Add extendsNativeError diagnostic

.changeset/extends-native-error-diagnostic.md

@@ -0,0 +1,7 @@
+---
+"@effect/language-service": minor
+---
+
+Add the `extendsNativeError` diagnostic to warn when classes directly extend the native `Error` constructor, including common local aliases such as `const E = Error`.
+
+This helps steer users toward tagged errors that preserve stronger typing in the Effect failure channel.

README.md

@@ -72,6 +72,7 @@ And you're done! You'll now be able to use a set of refactors and diagnostics th
 - Warn when using catch functions (`catchAll`, `catch`, `catchIf`, `catchSome`, `catchTag`, `catchTags`) on effects that never fail
 - Warn when catch callbacks in `Effect.tryPromise`, `Effect.tryMap`, or `Effect.tryMapPromise` return `unknown` or `any` types
 - Warn when catch callbacks in `Effect.tryPromise`, `Effect.try`, `Effect.tryMap`, or `Effect.tryMapPromise` return the global `Error` type instead of typed errors
+- Warn when classes directly extend the native `Error` class, including through local aliases, recommending tagged errors instead
 - Warn when using `Effect.runSync`, `Effect.runPromise`, `Effect.runFork`, or `Effect.runCallback` inside an Effect
 - Warn when using `Schema.decodeSync`, `Schema.decodeUnknownSync`, `Schema.encodeSync`, or `Schema.encodeUnknownSync` inside Effect generators, suggesting Effect-based alternatives
 - Suggest using Effect Schema for JSON operations instead of `JSON.parse`/`JSON.stringify` inside Effect contexts

