Merge multiple symbols even when re-exported (#49987)

* Merge multiple symbols even when re-exported

As far as I remember, the target of `mergeSymbol` needs to be a merged
symbol, not a symbol with a mergeId that points to mergedSymbol.
However, mergeSymbolTable didn't check for this.

I can't remember if symbol tables may contain
symbols-with-mergeId. If they can, then mergeSymbolTable needs to call
getMergedSymbol on the individual targets of the merge. That's what I
did in this PR.

* Call getMergeSymbol eagerly

On the source, not target, of mergeSymbolTable's contents

src/compiler/checker.ts

@@ -1426,7 +1426,7 @@ namespace ts {
         function mergeSymbolTable(target: SymbolTable, source: SymbolTable, unidirectional = false) {
             source.forEach((sourceSymbol, id) => {
                 const targetSymbol = target.get(id);
-                target.set(id, targetSymbol ? mergeSymbol(targetSymbol, sourceSymbol, unidirectional) : sourceSymbol);
+                target.set(id, targetSymbol ? mergeSymbol(targetSymbol, sourceSymbol, unidirectional) : getMergedSymbol(sourceSymbol));
             });
         }
 

tests/baselines/reference/mergeMultipleInterfacesReexported.js

@@ -0,0 +1,65 @@
+//// [tests/cases/compiler/mergeMultipleInterfacesReexported.ts] ////
+
+//// [index.ts]
+export * from './eventList';
+
+//// [test.ts]
+import { EventList } from "./eventList";
+
+declare const p012: "p0" | "p1" | "p2"
+const t: keyof EventList = p012
+
+//// [eventList.ts]
+export interface EventList {
+    p0: [];
+}
+
+//// [foo.ts]
+declare module './index' {
+    interface EventList {
+        p1: []
+    }
+}
+export {};
+
+
+//// [bar.ts]
+declare module './index' {
+    interface EventList {
+        p2: []
+    }
+}
+export {};
+
+
+//// [eventList.js]
+"use strict";
+exports.__esModule = true;
+//// [index.js]
+"use strict";
+var __createBinding = (this && this.__createBinding) || (Object.create ? (function(o, m, k, k2) {
+    if (k2 === undefined) k2 = k;
+    var desc = Object.getOwnPropertyDescriptor(m, k);
+    if (!desc || ("get" in desc ? !m.__esModule : desc.writable || desc.configurable)) {
+      desc = { enumerable: true, get: function() { return m[k]; } };
+    }
+    Object.defineProperty(o, k2, desc);
+}) : (function(o, m, k, k2) {
+    if (k2 === undefined) k2 = k;
+    o[k2] = m[k];
+}));
+var __exportStar = (this && this.__exportStar) || function(m, exports) {
+    for (var p in m) if (p !== "default" && !Object.prototype.hasOwnProperty.call(exports, p)) __createBinding(exports, m, p);
+};
+exports.__esModule = true;
+__exportStar(require("./eventList"), exports);
+//// [test.js]
+"use strict";
+exports.__esModule = true;
+var t = p012;
+//// [foo.js]
+"use strict";
+exports.__esModule = true;
+//// [bar.js]
+"use strict";
+exports.__esModule = true;

