Reduce b2 when reducing ConstraintExpressionFormula (#4315)

Fixes #4314
---------
Co-authored-by: Stephan Herrmann <[email protected]>

Author: coehlrich

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

@@ -132,6 +132,13 @@ public Object reduce(InferenceContext18 inferenceContext) throws InferenceFailur
 						inferenceContext.inferenceKind = inferenceContext.getInferenceKind(previousMethod, argumentTypes);
 						boolean isDiamond = method.isConstructor() && this.left.isPolyExpression(method);
 						inferInvocationApplicability(inferenceContext, method, argumentTypes, isDiamond, inferenceContext.inferenceKind);
+						try {
+							CapturingContext.enter(invocation.sourceStart(), invocation.sourceEnd(), inferenceContext.scope);
+							if (!inferenceContext.reduce())
+								return FALSE;
+						} finally {
+							CapturingContext.leave();
+						}
 						// b2 has been lifted, inferring poly invocation type amounts to lifting b3.
 					}
 					if (!inferenceContext.computeB3(invocation, this.right, method))

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

@@ -1074,7 +1074,7 @@ private boolean siSubI(TypeBinding si, TypeBinding funcI) {
 	/**
 	 * JLS 18.2. reduce all initial constraints
 	 */
-	private boolean reduce() throws InferenceFailureException {
+	public boolean reduce() throws InferenceFailureException {
 		// Caution: This can be reentered recursively even as an earlier call is munching through the constraints !
 		for (int i = 0; this.initialConstraints != null && i < this.initialConstraints.length; i++) {
 			final ConstraintFormula currentConstraint = this.initialConstraints[i];

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

@@ -1180,7 +1180,9 @@ Excuse excuseFor(JavacCompiler compiler) {
 			JavacBug8348928 = // https://bugs.openjdk.org/browse/JDK-8348928
 					new JavacHasABug(MismatchType.EclipseErrorsJavacWarnings),
 			JavacBug8348410 = // https://bugs.openjdk.org/browse/JDK-8348410
-					new JavacHasABug(MismatchType.EclipseErrorsJavacNone, ClassFileConstants.JDK25, 0000);
+					new JavacHasABug(MismatchType.EclipseErrorsJavacNone, ClassFileConstants.JDK25, 0000),
+			JavacBug8016196 = // https://bugs.openjdk.org/browse/JDK-8016196
+					new JavacHasABug(MismatchType.JavacErrorsEclipseNone);
 
 
 		// bugs that have been fixed but that we've not identified

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

@@ -42,6 +42,7 @@
 import java.util.Map;
 import junit.framework.Test;
 import org.eclipse.jdt.core.JavaCore;
+import org.eclipse.jdt.core.tests.compiler.regression.AbstractRegressionTest.JavacTestOptions.JavacHasABug;
 import org.eclipse.jdt.internal.compiler.classfmt.ClassFileConstants;
 import org.eclipse.jdt.internal.compiler.impl.CompilerOptions;
 
@@ -6974,5 +6975,88 @@ protected void run() {
 		}
 	);
 }
+
+public void testGH4314() {
+    runConformTest(new String[] {
+            "Test.java",
+            """
+            import java.util.function.Function;
+
+            public class Test {
+
+                public static void main(String[] args) {
+                    m(
+                            i -> new A<>(i),
+                            b -> b.intValue());
+                }
+
+                private static <T, R> void m(Function<Integer, A<T>> f1, Function<T, R> f2) {}
+                private static class A<T> {
+                    public A(T t) {}
+                }
+            }
+            """
+    });
+}
+public void testGH4314b() {
+	if (this.complianceLevel < ClassFileConstants.JDK22)
+		return; // uses unnamed lambda param
+	Runner runner = new Runner();
+	runner.testFiles = new String[] {
+			"Test.java",
+			"""
+			import java.util.function.Function;
+			public class Test {
+				public static void main(String[] args) {
+					C<B<?>> c = null;
+					m(
+							_ -> new A<>(c),
+							b -> b.intValue());
+				}
+				static <T, R> void m(Function<B<Number>, A<T>> f1, Function<T, R> f2) {}
+				static class A<U> {
+					public A(C<? extends C<U>> t) {}
+				}
+				record B<V extends Number>(V t) implements C<V> {
+
+				}
+				interface C<W> {
+					W t();
+				}
+			}
+			"""
+		};
+	runner.javacTestOptions = JavacHasABug.JavacBug8016196;
+	runner.runConformTest();
+}
+public void testGH4314c() {
+	if (this.complianceLevel < ClassFileConstants.JDK22)
+		return; // uses unnamed lambda param
+	runConformTest(new String[] {
+			"Test.java",
+			"""
+			import java.util.function.Function;
+			public class Test {
+				public static void main(String[] args) {
+					C<B<?>> c = null;
+					m(
+							_ -> new A<>(c),
+							b -> b.intValue());
+				}
+				static <T, R> void m(Function<B<Number>, A<T>> f1, Function<T, R> f2) {}
+				static class A<U> {
+					public A(C<? extends C<? extends U>> t) {}
+				}
+				record B<V extends Number>(V t) implements C<V> {
+
+				}
+				interface C<W> {
+					W t();
+				}
+			}
+			"""
+		},
+		"");
+}
 }
 

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

@@ -10581,33 +10581,17 @@ public void process() {
 				"""
 			},
 			"----------\n" +
-			"1. ERROR in TestMe.java (at line 15)\n" +
-			"	future = active.thenComposeAsync(recording -> {\n" +
-			"				recording.stop().run();\n" +
-			"// This code (should) have compile errors but instead triggers ClassCastException\n" +
-			"\n" +
-			"				return update().handleAsync(() -> recording.process());\n" +
-			"\n" +
-			"// Deleting the line and using this code would work\n" +
-			"//				return update().handleAsync((a, b) -> {\n" +
-			"//					recording.process();\n" +
-			"//					return null;\n" +
-			"//				});\n" +
-			"			});\n" +
-			"	         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n" +
-			"Type mismatch: cannot convert from CompletableFuture<Object> to CompletableFuture<Void>\n" +
-			"----------\n" +
-			"2. ERROR in TestMe.java (at line 19)\n" +
+			"1. ERROR in TestMe.java (at line 19)\n" +
 			"	return update().handleAsync(() -> recording.process());\n" +
 			"	                ^^^^^^^^^^^\n" +
 			"The method handleAsync(BiFunction<? super capture#1-of ?,Throwable,? extends U>) in the type CompletableFuture<capture#1-of ?> is not applicable for the arguments (() -> {})\n" +
 			"----------\n" +
-			"3. ERROR in TestMe.java (at line 19)\n" +
+			"2. ERROR in TestMe.java (at line 19)\n" +
 			"	return update().handleAsync(() -> recording.process());\n" +
 			"	                            ^^^^^^^^^^^^^^^^^^^^^^^^^\n" +
 			"Lambda expression's signature does not match the signature of the functional interface method apply(? super capture#1-of ?, Throwable)\n" +
 			"----------\n" +
-			"4. ERROR in TestMe.java (at line 19)\n" +
+			"3. ERROR in TestMe.java (at line 19)\n" +
 			"	return update().handleAsync(() -> recording.process());\n" +
 			"	                                  ^^^^^^^^^^^^^^^^^^^\n" +
 			"Cannot return a void result\n" +