Merge pull request #1039 from standard/ban-types

feat: @typescript-eslint/ban-types

Author: mightyiam

src/index.test.ts

@@ -92,6 +92,54 @@ test('export', (t): void => {
             minimumDescriptionLength: 3
           }],
           '@typescript-eslint/ban-tslint-comment': 'error',
+          '@typescript-eslint/ban-types': ['error', {
+            extendDefaults: false,
+            types: {
+              String: {
+                message: 'Use string instead',
+                fixWith: 'string'
+              },
+              Boolean: {
+                message: 'Use boolean instead',
+                fixWith: 'boolean'
+              },
+              Number: {
+                message: 'Use number instead',
+                fixWith: 'number'
+              },
+              Symbol: {
+                message: 'Use symbol instead',
+                fixWith: 'symbol'
+              },
+              BigInt: {
+                message: 'Use bigint instead',
+                fixWith: 'bigint'
+              },
+              Function: {
+                message: [
+                  'The `Function` type accepts any function-like value.',
+                  'It provides no type safety when calling the function, which can be a common source of bugs.',
+                  'It also accepts things like class declarations, which will throw at runtime as they will not be called with `new`.',
+                  'If you are expecting the function to accept certain arguments, you should explicitly define the function shape.'
+                ].join('\n')
+              },
+              // object typing
+              Object: {
+                message: [
+                  'The `Object` type actually means "any non-nullish value", so it is marginally better than `unknown`.',
+                  '- If you want a type meaning "any object", you probably want `Record<string, unknown>` instead.',
+                  '- If you want a type meaning "any value", you probably want `unknown` instead.'
+                ].join('\n')
+              },
+              '{}': {
+                message: [
+                  '`{}` actually means "any non-nullish value".',
+                  '- If you want a type meaning "any object", you probably want `Record<string, unknown>` instead.',
+                  '- If you want a type meaning "any value", you probably want `unknown` instead.'
+                ].join('\n')
+              }
+            }
+          }],
           '@typescript-eslint/brace-style': ['error', '1tbs', { allowSingleLine: true }],
           '@typescript-eslint/comma-dangle': ['error', {
             arrays: 'never',
@@ -371,7 +419,6 @@ test('all plugin rules are considered', (t) => {
   // This serves as a todo list and should ideally eventually end up empty
   // and then fail upon plugin upgrades where new rules are released.
   const notYetConsideredRules: string[] = [
-    'ban-types',
     'class-literal-property-style',
     'consistent-generic-constructors',
     'consistent-type-exports',

src/index.ts

@@ -81,6 +81,54 @@ const config: Linter.Config = {
           minimumDescriptionLength: 3
         }],
         '@typescript-eslint/ban-tslint-comment': 'error',
+        '@typescript-eslint/ban-types': ['error', {
+          extendDefaults: false,
+          types: {
+            String: {
+              message: 'Use string instead',
+              fixWith: 'string'
+            },
+            Boolean: {
+              message: 'Use boolean instead',
+              fixWith: 'boolean'
+            },
+            Number: {
+              message: 'Use number instead',
+              fixWith: 'number'
+            },
+            Symbol: {
+              message: 'Use symbol instead',
+              fixWith: 'symbol'
+            },
+            BigInt: {
+              message: 'Use bigint instead',
+              fixWith: 'bigint'
+            },
+            Function: {
+              message: [
+                'The `Function` type accepts any function-like value.',
+                'It provides no type safety when calling the function, which can be a common source of bugs.',
+                'It also accepts things like class declarations, which will throw at runtime as they will not be called with `new`.',
+                'If you are expecting the function to accept certain arguments, you should explicitly define the function shape.'
+              ].join('\n')
+            },
+            // object typing
+            Object: {
+              message: [
+                'The `Object` type actually means "any non-nullish value", so it is marginally better than `unknown`.',
+                '- If you want a type meaning "any object", you probably want `Record<string, unknown>` instead.',
+                '- If you want a type meaning "any value", you probably want `unknown` instead.'
+              ].join('\n')
+            },
+            '{}': {
+              message: [
+                '`{}` actually means "any non-nullish value".',
+                '- If you want a type meaning "any object", you probably want `Record<string, unknown>` instead.',
+                '- If you want a type meaning "any value", you probably want `unknown` instead.'
+              ].join('\n')
+            }
+          }
+        }],
         '@typescript-eslint/comma-dangle': ['error', {
           arrays: 'never',
           objects: 'never',