Don't include class getter in spread type

Author: Andy Hanson

src/compiler/checker.ts

@@ -4461,10 +4461,7 @@ namespace ts {
                 names.set(getTextOfPropertyName(name), true);
             }
             for (const prop of getPropertiesOfType(source)) {
-                const inNamesToRemove = names.has(prop.escapedName);
-                const isPrivate = getDeclarationModifierFlagsFromSymbol(prop) & (ModifierFlags.Private | ModifierFlags.Protected);
-                const isSetOnlyAccessor = prop.flags & SymbolFlags.SetAccessor && !(prop.flags & SymbolFlags.GetAccessor);
-                if (!inNamesToRemove && !isPrivate && !isClassMethod(prop) && !isSetOnlyAccessor) {
+                if (!names.has(prop.escapedName) && !(getDeclarationModifierFlagsFromSymbol(prop) & (ModifierFlags.Private | ModifierFlags.Protected)) && isSpreadableProperty(prop)) {
                     members.set(prop.escapedName, getNonReadonlySymbol(prop));
                 }
             }
@@ -9646,20 +9643,16 @@ namespace ts {
             }
 
             for (const rightProp of getPropertiesOfType(right)) {
-                // we approximate own properties as non-methods plus methods that are inside the object literal
-                const isSetterWithoutGetter = rightProp.flags & SymbolFlags.SetAccessor && !(rightProp.flags & SymbolFlags.GetAccessor);
                 if (getDeclarationModifierFlagsFromSymbol(rightProp) & (ModifierFlags.Private | ModifierFlags.Protected)) {
                     skippedPrivateMembers.set(rightProp.escapedName, true);
                 }
-                else if (!isClassMethod(rightProp) && !isSetterWithoutGetter) {
+                else if (isSpreadableProperty(rightProp)) {
                     members.set(rightProp.escapedName, getNonReadonlySymbol(rightProp));
                 }
             }
 
             for (const leftProp of getPropertiesOfType(left)) {
-                if (leftProp.flags & SymbolFlags.SetAccessor && !(leftProp.flags & SymbolFlags.GetAccessor)
-                    || skippedPrivateMembers.has(leftProp.escapedName)
-                    || isClassMethod(leftProp)) {
+                if (skippedPrivateMembers.has(leftProp.escapedName) || !isSpreadableProperty(leftProp)) {
                     continue;
                 }
                 if (members.has(leftProp.escapedName)) {
@@ -9694,6 +9687,13 @@ namespace ts {
             return spread;
         }
 
+        function isSpreadableProperty(prop: Symbol): boolean {
+            // We approximate own properties as non-methods plus methods that are inside the object literal
+            return prop.flags & (SymbolFlags.Method | SymbolFlags.GetAccessor)
+                ? !prop.declarations.some(decl => isClassLike(decl.parent))
+                : !(prop.flags & SymbolFlags.SetAccessor); // Setter without getter is not spreadable
+        }
+
         function getNonReadonlySymbol(prop: Symbol) {
             if (!isReadonlySymbol(prop)) {
                 return prop;
@@ -9714,10 +9714,6 @@ namespace ts {
             return index;
         }
 
-        function isClassMethod(prop: Symbol) {
-            return prop.flags & SymbolFlags.Method && find(prop.declarations, decl => isClassLike(decl.parent));
-        }
-
         function createLiteralType(flags: TypeFlags, value: string | number, symbol: Symbol | undefined) {
             const type = <LiteralType>createType(flags);
             type.symbol = symbol!;

tests/baselines/reference/spreadMethods.errors.txt

@@ -1,33 +1,56 @@
-tests/cases/conformance/types/spread/spreadMethods.ts(7,4): error TS2339: Property 'm' does not exist on type '{ p: number; }'.
-tests/cases/conformance/types/spread/spreadMethods.ts(9,5): error TS2339: Property 'm' does not exist on type '{ p: number; }'.
+tests/cases/conformance/types/spread/spreadMethods.ts(16,4): error TS2339: Property 'm' does not exist on type '{ p: number; }'.
+tests/cases/conformance/types/spread/spreadMethods.ts(17,4): error TS2339: Property 'g' does not exist on type '{ p: number; }'.
+tests/cases/conformance/types/spread/spreadMethods.ts(19,5): error TS2339: Property 'm' does not exist on type '{ p: number; }'.
+tests/cases/conformance/types/spread/spreadMethods.ts(20,5): error TS2339: Property 'g' does not exist on type '{ p: number; }'.
 
