More error/NPE fixes in completion

- handle completing package-qualified method parameter type
- do not suggest overriding existing or declaring new methods in
  annotation type declarations
- when building override method completions, if the `IMethod` of a given
  method binding cannot be found, use the parameter names from
  the bindings instead
- prevent NPE when attempting to suggest completion for a method with
  an incomplete parameter type

Signed-off-by: David Thompson <[email protected]>

Author: datho7561

org.eclipse.jdt.core.javac/src/org/eclipse/jdt/internal/codeassist/DOMCompletionEngine.java

@@ -805,7 +805,9 @@ public void complete(org.eclipse.jdt.internal.compiler.env.ICompilationUnit sour
 						typeDeclBinding = ((AnonymousClassDeclaration)simpleType.getParent().getParent()).resolveBinding();
 					}
 
-					findOverridableMethods(typeDeclBinding, this.javaProject, context);
+					if (!typeDeclBinding.isAnnotation()) {
+						findOverridableMethods(typeDeclBinding, this.javaProject, context);
+					}
 					suggestClassDeclarationLikeKeywords();
 					suggestTypeKeywords(true);
 					suggestModifierKeywords(bodyDeclaration.getModifiers());
@@ -829,7 +831,7 @@ public void complete(org.eclipse.jdt.internal.compiler.env.ICompilationUnit sour
 							})
 							.map(this::toProposal).forEach(this.requestor::accept);
 					}
-					if (!this.requestor.isIgnored(CompletionProposal.POTENTIAL_METHOD_DECLARATION)) {
+					if (!this.requestor.isIgnored(CompletionProposal.POTENTIAL_METHOD_DECLARATION) && !typeDeclBinding.isAnnotation()) {
 						int cursorStart = this.offset - this.prefix.length() - 1;
 						while (cursorStart > 0 && Character.isWhitespace(this.textContent.charAt(cursorStart))) {
 							cursorStart--;
@@ -1172,7 +1174,7 @@ public void complete(org.eclipse.jdt.internal.compiler.env.ICompilationUnit sour
 
 						suggestDefaultCompletions = false;
 					} else if (qualifiedNameBinding instanceof IPackageBinding qualifierPackageBinding) {
-						if (!qualifierPackageBinding.isRecovered()) {
+						if (!qualifierPackageBinding.isRecovered() || (qualifiedName.getParent() instanceof Type && qualifiedName.getParent().getParent() instanceof VariableDeclaration)) {
 							// start of a known package
 							suggestPackages(null);
 							// suggests types in the package
@@ -3532,7 +3534,11 @@ private void findOverridableMethods0(ITypeBinding currentType, ITypeBinding type
 			proposal.setSignature(SignatureUtils.getSignatureChar(method));
 
 			try {
-				proposal.setParameterNames(Stream.of(((IMethod)method.getJavaElement()).getParameterNames()).map(name -> name.toCharArray()).toArray(char[][]::new));
+				if (method.getJavaElement() != null) {
+					proposal.setParameterNames(Stream.of(((IMethod)method.getJavaElement()).getParameterNames()).map(name -> name.toCharArray()).toArray(char[][]::new));
+				} else {
+					proposal.setParameterNames(Stream.of(method.getParameterNames()).map(name -> name.toCharArray()).toArray(char[][]::new));
+				}
 			} catch (JavaModelException e) {
 				proposal.setParameterNames(Stream.of(method.getParameterNames()).map(name -> name.toCharArray()).toArray(char[][]::new));
 			}
@@ -3794,10 +3800,10 @@ public void acceptTypeNameMatch(TypeNameMatch match) {
 				.map(t -> processMembers(t, searchEngine, scope))
 				.flatMap(Function.identity()));
 	}
-
+	
 	private String getSignature(IMethodBinding method) {
 		return method.getName() + '(' +
-				Arrays.stream(method.getParameterTypes()).map(ITypeBinding::getName).collect(Collectors.joining(","))
+				Arrays.stream(method.getParameterTypes()).map(paramType -> paramType != null ? paramType.getName() : "Object").collect(Collectors.joining(","))
 				+ ')';
 	}
 

org.eclipse.jdt.core.javac/src/org/eclipse/jdt/internal/codeassist/DOMCompletionEngineBuilder.java

@@ -73,7 +73,11 @@ static void createMethod(IMethodBinding methodBinding, StringBuilder completion,
 		ITypeBinding[] parameterTypes = methodBinding.getParameterTypes();
 		String[] parameterNames;
 		try {
-			parameterNames = ((IMethod)methodBinding.getJavaElement()).getParameterNames();
+			if (methodBinding.getJavaElement() != null) {
+				parameterNames = ((IMethod)methodBinding.getJavaElement()).getParameterNames();
+			} else {
+				parameterNames = methodBinding.getParameterNames();
+			}
 		} catch (JavaModelException e) {
 			parameterNames = methodBinding.getParameterNames();
 		}

org.eclipse.jdt.core.javac/src/org/eclipse/jdt/internal/codeassist/SignatureUtils.java

@@ -123,15 +123,15 @@ public static char[] getSignatureChar(ITypeBinding typeBinding) {
 	public static String getSignatureForTypeKey(String key) {
 		return key.replace('/', '.').replaceFirst("(?<=\\.|L)[_$A-Za-z][_$A-Za-z0-9]*~", "");
 	}
-
+	
 	/**
 	 * Returns the signature of the given method binding as a character array.
 	 *
 	 * @param methodBinding the method binding to get the signature of
 	 * @return the signature of the given method binding as a character array
 	 */
 	public static char[] getSignatureChar(IMethodBinding methodBinding) {
-		return SignatureUtils.getSignatureForMethodKey(methodBinding.getKey()).toCharArray();
+		return getSignatureForMethodKey(methodBinding.getKey()).toCharArray();
 	}
 
 	/**