From 4e5b9e0f6574829e68a0ce96d73511eae6a459bd Mon Sep 17 00:00:00 2001
From: Stephan Herrmann <stephan.herrmann@berlin.de>
Date: Sun, 7 Apr 2024 22:58:21 +0200
Subject: [PATCH] Erroneous "Cannot infer type arguments" error
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fixes #1475

Implementation of JLS 15.9.3. failed to substitute an enclosing type in
 -  The return type of mj is θj applied to D<F1, ..., Fp>.
---
 .../jdt/internal/compiler/lookup/Scope.java   |  4 ++-
 .../GenericsRegressionTest_1_8.java           | 28 +++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/lookup/Scope.java b/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/lookup/Scope.java
index 3cecc776fd8..de06d99f68a 100644
--- a/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/lookup/Scope.java
+++ b/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/lookup/Scope.java
@@ -5382,7 +5382,9 @@ public TypeBinding substitute(TypeVariableBinding typeVariable) {
 						}
 				}
 			}
-			staticFactory.returnType = environment.createParameterizedType(genericType, Scope.substitute(substitution, genericType.typeVariables()), originalEnclosingType);
+			staticFactory.returnType = environment.createParameterizedType(genericType,
+					Scope.substitute(substitution, genericType.typeVariables()),
+					(ReferenceBinding) Scope.substitute(substitution, originalEnclosingType));
 			staticFactory.parameters = Scope.substitute(substitution, method.parameters);
 			staticFactory.thrownExceptions = Scope.substitute(substitution, method.thrownExceptions);
 			if (staticFactory.thrownExceptions == null) {
diff --git a/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/GenericsRegressionTest_1_8.java b/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/GenericsRegressionTest_1_8.java
index 4edc27eb36c..856b0c1d919 100644
--- a/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/GenericsRegressionTest_1_8.java
+++ b/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/GenericsRegressionTest_1_8.java
@@ -10682,4 +10682,32 @@ public int getWeaveCount() {
 			"----------\n",
 			null, true, customOptions);
 	}
+	public void testGH1475() {
+		runConformTest(
+			new String[] {
+				"CannotInferTypeArguments.java",
+				"""
+				public class CannotInferTypeArguments<V extends java.util.concurrent.Semaphore> {
+					class Fish {
+						public V getFlavour() {
+							return null;
+						}
+					}
+
+					class Shark<E extends Fish> {
+					}
+
+					<E extends Fish> Shark<E> fish() {
+						// This compiles fine with javac, but will only work in Eclipse with new Shark<E>();
+						return new Shark<>();
+					}
+
+					<E extends Fish> Shark<E> fish2() {
+						Shark<E> s = new Shark<>();
+						return s;
+					}
+				}
+				"""
+			});
+	}
 }