Retain CheckFlags.Late on symbols manufactured based on Late-bound symbols

src/compiler/checker.ts

@@ -10630,6 +10630,10 @@ namespace ts {
             return type;
         }
 
+        function getIsLateCheckFlag(s: Symbol): CheckFlags {
+            return getCheckFlags(s) & CheckFlags.Late;
+        }
+
         /** Resolve the members of a mapped type { [P in K]: T } */
         function resolveMappedTypeMembers(type: MappedType) {
             const members: SymbolTable = createSymbolTable();
@@ -10688,8 +10692,9 @@ namespace ts {
                         const isReadonly = !!(templateModifiers & MappedTypeModifiers.IncludeReadonly ||
                             !(templateModifiers & MappedTypeModifiers.ExcludeReadonly) && modifiersProp && isReadonlySymbol(modifiersProp));
                         const stripOptional = strictNullChecks && !isOptional && modifiersProp && modifiersProp.flags & SymbolFlags.Optional;
+                        const lateFlag: CheckFlags = modifiersProp ? getIsLateCheckFlag(modifiersProp) : 0;
                         const prop = <MappedSymbol>createSymbol(SymbolFlags.Property | (isOptional ? SymbolFlags.Optional : 0), propName,
-                            CheckFlags.Mapped | (isReadonly ? CheckFlags.Readonly : 0) | (stripOptional ? CheckFlags.StripOptional : 0));
+                            lateFlag | CheckFlags.Mapped | (isReadonly ? CheckFlags.Readonly : 0) | (stripOptional ? CheckFlags.StripOptional : 0));
                         prop.mappedType = type;
                         prop.nameType = propNameType;
                         prop.keyType = keyType;
@@ -14666,7 +14671,7 @@ namespace ts {
                     else if (isSpreadableProperty(prop)) {
                         const isSetonlyAccessor = prop.flags & SymbolFlags.SetAccessor && !(prop.flags & SymbolFlags.GetAccessor);
                         const flags = SymbolFlags.Property | SymbolFlags.Optional;
-                        const result = createSymbol(flags, prop.escapedName, readonly ? CheckFlags.Readonly : 0);
+                        const result = createSymbol(flags, prop.escapedName, getIsLateCheckFlag(prop) | (readonly ? CheckFlags.Readonly : 0));
                         result.type = isSetonlyAccessor ? undefinedType : getTypeOfSymbol(prop);
                         result.declarations = prop.declarations;
                         result.nameType = getSymbolLinks(prop).nameType;
@@ -14814,7 +14819,7 @@ namespace ts {
                 return prop;
             }
             const flags = SymbolFlags.Property | (prop.flags & SymbolFlags.Optional);
-            const result = createSymbol(flags, prop.escapedName, readonly ? CheckFlags.Readonly : 0);
+            const result = createSymbol(flags, prop.escapedName, getIsLateCheckFlag(prop) | (readonly ? CheckFlags.Readonly : 0));
             result.type = isSetonlyAccessor ? undefinedType : getTypeOfSymbol(prop);
             result.declarations = prop.declarations;
             result.nameType = getSymbolLinks(prop).nameType;

