diff --git a/org.eclipse.jdt.core/codeassist/org/eclipse/jdt/internal/codeassist/DOMCodeSelector.java b/org.eclipse.jdt.core/codeassist/org/eclipse/jdt/internal/codeassist/DOMCodeSelector.java
index fafdcb31a64..ec77e07170a 100644
--- a/org.eclipse.jdt.core/codeassist/org/eclipse/jdt/internal/codeassist/DOMCodeSelector.java
+++ b/org.eclipse.jdt.core/codeassist/org/eclipse/jdt/internal/codeassist/DOMCodeSelector.java
@@ -60,7 +60,7 @@ public IJavaElement[] codeSelect(int offset, int length) throws JavaModelExcepti
 		if (offset + length > this.unit.getSource().length()) {
 			throw new JavaModelException(new IndexOutOfBoundsException(offset + length), IJavaModelStatusConstants.INDEX_OUT_OF_BOUNDS);
 		}
-		org.eclipse.jdt.core.dom.CompilationUnit currentAST = this.unit.getOrBuildAST(this.owner);
+		org.eclipse.jdt.core.dom.CompilationUnit currentAST = this.unit.getOrBuildAST(this.owner, this.unit.getBuffer().getLength() < 50000 ? -1 : offset);
 		if (currentAST == null) {
 			return new IJavaElement[0];
 		}
@@ -197,6 +197,10 @@ public IJavaElement[] codeSelect(int offset, int length) throws JavaModelExcepti
 				return reorderedOverloadedMethods;
 			}
 			return new IJavaElement[] { importBinding.getJavaElement() };
+		} else if (node instanceof MethodDeclaration decl && offset > decl.getName().getStartPosition()) {
+			// most likely inside and empty `()`
+			// case for TypeHierarchyCommandTest.testTypeHierarchy()
+			return null;
 		} else if (findTypeDeclaration(node) == null) {
 			IBinding binding = resolveBinding(node);
 			if (binding != null && !binding.isRecovered()) {
@@ -372,7 +376,7 @@ public IJavaElement[] codeSelect(int offset, int length) throws JavaModelExcepti
 		return new IJavaElement[0];
 	}
 
-	static IBinding resolveBinding(ASTNode node) {
+	public static IBinding resolveBinding(ASTNode node) {
 		if (node instanceof MethodDeclaration decl) {
 			return decl.resolveBinding();
 		}
@@ -450,7 +454,7 @@ static IBinding resolveBinding(ASTNode node) {
 				}
 				IMethod methodModel = ((IMethod)methodBinding.getJavaElement());
 				boolean allowExtraParam = true;
-				if ((methodModel.getFlags() & Flags.AccStatic) != 0) {
+				if (methodModel != null && (methodModel.getFlags() & Flags.AccStatic) != 0) {
 					allowExtraParam = false;
 					if (methodRef.getExpression() instanceof ClassInstanceCreation) {
 						return null;
@@ -463,15 +467,21 @@ static IBinding resolveBinding(ASTNode node) {
 				while (type == null && cursor != null) {
 					if (cursor.getParent() instanceof VariableDeclarationFragment declFragment) {
 						type = declFragment.resolveBinding().getType();
-					}
-					else if (cursor.getParent() instanceof MethodInvocation methodInvocation) {
+					} else if (cursor.getParent() instanceof MethodInvocation methodInvocation) {
 						IMethodBinding methodInvocationBinding = methodInvocation.resolveMethodBinding();
-						int index = methodInvocation.arguments().indexOf(cursor);
-						type = methodInvocationBinding.getParameterTypes()[index];
+						if (methodInvocationBinding != null) {
+							int index = methodInvocation.arguments().indexOf(cursor);
+							type = methodInvocationBinding.getParameterTypes()[index];
+						} else {
+							cursor = null;
+						}
 					} else {
 						cursor = cursor.getParent();
 					}
 				}
+				if (type == null) {
+					return null;
+				}
 
 				IMethodBinding boundMethod = type.getDeclaredMethods()[0];
 
@@ -562,6 +572,9 @@ private static boolean matchSignatures(IMethodBinding invocation, IMethodBinding
 	}
 
 	private IJavaElement[] findTypeInIndex(String packageName, String simpleName) throws JavaModelException {
+		if (simpleName == null) {
+			return new IJavaElement[0];
+		}
 		List<IType> indexMatch = new ArrayList<>();
 		TypeNameMatchRequestor requestor = new TypeNameMatchRequestor() {
 			@Override
diff --git a/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/CompilationUnit.java b/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/CompilationUnit.java
index b276422e750..e40405634f5 100644
--- a/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/CompilationUnit.java
+++ b/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/CompilationUnit.java
@@ -172,6 +172,10 @@ protected boolean buildStructure(OpenableElementInfo info, final IProgressMonito
 		ASTNode dom = null;
 		try {
 			dom = astParser.createAST(pm);
+			if (computeProblems) {
+				// force resolution of bindings to load more problems
+				dom.getAST().resolveWellKnownType(Object.class.getName());
+			}
 		} catch (AbortCompilationUnit e) {
 			var problem = e.problem;
 			if (problem == null && e.exception instanceof IOException ioEx) {
@@ -472,12 +476,14 @@ public IJavaElement[] codeSelect(int offset, int length, WorkingCopyOwner workin
 	}
 }
 
-public org.eclipse.jdt.core.dom.CompilationUnit getOrBuildAST(WorkingCopyOwner workingCopyOwner) throws JavaModelException {
+public org.eclipse.jdt.core.dom.CompilationUnit getOrBuildAST(WorkingCopyOwner workingCopyOwner, int focalPosition) throws JavaModelException {
 	if (this.ast != null) {
 		return this.ast;
 	}
 	Map<String, String> options = getOptions(true);
 	ASTParser parser = ASTParser.newParser(new AST(options).apiLevel()); // go through AST constructor to convert options to apiLevel
+	// but we should probably instead just use the latest Java version
+	// supported by the compiler
 	parser.setWorkingCopyOwner(workingCopyOwner);
 	parser.setSource(this);
 	// greedily enable everything assuming the AST will be used extensively for edition
@@ -485,7 +491,12 @@ public org.eclipse.jdt.core.dom.CompilationUnit getOrBuildAST(WorkingCopyOwner w
 	parser.setStatementsRecovery(true);
 	parser.setBindingsRecovery(true);
 	parser.setCompilerOptions(options);
+	parser.setFocalPosition(focalPosition);
 	if (parser.createAST(null) instanceof org.eclipse.jdt.core.dom.CompilationUnit newAST) {
+		if (focalPosition >= 0) {
+			// do not store
+			return newAST;
+		}
 		this.ast = newAST;
 	}
 	return this.ast;