bounded, and parameterized wildcard bounds, as well as source wildcards
and type variables.
- With the original upstream `Class` check restored, all five new test
methods fail; the three existing #1548 tests pass.
- With the fix applied, the default `mvn` command succeeds: **96,027 tests,
0 failures, 0 errors, 16 skipped**. Its default goals also run Apache RAT,
Checkstyle, japicmp, SpotBugs, PMD, and Javadoc.
- Checked representative positive assignments against `javac
-Xlint:unchecked -Werror`.
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