Consider all union types matching discriminator for excess property checks

Fixes microsoft#51873

Author: nebkat

src/compiler/checker.ts

@@ -22048,15 +22048,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         if (match === -1) {
             return defaultValue;
         }
-        // make sure exactly 1 matches before returning it
-        let nextMatch = discriminable.indexOf(/*searchElement*/ true, match + 1);
-        while (nextMatch !== -1) {
-            if (!isTypeIdenticalTo(target.types[match], target.types[nextMatch])) {
-                return defaultValue;
-            }
-            nextMatch = discriminable.indexOf(/*searchElement*/ true, nextMatch + 1);
-        }
-        return target.types[match];
+        return getUnionType(target.types.filter((_, index) => discriminable[index]));
     }
 
     /**

tests/baselines/reference/excessPropertyCheckWithMultipleDiscriminants.errors.txt

@@ -2,11 +2,13 @@ tests/cases/compiler/excessPropertyCheckWithMultipleDiscriminants.ts(30,5): erro
   Object literal may only specify known properties, and 'multipleOf' does not exist in type 'Float'.
 tests/cases/compiler/excessPropertyCheckWithMultipleDiscriminants.ts(41,5): error TS2322: Type '{ p1: "left"; p2: false; p3: number; p4: string; }' is not assignable to type 'DisjointDiscriminants'.
   Object literal may only specify known properties, and 'p3' does not exist in type '{ p1: "left"; p2: boolean; }'.
+tests/cases/compiler/excessPropertyCheckWithMultipleDiscriminants.ts(50,5): error TS2322: Type '{ p1: "left"; p2: true; p3: number; p4: string; }' is not assignable to type 'DisjointDiscriminants'.
+  Object literal may only specify known properties, and 'p4' does not exist in type '{ p1: "left"; p2: true; p3: number; } | { p1: "left"; p2: boolean; }'.
 tests/cases/compiler/excessPropertyCheckWithMultipleDiscriminants.ts(57,5): error TS2322: Type '{ p1: "right"; p2: false; p3: number; p4: string; }' is not assignable to type 'DisjointDiscriminants'.
   Object literal may only specify known properties, and 'p3' does not exist in type '{ p1: "right"; p2: false; p4: string; }'.
 
 
-==== tests/cases/compiler/excessPropertyCheckWithMultipleDiscriminants.ts (3 errors) ====
+==== tests/cases/compiler/excessPropertyCheckWithMultipleDiscriminants.ts (4 errors) ====
     // Repro from #32657
 
     interface Base<T> {
@@ -57,12 +59,15 @@ tests/cases/compiler/excessPropertyCheckWithMultipleDiscriminants.ts(57,5): erro
         p4: "hello"
     };
 
