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Merge pull request #28234 from Microsoft/genericSpread
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Generic spread expressions in object literals
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@ahejlsberg
ahejlsberg authored Oct 31, 2018
2 parents 6fd6a04 + 1577f94 commit 8e4b90d
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Showing 15 changed files with 582 additions and 319 deletions.
26 changes: 23 additions & 3 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -4639,7 +4639,7 @@ namespace ts {
let type: Type | undefined;
if (pattern.kind === SyntaxKind.ObjectBindingPattern) {
if (declaration.dotDotDotToken) {
if (parentType.flags & TypeFlags.Unknown || !isValidSpreadType(parentType)) {
if (parentType.flags & TypeFlags.Unknown || !isValidSpreadType(parentType) || isGenericObjectType(parentType)) {
error(declaration, Diagnostics.Rest_types_may_only_be_created_from_object_types);
return errorType;
}
Expand Down Expand Up @@ -9842,6 +9842,10 @@ namespace ts {
return symbol ? getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol) : undefined;
}

function isNonGenericObjectType(type: Type) {
return !!(type.flags & TypeFlags.Object) && !isGenericMappedType(type);
}

/**
* Since the source of spread types are object literals, which are not binary,
* this function should be called in a left folding style, with left = previous result of getSpreadType
Expand Down Expand Up @@ -9870,6 +9874,23 @@ namespace ts {
return left;
}

if (isGenericObjectType(left) || isGenericObjectType(right)) {
if (isEmptyObjectType(left)) {
return right;
}
// When the left type is an intersection, we may need to merge the last constituent of the
// intersection with the right type. For example when the left type is 'T & { a: string }'
// and the right type is '{ b: string }' we produce 'T & { a: string, b: string }'.
if (left.flags & TypeFlags.Intersection) {
const types = (<IntersectionType>left).types;
const lastLeft = types[types.length - 1];
if (isNonGenericObjectType(lastLeft) && isNonGenericObjectType(right)) {
return getIntersectionType(concatenate(types.slice(0, types.length - 1), [getSpreadType(lastLeft, right, symbol, typeFlags, objectFlags)]));
}
}
return getIntersectionType([left, right]);
}

const members = createSymbolTable();
const skippedPrivateMembers = createUnderscoreEscapedMap<boolean>();
let stringIndexInfo: IndexInfo | undefined;
Expand Down Expand Up @@ -17700,9 +17721,8 @@ namespace ts {
}

function isValidSpreadType(type: Type): boolean {
return !!(type.flags & (TypeFlags.AnyOrUnknown | TypeFlags.NonPrimitive) ||
return !!(type.flags & (TypeFlags.AnyOrUnknown | TypeFlags.NonPrimitive | TypeFlags.Object | TypeFlags.InstantiableNonPrimitive) ||
getFalsyFlags(type) & TypeFlags.DefinitelyFalsy && isValidSpreadType(removeDefinitelyFalsyTypes(type)) ||
type.flags & TypeFlags.Object && !isGenericMappedType(type) ||
type.flags & TypeFlags.UnionOrIntersection && every((<UnionOrIntersectionType>type).types, isValidSpreadType));
}

Expand Down
62 changes: 62 additions & 0 deletions tests/baselines/reference/objectSpread.js
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Original file line number Diff line number Diff line change
Expand Up @@ -119,6 +119,41 @@ let a = 12;
let shortCutted: { a: number, b: string } = { ...o, a }
// non primitive
let spreadNonPrimitive = { ...<object>{}};

// generic spreads

function f<T, U>(t: T, u: U) {
return { ...t, ...u, id: 'id' };
}

let exclusive: { id: string, a: number, b: string, c: string, d: boolean } =
f({ a: 1, b: 'yes' }, { c: 'no', d: false })
let overlap: { id: string, a: number, b: string } =
f({ a: 1 }, { a: 2, b: 'extra' })
let overlapConflict: { id:string, a: string } =
f({ a: 1 }, { a: 'mismatch' })
let overwriteId: { id: string, a: number, c: number, d: string } =
f({ a: 1, id: true }, { c: 1, d: 'no' })

function genericSpread<T, U>(t: T, u: U, v: T | U, w: T | { s: string }, obj: { x: number }) {
let x01 = { ...t };
let x02 = { ...t, ...t };
let x03 = { ...t, ...u };
let x04 = { ...u, ...t };
let x05 = { a: 5, b: 'hi', ...t };
let x06 = { ...t, a: 5, b: 'hi' };
let x07 = { a: 5, b: 'hi', ...t, c: true, ...obj };
let x09 = { a: 5, ...t, b: 'hi', c: true, ...obj };
let x10 = { a: 5, ...t, b: 'hi', ...u, ...obj };
let x11 = { ...v };
let x12 = { ...v, ...obj };
let x13 = { ...w };
let x14 = { ...w, ...obj };
let x15 = { ...t, ...v };
let x16 = { ...t, ...w };
let x17 = { ...t, ...w, ...obj };
let x18 = { ...t, ...v, ...w };
}