packages/harness-effect-v3/__snapshots__/completions.test.ts.snap

@@ -248,7 +248,7 @@ exports[`Completion effectDataClasses > effectDataClasses_directImportTaggedErro
 exports[`Completion effectDiagnosticsComment > effectDiagnosticsComment.ts at 2:5 1`] = `
 [
   {
-    "insertText": "@effect-diagnostics \${1|anyUnknownInErrorContext,catchAllToMapError,catchUnfailableEffect,classSelfMismatch,deterministicKeys,duplicatePackage,effectFnIife,effectFnOpportunity,effectGenUsesAdapter,effectInFailure,effectInVoidSuccess,effectMapVoid,effectSucceedWithVoid,floatingEffect,genericEffectServices,globalErrorInEffectCatch,globalErrorInEffectFailure,importFromBarrel,instanceOfSchema,layerMergeAllWithDependencies,leakingRequirements,missedPipeableOpportunity,missingEffectContext,missingEffectError,missingEffectServiceDependency,missingLayerContext,missingReturnYieldStar,missingStarInYieldEffectGen,multipleEffectProvide,nonObjectEffectServiceType,outdatedApi,outdatedEffectCodegen,overriddenSchemaConstructor,preferSchemaOverJson,redundantSchemaTagIdentifier,returnEffectInGen,runEffectInsideEffect,schemaStructWithTag,schemaSyncInEffect,schemaUnionOfLiterals,scopeInLayerEffect,strictBooleanExpressions,strictEffectProvide,tryCatchInEffectGen,unknownInEffectCatch,unnecessaryEffectGen,unnecessaryFailYieldableError,unnecessaryPipe,unnecessaryPipeChain,unsupportedServiceAccessors|}:\${2|off,warning,error,message,suggestion|}$0",
+    "insertText": "@effect-diagnostics \${1|anyUnknownInErrorContext,catchAllToMapError,catchUnfailableEffect,classSelfMismatch,deterministicKeys,duplicatePackage,effectFnIife,effectFnOpportunity,effectGenUsesAdapter,effectInFailure,effectInVoidSuccess,effectMapVoid,effectSucceedWithVoid,extendsNativeError,floatingEffect,genericEffectServices,globalErrorInEffectCatch,globalErrorInEffectFailure,importFromBarrel,instanceOfSchema,layerMergeAllWithDependencies,leakingRequirements,missedPipeableOpportunity,missingEffectContext,missingEffectError,missingEffectServiceDependency,missingLayerContext,missingReturnYieldStar,missingStarInYieldEffectGen,multipleEffectProvide,nonObjectEffectServiceType,outdatedApi,outdatedEffectCodegen,overriddenSchemaConstructor,preferSchemaOverJson,redundantSchemaTagIdentifier,returnEffectInGen,runEffectInsideEffect,schemaStructWithTag,schemaSyncInEffect,schemaUnionOfLiterals,scopeInLayerEffect,strictBooleanExpressions,strictEffectProvide,tryCatchInEffectGen,unknownInEffectCatch,unnecessaryEffectGen,unnecessaryFailYieldableError,unnecessaryPipe,unnecessaryPipeChain,unsupportedServiceAccessors|}:\${2|off,warning,error,message,suggestion|}$0",
     "isSnippet": true,
     "kind": "string",
     "name": "@effect-diagnostics",
@@ -259,7 +259,7 @@ exports[`Completion effectDiagnosticsComment > effectDiagnosticsComment.ts at 2:
     "sortText": "11",
   },
   {
-    "insertText": "@effect-diagnostics-next-line \${1|anyUnknownInErrorContext,catchAllToMapError,catchUnfailableEffect,classSelfMismatch,deterministicKeys,duplicatePackage,effectFnIife,effectFnOpportunity,effectGenUsesAdapter,effectInFailure,effectInVoidSuccess,effectMapVoid,effectSucceedWithVoid,floatingEffect,genericEffectServices,globalErrorInEffectCatch,globalErrorInEffectFailure,importFromBarrel,instanceOfSchema,layerMergeAllWithDependencies,leakingRequirements,missedPipeableOpportunity,missingEffectContext,missingEffectError,missingEffectServiceDependency,missingLayerContext,missingReturnYieldStar,missingStarInYieldEffectGen,multipleEffectProvide,nonObjectEffectServiceType,outdatedApi,outdatedEffectCodegen,overriddenSchemaConstructor,preferSchemaOverJson,redundantSchemaTagIdentifier,returnEffectInGen,runEffectInsideEffect,schemaStructWithTag,schemaSyncInEffect,schemaUnionOfLiterals,scopeInLayerEffect,strictBooleanExpressions,strictEffectProvide,tryCatchInEffectGen,unknownInEffectCatch,unnecessaryEffectGen,unnecessaryFailYieldableError,unnecessaryPipe,unnecessaryPipeChain,unsupportedServiceAccessors|}:\${2|off,warning,error,message,suggestion|}$0",
+    "insertText": "@effect-diagnostics-next-line \${1|anyUnknownInErrorContext,catchAllToMapError,catchUnfailableEffect,classSelfMismatch,deterministicKeys,duplicatePackage,effectFnIife,effectFnOpportunity,effectGenUsesAdapter,effectInFailure,effectInVoidSuccess,effectMapVoid,effectSucceedWithVoid,extendsNativeError,floatingEffect,genericEffectServices,globalErrorInEffectCatch,globalErrorInEffectFailure,importFromBarrel,instanceOfSchema,layerMergeAllWithDependencies,leakingRequirements,missedPipeableOpportunity,missingEffectContext,missingEffectError,missingEffectServiceDependency,missingLayerContext,missingReturnYieldStar,missingStarInYieldEffectGen,multipleEffectProvide,nonObjectEffectServiceType,outdatedApi,outdatedEffectCodegen,overriddenSchemaConstructor,preferSchemaOverJson,redundantSchemaTagIdentifier,returnEffectInGen,runEffectInsideEffect,schemaStructWithTag,schemaSyncInEffect,schemaUnionOfLiterals,scopeInLayerEffect,strictBooleanExpressions,strictEffectProvide,tryCatchInEffectGen,unknownInEffectCatch,unnecessaryEffectGen,unnecessaryFailYieldableError,unnecessaryPipe,unnecessaryPipeChain,unsupportedServiceAccessors|}:\${2|off,warning,error,message,suggestion|}$0",
     "isSnippet": true,
     "kind": "string",
     "name": "@effect-diagnostics-next-line",

packages/harness-effect-v3/__snapshots__/diagnostics/extendsNativeError.ts.codefixes

@@ -0,0 +1,6 @@
+extendsNativeError_skipNextLine from 90 to 97
+extendsNativeError_skipFile from 90 to 97
+extendsNativeError_skipNextLine from 160 to 168
+extendsNativeError_skipFile from 160 to 168
+extendsNativeError_skipNextLine from 244 to 248
+extendsNativeError_skipFile from 244 to 248

packages/harness-effect-v3/__snapshots__/diagnostics/extendsNativeError.ts.output

