Add a test case

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/symbols/internal/ast/AstSymbolicAnnot.java

@@ -62,6 +62,7 @@ class AstSymbolicAnnot implements SymbolicValue.SymAnnot {
 
     @Override
     public boolean appliesToTypeUse() {
+        // todo look into whether hardcoding Override is good for perf, as it's very frequent
         return node.getTypeMirror().getSymbol().annotationAppliesTo(ElementType.TYPE_USE);
     }
 

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/types/TypeOps.java

@@ -117,19 +117,23 @@ public final class TypeOps {
         }
     }
 
-    public static boolean areSameTypes(List<JTypeMirror> ts, List<JTypeMirror> ss, boolean inInference) {
-        return areSameTypes(ts, ss, EMPTY, inInference, false);
+    public static boolean areSameTypes(List<JTypeMirror> ts, List<JTypeMirror> ss) {
+        return areSameTypes(ts, ss, EMPTY, false, false);
     }
 
-    public static boolean areSameTypes(List<JTypeMirror> ts, List<JTypeMirror> ss, boolean inInference, boolean considerAnnotations) {
+    public static boolean areSameTypesInInference(List<JTypeMirror> ts, List<JTypeMirror> ss) {
+        return areSameTypes(ts, ss, EMPTY, true, false);
+    }
+
+    private static boolean areSameTypes(List<JTypeMirror> ts, List<JTypeMirror> ss, boolean inInference, boolean considerAnnotations) {
         return areSameTypes(ts, ss, EMPTY, inInference, considerAnnotations);
     }
 
-    public static boolean areSameTypes(List<JTypeMirror> ts, List<JTypeMirror> ss, Substitution subst) {
+    private static boolean areSameTypes(List<JTypeMirror> ts, List<JTypeMirror> ss, Substitution subst) {
         return areSameTypes(ts, ss, subst, false, false);
     }
 
-    public static boolean areSameTypes(List<JTypeMirror> ts, List<JTypeMirror> ss, Substitution subst, boolean inInference, boolean considerAnnotations) {
+    private static boolean areSameTypes(List<JTypeMirror> ts, List<JTypeMirror> ss, Substitution subst, boolean inInference, boolean considerAnnotations) {
         if (ts.size() != ss.size()) {
             return false;
         }

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/types/TypeVarImpl.java

@@ -115,12 +115,15 @@ abstract class TypeVarImpl implements JTypeVar {
 
         @Override
         public JTypeVar withAnnotations(PSet<SymAnnot> newTypeAnnots) {
+            if (newTypeAnnots.isEmpty() && this.typeAnnots.isEmpty()) {
+                return this;
+            }
             return new RegularTypeVar(this, newTypeAnnots);
         }
 
         @Override
         public JTypeVar addAnnotation(@NonNull SymAnnot newAnnot) {
-            return new RegularTypeVar(this, typeAnnots.plus(newAnnot));
+            return withAnnotations(typeAnnots.plus(newAnnot));
         }
 
         @Override

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/types/internal/infer/ExprCheckHelper.java

@@ -5,7 +5,7 @@
 package net.sourceforge.pmd.lang.java.types.internal.infer;
 
 import static net.sourceforge.pmd.lang.java.types.TypeConversion.capture;
-import static net.sourceforge.pmd.lang.java.types.TypeOps.areSameTypes;
+import static net.sourceforge.pmd.lang.java.types.TypeOps.areSameTypesInInference;
 import static net.sourceforge.pmd.lang.java.types.TypeOps.asClassType;
 import static net.sourceforge.pmd.lang.java.types.TypeOps.findFunctionalInterfaceMethod;
 import static net.sourceforge.pmd.lang.java.types.TypeOps.mentionsAny;
@@ -539,7 +539,7 @@ final class ExprCheckHelper {
         // and the function type has parameter types G1, ..., Gn, then
         // i) for all i (1 ≤ i ≤ n), ‹Fi = Gi›
         if (lambda.isExplicitlyTyped()
-            && !areSameTypes(groundFun.getFormalParameters(), lambda.getExplicitParameterTypes(), true)) {
+            && !areSameTypesInInference(groundFun.getFormalParameters(), lambda.getExplicitParameterTypes())) {
             throw ResolutionFailedException.mismatchedLambdaParameters(infer.LOG, groundFun, lambda.getExplicitParameterTypes(), lambda);
         }
 

pmd-java/src/test/java/net/sourceforge/pmd/lang/java/JavaParsingHelper.java

@@ -96,6 +96,10 @@ public class JavaParsingHelper extends BaseParsingHelper<JavaParsingHelper, ASTC
         return new JavaParsingHelper(this.getParams(), this.semanticLogger, this.ts, logger);
     }
 
