Grab the left type when narrowing by in operator lazily (#54795)

src/compiler/checker.ts

@@ -27175,14 +27175,16 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                         return narrowTypeByPrivateIdentifierInInExpression(type, expr, assumeTrue);
                     }
                     const target = getReferenceCandidate(expr.right);
-                    const leftType = getTypeOfExpression(expr.left);
-                    if (leftType.flags & TypeFlags.StringOrNumberLiteralOrUnique) {
-                        if (containsMissingType(type) && isAccessExpression(reference) && isMatchingReference(reference.expression, target) &&
-                            getAccessedPropertyName(reference) === getPropertyNameFromType(leftType as StringLiteralType | NumberLiteralType | UniqueESSymbolType)) {
+                    if (containsMissingType(type) && isAccessExpression(reference) && isMatchingReference(reference.expression, target)) {
+                        const leftType = getTypeOfExpression(expr.left);
+                        if (isTypeUsableAsPropertyName(leftType) && getAccessedPropertyName(reference) === getPropertyNameFromType(leftType)) {
                             return getTypeWithFacts(type, assumeTrue ? TypeFacts.NEUndefined : TypeFacts.EQUndefined);
                         }
-                        if (isMatchingReference(reference, target)) {
-                            return narrowTypeByInKeyword(type, leftType as StringLiteralType | NumberLiteralType | UniqueESSymbolType, assumeTrue);
+                    }
+                    if (isMatchingReference(reference, target)) {
+                        const leftType = getTypeOfExpression(expr.left);
+                        if (isTypeUsableAsPropertyName(leftType)) {
+                            return narrowTypeByInKeyword(type, leftType, assumeTrue);
                         }
                     }
                     break;

tests/baselines/reference/controlFlowInOperator.js

@@ -27,6 +27,45 @@ if (a in c) {
 if (d in c) {
     c; // never
 }
+
+// repro from https://github.com/microsoft/TypeScript/issues/54790
+
+function uniqueID_54790(
+  id: string | undefined,
+  seenIDs: { [key: string]: string }
+): string {
+  if (id === undefined) {
+    id = "1";
+  }
+  if (!(id in seenIDs)) {
+    return id;
+  }
+  for (let i = 1; i < Number.MAX_VALUE; i++) {
+    const newID = `${id}-${i}`;
+    if (!(newID in seenIDs)) {
+      return newID;
+    }
+  }
+  throw Error("heat death of the universe");
+}
+
+function uniqueID_54790_2(id: string | number, seenIDs: object) {
+  id = "a";
+  for (let i = 1; i < 3; i++) {
+    const newID = `${id}`;
+    if (newID in seenIDs) {
+    }
+  }
+}
+
+function uniqueID_54790_3(id: string | number, seenIDs: object) {
+  id = "a";
+  for (let i = 1; i < 3; i++) {
+    const newID = id;
+    if (newID in seenIDs) {
+    }
+  }
+}
 
 
 //// [controlFlowInOperator.js]
@@ -47,3 +86,35 @@ if (a in c) {
 if (d in c) {
     c; // never
 }
+// repro from https://github.com/microsoft/TypeScript/issues/54790
+function uniqueID_54790(id, seenIDs) {
+    if (id === undefined) {
+        id = "1";
+    }
+    if (!(id in seenIDs)) {
+        return id;
+    }
+    for (var i = 1; i < Number.MAX_VALUE; i++) {
+        var newID = "".concat(id, "-").concat(i);
+        if (!(newID in seenIDs)) {
+            return newID;
+        }
+    }
+    throw Error("heat death of the universe");
+}
+function uniqueID_54790_2(id, seenIDs) {
+    id = "a";
+    for (var i = 1; i < 3; i++) {
+        var newID = "".concat(id);
+        if (newID in seenIDs) {
+        }
+    }
+}
+function uniqueID_54790_3(id, seenIDs) {
+    id = "a";
+    for (var i = 1; i < 3; i++) {
+        var newID = id;
+        if (newID in seenIDs) {
+        }
+    }
+}

tests/baselines/reference/controlFlowInOperator.symbols

@@ -63,3 +63,103 @@ if (d in c) {
 >c : Symbol(c, Decl(controlFlowInOperator.ts, 7, 13))
 }
 
