GROOVY-10660: STC: infer closure parameter types from method return type

3_0_X backport
apache · Nov 30, 2023 · fdbd736 · fdbd736
1 parent 53f48ee
commit fdbd736
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Showing 2 changed files with 45 additions and 1 deletion.
diff --git a/src/main/java/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java b/src/main/java/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java
@@ -2219,11 +2219,15 @@ private void negativeOrPositiveUnary(final Expression expression, final String n
     @Override
     protected void visitConstructorOrMethod(final MethodNode node, final boolean isConstructor) {
         typeCheckingContext.pushEnclosingMethod(node);
+        final ClassNode returnType = node.getReturnType(); // GROOVY-10660: implicit return case
+        if (!isConstructor && (isClosureWithType(returnType) || isFunctionalInterface(returnType))) {
+            new ReturnAdder(returnStmt -> applyTargetType(returnType, returnStmt.getExpression())).visitMethod(node);
+        }
         if (!isSkipMode(node) && !shouldSkipMethodNode(node)) {
             super.visitConstructorOrMethod(node, isConstructor);
         }
         if (!isConstructor) {
-            returnAdder.visitMethod(node); // return statement added after visitConstructorOrMethod finished... we can not count these auto-generated return statements(GROOVY-7753), see `typeCheckingContext.pushEnclosingReturnStatement`
+            returnAdder.visitMethod(node); // GROOVY-7753: we cannot count these auto-generated return statements, see `typeCheckingContext.pushEnclosingReturnStatement`
         }
         typeCheckingContext.popEnclosingMethod();
     }
@@ -2237,6 +2241,12 @@ public void visitExpressionStatement(final ExpressionStatement statement) {
 
     @Override
     public void visitReturnStatement(final ReturnStatement statement) {
+        if (typeCheckingContext.getEnclosingClosure() == null) {
+            MethodNode method = typeCheckingContext.getEnclosingMethod();
+            if (method != null && !method.isVoidMethod() && !method.isDynamicReturnType()) {
+                applyTargetType(method.getReturnType(), statement.getExpression()); // GROOVY-10660
+            }
+        }
         super.visitReturnStatement(statement);
         returnListener.returnStatementAdded(statement);
     }

diff --git a/src/test/groovy/transform/stc/ClosureParamTypeInferenceSTCTest.groovy b/src/test/groovy/transform/stc/ClosureParamTypeInferenceSTCTest.groovy
@@ -712,6 +712,40 @@ class ClosureParamTypeInferenceSTCTest extends StaticTypeCheckingTestCase {
         '''
     }
 
+    void testGroovy10660() {
+        assertScript '''
+            <T> BiConsumer<String, List<T>> m(BiConsumer<String, ? super T> proc) {
+                // batch processor:
+                return { text, list ->
+                    for (item in list) proc.accept(text, item)
+                }
+            }
+
+            m { text, item -> }
+        '''
+
+        assertScript '''
+            <T> BiConsumer<String, List<T>> m(BiConsumer<String, ? super T> proc) {
+                // batch processor:
+                return (text, list) -> {
+                    for (item in list) proc.accept(text, item)
+                }
+            }
+
+            m((text, item) -> { })
+        '''
+
+        assertScript '''
+            <T> BiConsumer<String, List<T>> m(BiConsumer<String, ? super T> proc) {
+                /*implicit return*/ (text, list) -> {
+                    for (item in list) proc.accept(text, item)
+                }
+            }
+
+            m((text, item) -> { })
+        '''
+    }
+
     void testGroovy10673() {
         assertScript '''
             void proc(Consumer<Number> action) {