IAE at org.eclipse.jdt.core.Signature.encodeQualifiedName" on hyperlink request

org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/model/ResolveTests10.java

@@ -178,4 +178,72 @@ private void mat() {
 				selected
 			);
 	}
+
+
+	// https://github.com/eclipse-jdt/eclipse.jdt.core/issues/4218
+	// IAE at org.eclipse.jdt.core.Signature.encodeQualifiedName" on hyperlink request
+	public void testIssue4218() throws CoreException {
+		this.wc = getWorkingCopy("/Resolve/src/Test.java",
+		"""
+		@FunctionalInterface
+		interface Callable<V> {
+		    /**
+		     * Computes a result, or throws an exception if unable to do so.
+		     *
+		     * @return computed result
+		     * @throws Exception if unable to compute a result
+		     */
+		    V call() throws Exception;
+		}
+		public class Test {
+
+			public static <T> void createObjectBinding(final Callable<T> func) {
+				return;
+			}
+
+			sealed interface Index {
+				enum SS implements Index {}
+				enum TS implements Index {}
+			}
+
+			public abstract sealed class Entity<S extends Index> permits Struct, Time {}
+
+			final class Struct extends Entity<Index.SS> {}
+
+			final class Time extends Entity<Index.TS> {
+
+				Struct getStruct() {
+					return null;
+				}
+
+				public Object getOther() {
+					return null;
+				}
+			}
+
+			private <T> T createMap(Object other) {
+				return null;
+			}
+
+			private void setMaterials(Time entity) {
+				var selfIllumImage = createObjectBinding(() -> {
+						var entity2 = entity.getStruct() == null ? entity : entity.getStruct();
+						return createMap(entity.getOther());
+				});
+			}
+		}
+		""");
+		String str = this.wc.getSource();
+		String selection = "entity2";
+		int start = str.lastIndexOf(selection);
+		int length = selection.length();
+
+		IJavaElement[] selected = this.wc.codeSelect(start, length);
+		assertEquals(1, selected.length);
+		assertElementsEqual(
+				"Unexpected elements",
+				"entity2 [in call() [in <lambda #1> [in setMaterials(Time) [in Entity [in Test [in [Working copy] Test.java [in <default> [in src [in Resolve]]]]]]]]]",
+				selected
+			);
+	}
 }

org.eclipse.jdt.core/model/org/eclipse/jdt/core/Signature.java

@@ -1501,46 +1501,42 @@ private static int encodeTypeSignature(char[] typeName, int start, boolean isRes
 	    end = -1;
 	}
 	buffer.append(isResolved ? C_RESOLVED : C_UNRESOLVED);
-	while (true) { // loop on type[&type]*
-		while (true) { // loop on qualifiedName[<args>][.qualifiedName[<args>]*
-		    pos = encodeQualifiedName(typeName, pos, length, buffer);
-			checkPos = checkNextChar(typeName, '<', pos, length, true);
-			if (checkPos > 0) {
-				buffer.append(C_GENERIC_START);
-				// Stop gap fix for <>.
-				if ((pos = checkNextChar(typeName, '>', checkPos, length, true)) > 0) {
-					buffer.append(C_GENERIC_END);
-				} else {
+
+	while (true) { // loop on qualifiedName[<args>][.qualifiedName[<args>]*
+	    pos = encodeQualifiedName(typeName, pos, length, buffer);
+		checkPos = checkNextChar(typeName, '<', pos, length, true);
+		if (checkPos > 0) {
+			buffer.append(C_GENERIC_START);
+			// Stop gap fix for <>.
+			if ((pos = checkNextChar(typeName, '>', checkPos, length, true)) > 0) {
+				buffer.append(C_GENERIC_END);
+			} else {
+				pos = encodeTypeSignature(typeName, checkPos, isResolved, length, buffer);
+				while ((checkPos = checkNextChar(typeName, ',', pos, length, true)) > 0) {
 					pos = encodeTypeSignature(typeName, checkPos, isResolved, length, buffer);
-					while ((checkPos = checkNextChar(typeName, ',', pos, length, true)) > 0) {
-						pos = encodeTypeSignature(typeName, checkPos, isResolved, length, buffer);
-					}
-					pos = checkNextChar(typeName, '>', pos, length, false);
-					buffer.append(C_GENERIC_END);
 				}
-			}
-			checkPos = checkNextChar(typeName, '.', pos, length, true);
-			if (checkPos > 0) {
-				buffer.append(C_DOT);
-				pos = checkPos;
-			} else {
-				break;
+				pos = checkNextChar(typeName, '>', pos, length, false);
+				buffer.append(C_GENERIC_END);
 			}
 		}
-		buffer.append(C_NAME_END);
-		checkPos = checkNextChar(typeName, '&', pos, length, true);
+		checkPos = checkNextChar(typeName, '.', pos, length, true);
 		if (checkPos > 0) {
-			if (buffer.charAt(0) != C_UNION) // the constant name is wrong, its value is correct :-X
-				buffer.insert(0, C_UNION);
-			buffer.append(C_COLON);
-			pos = encodeTypeSignature(typeName, checkPos, isResolved, length, buffer);
-			if (pos == length) {
-				break;
-			}
+			buffer.append(C_DOT);
+			pos = checkPos;
 		} else {
 			break;
 		}
 	}
+	buffer.append(C_NAME_END);
+	while ((checkPos = checkNextChar(typeName, '&', pos, length, true)) > 0) {
+		if (buffer.charAt(0) != C_UNION) // the constant name is wrong, its value is correct :-X
+			buffer.insert(0, C_UNION);
+		buffer.append(C_COLON);
+		pos = encodeTypeSignature(typeName, checkPos, isResolved, length, buffer);
+		if (pos == length) {
+			break;
+		}
+	}
 	if (end > 0) pos = end; // skip array dimension which were preprocessed
     return pos;
 }