//// [objectSpread.js]
Expand Down Expand Up @@ -214,3 +249,30 @@ var a = 12;
var shortCutted = __assign({}, o, { a: a });
// non primitive
var spreadNonPrimitive = __assign({}, {});
// generic spreads
function f(t, u) {
return __assign({}, t, u, { id: 'id' });
}
var exclusive = f({ a: 1, b: 'yes' }, { c: 'no', d: false });
var overlap = f({ a: 1 }, { a: 2, b: 'extra' });
var overlapConflict = f({ a: 1 }, { a: 'mismatch' });
var overwriteId = f({ a: 1, id: true }, { c: 1, d: 'no' });
function genericSpread(t, u, v, w, obj) {
var x01 = __assign({}, t);
var x02 = __assign({}, t, t);
var x03 = __assign({}, t, u);
var x04 = __assign({}, u, t);
var x05 = __assign({ a: 5, b: 'hi' }, t);
var x06 = __assign({}, t, { a: 5, b: 'hi' });
var x07 = __assign({ a: 5, b: 'hi' }, t, { c: true }, obj);
var x09 = __assign({ a: 5 }, t, { b: 'hi', c: true }, obj);
var x10 = __assign({ a: 5 }, t, { b: 'hi' }, u, obj);
var x11 = __assign({}, v);
var x12 = __assign({}, v, obj);
var x13 = __assign({}, w);
var x14 = __assign({}, w, obj);
var x15 = __assign({}, t, v);
var x16 = __assign({}, t, w);
var x17 = __assign({}, t, w, obj);
var x18 = __assign({}, t, v, w);
}
181 changes: 181 additions & 0 deletions tests/baselines/reference/objectSpread.symbols
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Original file line number Diff line number Diff line change
Expand Up @@ -452,3 +452,184 @@ let shortCutted: { a: number, b: string } = { ...o, a }
let spreadNonPrimitive = { ...<object>{}};
>spreadNonPrimitive : Symbol(spreadNonPrimitive, Decl(objectSpread.ts, 119, 3))

// generic spreads

function f<T, U>(t: T, u: U) {
>f : Symbol(f, Decl(objectSpread.ts, 119, 42))
>T : Symbol(T, Decl(objectSpread.ts, 123, 11))
>U : Symbol(U, Decl(objectSpread.ts, 123, 13))
>t : Symbol(t, Decl(objectSpread.ts, 123, 17))
>T : Symbol(T, Decl(objectSpread.ts, 123, 11))
>u : Symbol(u, Decl(objectSpread.ts, 123, 22))
>U : Symbol(U, Decl(objectSpread.ts, 123, 13))

return { ...t, ...u, id: 'id' };
>t : Symbol(t, Decl(objectSpread.ts, 123, 17))
>u : Symbol(u, Decl(objectSpread.ts, 123, 22))
>id : Symbol(id, Decl(objectSpread.ts, 124, 24))
}

let exclusive: { id: string, a: number, b: string, c: string, d: boolean } =
>exclusive : Symbol(exclusive, Decl(objectSpread.ts, 127, 3))
>id : Symbol(id, Decl(objectSpread.ts, 127, 16))
>a : Symbol(a, Decl(objectSpread.ts, 127, 28))
>b : Symbol(b, Decl(objectSpread.ts, 127, 39))
>c : Symbol(c, Decl(objectSpread.ts, 127, 50))
>d : Symbol(d, Decl(objectSpread.ts, 127, 61))

f({ a: 1, b: 'yes' }, { c: 'no', d: false })
>f : Symbol(f, Decl(objectSpread.ts, 119, 42))
>a : Symbol(a, Decl(objectSpread.ts, 128, 7))
>b : Symbol(b, Decl(objectSpread.ts, 128, 13))
>c : Symbol(c, Decl(objectSpread.ts, 128, 27))
>d : Symbol(d, Decl(objectSpread.ts, 128, 36))

