missing pieces in the AST: parser seems to skip broken annotation

altogether when on method parameters

recover incomplete annotation on argument

fixes eclipse-jdt#3155

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/parser/RecoveredMethod.java

@@ -97,6 +97,10 @@ public RecoveredElement add(Block nestedBlockDeclaration, int bracketBalanceValu
  */
 @Override
 public RecoveredElement add(FieldDeclaration fieldDeclaration, int bracketBalanceValue) {
+	if (recoverAsArgument(fieldDeclaration)) {
+		resetPendingModifiers();
+		return this;
+	}
 	resetPendingModifiers();
 
 	/* local variables inside method can only be final and non void */
@@ -133,6 +137,27 @@ public RecoveredElement add(FieldDeclaration fieldDeclaration, int bracketBalanc
 	// still inside method, treat as local variable
 	return this; // ignore
 }
+
+private boolean recoverAsArgument(FieldDeclaration fieldDeclaration) {
+	if (!this.foundOpeningBrace
+			&& this.methodDeclaration.declarationSourceEnd == 0
+			&& this.methodDeclaration.arguments == null) { // misparsed parameter?
+		long position = ((long) fieldDeclaration.sourceStart << 32)+fieldDeclaration.sourceEnd;
+		Argument arg = new Argument(fieldDeclaration.name, position, fieldDeclaration.type, fieldDeclaration.modifiers);
+		this.methodDeclaration.arguments = new Argument[] { arg };
+		int annotCount = this.pendingAnnotationCount;
+		if (this.pendingAnnotations != null) {
+			arg.annotations = new Annotation[annotCount];
+			for (int i = 0; i < this.pendingAnnotationCount; i++) {
+				arg.annotations[i] = this.pendingAnnotations[i].annotation;
+				if (i == 0)
+					arg.declarationSourceStart = arg.annotations[i].sourceStart;
+			}
+		}
+		return true;
+	}
+	return false;
+}
 /*
  * Record a local declaration - regular method should have been created a block body
  */

org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/dom/ASTConverterRecoveryTest.java

@@ -1085,4 +1085,39 @@ public void test0021() throws JavaModelException {
 			List statements = block.statements();
 			assertEquals("wrong size", 0, statements.size()); //$NON-NLS-1$
 		}
+
+	public void testGH3155() throws JavaModelException {
+		this.workingCopies = new ICompilationUnit[1];
+		this.workingCopies[0] = getWorkingCopy(
+			"/Converter18/src/test/TestDependsOnClass.java",
+			"""
+			package test;
+			public class TestDependsOnClass {
+				public TestDependsOnClass(@Qualifier(value= ) Object mybean) { }
+			}
+			""");
+		ASTNode result = runConversion(getJLS8(), this.workingCopies[0], true, true);
+
+		assertASTNodeEquals(
+			"""
+			package test;
+			public class TestDependsOnClass {
+			  public TestDependsOnClass(  @Qualifier(value=$missing$) Object mybean){
+			  }
+			}
+			""",
+			result);
+
+		ASTNode node = getASTNode((CompilationUnit) result, 0, 0);
+		assertNotNull(node);
+		assertTrue("Not a method declaration", node.getNodeType() == ASTNode.METHOD_DECLARATION); //$NON-NLS-1$
+		MethodDeclaration methodDeclaration = (MethodDeclaration) node;
+		assertTrue(methodDeclaration.isConstructor());
+		assertEquals(1, methodDeclaration.parameters().size());
+		SingleVariableDeclaration param = (SingleVariableDeclaration) methodDeclaration.parameters().get(0);
+		assertEquals(1, param.modifiers().size());
+		IExtendedModifier mod = (IExtendedModifier) param.modifiers().get(0);
+		assertTrue(mod.isAnnotation());
+		assertEquals("Qualifier", ((Annotation) mod).getTypeName().toString());
+	}
 }