Fix type lookup for Effect heritage clauses (#706)

Author: mattiamanzati

.changeset/five-flies-bathe.md

@@ -0,0 +1,5 @@
+---
+"@effect/language-service": patch
+---
+
+Fix `getTypeAtLocation` to ignore type-only heritage expressions like `interface X extends Effect.Effect<...>` so the language service no longer triggers bogus TS2689 diagnostics.

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

@@ -0,0 +1 @@
+no codefixes

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

@@ -0,0 +1 @@
+// no diagnostics

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

@@ -0,0 +1,3 @@
+import * as Effect from "effect/Effect"
+
+export interface Abc extends Effect.Effect<never, never, never> {}

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

@@ -0,0 +1 @@
+no codefixes

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

@@ -0,0 +1 @@
+// no diagnostics

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

@@ -0,0 +1,3 @@
+import * as Effect from "effect/Effect"
+
+export interface Abc extends Effect.Effect<never, never, never> {}

packages/language-service/src/core/TypeCheckerUtils.ts

@@ -490,11 +490,54 @@ export function makeTypeCheckerUtils(
     if (node.parent && ts.isJsxClosingElement(node.parent) && node.parent.tagName === node) return
     if (node.parent && ts.isJsxAttribute(node.parent) && node.parent.name === node) return
 
+    if (isInsideTypeOnlyHeritageExpression(node)) return
+
     if (ts.isExpression(node) || ts.isTypeNode(node)) {
       return typeChecker.getTypeAtLocation(node)
     }
   }
 
+  function isInsideTypeOnlyHeritageExpression(node: ts.Node): boolean {
+    if (ts.isExpressionWithTypeArguments(node)) {
+      return isTypeOnlyHeritageClause(node.parent)
+    }
+
+    if (!ts.isIdentifier(node) && !ts.isPropertyAccessExpression(node)) {
+      return false
+    }
+
+    for (let current = node.parent; current; current = current.parent) {
+      if (ts.isPropertyAccessExpression(current)) {
+        continue
+      }
+
+      if (ts.isExpressionWithTypeArguments(current)) {
+        return isTypeOnlyHeritageClause(current.parent)
+      }
+
+      return false
+    }
+
+    return false
+  }
+
+  function isTypeOnlyHeritageClause(node: ts.Node | undefined): boolean {
+    if (!node || !ts.isHeritageClause(node)) {
+      return false
+    }
+
+    const container = node.parent
+    if (!container) {
+      return false
+    }
+
+    if (ts.isInterfaceDeclaration(container)) {
+      return true
+    }
+
+    return ts.isClassLike(container) && node.token === ts.SyntaxKind.ImplementsKeyword
+  }
+
   function resolveToGlobalSymbol(symbol: ts.Symbol): ts.Symbol {
     if (symbol.flags & ts.SymbolFlags.Alias) {
       symbol = typeChecker.getAliasedSymbol(symbol)