 
-==== tests/cases/conformance/types/spread/spreadMethods.ts (2 errors) ====
-    class K { p = 12; m() { } }
-    interface I { p: number, m(): void }
+==== tests/cases/conformance/types/spread/spreadMethods.ts (4 errors) ====
+    class K {
+        p = 12;
+        m() { }
+        get g() { return 0; }
+    }
+    interface I {
+        p: number;
+        m(): void;
+        readonly g: number;
+    }
+    
     let k = new K()
     let sk = { ...k };
     let ssk = { ...k, ...k };
     sk.p;
     sk.m(); // error
        ~
 !!! error TS2339: Property 'm' does not exist on type '{ p: number; }'.
+    sk.g; // error
+       ~
+!!! error TS2339: Property 'g' does not exist on type '{ p: number; }'.
     ssk.p;
     ssk.m(); // error
         ~
 !!! error TS2339: Property 'm' does not exist on type '{ p: number; }'.
-    let i: I = { p: 12, m() { } };
+    ssk.g; // error
+        ~
+!!! error TS2339: Property 'g' does not exist on type '{ p: number; }'.
+    
+    let i: I = { p: 12, m() { }, get g() { return 0; } };
     let si = { ...i };
     let ssi = { ...i, ...i };
     si.p;
     si.m(); // ok
+    si.g; // ok
     ssi.p;
     ssi.m(); // ok
-    let o = { p: 12, m() { } };
+    ssi.g; // ok
+    
+    let o = { p: 12, m() { }, get g() { return 0; } };
     let so = { ...o };
     let sso = { ...o, ...o };
     so.p;
     so.m(); // ok
+    so.g; // ok
     sso.p;
     sso.m(); // ok
+    sso.g; // ok
 

tests/baselines/reference/spreadMethods.js

@@ -1,66 +1,78 @@
 //// [spreadMethods.ts]
-class K { p = 12; m() { } }
-interface I { p: number, m(): void }
+class K {
+    p = 12;
+    m() { }
+    get g() { return 0; }
+}
+interface I {
+    p: number;
+    m(): void;
+    readonly g: number;
+}
+
 let k = new K()
 let sk = { ...k };
 let ssk = { ...k, ...k };
 sk.p;
 sk.m(); // error
+sk.g; // error
 ssk.p;
 ssk.m(); // error
-let i: I = { p: 12, m() { } };
+ssk.g; // error
+
+let i: I = { p: 12, m() { }, get g() { return 0; } };
 let si = { ...i };
 let ssi = { ...i, ...i };
 si.p;
 si.m(); // ok
+si.g; // ok
 ssi.p;
 ssi.m(); // ok
-let o = { p: 12, m() { } };
+ssi.g; // ok
+
+let o = { p: 12, m() { }, get g() { return 0; } };
 let so = { ...o };
 let sso = { ...o, ...o };
 so.p;
 so.m(); // ok
+so.g; // ok
 sso.p;
 sso.m(); // ok
+sso.g; // ok
 
 
 //// [spreadMethods.js]
-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);
-};
-var K = /** @class */ (function () {
-    function K() {
+class K {
+    constructor() {
         this.p = 12;
     }
-    K.prototype.m = function () { };
-    return K;
-}());
-var k = new K();
-var sk = __assign({}, k);
-var ssk = __assign({}, k, k);
+    m() { }
+    get g() { return 0; }
+}
+let k = new K();
+let sk = { ...k };
+let ssk = { ...k, ...k };
 sk.p;
 sk.m(); // error
+sk.g; // error
 ssk.p;
 ssk.m(); // error
-var i = { p: 12, m: function () { } };
-var si = __assign({}, i);
-var ssi = __assign({}, i, i);
+ssk.g; // error
+let i = { p: 12, m() { }, get g() { return 0; } };
+let si = { ...i };
+let ssi = { ...i, ...i };
 si.p;
 si.m(); // ok
+si.g; // ok
 ssi.p;
 ssi.m(); // ok
-var o = { p: 12, m: function () { } };
-var so = __assign({}, o);
-var sso = __assign({}, o, o);
+ssi.g; // ok
+let o = { p: 12, m() { }, get g() { return 0; } };
+let so = { ...o };
+let sso = { ...o, ...o };
 so.p;
 so.m(); // ok
+so.g; // ok
 sso.p;
 sso.m(); // ok
+sso.g; // ok