Incorrect overload resolution ends in type error. (#3515)

+ record when Poly*Method is part of a set of overloads
  + in that case don't propagate premature bounds inner -> outer

Fixes #2941

Author: stephan-herrmann

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/lookup/InferenceContext18.java

@@ -691,6 +691,8 @@ private boolean addConstraintsToC_OneExpr(Expression expri, Set<ConstraintFormul
 			MethodBinding innerMethod = invocation.binding();
 			if (innerMethod == null)
 				return true; 		  // -> proceed with no new C set elements.
+			if (innerMethod instanceof PolyParameterizedGenericMethodBinding poly && poly.hasOverloads)
+				return true;		  // don't let ambiguous inner method influence outer inference
 
 			Expression[] arguments = invocation.arguments();
 			TypeBinding[] argumentTypes = arguments == null ? Binding.NO_PARAMETERS : new TypeBinding[arguments.length];

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/lookup/PolyParameterizedGenericMethodBinding.java

@@ -15,6 +15,8 @@
 
 public class PolyParameterizedGenericMethodBinding extends ParameterizedGenericMethodBinding { // confused citizen.
 
+	public boolean hasOverloads;
+
 	private final ParameterizedGenericMethodBinding wrappedBinding;
 	public PolyParameterizedGenericMethodBinding(ParameterizedGenericMethodBinding applicableMethod) {
 		super(applicableMethod.originalMethod, applicableMethod.typeArguments, applicableMethod.environment, applicableMethod.inferredWithUncheckedConversion, false,  applicableMethod.targetType);

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/lookup/ProblemMethodBinding.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2018 IBM Corporation and others.
+ * Copyright (c) 2000, 2025 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -38,14 +38,19 @@ public ProblemMethodBinding(char[] selector, TypeBinding[] args, ReferenceBindin
 public ProblemMethodBinding(MethodBinding closestMatch, char[] selector, TypeBinding[] args, int problemReason) {
 	this(selector, args, problemReason);
 	this.closestMatch = closestMatch;
-	if (closestMatch != null && problemReason != ProblemReasons.Ambiguous) {
-		this.declaringClass = closestMatch.declaringClass;
-		this.returnType = closestMatch.returnType;
-		if (problemReason == ProblemReasons.InvocationTypeInferenceFailure || problemReason == ProblemReasons.ContradictoryNullAnnotations) {
-			this.thrownExceptions = closestMatch.thrownExceptions;
-			this.typeVariables = closestMatch.typeVariables;
-			this.modifiers = closestMatch.modifiers;
-			this.tagBits = closestMatch.tagBits;
+	if (problemReason == ProblemReasons.Ambiguous) {
+		if (closestMatch instanceof PolyParameterizedGenericMethodBinding poly)
+			poly.hasOverloads = true;
+	} else {
+		if (closestMatch != null) {
+			this.declaringClass = closestMatch.declaringClass;
+			this.returnType = closestMatch.returnType;
+			if (problemReason == ProblemReasons.InvocationTypeInferenceFailure || problemReason == ProblemReasons.ContradictoryNullAnnotations) {
+				this.thrownExceptions = closestMatch.thrownExceptions;
+				this.typeVariables = closestMatch.typeVariables;
+				this.modifiers = closestMatch.modifiers;
+				this.tagBits = closestMatch.tagBits;
+			}
 		}
 	}
 }

org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/OverloadResolutionTest8.java

@@ -2722,4 +2722,68 @@ public void test482440b() {
 			"}\n"
 		});
 }
+public void testGH2941_a() {
+	runConformTest(
+		new String[] {
+			"BiStream.java",
+			"""
+			import static java.util.stream.Collectors.collectingAndThen;
+
+			import java.util.function.Function;
+			import java.util.stream.Collector;
+			import java.util.stream.Stream;
+
+			public abstract class BiStream<K, V> {
+			  public static <E, K, V> Collector<E, ?, BiStream<K, V>> toBiStream(
+			      Function<? super E, ? extends K> toKey, Function<? super E, ? extends V> toValue) {
+			    return collectingAndThen(toStream(), stream -> from(stream));
+			  }
+
+			  private static <T> Collector<T, ?, Stream<T>> toStream() {
+			    return null;
+			  }
+
+			  public static <T, K, V> BiStream<K, V> from(Iterable<T> elements) {
+			    return null;
+			  }
+
+			  public static <T, K, V> BiStream<K, V> from(Stream<T> stream) {
+			    return null;
+			  }
+			}
+			"""
+		});
+}
+public void testGH2941_b() {
+	runConformTest(
+		new String[] {
+			"BiStream.java",
+			"""
+			import static java.util.stream.Collectors.collectingAndThen;
+
+			import java.util.function.Function;
+			import java.util.stream.Collector;
+			import java.util.stream.Stream;
+
+			public abstract class BiStream<K, V> {
+			  public static <E, K, V> Collector<E, ?, BiStream<K, V>> toBiStream(
+			      Function<? super E, ? extends K> toKey, Function<? super E, ? extends V> toValue) {
+			    return collectingAndThen(toStream(), stream -> from(stream));
+			  }
+
+			  private static <T> Collector<T, ?, Stream<T>> toStream() {
+			    return null;
+			  }
+
+			  public static <T, K, V> BiStream<K, V> from(Stream<T> stream) {
+			    return null;
+			  }
+
+			  public static <T, K, V> BiStream<K, V> from(Iterable<T> elements) {
+			    return null;
+			  }
+			}
+			"""
+		});
+}
 }