From 10b240cde3ab3bfe95fa09275760389c082a4a80 Mon Sep 17 00:00:00 2001
From: Wesley Wigham <wewigham@microsoft.com>
Date: Tue, 22 Sep 2020 21:21:13 -0700
Subject: [PATCH] Allow an infer type node to resolve its own name (#40483)

---
 src/compiler/checker.ts                       |  9 +++
 ...declarationEmitShadowingInferNotRenamed.js | 40 +++++++++++++
 ...rationEmitShadowingInferNotRenamed.symbols | 58 +++++++++++++++++++
 ...larationEmitShadowingInferNotRenamed.types | 40 +++++++++++++
 ...declarationEmitShadowingInferNotRenamed.ts | 22 +++++++
 5 files changed, 169 insertions(+)
 create mode 100644 tests/baselines/reference/declarationEmitShadowingInferNotRenamed.js
 create mode 100644 tests/baselines/reference/declarationEmitShadowingInferNotRenamed.symbols
 create mode 100644 tests/baselines/reference/declarationEmitShadowingInferNotRenamed.types
 create mode 100644 tests/cases/compiler/declarationEmitShadowingInferNotRenamed.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 947ecc6e1ff..2e1ed38efe0 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -1954,6 +1954,15 @@ namespace ts {
                             }
                         }
                         break;
+                    case SyntaxKind.InferType:
+                        if (meaning & SymbolFlags.TypeParameter) {
+                            const parameterName = (<InferTypeNode>location).typeParameter.name;
+                            if (parameterName && name === parameterName.escapedText) {
+                                result = (<InferTypeNode>location).typeParameter.symbol;
+                                break loop;
+                            }
+                        }
+                        break;
                 }
                 if (isSelfReferenceLocation(location)) {
                     lastSelfReferenceLocation = location;
diff --git a/tests/baselines/reference/declarationEmitShadowingInferNotRenamed.js b/tests/baselines/reference/declarationEmitShadowingInferNotRenamed.js
new file mode 100644
index 00000000000..d69903c0413
--- /dev/null
+++ b/tests/baselines/reference/declarationEmitShadowingInferNotRenamed.js
@@ -0,0 +1,40 @@
+//// [declarationEmitShadowingInferNotRenamed.ts]
+// Any instance type
+type Client = string
+
+// Modified instance
+type UpdatedClient<C> = C & {foo: number}
+
+export const createClient = <
+  D extends
+    | (new (...args: any[]) => Client) // accept class
+    | Record<string, new (...args: any[]) => Client> // or map of classes
+>(
+  clientDef: D
+): D extends new (...args: any[]) => infer C
+  ? UpdatedClient<C> // return instance
+  : {
+      [K in keyof D]: D[K] extends new (...args: any[]) => infer C // or map of instances respectively
+        ? UpdatedClient<C>
+        : never
+    } => {
+  return null as any
+}
+
+//// [declarationEmitShadowingInferNotRenamed.js]
+"use strict";
+exports.__esModule = true;
+exports.createClient = void 0;
+var createClient = function (clientDef) {
+    return null;
+};
+exports.createClient = createClient;
+
+
+//// [declarationEmitShadowingInferNotRenamed.d.ts]
+declare type Client = string;
+declare type UpdatedClient<C> = C & {
+    foo: number;
+};
+export declare const createClient: <D extends Record<string, new (...args: any[]) => Client> | (new (...args: any[]) => Client)>(clientDef: D) => D extends new (...args: any[]) => infer C ? UpdatedClient<C> : { [K in keyof D]: D[K] extends new (...args: any[]) => infer C_1 ? UpdatedClient<C_1> : never; };
+export {};
diff --git a/tests/baselines/reference/declarationEmitShadowingInferNotRenamed.symbols b/tests/baselines/reference/declarationEmitShadowingInferNotRenamed.symbols
new file mode 100644
index 00000000000..923c839a7bc
--- /dev/null
+++ b/tests/baselines/reference/declarationEmitShadowingInferNotRenamed.symbols
@@ -0,0 +1,58 @@
+=== tests/cases/compiler/declarationEmitShadowingInferNotRenamed.ts ===
+// Any instance type
+type Client = string
+>Client : Symbol(Client, Decl(declarationEmitShadowingInferNotRenamed.ts, 0, 0))
+
+// Modified instance
+type UpdatedClient<C> = C & {foo: number}
+>UpdatedClient : Symbol(UpdatedClient, Decl(declarationEmitShadowingInferNotRenamed.ts, 1, 20))
+>C : Symbol(C, Decl(declarationEmitShadowingInferNotRenamed.ts, 4, 19))
+>C : Symbol(C, Decl(declarationEmitShadowingInferNotRenamed.ts, 4, 19))
+>foo : Symbol(foo, Decl(declarationEmitShadowingInferNotRenamed.ts, 4, 29))
+
+export const createClient = <
+>createClient : Symbol(createClient, Decl(declarationEmitShadowingInferNotRenamed.ts, 6, 12))
+
+  D extends
+>D : Symbol(D, Decl(declarationEmitShadowingInferNotRenamed.ts, 6, 29))
+
+    | (new (...args: any[]) => Client) // accept class
+>args : Symbol(args, Decl(declarationEmitShadowingInferNotRenamed.ts, 8, 12))
+>Client : Symbol(Client, Decl(declarationEmitShadowingInferNotRenamed.ts, 0, 0))
