Safely check all array accesses (#749)

Author: danez

.eslintrc.cjs

@@ -56,6 +56,7 @@ module.exports = {
         '@typescript-eslint/ban-ts-comment': 'off',
         '@typescript-eslint/consistent-type-imports': 'error',
         '@typescript-eslint/no-duplicate-imports': 'error',
+        '@typescript-eslint/no-non-null-assertion': 'off',
         '@typescript-eslint/sort-type-union-intersection-members': 'error',
       },
     },

packages/react-docgen-cli/src/commands/parse/options/loadReactDocgenPlugin.ts

@@ -7,7 +7,7 @@ export default async function loadReactDocgenPlugin<T>(
   builtins?: Record<string, T>,
 ): Promise<T> {
   if (builtins?.[input]) {
-    return builtins[input];
+    return builtins[input]!;
   }
 
   const path = resolve(process.cwd(), input);

packages/react-docgen-cli/src/commands/parse/options/loadResolvers.ts

@@ -54,5 +54,5 @@ export default async function loadResolvers(
     });
   }
 
-  return loadResolver(input[0]);
+  return loadResolver(input[0]!);
 }

packages/react-docgen/src/handlers/componentMethodsHandler.ts

@@ -103,7 +103,7 @@ const explodedImperativeHandleVisitors =
         // useImperativeHandle(ref, () => ({ name: () => {}, ...}))
         const arg = path.get('arguments')[1];
 
-        if (arg && !arg.isFunction()) {
+        if (!arg || !arg.isFunction()) {
           return path.skip();
         }
 

packages/react-docgen/src/resolver/FindAllDefinitionsResolver.ts

@@ -53,20 +53,24 @@ const explodedVisitors = visitors.explode<TraverseState>({
   ClassDeclaration: { enter: classVisitor },
   CallExpression: {
     enter: function (path, state): void {
+      const argument = path.get('arguments')[0];
+
+      if (!argument) {
+        return;
+      }
+
       if (isReactForwardRefCall(path)) {
         // If the the inner function was previously identified as a component
         // replace it with the parent node
-        const inner = resolveToValue(
-          path.get('arguments')[0],
-        ) as ComponentNodePath;
+        const inner = resolveToValue(argument) as ComponentNodePath;
 
         state.foundDefinitions.delete(inner);
         state.foundDefinitions.add(path);
 
         // Do not traverse into arguments
         return path.skip();
       } else if (isReactCreateClassCall(path)) {
-        const resolvedPath = resolveToValue(path.get('arguments')[0]);
+        const resolvedPath = resolveToValue(argument);
 
         if (resolvedPath.isObjectExpression()) {
           state.foundDefinitions.add(resolvedPath);

packages/react-docgen/src/utils/docblock.ts

@@ -35,7 +35,7 @@ export function getDocblock(path: NodePath, trailing = false): string | null {
   }
 
   if (comments.length > 0) {
-    return parseDocblock(comments[comments.length - 1].value);
+    return parseDocblock(comments[comments.length - 1]!.value);
   }
 
   return null;
@@ -50,7 +50,7 @@ export function getDoclets(str: string): Record<string, string> {
   let match: RegExpExecArray | null;
 
   while ((match = DOCLET_PATTERN.exec(str))) {
-    doclets[match[1]] = match[2] || true;
+    doclets[match[1]!] = match[2] || true;
   }
 
   return doclets;

packages/react-docgen/src/utils/getFlowType.ts

@@ -159,7 +159,7 @@ function handleGenericTypeAnnotation(
   if (
     typeParams &&
     typeParams[type.name] &&
-    typeParams[type.name].isGenericTypeAnnotation()
+    typeParams[type.name]!.isGenericTypeAnnotation()
   ) {
     return type;
   }

packages/react-docgen/src/utils/getMemberExpressionValuePath.ts

@@ -17,7 +17,8 @@ function resolveName(path: NodePath): string | undefined {
           ' declarations.',
       );
     }
-    const id = declarations[0].get('id');
+    // VariableDeclarator always has at least one declaration, hence the non-null-assertion
+    const id = declarations[0]!.get('id');
 
     if (id.isIdentifier()) {
       return id.node.name;

packages/react-docgen/src/utils/getTSType.ts

@@ -207,15 +207,19 @@ function handleTSTypeLiteral(
     } else if (param.isTSCallSignatureDeclaration()) {
       type.signature.constructor = handleTSFunctionType(param, typeParams);
     } else if (param.isTSIndexSignature() && typeAnnotation.hasNode()) {
-      const idTypeAnnotation = param
-        .get('parameters')[0]
-        .get('typeAnnotation') as NodePath<TSTypeAnnotation | null | undefined>;
-
-      if (idTypeAnnotation.hasNode()) {
-        type.signature.properties.push({
-          key: getTSTypeWithResolvedTypes(idTypeAnnotation, typeParams),
-          value: getTSTypeWithRequirements(typeAnnotation, typeParams),
-        });
+      const parameters = param.get('parameters');
+
+      if (parameters[0]) {
+        const idTypeAnnotation = parameters[0].get(
+          'typeAnnotation',
+        ) as NodePath<TSTypeAnnotation | null | undefined>;
+
+        if (idTypeAnnotation.hasNode()) {
+          type.signature.properties.push({
+            key: getTSTypeWithResolvedTypes(idTypeAnnotation, typeParams),
+            value: getTSTypeWithRequirements(typeAnnotation, typeParams),
+          });
+        }
       }
     }
   });

packages/react-docgen/src/utils/getTypeFromReactComponent.ts

@@ -52,7 +52,9 @@ export default (path: NodePath): NodePath | null => {
     if (superTypes.hasNode()) {
       const params = superTypes.get('params');
 