@@ -0,0 +1,8 @@
+MyError
+4:6 - 4:13 | 0 | Avoid extending the native 'Error' class directly. Consider using a tagged error (e.g. Data.TaggedError) to maintain type safety in the Effect failure channel.    effect(extendsNativeError)
+
+MyError2
+8:6 - 8:14 | 0 | Avoid extending the native 'Error' class directly. Consider using a tagged error (e.g. Data.TaggedError) to maintain type safety in the Effect failure channel.    effect(extendsNativeError)
+
+Base
+11:6 - 11:10 | 0 | Avoid extending the native 'Error' class directly. Consider using a tagged error (e.g. Data.TaggedError) to maintain type safety in the Effect failure channel.    effect(extendsNativeError)

packages/harness-effect-v3/examples/diagnostics/extendsNativeError.ts

@@ -0,0 +1,16 @@
+// @effect-diagnostics extendsNativeError:warning
+
+// Flagged: direct extends Error
+class MyError extends Error {}
+
+// Flagged: via alias
+const E = Error
+class MyError2 extends E {}
+
+// Not flagged: indirect (extends a subclass of Error)
+class Base extends Error {}
+class MyError3 extends Base {}
+
+// Not flagged: unrelated class
+class Bar {}
+class Foo extends Bar {}

packages/harness-effect-v4/__snapshots__/completions.test.ts.snap

@@ -143,7 +143,7 @@ exports[`Completion effectDataClasses > effectDataClasses.ts at 4:35 1`] = `
 exports[`Completion effectDiagnosticsComment > effectDiagnosticsComment.ts at 2:5 1`] = `
 [
   {
-    "insertText": "@effect-diagnostics \${1|anyUnknownInErrorContext,catchAllToMapError,catchUnfailableEffect,classSelfMismatch,deterministicKeys,duplicatePackage,effectFnIife,effectFnOpportunity,effectGenUsesAdapter,effectInFailure,effectInVoidSuccess,effectMapVoid,effectSucceedWithVoid,floatingEffect,genericEffectServices,globalErrorInEffectCatch,globalErrorInEffectFailure,importFromBarrel,instanceOfSchema,layerMergeAllWithDependencies,leakingRequirements,missedPipeableOpportunity,missingEffectContext,missingEffectError,missingEffectServiceDependency,missingLayerContext,missingReturnYieldStar,missingStarInYieldEffectGen,multipleEffectProvide,nonObjectEffectServiceType,outdatedApi,outdatedEffectCodegen,overriddenSchemaConstructor,preferSchemaOverJson,redundantSchemaTagIdentifier,returnEffectInGen,runEffectInsideEffect,schemaStructWithTag,schemaSyncInEffect,schemaUnionOfLiterals,scopeInLayerEffect,strictBooleanExpressions,strictEffectProvide,tryCatchInEffectGen,unknownInEffectCatch,unnecessaryEffectGen,unnecessaryFailYieldableError,unnecessaryPipe,unnecessaryPipeChain,unsupportedServiceAccessors|}:\${2|off,warning,error,message,suggestion|}$0",
+    "insertText": "@effect-diagnostics \${1|anyUnknownInErrorContext,catchAllToMapError,catchUnfailableEffect,classSelfMismatch,deterministicKeys,duplicatePackage,effectFnIife,effectFnOpportunity,effectGenUsesAdapter,effectInFailure,effectInVoidSuccess,effectMapVoid,effectSucceedWithVoid,extendsNativeError,floatingEffect,genericEffectServices,globalErrorInEffectCatch,globalErrorInEffectFailure,importFromBarrel,instanceOfSchema,layerMergeAllWithDependencies,leakingRequirements,missedPipeableOpportunity,missingEffectContext,missingEffectError,missingEffectServiceDependency,missingLayerContext,missingReturnYieldStar,missingStarInYieldEffectGen,multipleEffectProvide,nonObjectEffectServiceType,outdatedApi,outdatedEffectCodegen,overriddenSchemaConstructor,preferSchemaOverJson,redundantSchemaTagIdentifier,returnEffectInGen,runEffectInsideEffect,schemaStructWithTag,schemaSyncInEffect,schemaUnionOfLiterals,scopeInLayerEffect,strictBooleanExpressions,strictEffectProvide,tryCatchInEffectGen,unknownInEffectCatch,unnecessaryEffectGen,unnecessaryFailYieldableError,unnecessaryPipe,unnecessaryPipeChain,unsupportedServiceAccessors|}:\${2|off,warning,error,message,suggestion|}$0",
     "isSnippet": true,
     "kind": "string",
     "name": "@effect-diagnostics",
@@ -154,7 +154,7 @@ exports[`Completion effectDiagnosticsComment > effectDiagnosticsComment.ts at 2:
     "sortText": "11",
   },
   {
-    "insertText": "@effect-diagnostics-next-line \${1|anyUnknownInErrorContext,catchAllToMapError,catchUnfailableEffect,classSelfMismatch,deterministicKeys,duplicatePackage,effectFnIife,effectFnOpportunity,effectGenUsesAdapter,effectInFailure,effectInVoidSuccess,effectMapVoid,effectSucceedWithVoid,floatingEffect,genericEffectServices,globalErrorInEffectCatch,globalErrorInEffectFailure,importFromBarrel,instanceOfSchema,layerMergeAllWithDependencies,leakingRequirements,missedPipeableOpportunity,missingEffectContext,missingEffectError,missingEffectServiceDependency,missingLayerContext,missingReturnYieldStar,missingStarInYieldEffectGen,multipleEffectProvide,nonObjectEffectServiceType,outdatedApi,outdatedEffectCodegen,overriddenSchemaConstructor,preferSchemaOverJson,redundantSchemaTagIdentifier,returnEffectInGen,runEffectInsideEffect,schemaStructWithTag,schemaSyncInEffect,schemaUnionOfLiterals,scopeInLayerEffect,strictBooleanExpressions,strictEffectProvide,tryCatchInEffectGen,unknownInEffectCatch,unnecessaryEffectGen,unnecessaryFailYieldableError,unnecessaryPipe,unnecessaryPipeChain,unsupportedServiceAccessors|}:\${2|off,warning,error,message,suggestion|}$0",
+    "insertText": "@effect-diagnostics-next-line \${1|anyUnknownInErrorContext,catchAllToMapError,catchUnfailableEffect,classSelfMismatch,deterministicKeys,duplicatePackage,effectFnIife,effectFnOpportunity,effectGenUsesAdapter,effectInFailure,effectInVoidSuccess,effectMapVoid,effectSucceedWithVoid,extendsNativeError,floatingEffect,genericEffectServices,globalErrorInEffectCatch,globalErrorInEffectFailure,importFromBarrel,instanceOfSchema,layerMergeAllWithDependencies,leakingRequirements,missedPipeableOpportunity,missingEffectContext,missingEffectError,missingEffectServiceDependency,missingLayerContext,missingReturnYieldStar,missingStarInYieldEffectGen,multipleEffectProvide,nonObjectEffectServiceType,outdatedApi,outdatedEffectCodegen,overriddenSchemaConstructor,preferSchemaOverJson,redundantSchemaTagIdentifier,returnEffectInGen,runEffectInsideEffect,schemaStructWithTag,schemaSyncInEffect,schemaUnionOfLiterals,scopeInLayerEffect,strictBooleanExpressions,strictEffectProvide,tryCatchInEffectGen,unknownInEffectCatch,unnecessaryEffectGen,unnecessaryFailYieldableError,unnecessaryPipe,unnecessaryPipeChain,unsupportedServiceAccessors|}:\${2|off,warning,error,message,suggestion|}$0",
     "isSnippet": true,
     "kind": "string",
     "name": "@effect-diagnostics-next-line",