let overlap: { id: string, a: number, b: string } =
>overlap : Symbol(overlap, Decl(objectSpread.ts, 129, 3))
>id : Symbol(id, Decl(objectSpread.ts, 129, 14))
>a : Symbol(a, Decl(objectSpread.ts, 129, 26))
>b : Symbol(b, Decl(objectSpread.ts, 129, 37))

f({ a: 1 }, { a: 2, b: 'extra' })
>f : Symbol(f, Decl(objectSpread.ts, 119, 42))
>a : Symbol(a, Decl(objectSpread.ts, 130, 7))
>a : Symbol(a, Decl(objectSpread.ts, 130, 17))
>b : Symbol(b, Decl(objectSpread.ts, 130, 23))

let overlapConflict: { id:string, a: string } =
>overlapConflict : Symbol(overlapConflict, Decl(objectSpread.ts, 131, 3))
>id : Symbol(id, Decl(objectSpread.ts, 131, 22))
>a : Symbol(a, Decl(objectSpread.ts, 131, 33))

f({ a: 1 }, { a: 'mismatch' })
>f : Symbol(f, Decl(objectSpread.ts, 119, 42))
>a : Symbol(a, Decl(objectSpread.ts, 132, 7))
>a : Symbol(a, Decl(objectSpread.ts, 132, 17))

let overwriteId: { id: string, a: number, c: number, d: string } =
>overwriteId : Symbol(overwriteId, Decl(objectSpread.ts, 133, 3))
>id : Symbol(id, Decl(objectSpread.ts, 133, 18))
>a : Symbol(a, Decl(objectSpread.ts, 133, 30))
>c : Symbol(c, Decl(objectSpread.ts, 133, 41))
>d : Symbol(d, Decl(objectSpread.ts, 133, 52))

f({ a: 1, id: true }, { c: 1, d: 'no' })
>f : Symbol(f, Decl(objectSpread.ts, 119, 42))
>a : Symbol(a, Decl(objectSpread.ts, 134, 7))
>id : Symbol(id, Decl(objectSpread.ts, 134, 13))
>c : Symbol(c, Decl(objectSpread.ts, 134, 27))
>d : Symbol(d, Decl(objectSpread.ts, 134, 33))

function genericSpread<T, U>(t: T, u: U, v: T | U, w: T | { s: string }, obj: { x: number }) {
>genericSpread : Symbol(genericSpread, Decl(objectSpread.ts, 134, 44))
>T : Symbol(T, Decl(objectSpread.ts, 136, 23))
>U : Symbol(U, Decl(objectSpread.ts, 136, 25))
>t : Symbol(t, Decl(objectSpread.ts, 136, 29))
>T : Symbol(T, Decl(objectSpread.ts, 136, 23))
>u : Symbol(u, Decl(objectSpread.ts, 136, 34))
>U : Symbol(U, Decl(objectSpread.ts, 136, 25))
>v : Symbol(v, Decl(objectSpread.ts, 136, 40))
>T : Symbol(T, Decl(objectSpread.ts, 136, 23))
>U : Symbol(U, Decl(objectSpread.ts, 136, 25))
>w : Symbol(w, Decl(objectSpread.ts, 136, 50))
>T : Symbol(T, Decl(objectSpread.ts, 136, 23))
>s : Symbol(s, Decl(objectSpread.ts, 136, 59))
>obj : Symbol(obj, Decl(objectSpread.ts, 136, 72))
>x : Symbol(x, Decl(objectSpread.ts, 136, 79))

let x01 = { ...t };
>x01 : Symbol(x01, Decl(objectSpread.ts, 137, 7))
>t : Symbol(t, Decl(objectSpread.ts, 136, 29))

let x02 = { ...t, ...t };
>x02 : Symbol(x02, Decl(objectSpread.ts, 138, 7))
>t : Symbol(t, Decl(objectSpread.ts, 136, 29))
>t : Symbol(t, Decl(objectSpread.ts, 136, 29))

let x03 = { ...t, ...u };
>x03 : Symbol(x03, Decl(objectSpread.ts, 139, 7))
>t : Symbol(t, Decl(objectSpread.ts, 136, 29))
>u : Symbol(u, Decl(objectSpread.ts, 136, 34))

let x04 = { ...u, ...t };
>x04 : Symbol(x04, Decl(objectSpread.ts, 140, 7))
>u : Symbol(u, Decl(objectSpread.ts, 136, 34))
>t : Symbol(t, Decl(objectSpread.ts, 136, 29))

