Copilot commented on code in PR #2493:
URL: https://github.com/apache/groovy/pull/2493#discussion_r3143665471
##########
src/main/java/org/codehaus/groovy/transform/sc/transformers/ListExpressionTransformer.java:
##########
@@ -111,6 +113,13 @@ public void visit(final GroovyCodeVisitor visitor) {
var list = new ConstructorCallExpression(ArrayList_TYPE, new
ConstantExpression(getExpressions().size(), true));
list.putNodeMetaData(StaticTypesMarker.DIRECT_METHOD_CALL_TARGET,
ArrayList_NEW);
list.visit(visitor);
+ // GROOVY-11967: indy-mode constructor call leaves Object on
the JVM
+ // stack, so the following INVOKEVIRTUAL ArrayList.add needs a
CHECKCAST.
+ // Non-indy mode emits INVOKESPECIAL which already leaves
ArrayList on
+ // the stack, so the cast would be redundant — skip it there.
+ if (g.getController().getInvocationWriter() instanceof
InvokeDynamicWriter) {
+ mv.visitTypeInsn(CHECKCAST, "java/util/ArrayList");
+ }
Review Comment:
The CAST is currently gated on `instanceof InvokeDynamicWriter`, but a
constructor call can also be emitted via the non-indy
`CallSiteWriter.callConstructor(...)` path (declared to return `Object`) when
the controller is using `InvocationWriter` (non-indy) and not in a
statically-checked method. In that case the following `INVOKEVIRTUAL
java/util/ArrayList.add` would still see `Object` on the stack and can
VerifyError as well. Consider making the cast unconditional, or key it off the
actual stack/top operand type after `list.visit(visitor)` (e.g., if the top
operand isn’t `ArrayList_TYPE`, emit the CHECKCAST).
##########
src/test/groovy/bugs/Groovy11967.groovy:
##########
@@ -0,0 +1,122 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package bugs
+
+import org.junit.jupiter.api.Test
+
+import static groovy.test.GroovyAssert.assertScript
+
+/**
+ * Regression coverage for the synthesised lower-arity bridge constructor that
+ * {@code @CompileStatic} emits for a constructor with a default-valued list
+ * parameter. The bridge inlines the default {@code [...]} literal as
+ * {@code new ArrayList(n) + .add(...)}; in indy mode the constructor call
+ * returns {@code Object} on the JVM stack, so the {@code INVOKEVIRTUAL
+ * ArrayList.add} that follows must be preceded by a {@code CHECKCAST
ArrayList}
+ * to satisfy the verifier.
Review Comment:
The explanatory pseudo-code in the class Javadoc reads `new ArrayList(n) +
.add(...)`, which looks like an accidental `+` and could confuse readers.
Consider rephrasing it to reflect the actual bytecode shape (allocate `new
ArrayList(n)` then invoke one or more `add` calls).
```suggestion
* parameter. The bridge inlines the default {@code [...]} literal by
* allocating {@code new ArrayList(n)} and then invoking one or more
* {@code add(...)} calls; in indy mode the constructor call returns
* {@code Object} on the JVM stack, so the {@code INVOKEVIRTUAL
ArrayList.add}
* that follows must be preceded by a {@code CHECKCAST ArrayList} to satisfy
* the verifier.
```
##########
src/main/java/org/codehaus/groovy/transform/sc/transformers/ListExpressionTransformer.java:
##########
@@ -111,6 +113,13 @@ public void visit(final GroovyCodeVisitor visitor) {
var list = new ConstructorCallExpression(ArrayList_TYPE, new
ConstantExpression(getExpressions().size(), true));
list.putNodeMetaData(StaticTypesMarker.DIRECT_METHOD_CALL_TARGET,
ArrayList_NEW);
list.visit(visitor);
+ // GROOVY-11967: indy-mode constructor call leaves Object on
the JVM
+ // stack, so the following INVOKEVIRTUAL ArrayList.add needs a
CHECKCAST.
+ // Non-indy mode emits INVOKESPECIAL which already leaves
ArrayList on
+ // the stack, so the cast would be redundant — skip it there.
+ if (g.getController().getInvocationWriter() instanceof
InvokeDynamicWriter) {
+ mv.visitTypeInsn(CHECKCAST, "java/util/ArrayList");
Review Comment:
After emitting the `CHECKCAST`, the `OperandStack` model is still whatever
`list.visit(visitor)` left behind (likely `Object` when routed through
indy/call-site code). To keep subsequent static compilation/type-driven codegen
consistent, update the operand stack type to `ArrayList` (e.g. replace the top
operand) when the cast is inserted.
```suggestion
mv.visitTypeInsn(CHECKCAST, "java/util/ArrayList");
os.replace(ArrayList_TYPE);
```
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