packages/harness-effect-v4/__snapshots__/diagnostics/extendsNativeError.ts.codefixes

@@ -0,0 +1,6 @@
+extendsNativeError_skipNextLine from 90 to 97
+extendsNativeError_skipFile from 90 to 97
+extendsNativeError_skipNextLine from 160 to 168
+extendsNativeError_skipFile from 160 to 168
+extendsNativeError_skipNextLine from 244 to 248
+extendsNativeError_skipFile from 244 to 248

packages/harness-effect-v4/__snapshots__/diagnostics/extendsNativeError.ts.output

@@ -0,0 +1,8 @@
+MyError
+4:6 - 4:13 | 0 | Avoid extending the native 'Error' class directly. Consider using a tagged error (e.g. Data.TaggedError) to maintain type safety in the Effect failure channel.    effect(extendsNativeError)
+
+MyError2
+8:6 - 8:14 | 0 | Avoid extending the native 'Error' class directly. Consider using a tagged error (e.g. Data.TaggedError) to maintain type safety in the Effect failure channel.    effect(extendsNativeError)
+
+Base
+11:6 - 11:10 | 0 | Avoid extending the native 'Error' class directly. Consider using a tagged error (e.g. Data.TaggedError) to maintain type safety in the Effect failure channel.    effect(extendsNativeError)