-      typePath = params[params.length === 3 ? 1 : 0];
+      if (params.length >= 1) {
+        typePath = params[params.length === 3 ? 1 : 0]!;
+      }
     } else {
       const propsMemberPath = getMemberValuePath(path, 'props');
 

packages/react-docgen/src/utils/getTypeParameters.ts

@@ -56,7 +56,7 @@ export default function getTypeParameters(
           typeName.isIdentifier() &&
           inputParams[typeName.node.name]
         ) {
-          resolvedTypePath = inputParams[typeName.node.name];
+          resolvedTypePath = inputParams[typeName.node.name]!;
         }
 
         params[key] = resolvedTypePath;

packages/react-docgen/src/utils/postProcessDocumentation.ts

@@ -6,10 +6,8 @@ export default function (
   const props = documentation.props;
 
   if (props) {
-    // props with default values should not be required
-    Object.keys(props).forEach((prop) => {
-      const propInfo = props[prop];
-
+    Object.values(props).forEach((propInfo) => {
+      // props with default values should not be required
       if (propInfo.defaultValue) {
         propInfo.required = false;
       }

packages/react-docgen/src/utils/resolveHOC.ts

@@ -20,7 +20,7 @@ export default function resolveHOC(path: NodePath): NodePath {
 
     if (argumentLength && argumentLength > 0) {
       const args = path.get('arguments');
-      const firstArg = args[0];
+      const firstArg = args[0]!;
 
       // If the first argument is one of these types then the component might be the last argument
       // If there are all identifiers then we cannot figure out exactly and have to assume it is the first
@@ -31,7 +31,7 @@ export default function resolveHOC(path: NodePath): NodePath {
           firstArg.isArrayExpression() ||
           firstArg.isSpreadElement())
       ) {
-        return resolveHOC(resolveToValue(args[argumentLength - 1]));
+        return resolveHOC(resolveToValue(args[argumentLength - 1]!));
       }
 
       return resolveHOC(resolveToValue(firstArg));

packages/react-docgen/src/utils/resolveObjectKeysToArray.ts

@@ -142,7 +142,11 @@ export default function resolveObjectKeysToArray(
   path: NodePath,
 ): string[] | null {
   if (isObjectKeysCall(path)) {
-    const objectExpression = resolveToValue(path.get('arguments')[0]);
+    const argument = path.get('arguments')[0];
+    const objectExpression = resolveToValue(
+      // isObjectKeysCall already asserts that there is at least one argument, hence the non-null-assertion
+      argument!,
+    );
     const values = resolveObjectToNameArray(objectExpression);
 
     if (values) {

packages/react-docgen/src/utils/resolveObjectValuesToArray.ts

@@ -99,7 +99,11 @@ export default function resolveObjectValuesToArray(
   path: NodePath,
 ): string[] | null {
   if (isObjectValuesCall(path)) {
-    const objectExpression = resolveToValue(path.get('arguments')[0]);
+    const argument = path.get('arguments')[0];
+    const objectExpression = resolveToValue(
+      // isObjectValuesCall already asserts that there is at least one argument, hence the non-null-assertion
+      argument!,
+    );
     const values = resolveObjectToPropMap(objectExpression);
 
     if (values) {

packages/react-docgen/src/utils/resolveToValue.ts

@@ -12,9 +12,9 @@ import initialize from './ts-types/index.js';
 import getNameOrValue from './getNameOrValue.js';
 
 function findScopePath(
-  bindingIdentifiers: Array<NodePath<Identifier>>,
+  bindingIdentifiers: Array<NodePath<Identifier>> | undefined,
 ): NodePath | null {
-  if (bindingIdentifiers && bindingIdentifiers.length >= 1) {
+  if (bindingIdentifiers && bindingIdentifiers[0]) {
     const resolvedParentPath = bindingIdentifiers[0].parentPath;
 
     if (
@@ -136,9 +136,7 @@ export default function resolveToValue(path: NodePath): NodePath {
       // block where it is defined (i.e. we are not traversing into statements)
       resolvedPath = findLastAssignedValue(binding.scope.path, path);
       if (!resolvedPath) {
-        const bindingMap = binding.path.getOuterBindingIdentifierPaths(
-          true,
-        ) as Record<string, Array<NodePath<Identifier>>>;
+        const bindingMap = binding.path.getOuterBindingIdentifierPaths(true);
 
         resolvedPath = findScopePath(bindingMap[path.node.name]);
       }

packages/react-docgen/src/utils/ts-types/index.ts

@@ -32,7 +32,7 @@ declare module '@babel/traverse' {
   export interface Scope {
     typeBindings: Record<string, TypeBinding>;
     getTypeBinding(name: string): TypeBinding | undefined;
-    getOwnTypeBinding(name: string): TypeBinding;
+    getOwnTypeBinding(name: string): TypeBinding | undefined;
     registerTypeBinding(
       this: BaseScope,
       typeKind: TypeKind,
@@ -128,7 +128,10 @@ function getTypeBinding(
   return undefined;
 }
 
-function getOwnTypeBinding(this: BaseScope, name: string): TypeBinding {
+function getOwnTypeBinding(
+  this: BaseScope,
+  name: string,
+): TypeBinding | undefined {
   return this.typeBindings[name];
 }
 

tsconfig.base.json

@@ -8,7 +8,7 @@
     "strict": true,
     "noImplicitAny": false,
     "noImplicitReturns": true,
-    "noUncheckedIndexedAccess": false,
+    "noUncheckedIndexedAccess": true,
     "noUnusedLocals": true,
     "noUnusedParameters": true,
     "moduleResolution": "node16",