tests/baselines/reference/mergeMultipleInterfacesReexported.symbols

@@ -0,0 +1,50 @@
+=== tests/cases/compiler/index.ts ===
+export * from './eventList';
+No type information for this code.
+No type information for this code.=== tests/cases/compiler/test.ts ===
+import { EventList } from "./eventList";
+>EventList : Symbol(EventList, Decl(test.ts, 0, 8))
+
+declare const p012: "p0" | "p1" | "p2"
+>p012 : Symbol(p012, Decl(test.ts, 2, 13))
+
+const t: keyof EventList = p012
+>t : Symbol(t, Decl(test.ts, 3, 5))
+>EventList : Symbol(EventList, Decl(test.ts, 0, 8))
+>p012 : Symbol(p012, Decl(test.ts, 2, 13))
+
+=== tests/cases/compiler/eventList.ts ===
+export interface EventList {
+>EventList : Symbol(EventList, Decl(eventList.ts, 0, 0), Decl(foo.ts, 0, 26), Decl(bar.ts, 0, 26))
+
+    p0: [];
+>p0 : Symbol(EventList.p0, Decl(eventList.ts, 0, 28))
+}
+
+=== tests/cases/compiler/foo.ts ===
+declare module './index' {
+>'./index' : Symbol("tests/cases/compiler/index", Decl(index.ts, 0, 0), Decl(foo.ts, 0, 0), Decl(bar.ts, 0, 0))
+
+    interface EventList {
+>EventList : Symbol(EventList, Decl(eventList.ts, 0, 0), Decl(foo.ts, 0, 26), Decl(bar.ts, 0, 26))
+
+        p1: []
+>p1 : Symbol(EventList.p1, Decl(foo.ts, 1, 25))
+    }
+}
+export {};
+
+
+=== tests/cases/compiler/bar.ts ===
+declare module './index' {
+>'./index' : Symbol("tests/cases/compiler/index", Decl(index.ts, 0, 0), Decl(foo.ts, 0, 0), Decl(bar.ts, 0, 0))
+
+    interface EventList {
+>EventList : Symbol(EventList, Decl(eventList.ts, 0, 0), Decl(foo.ts, 0, 26), Decl(bar.ts, 0, 26))
+
+        p2: []
+>p2 : Symbol(EventList.p2, Decl(bar.ts, 1, 25))
+    }
+}
+export {};
+

tests/baselines/reference/mergeMultipleInterfacesReexported.types

@@ -0,0 +1,43 @@
+=== tests/cases/compiler/index.ts ===
+export * from './eventList';
+No type information for this code.
+No type information for this code.=== tests/cases/compiler/test.ts ===
+import { EventList } from "./eventList";
+>EventList : any
+
+declare const p012: "p0" | "p1" | "p2"
+>p012 : "p0" | "p1" | "p2"
+
+const t: keyof EventList = p012
+>t : keyof EventList
+>p012 : "p0" | "p1" | "p2"
+
+=== tests/cases/compiler/eventList.ts ===
+export interface EventList {
+    p0: [];
+>p0 : []
+}
+
+=== tests/cases/compiler/foo.ts ===
+declare module './index' {
+>'./index' : typeof import("tests/cases/compiler/index")
+
+    interface EventList {
+        p1: []
+>p1 : []
+    }
+}
+export {};
+
+
+=== tests/cases/compiler/bar.ts ===
+declare module './index' {
+>'./index' : typeof import("tests/cases/compiler/index")
+
+    interface EventList {
+        p2: []
+>p2 : []
+    }
+}
+export {};
+

tests/baselines/reference/moduleAugmentationDoesNamespaceEnumMergeOfReexport.symbols

@@ -45,9 +45,9 @@ const g: ns.Root = ns.Root.A;
 >ns : Symbol(ns, Decl(augment.ts, 0, 6))
 >Root : Symbol(ns.Root, Decl(file.ts, 0, 0), Decl(augment.ts, 2, 29))
 >ns.Root.A : Symbol(ns.Root.A, Decl(augment.ts, 4, 22))
->ns.Root : Symbol(ns.Root, Decl(augment.ts, 2, 29))
+>ns.Root : Symbol(ns.Root, Decl(file.ts, 0, 0), Decl(augment.ts, 2, 29))
 >ns : Symbol(ns, Decl(augment.ts, 0, 6))
->Root : Symbol(ns.Root, Decl(augment.ts, 2, 29))
+>Root : Symbol(ns.Root, Decl(file.ts, 0, 0), Decl(augment.ts, 2, 29))
 >A : Symbol(ns.Root.A, Decl(augment.ts, 4, 22))
 
 f.x;

tests/cases/compiler/mergeMultipleInterfacesReexported.ts

@@ -0,0 +1,30 @@
+// @filename: index.ts
+export * from './eventList';
+
+// @filename: test.ts
+import { EventList } from "./eventList";
+
+declare const p012: "p0" | "p1" | "p2"
+const t: keyof EventList = p012
+
+// @filename: eventList.ts
+export interface EventList {
+    p0: [];
+}
+
+// @filename: foo.ts
+declare module './index' {
+    interface EventList {
+        p1: []
+    }
+}
+export {};
+
+
+// @filename: bar.ts
+declare module './index' {
+    interface EventList {
+        p2: []
+    }
+}
+export {};