packages/harness-effect-v4/examples/diagnostics/extendsNativeError.ts

@@ -0,0 +1,16 @@
+// @effect-diagnostics extendsNativeError:warning
+
+// Flagged: direct extends Error
+class MyError extends Error {}
+
+// Flagged: via alias
+const E = Error
+class MyError2 extends E {}
+
+// Not flagged: indirect (extends a subclass of Error)
+class Base extends Error {}
+class MyError3 extends Base {}
+
+// Not flagged: unrelated class
+class Bar {}
+class Foo extends Bar {}

packages/language-service/src/diagnostics.ts

@@ -11,6 +11,7 @@ import { effectInFailure } from "./diagnostics/effectInFailure.js"
 import { effectInVoidSuccess } from "./diagnostics/effectInVoidSuccess.js"
 import { effectMapVoid } from "./diagnostics/effectMapVoid.js"
 import { effectSucceedWithVoid } from "./diagnostics/effectSucceedWithVoid.js"
+import { extendsNativeError } from "./diagnostics/extendsNativeError.js"
 import { floatingEffect } from "./diagnostics/floatingEffect.js"
 import { genericEffectServices } from "./diagnostics/genericEffectServices.js"
 import { globalErrorInEffectCatch } from "./diagnostics/globalErrorInEffectCatch.js"
@@ -99,5 +100,6 @@ export const diagnostics = [
   effectFnOpportunity,
   redundantSchemaTagIdentifier,
   schemaSyncInEffect,
-  preferSchemaOverJson
+  preferSchemaOverJson,
+  extendsNativeError
 ]

packages/language-service/src/diagnostics/extendsNativeError.ts

@@ -0,0 +1,64 @@
+import type ts from "typescript"
+import * as LSP from "../core/LSP.js"
+import * as Nano from "../core/Nano.js"
+import * as TypeCheckerApi from "../core/TypeCheckerApi.js"
+import * as TypeScriptApi from "../core/TypeScriptApi.js"
+
+export const extendsNativeError = LSP.createDiagnostic({
+  name: "extendsNativeError",
+  code: 50,
+  description: "Warns when a class directly extends the native Error class",
+  severity: "off",
+  apply: Nano.fn("extendsNativeError.apply")(function*(sourceFile, report) {
+    const ts = yield* Nano.service(TypeScriptApi.TypeScriptApi)
+    const typeChecker = yield* Nano.service(TypeCheckerApi.TypeCheckerApi)
+
+    const errorSymbol = typeChecker.resolveName("Error", undefined, ts.SymbolFlags.Type, false)
+    if (!errorSymbol) return
+
+    const nodeToVisit: Array<ts.Node> = []
+    const appendNodeToVisit = (node: ts.Node) => {
+      nodeToVisit.push(node)
+      return undefined
+    }
+    ts.forEachChild(sourceFile, appendNodeToVisit)
+
+    while (nodeToVisit.length > 0) {
+      const node = nodeToVisit.shift()!
+
+      if (ts.isClassDeclaration(node) && node.heritageClauses) {
+        for (const clause of node.heritageClauses) {
+          if (clause.token === ts.SyntaxKind.ExtendsKeyword && clause.types.length > 0) {
+            const typeExpression = clause.types[0].expression
+            const exprSymbol = typeChecker.getSymbolAtLocation(typeExpression)
+            // Resolve import aliases to their target symbol
+            const resolvedSymbol = exprSymbol && (exprSymbol.flags & ts.SymbolFlags.Alias)
+              ? typeChecker.getAliasedSymbol(exprSymbol)
+              : exprSymbol
+            // Direct symbol match or variable alias (e.g. const E = Error)
+            const isNativeError = resolvedSymbol === errorSymbol || (() => {
+              if (!resolvedSymbol || resolvedSymbol === errorSymbol) return false
+              const exprType = typeChecker.getTypeAtLocation(typeExpression)
+              const constructSignatures = exprType.getConstructSignatures()
+              if (constructSignatures.length > 0) {
+                const instanceType = typeChecker.getReturnTypeOfSignature(constructSignatures[0])
+                return instanceType.getSymbol() === errorSymbol
+              }
+              return false
+            })()
+            if (isNativeError) {
+              report({
+                location: node.name ?? typeExpression,
+                messageText:
+                  "Avoid extending the native 'Error' class directly. Consider using a tagged error (e.g. Data.TaggedError) to maintain type safety in the Effect failure channel.",
+                fixes: []
+              })
+            }
+          }
+        }
+      }
+
+      ts.forEachChild(node, appendNodeToVisit)
+    }
+  })
+})