fix(eslint-plugin): [no-unsafe-argument] handle tuple types on rest a…

…rguments (#3269)

packages/eslint-plugin/src/rules/no-unsafe-argument.ts

@@ -11,7 +11,31 @@ type MessageIds =
   | 'unsafeArraySpread'
   | 'unsafeSpread';
 
+const enum RestTypeKind {
+  Array,
+  Tuple,
+  Other,
+}
+type RestType =
+  | {
+      type: ts.Type;
+      kind: RestTypeKind.Array;
+      index: number;
+    }
+  | {
+      typeArguments: readonly ts.Type[];
+      kind: RestTypeKind.Tuple;
+      index: number;
+    }
+  | {
+      type: ts.Type;
+      kind: RestTypeKind.Other;
+      index: number;
+    };
+
 class FunctionSignature {
+  private parameterTypeIndex = 0;
+
   public static create(
     checker: ts.TypeChecker,
     tsNode: ts.CallLikeExpression,
@@ -22,18 +46,34 @@ class FunctionSignature {
     }
 
     const paramTypes: ts.Type[] = [];
-    let restType: ts.Type | null = null;
+    let restType: RestType | null = null;
 
-    for (const param of signature.getParameters()) {
+    const parameters = signature.getParameters();
+    for (let i = 0; i < parameters.length; i += 1) {
+      const param = parameters[i];
       const type = checker.getTypeOfSymbolAtLocation(param, tsNode);
 
       const decl = param.getDeclarations()?.[0];
       if (decl && ts.isParameter(decl) && decl.dotDotDotToken) {
         // is a rest param
         if (checker.isArrayType(type)) {
-          restType = checker.getTypeArguments(type)[0];
+          restType = {
+            type: checker.getTypeArguments(type)[0],
+            kind: RestTypeKind.Array,
+            index: i,
+          };
+        } else if (checker.isTupleType(type)) {
+          restType = {
+            typeArguments: checker.getTypeArguments(type),
+            kind: RestTypeKind.Tuple,
+            index: i,
+          };
         } else {
-          restType = type;
+          restType = {
+            type,
+            kind: RestTypeKind.Other,
+            index: i,
+          };
         }
         break;
       }
@@ -48,12 +88,41 @@ class FunctionSignature {
 
   private constructor(
     private paramTypes: ts.Type[],
-    private restType: ts.Type | null,
+    private restType: RestType | null,
   ) {}
 
-  public getParameterType(index: number): ts.Type | null {
+  public getNextParameterType(): ts.Type | null {
+    const index = this.parameterTypeIndex;
+    this.parameterTypeIndex += 1;
+
     if (index >= this.paramTypes.length || this.hasConsumedArguments) {
-      return this.restType;
+      if (this.restType == null) {
+        return null;
+      }
+
+      switch (this.restType.kind) {
+        case RestTypeKind.Tuple: {
+          const typeArguments = this.restType.typeArguments;
+          if (this.hasConsumedArguments) {
+            // all types consumed by a rest - just assume it's the last type
+            // there is one edge case where this is wrong, but we ignore it because
+            // it's rare and really complicated to handle
+            // eg: function foo(...a: [number, ...string[], number])
+            return typeArguments[typeArguments.length - 1];
+          }
+
+          const typeIndex = index - this.restType.index;
+          if (typeIndex >= typeArguments.length) {
+            return typeArguments[typeArguments.length - 1];
+          }
+
+          return typeArguments[typeIndex];
+        }
+
+        case RestTypeKind.Array:
+        case RestTypeKind.Other:
+          return this.restType.type;
+      }
     }
     return this.paramTypes[index];
   }
@@ -112,12 +181,7 @@ export default util.createRule<[], MessageIds>({
           return;
         }
 