+
+    | Record<string, new (...args: any[]) => Client> // or map of classes
+>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
+>args : Symbol(args, Decl(declarationEmitShadowingInferNotRenamed.ts, 9, 26))
+>Client : Symbol(Client, Decl(declarationEmitShadowingInferNotRenamed.ts, 0, 0))
+
+>(
+  clientDef: D
+>clientDef : Symbol(clientDef, Decl(declarationEmitShadowingInferNotRenamed.ts, 10, 2))
+>D : Symbol(D, Decl(declarationEmitShadowingInferNotRenamed.ts, 6, 29))
+
+): D extends new (...args: any[]) => infer C
+>D : Symbol(D, Decl(declarationEmitShadowingInferNotRenamed.ts, 6, 29))
+>args : Symbol(args, Decl(declarationEmitShadowingInferNotRenamed.ts, 12, 18))
+>C : Symbol(C, Decl(declarationEmitShadowingInferNotRenamed.ts, 12, 42))
+
+  ? UpdatedClient<C> // return instance
+>UpdatedClient : Symbol(UpdatedClient, Decl(declarationEmitShadowingInferNotRenamed.ts, 1, 20))
+>C : Symbol(C, Decl(declarationEmitShadowingInferNotRenamed.ts, 12, 42))
+
+  : {
+      [K in keyof D]: D[K] extends new (...args: any[]) => infer C // or map of instances respectively
+>K : Symbol(K, Decl(declarationEmitShadowingInferNotRenamed.ts, 15, 7))
+>D : Symbol(D, Decl(declarationEmitShadowingInferNotRenamed.ts, 6, 29))
+>D : Symbol(D, Decl(declarationEmitShadowingInferNotRenamed.ts, 6, 29))
+>K : Symbol(K, Decl(declarationEmitShadowingInferNotRenamed.ts, 15, 7))
+>args : Symbol(args, Decl(declarationEmitShadowingInferNotRenamed.ts, 15, 40))
+>C : Symbol(C, Decl(declarationEmitShadowingInferNotRenamed.ts, 15, 64))
+
+        ? UpdatedClient<C>
+>UpdatedClient : Symbol(UpdatedClient, Decl(declarationEmitShadowingInferNotRenamed.ts, 1, 20))
+>C : Symbol(C, Decl(declarationEmitShadowingInferNotRenamed.ts, 15, 64))
+
+        : never
+    } => {
+  return null as any
+}
diff --git a/tests/baselines/reference/declarationEmitShadowingInferNotRenamed.types b/tests/baselines/reference/declarationEmitShadowingInferNotRenamed.types
new file mode 100644
index 00000000000..850a5565891
--- /dev/null
+++ b/tests/baselines/reference/declarationEmitShadowingInferNotRenamed.types
@@ -0,0 +1,40 @@
+=== tests/cases/compiler/declarationEmitShadowingInferNotRenamed.ts ===
+// Any instance type
+type Client = string
+>Client : string
+
+// Modified instance
+type UpdatedClient<C> = C & {foo: number}
+>UpdatedClient : UpdatedClient<C>
+>foo : number
+
+export const createClient = <
+>createClient : <D extends Record<string, new (...args: any[]) => Client> | (new (...args: any[]) => Client)>(clientDef: D) => D extends new (...args: any[]) => infer C ? UpdatedClient<C> : { [K in keyof D]: D[K] extends new (...args: any[]) => infer C ? UpdatedClient<C> : never; }
+><  D extends    | (new (...args: any[]) => Client) // accept class    | Record<string, new (...args: any[]) => Client> // or map of classes>(  clientDef: D): D extends new (...args: any[]) => infer C  ? UpdatedClient<C> // return instance  : {      [K in keyof D]: D[K] extends new (...args: any[]) => infer C // or map of instances respectively        ? UpdatedClient<C>        : never    } => {  return null as any} : <D extends Record<string, new (...args: any[]) => Client> | (new (...args: any[]) => Client)>(clientDef: D) => D extends new (...args: any[]) => infer C ? UpdatedClient<C> : { [K in keyof D]: D[K] extends new (...args: any[]) => infer C ? UpdatedClient<C> : never; }
+
+  D extends
+    | (new (...args: any[]) => Client) // accept class
+>args : any[]
+
+    | Record<string, new (...args: any[]) => Client> // or map of classes
+>args : any[]
+
+>(
+  clientDef: D
+>clientDef : D
+
+): D extends new (...args: any[]) => infer C
+>args : any[]
+
+  ? UpdatedClient<C> // return instance
+  : {
+      [K in keyof D]: D[K] extends new (...args: any[]) => infer C // or map of instances respectively
+>args : any[]
+
+        ? UpdatedClient<C>
+        : never
+    } => {
+  return null as any
+>null as any : any
+>null : null
+}
diff --git a/tests/cases/compiler/declarationEmitShadowingInferNotRenamed.ts b/tests/cases/compiler/declarationEmitShadowingInferNotRenamed.ts
new file mode 100644
index 00000000000..ac29eeb9d80
--- /dev/null
+++ b/tests/cases/compiler/declarationEmitShadowingInferNotRenamed.ts
@@ -0,0 +1,22 @@
+// @declaration: true
+// Any instance type
+type Client = string
+
+// Modified instance
+type UpdatedClient<C> = C & {foo: number}
+
+export const createClient = <
+  D extends
+    | (new (...args: any[]) => Client) // accept class
+    | Record<string, new (...args: any[]) => Client> // or map of classes
+>(
+  clientDef: D
+): D extends new (...args: any[]) => infer C
+  ? UpdatedClient<C> // return instance
+  : {
+      [K in keyof D]: D[K] extends new (...args: any[]) => infer C // or map of instances respectively
+        ? UpdatedClient<C>
+        : never
+    } => {
+  return null as any
+}
\ No newline at end of file