-    // This has no excess error because variant one and three are both applicable.
+    // This has excess error because variant two is not applicable.
     const b: DisjointDiscriminants = {
         p1: 'left',
         p2: true,
         p3: 42,
         p4: "hello"
+        ~~~~~~~~~~~
+!!! error TS2322: Type '{ p1: "left"; p2: true; p3: number; p4: string; }' is not assignable to type 'DisjointDiscriminants'.
+!!! error TS2322:   Object literal may only specify known properties, and 'p4' does not exist in type '{ p1: "left"; p2: true; p3: number; } | { p1: "left"; p2: boolean; }'.
     };
 
     // This has excess error because variant two is the only applicable case

tests/baselines/reference/excessPropertyCheckWithMultipleDiscriminants.js

@@ -43,7 +43,7 @@ const a: DisjointDiscriminants = {
     p4: "hello"
 };
 
-// This has no excess error because variant one and three are both applicable.
+// This has excess error because variant two is not applicable.
 const b: DisjointDiscriminants = {
     p1: 'left',
     p2: true,
@@ -75,7 +75,7 @@ var a = {
     p3: 42,
     p4: "hello"
 };
-// This has no excess error because variant one and three are both applicable.
+// This has excess error because variant two is not applicable.
 var b = {
     p1: 'left',
     p2: true,

tests/baselines/reference/excessPropertyCheckWithMultipleDiscriminants.symbols

@@ -103,7 +103,7 @@ const a: DisjointDiscriminants = {
 
 };
 
-// This has no excess error because variant one and three are both applicable.
+// This has excess error because variant two is not applicable.
 const b: DisjointDiscriminants = {
 >b : Symbol(b, Decl(excessPropertyCheckWithMultipleDiscriminants.ts, 45, 5))
 >DisjointDiscriminants : Symbol(DisjointDiscriminants, Decl(excessPropertyCheckWithMultipleDiscriminants.ts, 31, 1))

tests/baselines/reference/excessPropertyCheckWithMultipleDiscriminants.types

@@ -93,7 +93,7 @@ const a: DisjointDiscriminants = {
 
 };
 
-// This has no excess error because variant one and three are both applicable.
+// This has excess error because variant two is not applicable.
 const b: DisjointDiscriminants = {
 >b : DisjointDiscriminants
 >{    p1: 'left',    p2: true,    p3: 42,    p4: "hello"} : { p1: "left"; p2: true; p3: number; p4: string; }

tests/baselines/reference/excessPropertyCheckWithUnions.errors.txt

@@ -5,30 +5,27 @@ tests/cases/compiler/excessPropertyCheckWithUnions.ts(11,21): error TS2322: Type
 tests/cases/compiler/excessPropertyCheckWithUnions.ts(12,1): error TS2322: Type '{ tag: "D"; }' is not assignable to type 'ADT'.
   Property 'd20' is missing in type '{ tag: "D"; }' but required in type '{ tag: "D"; d20: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20; }'.
 tests/cases/compiler/excessPropertyCheckWithUnions.ts(33,28): error TS2322: Type '{ tag: "A"; x: string; extra: number; }' is not assignable to type 'Ambiguous'.
-  Object literal may only specify known properties, and 'extra' does not exist in type 'Ambiguous'.
+  Object literal may only specify known properties, and 'extra' does not exist in type '{ tag: "A"; x: string; } | { tag: "A"; y: number; }'.
 tests/cases/compiler/excessPropertyCheckWithUnions.ts(34,26): error TS2322: Type '{ tag: "A"; y: number; extra: number; }' is not assignable to type 'Ambiguous'.
-  Object literal may only specify known properties, and 'extra' does not exist in type 'Ambiguous'.
-tests/cases/compiler/excessPropertyCheckWithUnions.ts(39,1): error TS2322: Type '{ tag: "A"; }' is not assignable to type 'Ambiguous'.
-  Type '{ tag: "A"; }' is not assignable to type '{ tag: "C"; }'.
-    Types of property 'tag' are incompatible.
-      Type '"A"' is not assignable to type '"C"'.
-tests/cases/compiler/excessPropertyCheckWithUnions.ts(40,1): error TS2322: Type '{ tag: "A"; z: true; }' is not assignable to type 'Ambiguous'.