let x05 = { a: 5, b: 'hi', ...t };
>x05 : Symbol(x05, Decl(objectSpread.ts, 141, 7))
>a : Symbol(a, Decl(objectSpread.ts, 141, 15))
>b : Symbol(b, Decl(objectSpread.ts, 141, 21))
>t : Symbol(t, Decl(objectSpread.ts, 136, 29))

let x06 = { ...t, a: 5, b: 'hi' };
>x06 : Symbol(x06, Decl(objectSpread.ts, 142, 7))
>t : Symbol(t, Decl(objectSpread.ts, 136, 29))
>a : Symbol(a, Decl(objectSpread.ts, 142, 21))
>b : Symbol(b, Decl(objectSpread.ts, 142, 27))

let x07 = { a: 5, b: 'hi', ...t, c: true, ...obj };
>x07 : Symbol(x07, Decl(objectSpread.ts, 143, 7))
>a : Symbol(a, Decl(objectSpread.ts, 143, 15))
>b : Symbol(b, Decl(objectSpread.ts, 143, 21))
>t : Symbol(t, Decl(objectSpread.ts, 136, 29))
>c : Symbol(c, Decl(objectSpread.ts, 143, 36))
>obj : Symbol(obj, Decl(objectSpread.ts, 136, 72))

let x09 = { a: 5, ...t, b: 'hi', c: true, ...obj };
>x09 : Symbol(x09, Decl(objectSpread.ts, 144, 7))
>a : Symbol(a, Decl(objectSpread.ts, 144, 15))
>t : Symbol(t, Decl(objectSpread.ts, 136, 29))
>b : Symbol(b, Decl(objectSpread.ts, 144, 27))
>c : Symbol(c, Decl(objectSpread.ts, 144, 36))
>obj : Symbol(obj, Decl(objectSpread.ts, 136, 72))

let x10 = { a: 5, ...t, b: 'hi', ...u, ...obj };
>x10 : Symbol(x10, Decl(objectSpread.ts, 145, 7))
>a : Symbol(a, Decl(objectSpread.ts, 145, 15))
>t : Symbol(t, Decl(objectSpread.ts, 136, 29))
>b : Symbol(b, Decl(objectSpread.ts, 145, 27))
>u : Symbol(u, Decl(objectSpread.ts, 136, 34))
>obj : Symbol(obj, Decl(objectSpread.ts, 136, 72))

let x11 = { ...v };
>x11 : Symbol(x11, Decl(objectSpread.ts, 146, 7))
>v : Symbol(v, Decl(objectSpread.ts, 136, 40))

let x12 = { ...v, ...obj };
>x12 : Symbol(x12, Decl(objectSpread.ts, 147, 7))
>v : Symbol(v, Decl(objectSpread.ts, 136, 40))
>obj : Symbol(obj, Decl(objectSpread.ts, 136, 72))

let x13 = { ...w };
>x13 : Symbol(x13, Decl(objectSpread.ts, 148, 7))
>w : Symbol(w, Decl(objectSpread.ts, 136, 50))

let x14 = { ...w, ...obj };
>x14 : Symbol(x14, Decl(objectSpread.ts, 149, 7))
>w : Symbol(w, Decl(objectSpread.ts, 136, 50))
>obj : Symbol(obj, Decl(objectSpread.ts, 136, 72))

let x15 = { ...t, ...v };
>x15 : Symbol(x15, Decl(objectSpread.ts, 150, 7))
>t : Symbol(t, Decl(objectSpread.ts, 136, 29))
>v : Symbol(v, Decl(objectSpread.ts, 136, 40))

let x16 = { ...t, ...w };
>x16 : Symbol(x16, Decl(objectSpread.ts, 151, 7))
>t : Symbol(t, Decl(objectSpread.ts, 136, 29))
>w : Symbol(w, Decl(objectSpread.ts, 136, 50))

let x17 = { ...t, ...w, ...obj };
>x17 : Symbol(x17, Decl(objectSpread.ts, 152, 7))
>t : Symbol(t, Decl(objectSpread.ts, 136, 29))
>w : Symbol(w, Decl(objectSpread.ts, 136, 50))
>obj : Symbol(obj, Decl(objectSpread.ts, 136, 72))

let x18 = { ...t, ...v, ...w };
>x18 : Symbol(x18, Decl(objectSpread.ts, 153, 7))
>t : Symbol(t, Decl(objectSpread.ts, 136, 29))
>v : Symbol(v, Decl(objectSpread.ts, 136, 40))
>w : Symbol(w, Decl(objectSpread.ts, 136, 50))
}

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