+    public JavaParsingHelper logTypeInferenceVerbose() {
+        return logTypeInference(true, System.out);
+    }
+
     @Override
     protected @NonNull JavaParsingHelper clone(@NonNull Params params) {
         return new JavaParsingHelper(params, semanticLogger, ts, typeInfLogger);

pmd-java/src/test/java/net/sourceforge/pmd/lang/java/types/TypesTreeDumpTest.java

@@ -15,6 +15,7 @@ import net.sourceforge.pmd.lang.ast.test.BaseTreeDumpTest;
 import net.sourceforge.pmd.lang.ast.test.RelevantAttributePrinter;
 import net.sourceforge.pmd.lang.java.JavaParsingHelper;
 import net.sourceforge.pmd.lang.java.ast.ASTAssignableExpr.ASTNamedReferenceExpr;
+import net.sourceforge.pmd.lang.java.ast.ASTMethodDeclaration;
 import net.sourceforge.pmd.lang.java.ast.ASTVariableDeclaratorId;
 import net.sourceforge.pmd.lang.java.ast.InvocationNode;
 import net.sourceforge.pmd.lang.java.ast.TypeNode;
@@ -71,6 +72,9 @@ class TypesTreeDumpTest extends BaseTreeDumpTest {
             if (node instanceof ASTVariableDeclaratorId) {
                 result.add(new AttributeInfo("Name", ((ASTVariableDeclaratorId) node).getName()));
             }
+            if (node instanceof ASTMethodDeclaration) {
+                result.add(new AttributeInfo("Name", ((ASTMethodDeclaration) node).getName()));
+            }
         }
 
         @Override

pmd-java/src/test/kotlin/net/sourceforge/pmd/lang/java/types/internal/infer/LambdaInferenceTest.kt

@@ -726,4 +726,43 @@ class NodeStream<T> {
         }
     }
 
+
+    parserTest("f:inference of call within lambda fails") {
+
+        val (acu, spy) = parser.logTypeInferenceVerbose().parseWithTypeInferenceSpy("""
+
+interface Iterator<Q> {}
+interface Function<U,V> { 
+    V apply(U u);
+}
+interface Iterable<Q> {
+    Iterator<Q> iterator();
+}
+
+class NodeStream {
+    
+    public static <T, R> Iterable<R> mapIterator(Iterable<? extends T> iter, Function<? super Iterator<? extends T>, ? extends Iterator<R>> mapper) {
+        return () -> mapper.apply(iter.iterator());
+    }
+
+}
+            """)
+
+        val (t_Iterator, t_Function, t_Iterable) = acu.declaredTypeSignatures()
+        val (lambda) = acu.descendants(ASTLambdaExpression::class.java).crossFindBoundaries().toList()
+        val (_, _, _, _, tvar, rvar) = acu.typeVariables()
+
+        spy.shouldBeOk {
+            lambda shouldHaveType t_Iterable[rvar]
+            lambda.expressionBody!!.shouldBeA<ASTMethodCall> {
+                it.methodType.shouldMatchMethod(
+                    named = "apply",
+                    withFormals = listOf(t_Iterator[`?` extends tvar])
+                )
+                it shouldHaveType t_Iterator[rvar]
+            }
+        }
+    }
+
+
 })

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/types/IteratorUtilCopy.java

@@ -3,8 +3,8 @@
  */
 
 
-package net.sourceforge.pmd.internal.util;
-
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Target;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -30,10 +30,13 @@ public final class IteratorUtilCopy {
     private static final int MATCH_ALL = 1;
     private static final int MATCH_NONE = 2;
 
-    private IteratorUtil() {
+    private IteratorUtilCopy() {
 
     }
 
+    @Target(ElementType.TYPE_USE)
+    @interface Nullable {}
+
     public static <T> Iterator<T> takeWhile(Iterator<T> iter, Predicate<? super T> predicate) {
         return new AbstractIterator<T>() {
             @Override
@@ -246,8 +249,6 @@ public final class IteratorUtilCopy {
 
 
     public static void advance(Iterator<?> iterator, int n) {
-        AssertionUtil.requireNonNegative("n", n);
-
         while (n > 0 && iterator.hasNext()) {
             iterator.next();
             n--;
@@ -256,7 +257,6 @@ public final class IteratorUtilCopy {
 
 
     public static <T> Iterator<T> take(Iterator<? extends T> iterator, final int n) {
-        AssertionUtil.requireNonNegative("n", n);
         if (n == 0) {
             return Collections.emptyIterator();
         }
@@ -278,7 +278,6 @@ public final class IteratorUtilCopy {
 
 
     public static <T> Iterator<T> drop(Iterator<? extends T> source, final int n) {
-        AssertionUtil.requireNonNegative("n", n);
         if (n == 0) {
             return (Iterator<T>) source;
         }