-  Type '{ tag: "A"; z: true; }' is not assignable to type '{ tag: "B"; z: boolean; }'.
-    Types of property 'tag' are incompatible.
-      Type '"A"' is not assignable to type '"B"'.
-tests/cases/compiler/excessPropertyCheckWithUnions.ts(49,35): error TS2322: Type '{ a: 1; b: 1; first: string; second: string; }' is not assignable to type 'Overlapping'.
+  Object literal may only specify known properties, and 'extra' does not exist in type '{ tag: "A"; x: string; } | { tag: "A"; y: number; }'.
+tests/cases/compiler/excessPropertyCheckWithUnions.ts(37,1): error TS2322: Type '{ tag: "A"; }' is not assignable to type 'Ambiguous'.
+  Type '{ tag: "A"; }' is not assignable to type '{ tag: "A"; x: string; } | { tag: "A"; y: number; }'.
+    Property 'y' is missing in type '{ tag: "A"; }' but required in type '{ tag: "A"; y: number; }'.
+tests/cases/compiler/excessPropertyCheckWithUnions.ts(38,19): error TS2322: Type '{ tag: "A"; z: boolean; }' is not assignable to type 'Ambiguous'.
+  Object literal may only specify known properties, and 'z' does not exist in type '{ tag: "A"; x: string; } | { tag: "A"; y: number; }'.
+tests/cases/compiler/excessPropertyCheckWithUnions.ts(47,35): error TS2322: Type '{ a: 1; b: 1; first: string; second: string; }' is not assignable to type 'Overlapping'.
   Object literal may only specify known properties, and 'second' does not exist in type '{ a: 1; b: 1; first: string; }'.
-tests/cases/compiler/excessPropertyCheckWithUnions.ts(50,35): error TS2322: Type '{ a: 1; b: 1; first: string; third: string; }' is not assignable to type 'Overlapping'.
+tests/cases/compiler/excessPropertyCheckWithUnions.ts(48,35): error TS2322: Type '{ a: 1; b: 1; first: string; third: string; }' is not assignable to type 'Overlapping'.
   Object literal may only specify known properties, and 'third' does not exist in type '{ a: 1; b: 1; first: string; }'.
-tests/cases/compiler/excessPropertyCheckWithUnions.ts(66,9): error TS2322: Type '{ kind: "A"; n: { a: string; b: string; }; }' is not assignable to type 'AB'.
+tests/cases/compiler/excessPropertyCheckWithUnions.ts(64,9): error TS2322: Type '{ kind: "A"; n: { a: string; b: string; }; }' is not assignable to type 'AB'.
   Types of property 'n' are incompatible.
     Type '{ a: string; b: string; }' is not assignable to type 'AN'.
       Object literal may only specify known properties, and 'b' does not exist in type 'AN'.
-tests/cases/compiler/excessPropertyCheckWithUnions.ts(87,5): error TS2322: Type '{ tag: "button"; type: "submit"; href: string; }' is not assignable to type 'Union'.
+tests/cases/compiler/excessPropertyCheckWithUnions.ts(85,5): error TS2322: Type '{ tag: "button"; type: "submit"; href: string; }' is not assignable to type 'Union'.
   Object literal may only specify known properties, and 'href' does not exist in type 'Button'.
-tests/cases/compiler/excessPropertyCheckWithUnions.ts(108,5): error TS2322: Type 'string' is not assignable to type 'IValue'.
-tests/cases/compiler/excessPropertyCheckWithUnions.ts(113,67): error TS2322: Type 'string' is not assignable to type 'number'.
-tests/cases/compiler/excessPropertyCheckWithUnions.ts(114,63): error TS2322: Type 'string' is not assignable to type 'number'.
+tests/cases/compiler/excessPropertyCheckWithUnions.ts(106,5): error TS2322: Type 'string' is not assignable to type 'IValue'.
+tests/cases/compiler/excessPropertyCheckWithUnions.ts(111,67): error TS2322: Type 'string' is not assignable to type 'number'.
+tests/cases/compiler/excessPropertyCheckWithUnions.ts(112,63): error TS2322: Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/compiler/excessPropertyCheckWithUnions.ts (14 errors) ====
@@ -77,27 +74,23 @@ tests/cases/compiler/excessPropertyCheckWithUnions.ts(114,63): error TS2322: Typ
     amb = { tag: "A", x: "hi", extra: 12 }
                                ~~~~~~~~~
 !!! error TS2322: Type '{ tag: "A"; x: string; extra: number; }' is not assignable to type 'Ambiguous'.