tests/baselines/reference/declarationEmitReadonlyComputedProperty.errors.txt

@@ -0,0 +1,24 @@
+tests/cases/compiler/index.ts(3,14): error TS4023: Exported variable 'spread' has or is using name 'SYMBOL' from external module "tests/cases/compiler/bug" but cannot be named.
+
+
+==== tests/cases/compiler/bug.ts (0 errors) ====
+    export const SYMBOL = Symbol()
+
+    export interface Interface {
+      readonly [SYMBOL]: string; // remove readonly and @showEmit to see the expected error
+    }
+
+    export function createInstance(): Interface {
+      return {
+        [SYMBOL]: ''
+      }
+    }
+
+==== tests/cases/compiler/index.ts (1 errors) ====
+    import { createInstance } from './bug'
+
+    export const spread = {
+                 ~~~~~~
+!!! error TS4023: Exported variable 'spread' has or is using name 'SYMBOL' from external module "tests/cases/compiler/bug" but cannot be named.
+      ...createInstance(),
+    }

tests/baselines/reference/declarationEmitReadonlyComputedProperty.js

@@ -0,0 +1,59 @@
+//// [tests/cases/compiler/declarationEmitReadonlyComputedProperty.ts] ////
+
+//// [bug.ts]
+export const SYMBOL = Symbol()
+
+export interface Interface {
+  readonly [SYMBOL]: string; // remove readonly and @showEmit to see the expected error
+}
+
+export function createInstance(): Interface {
+  return {
+    [SYMBOL]: ''
+  }
+}
+
+//// [index.ts]
+import { createInstance } from './bug'
+
+export const spread = {
+  ...createInstance(),
+}
+
+//// [bug.js]
+"use strict";
+exports.__esModule = true;
+exports.createInstance = exports.SYMBOL = void 0;
+exports.SYMBOL = Symbol();
+function createInstance() {
+    var _a;
+    return _a = {},
+        _a[exports.SYMBOL] = '',
+        _a;
+}
+exports.createInstance = createInstance;
+//// [index.js]
+"use strict";
+var __assign = (this && this.__assign) || function () {
+    __assign = Object.assign || function(t) {
+        for (var s, i = 1, n = arguments.length; i < n; i++) {
+            s = arguments[i];
+            for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
+                t[p] = s[p];
+        }
+        return t;
+    };
+    return __assign.apply(this, arguments);
+};
+exports.__esModule = true;
+exports.spread = void 0;
+var bug_1 = require("./bug");
+exports.spread = __assign({}, bug_1.createInstance());
+
+
+//// [bug.d.ts]
+export declare const SYMBOL: unique symbol;
+export interface Interface {
+    readonly [SYMBOL]: string;
+}
+export declare function createInstance(): Interface;

tests/baselines/reference/declarationEmitReadonlyComputedProperty.symbols

@@ -0,0 +1,34 @@
+=== tests/cases/compiler/bug.ts ===
+export const SYMBOL = Symbol()
+>SYMBOL : Symbol(SYMBOL, Decl(bug.ts, 0, 12))
+>Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --))
+
+export interface Interface {
+>Interface : Symbol(Interface, Decl(bug.ts, 0, 30))
+
+  readonly [SYMBOL]: string; // remove readonly and @showEmit to see the expected error
+>[SYMBOL] : Symbol(Interface[SYMBOL], Decl(bug.ts, 2, 28))
+>SYMBOL : Symbol(SYMBOL, Decl(bug.ts, 0, 12))
+}
+
+export function createInstance(): Interface {
+>createInstance : Symbol(createInstance, Decl(bug.ts, 4, 1))
+>Interface : Symbol(Interface, Decl(bug.ts, 0, 30))
+
+  return {
+    [SYMBOL]: ''
+>[SYMBOL] : Symbol([SYMBOL], Decl(bug.ts, 7, 10))
+>SYMBOL : Symbol(SYMBOL, Decl(bug.ts, 0, 12))
+  }
+}
+
+=== tests/cases/compiler/index.ts ===
+import { createInstance } from './bug'
+>createInstance : Symbol(createInstance, Decl(index.ts, 0, 8))
+
+export const spread = {
+>spread : Symbol(spread, Decl(index.ts, 2, 12))
+
+  ...createInstance(),
+>createInstance : Symbol(createInstance, Decl(index.ts, 0, 8))
+}

tests/baselines/reference/declarationEmitReadonlyComputedProperty.types

@@ -0,0 +1,37 @@
+=== tests/cases/compiler/bug.ts ===
+export const SYMBOL = Symbol()
+>SYMBOL : unique symbol
+>Symbol() : unique symbol
+>Symbol : SymbolConstructor
+
+export interface Interface {
+  readonly [SYMBOL]: string; // remove readonly and @showEmit to see the expected error
+>[SYMBOL] : string
+>SYMBOL : unique symbol
+}
+
+export function createInstance(): Interface {
+>createInstance : () => Interface
+
+  return {
+>{    [SYMBOL]: ''  } : { [SYMBOL]: string; }
+
+    [SYMBOL]: ''
+>[SYMBOL] : string
+>SYMBOL : unique symbol
+>'' : ""
+  }
+}
+
+=== tests/cases/compiler/index.ts ===
+import { createInstance } from './bug'
+>createInstance : () => import("tests/cases/compiler/bug").Interface
+
+export const spread = {
+>spread : { [SYMBOL]: string; }
+>{  ...createInstance(),} : { [SYMBOL]: string; }
+
+  ...createInstance(),
+>createInstance() : import("tests/cases/compiler/bug").Interface
+>createInstance : () => import("tests/cases/compiler/bug").Interface
+}

tests/cases/compiler/declarationEmitReadonlyComputedProperty.ts

@@ -0,0 +1,22 @@
+// @declaration: true
+// @lib: es2015
+
+// @filename: bug.ts
+export const SYMBOL = Symbol()
+
+export interface Interface {
+  readonly [SYMBOL]: string; // remove readonly and @showEmit to see the expected error
+}
+
+export function createInstance(): Interface {
+  return {
+    [SYMBOL]: ''
+  }
+}
+
+// @filename: index.ts
+import { createInstance } from './bug'
+
+export const spread = {
+  ...createInstance(),
+}