Fixed an issue with missingType narrowing by case undefined in de…

…fault cases (#58001)
microsoft · May 1, 2024 · f01cae8 · f01cae8
1 parent 33b1561
commit f01cae8
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Showing 10 changed files with 837 additions and 1 deletion.
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -28543,7 +28543,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             if (!hasDefaultClause) {
                 return caseType;
             }
-            const defaultType = filterType(type, t => !(isUnitLikeType(t) && contains(switchTypes, getRegularTypeOfLiteralType(extractUnitType(t)))));
+            const defaultType = filterType(type, t => !(isUnitLikeType(t) && contains(switchTypes, t.flags & TypeFlags.Undefined ? undefinedType : getRegularTypeOfLiteralType(extractUnitType(t)))));
             return caseType.flags & TypeFlags.Never ? defaultType : getUnionType([caseType, defaultType]);
         }
 

diff --git a/...ntUndefinedCase1(exactoptionalpropertytypes=false,nouncheckedindexedaccess=false).symbols b/...ntUndefinedCase1(exactoptionalpropertytypes=false,nouncheckedindexedaccess=false).symbols
@@ -0,0 +1,75 @@
+//// [tests/cases/compiler/narrowBySwitchDiscriminantUndefinedCase1.ts] ////
+
+=== narrowBySwitchDiscriminantUndefinedCase1.ts ===
+// https://github.com/microsoft/TypeScript/issues/57999
+
+interface A {
+>A : Symbol(A, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 0, 0))
+
+  optionalProp?: "hello";
+>optionalProp : Symbol(A.optionalProp, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 2, 13))
+}
+
+function func(arg: A) {
+>func : Symbol(func, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 4, 1))
+>arg : Symbol(arg, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 6, 14))
+>A : Symbol(A, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 0, 0))
+
+  const { optionalProp } = arg;
+>optionalProp : Symbol(optionalProp, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 7, 9))
+>arg : Symbol(arg, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 6, 14))
+
+  switch (optionalProp) {
+>optionalProp : Symbol(optionalProp, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 7, 9))
+
+    case undefined:
+>undefined : Symbol(undefined)
+
+      return undefined;
+>undefined : Symbol(undefined)
+
+    case "hello":
+      return "hello";
+    default:
+      assertUnreachable(optionalProp);
+>assertUnreachable : Symbol(assertUnreachable, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 30, 1))
+>optionalProp : Symbol(optionalProp, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 7, 9))
+  }
+}
+
+function func2() {
+>func2 : Symbol(func2, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 17, 1))
+
+  const optionalProp = ["hello" as const][Math.random()];
+>optionalProp : Symbol(optionalProp, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 20, 7))
+>const : Symbol(const)
+>Math.random : Symbol(Math.random, Decl(lib.es5.d.ts, --, --))
+>Math : Symbol(Math, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>random : Symbol(Math.random, Decl(lib.es5.d.ts, --, --))
+
+  switch (optionalProp) {
+>optionalProp : Symbol(optionalProp, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 20, 7))
+
+    case undefined:
+>undefined : Symbol(undefined)
+
+      return undefined;
+>undefined : Symbol(undefined)
+
+    case "hello":
+      return "hello";
+    default:
+      assertUnreachable(optionalProp);
+>assertUnreachable : Symbol(assertUnreachable, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 30, 1))
+>optionalProp : Symbol(optionalProp, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 20, 7))
+  }
+}
+
+function assertUnreachable(_: never): never {
+>assertUnreachable : Symbol(assertUnreachable, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 30, 1))
+>_ : Symbol(_, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 32, 27))
+
+  throw new Error("Unreachable path taken");
+>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+}
+
diff --git a/...nantUndefinedCase1(exactoptionalpropertytypes=false,nouncheckedindexedaccess=false).types b/...nantUndefinedCase1(exactoptionalpropertytypes=false,nouncheckedindexedaccess=false).types
@@ -0,0 +1,124 @@
+//// [tests/cases/compiler/narrowBySwitchDiscriminantUndefinedCase1.ts] ////
+
+=== narrowBySwitchDiscriminantUndefinedCase1.ts ===
+// https://github.com/microsoft/TypeScript/issues/57999
+
+interface A {
+  optionalProp?: "hello";
+>optionalProp : "hello" | undefined
+>             : ^^^^^^^^^^^^^^^^^^^
+}
+
+function func(arg: A) {
+>func : (arg: A) => "hello" | undefined
+>     : ^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^
+>arg : A
+>    : ^
+
+  const { optionalProp } = arg;
+>optionalProp : "hello" | undefined
+>             : ^^^^^^^^^^^^^^^^^^^
+>arg : A
+>    : ^
+
+  switch (optionalProp) {
+>optionalProp : "hello" | undefined
+>             : ^^^^^^^^^^^^^^^^^^^
+
+    case undefined:
+>undefined : undefined
+>          : ^^^^^^^^^
+
+      return undefined;
+>undefined : undefined
+>          : ^^^^^^^^^
+
+    case "hello":
+>"hello" : "hello"
+>        : ^^^^^^^
+