-!!! error TS2322:   Object literal may only specify known properties, and 'extra' does not exist in type 'Ambiguous'.
+!!! error TS2322:   Object literal may only specify known properties, and 'extra' does not exist in type '{ tag: "A"; x: string; } | { tag: "A"; y: number; }'.
     amb = { tag: "A", y: 12, extra: 12 }
                              ~~~~~~~~~
 !!! error TS2322: Type '{ tag: "A"; y: number; extra: number; }' is not assignable to type 'Ambiguous'.
-!!! error TS2322:   Object literal may only specify known properties, and 'extra' does not exist in type 'Ambiguous'.
+!!! error TS2322:   Object literal may only specify known properties, and 'extra' does not exist in type '{ tag: "A"; x: string; } | { tag: "A"; y: number; }'.
 
-    // assignability errors still work.
-    // But note that the error for `z: true` is the fallback one of reporting on
-    // the last constituent since assignability error reporting can't find a single best discriminant either.
+    // assignability errors still work
     amb = { tag: "A" }
     ~~~
 !!! error TS2322: Type '{ tag: "A"; }' is not assignable to type 'Ambiguous'.
-!!! error TS2322:   Type '{ tag: "A"; }' is not assignable to type '{ tag: "C"; }'.
-!!! error TS2322:     Types of property 'tag' are incompatible.
-!!! error TS2322:       Type '"A"' is not assignable to type '"C"'.
+!!! error TS2322:   Type '{ tag: "A"; }' is not assignable to type '{ tag: "A"; x: string; } | { tag: "A"; y: number; }'.
+!!! error TS2322:     Property 'y' is missing in type '{ tag: "A"; }' but required in type '{ tag: "A"; y: number; }'.
+!!! related TS2728 tests/cases/compiler/excessPropertyCheckWithUnions.ts:19:5: 'y' is declared here.
     amb = { tag: "A", z: true }
-    ~~~
-!!! error TS2322: Type '{ tag: "A"; z: true; }' is not assignable to type 'Ambiguous'.
-!!! error TS2322:   Type '{ tag: "A"; z: true; }' is not assignable to type '{ tag: "B"; z: boolean; }'.
-!!! error TS2322:     Types of property 'tag' are incompatible.
-!!! error TS2322:       Type '"A"' is not assignable to type '"B"'.
+                      ~~~~~~~
+!!! error TS2322: Type '{ tag: "A"; z: boolean; }' is not assignable to type 'Ambiguous'.
+!!! error TS2322:   Object literal may only specify known properties, and 'z' does not exist in type '{ tag: "A"; x: string; } | { tag: "A"; y: number; }'.
 
     type Overlapping =
         | { a: 1, b: 1, first: string }
@@ -167,7 +160,7 @@ tests/cases/compiler/excessPropertyCheckWithUnions.ts(114,63): error TS2322: Typ
       value: string
     }
 
-    interface StringKeys { 
+    interface StringKeys {
         [propertyName: string]: IValue;
     };
 

tests/baselines/reference/excessPropertyCheckWithUnions.js

@@ -34,9 +34,7 @@ amb = { tag: "A", x: "hi", y: 12 }
 amb = { tag: "A", x: "hi", extra: 12 }
 amb = { tag: "A", y: 12, extra: 12 }
 
-// assignability errors still work.
-// But note that the error for `z: true` is the fallback one of reporting on
-// the last constituent since assignability error reporting can't find a single best discriminant either.
+// assignability errors still work
 amb = { tag: "A" }
 amb = { tag: "A", z: true }
 
@@ -94,7 +92,7 @@ interface IValue {
   value: string
 }
 
-interface StringKeys { 
+interface StringKeys {
     [propertyName: string]: IValue;
 };
 
@@ -178,9 +176,7 @@ amb = { tag: "A", x: "hi", y: 12 };
 // correctly error on excess property 'extra', even when ambiguous
 amb = { tag: "A", x: "hi", extra: 12 };
 amb = { tag: "A", y: 12, extra: 12 };
-// assignability errors still work.
-// But note that the error for `z: true` is the fallback one of reporting on
-// the last constituent since assignability error reporting can't find a single best discriminant either.
+// assignability errors still work
 amb = { tag: "A" };
 amb = { tag: "A", z: true };
 var over;