-        let parameterTypeIndex = 0;
-        for (
-          let i = 0;
-          i < node.arguments.length;
-          i += 1, parameterTypeIndex += 1
-        ) {
+        for (let i = 0; i < node.arguments.length; i += 1) {
           const argument = node.arguments[i];
 
           switch (argument.type) {
@@ -146,15 +210,9 @@ export default util.createRule<[], MessageIds>({
                 const spreadTypeArguments = checker.getTypeArguments(
                   spreadArgType,
                 );
-                for (
-                  let j = 0;
-                  j < spreadTypeArguments.length;
-                  j += 1, parameterTypeIndex += 1
-                ) {
+                for (let j = 0; j < spreadTypeArguments.length; j += 1) {
                   const tupleType = spreadTypeArguments[j];
-                  const parameterType = signature.getParameterType(
-                    parameterTypeIndex,
-                  );
+                  const parameterType = signature.getNextParameterType();
                   if (parameterType == null) {
                     continue;
                   }
@@ -188,7 +246,7 @@ export default util.createRule<[], MessageIds>({
             }
 
             default: {
-              const parameterType = signature.getParameterType(i);
+              const parameterType = signature.getNextParameterType();
               if (parameterType == null) {
                 continue;
               }

packages/eslint-plugin/tests/rules/no-unsafe-argument.test.ts

@@ -11,9 +11,19 @@ const ruleTester = new RuleTester({
 
 ruleTester.run('no-unsafe-argument', rule, {
   valid: [
+    // unknown function should be ignored
+    `
+doesNotExist(1 as any);
+    `,
+    // non-function call should be ignored
+    `
+const foo = 1;
+foo(1 as any);
+    `,
+    // too many arguments should be ignored as this is a TS error
     `
 declare function foo(arg: number): void;
-foo(1);
+foo(1, 1 as any, 2 as any);
     `,
     `
 declare function foo(arg: number, arg2: string): void;
@@ -60,6 +70,21 @@ foo(new Set<string>(), ...x);
 declare function foo(arg1: unknown, arg2: Set<unkown>, arg3: unknown[]): void;
 foo(1 as any, new Set<any>(), [] as any[]);
     `,
+    `
+declare function foo(...params: [number, string, any]): void;
+foo(1, 'a', 1 as any);
+    `,
+    // Unfortunately - we cannot handle this case because TS infers `params` to be a tuple type
+    // that tuple type is the same as the type of
+    `
+declare function foo<E extends string[]>(...params: E): void;
+
+foo('a', 'b', 1 as any);
+    `,
+    `
+declare function toHaveBeenCalledWith<E extends any[]>(...params: E): void;
+toHaveBeenCalledWith(1 as any);
+    `,
   ],
   invalid: [
     {
@@ -264,5 +289,61 @@ foo(new Set<any>(), ...x);
         },
       ],
     },
+    {
+      code: `
+declare function foo(...params: [number, string, any]): void;
+foo(1 as any, 'a' as any, 1 as any);
+      `,
+      errors: [
+        {
+          messageId: 'unsafeArgument',
+          line: 3,
+          column: 5,
+          endColumn: 13,
+          data: {
+            sender: 'any',
+            receiver: 'number',
+          },
+        },
+        {
+          messageId: 'unsafeArgument',
+          line: 3,
+          column: 15,
+          endColumn: 25,
+          data: {
+            sender: 'any',
+            receiver: 'string',
+          },
+        },
+      ],
+    },
+    {
+      code: `
+declare function foo(param1: string, ...params: [number, string, any]): void;
+foo('a', 1 as any, 'a' as any, 1 as any);
+      `,
+      errors: [
+        {
+          messageId: 'unsafeArgument',
+          line: 3,
+          column: 10,
+          endColumn: 18,
+          data: {
+            sender: 'any',
+            receiver: 'number',
+          },
+        },
+        {
+          messageId: 'unsafeArgument',
+          line: 3,
+          column: 20,
+          endColumn: 30,
+          data: {
+            sender: 'any',
+            receiver: 'string',
+          },
+        },
+      ],
+    },
   ],
 });