+      return "hello";
+>"hello" : "hello"
+>        : ^^^^^^^
+
+    default:
+      assertUnreachable(optionalProp);
+>assertUnreachable(optionalProp) : never
+>                                : ^^^^^
+>assertUnreachable : (_: never) => never
+>                  : ^^^^^^^^^^^^^^^^^^^
+>optionalProp : never
+>             : ^^^^^
+  }
+}
+
+function func2() {
+>func2 : () => "hello" | undefined
+>      : ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+  const optionalProp = ["hello" as const][Math.random()];
+>optionalProp : "hello"
+>             : ^^^^^^^
+>["hello" as const][Math.random()] : "hello"
+>                                  : ^^^^^^^
+>["hello" as const] : "hello"[]
+>                   : ^^^^^^^^^
+>"hello" as const : "hello"
+>                 : ^^^^^^^
+>"hello" : "hello"
+>        : ^^^^^^^
+>Math.random() : number
+>              : ^^^^^^
+>Math.random : () => number
+>            : ^^^^^^^^^^^^
+>Math : Math
+>     : ^^^^
+>random : () => number
+>       : ^^^^^^^^^^^^
+
+  switch (optionalProp) {
+>optionalProp : "hello"
+>             : ^^^^^^^
+
+    case undefined:
+>undefined : undefined
+>          : ^^^^^^^^^
+
+      return undefined;
+>undefined : undefined
+>          : ^^^^^^^^^
+
+    case "hello":
+>"hello" : "hello"
+>        : ^^^^^^^
+
+      return "hello";
+>"hello" : "hello"
+>        : ^^^^^^^
+
+    default:
+      assertUnreachable(optionalProp);
+>assertUnreachable(optionalProp) : never
+>                                : ^^^^^
+>assertUnreachable : (_: never) => never
+>                  : ^^^^^^^^^^^^^^^^^^^
+>optionalProp : never
+>             : ^^^^^
+  }
+}
+
+function assertUnreachable(_: never): never {
+>assertUnreachable : (_: never) => never
+>                  : ^^^^     ^^^^^     
+>_ : never
+>  : ^^^^^
+
+  throw new Error("Unreachable path taken");
+>new Error("Unreachable path taken") : Error
+>                                    : ^^^^^
+>Error : ErrorConstructor
+>      : ^^^^^^^^^^^^^^^^
+>"Unreachable path taken" : "Unreachable path taken"
+>                         : ^^^^^^^^^^^^^^^^^^^^^^^^
+}
+
diff --git a/...antUndefinedCase1(exactoptionalpropertytypes=false,nouncheckedindexedaccess=true).symbols b/...antUndefinedCase1(exactoptionalpropertytypes=false,nouncheckedindexedaccess=true).symbols
@@ -0,0 +1,75 @@
+//// [tests/cases/compiler/narrowBySwitchDiscriminantUndefinedCase1.ts] ////
+
+=== narrowBySwitchDiscriminantUndefinedCase1.ts ===
+// https://github.com/microsoft/TypeScript/issues/57999
+
+interface A {
+>A : Symbol(A, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 0, 0))
+
+  optionalProp?: "hello";
+>optionalProp : Symbol(A.optionalProp, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 2, 13))
+}
+
+function func(arg: A) {
+>func : Symbol(func, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 4, 1))
+>arg : Symbol(arg, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 6, 14))
+>A : Symbol(A, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 0, 0))
+
+  const { optionalProp } = arg;
+>optionalProp : Symbol(optionalProp, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 7, 9))
+>arg : Symbol(arg, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 6, 14))
+
+  switch (optionalProp) {
+>optionalProp : Symbol(optionalProp, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 7, 9))
+
+    case undefined:
+>undefined : Symbol(undefined)
+
+      return undefined;
+>undefined : Symbol(undefined)
+
+    case "hello":
+      return "hello";
+    default:
+      assertUnreachable(optionalProp);
+>assertUnreachable : Symbol(assertUnreachable, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 30, 1))
+>optionalProp : Symbol(optionalProp, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 7, 9))
+  }
+}
+
+function func2() {
+>func2 : Symbol(func2, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 17, 1))
+
+  const optionalProp = ["hello" as const][Math.random()];
+>optionalProp : Symbol(optionalProp, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 20, 7))
+>const : Symbol(const)
+>Math.random : Symbol(Math.random, Decl(lib.es5.d.ts, --, --))
+>Math : Symbol(Math, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>random : Symbol(Math.random, Decl(lib.es5.d.ts, --, --))
+
+  switch (optionalProp) {
+>optionalProp : Symbol(optionalProp, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 20, 7))
+
+    case undefined:
+>undefined : Symbol(undefined)
+
+      return undefined;
+>undefined : Symbol(undefined)
+
+    case "hello":
+      return "hello";
+    default:
+      assertUnreachable(optionalProp);
+>assertUnreachable : Symbol(assertUnreachable, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 30, 1))
+>optionalProp : Symbol(optionalProp, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 20, 7))
+  }
+}
+
+function assertUnreachable(_: never): never {
+>assertUnreachable : Symbol(assertUnreachable, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 30, 1))
+>_ : Symbol(_, Decl(narrowBySwitchDiscriminantUndefinedCase1.ts, 32, 27))
+
+  throw new Error("Unreachable path taken");
+>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+}
+