+// repro from https://github.com/microsoft/TypeScript/issues/54790
+
+function uniqueID_54790(
+>uniqueID_54790 : Symbol(uniqueID_54790, Decl(controlFlowInOperator.ts, 25, 1))
+
+  id: string | undefined,
+>id : Symbol(id, Decl(controlFlowInOperator.ts, 29, 24))
+
+  seenIDs: { [key: string]: string }
+>seenIDs : Symbol(seenIDs, Decl(controlFlowInOperator.ts, 30, 25))
+>key : Symbol(key, Decl(controlFlowInOperator.ts, 31, 14))
+
+): string {
+  if (id === undefined) {
+>id : Symbol(id, Decl(controlFlowInOperator.ts, 29, 24))
+>undefined : Symbol(undefined)
+
+    id = "1";
+>id : Symbol(id, Decl(controlFlowInOperator.ts, 29, 24))
+  }
+  if (!(id in seenIDs)) {
+>id : Symbol(id, Decl(controlFlowInOperator.ts, 29, 24))
+>seenIDs : Symbol(seenIDs, Decl(controlFlowInOperator.ts, 30, 25))
+
+    return id;
+>id : Symbol(id, Decl(controlFlowInOperator.ts, 29, 24))
+  }
+  for (let i = 1; i < Number.MAX_VALUE; i++) {
+>i : Symbol(i, Decl(controlFlowInOperator.ts, 39, 10))
+>i : Symbol(i, Decl(controlFlowInOperator.ts, 39, 10))
+>Number.MAX_VALUE : Symbol(NumberConstructor.MAX_VALUE, Decl(lib.es5.d.ts, --, --))
+>Number : Symbol(Number, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>MAX_VALUE : Symbol(NumberConstructor.MAX_VALUE, Decl(lib.es5.d.ts, --, --))
+>i : Symbol(i, Decl(controlFlowInOperator.ts, 39, 10))
+
+    const newID = `${id}-${i}`;
+>newID : Symbol(newID, Decl(controlFlowInOperator.ts, 40, 9))
+>id : Symbol(id, Decl(controlFlowInOperator.ts, 29, 24))
+>i : Symbol(i, Decl(controlFlowInOperator.ts, 39, 10))
+
+    if (!(newID in seenIDs)) {
+>newID : Symbol(newID, Decl(controlFlowInOperator.ts, 40, 9))
+>seenIDs : Symbol(seenIDs, Decl(controlFlowInOperator.ts, 30, 25))
+
+      return newID;
+>newID : Symbol(newID, Decl(controlFlowInOperator.ts, 40, 9))
+    }
+  }
+  throw Error("heat death of the universe");
+>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+}
+
+function uniqueID_54790_2(id: string | number, seenIDs: object) {
+>uniqueID_54790_2 : Symbol(uniqueID_54790_2, Decl(controlFlowInOperator.ts, 46, 1))
+>id : Symbol(id, Decl(controlFlowInOperator.ts, 48, 26))
+>seenIDs : Symbol(seenIDs, Decl(controlFlowInOperator.ts, 48, 46))
+
+  id = "a";
+>id : Symbol(id, Decl(controlFlowInOperator.ts, 48, 26))
+
+  for (let i = 1; i < 3; i++) {
+>i : Symbol(i, Decl(controlFlowInOperator.ts, 50, 10))
+>i : Symbol(i, Decl(controlFlowInOperator.ts, 50, 10))
+>i : Symbol(i, Decl(controlFlowInOperator.ts, 50, 10))
+
+    const newID = `${id}`;
+>newID : Symbol(newID, Decl(controlFlowInOperator.ts, 51, 9))
+>id : Symbol(id, Decl(controlFlowInOperator.ts, 48, 26))
+
+    if (newID in seenIDs) {
+>newID : Symbol(newID, Decl(controlFlowInOperator.ts, 51, 9))
+>seenIDs : Symbol(seenIDs, Decl(controlFlowInOperator.ts, 48, 46))
+    }
+  }
+}
+
+function uniqueID_54790_3(id: string | number, seenIDs: object) {
+>uniqueID_54790_3 : Symbol(uniqueID_54790_3, Decl(controlFlowInOperator.ts, 55, 1))
+>id : Symbol(id, Decl(controlFlowInOperator.ts, 57, 26))
+>seenIDs : Symbol(seenIDs, Decl(controlFlowInOperator.ts, 57, 46))
+
+  id = "a";
+>id : Symbol(id, Decl(controlFlowInOperator.ts, 57, 26))
+
+  for (let i = 1; i < 3; i++) {
+>i : Symbol(i, Decl(controlFlowInOperator.ts, 59, 10))
+>i : Symbol(i, Decl(controlFlowInOperator.ts, 59, 10))
+>i : Symbol(i, Decl(controlFlowInOperator.ts, 59, 10))
+
+    const newID = id;
+>newID : Symbol(newID, Decl(controlFlowInOperator.ts, 60, 9))
+>id : Symbol(id, Decl(controlFlowInOperator.ts, 57, 26))
+
+    if (newID in seenIDs) {
+>newID : Symbol(newID, Decl(controlFlowInOperator.ts, 60, 9))
+>seenIDs : Symbol(seenIDs, Decl(controlFlowInOperator.ts, 57, 46))
+    }
+  }
+}
+

tests/baselines/reference/controlFlowInOperator.types

@@ -72,3 +72,133 @@ if (d in c) {
 >c : (A | B) & Record<"d", unknown>
 }
 
+// repro from https://github.com/microsoft/TypeScript/issues/54790
+
+function uniqueID_54790(
+>uniqueID_54790 : (id: string | undefined, seenIDs: { [key: string]: string; }) => string
+
+  id: string | undefined,
+>id : string
+
+  seenIDs: { [key: string]: string }
+>seenIDs : { [key: string]: string; }
+>key : string
+
+): string {
+  if (id === undefined) {
+>id === undefined : boolean
+>id : string
+>undefined : undefined
+
+    id = "1";
+>id = "1" : "1"
+>id : string
+>"1" : "1"
+  }
+  if (!(id in seenIDs)) {
+>!(id in seenIDs) : boolean
+>(id in seenIDs) : boolean
+>id in seenIDs : boolean
+>id : string
+>seenIDs : { [key: string]: string; }
+
+    return id;
+>id : string
+  }
+  for (let i = 1; i < Number.MAX_VALUE; i++) {
+>i : number
+>1 : 1
+>i < Number.MAX_VALUE : boolean
+>i : number
+>Number.MAX_VALUE : number
+>Number : NumberConstructor
+>MAX_VALUE : number
+>i++ : number
+>i : number
+
+    const newID = `${id}-${i}`;
+>newID : string
+>`${id}-${i}` : string
+>id : string
+>i : number
+
+    if (!(newID in seenIDs)) {
+>!(newID in seenIDs) : boolean
+>(newID in seenIDs) : boolean
+>newID in seenIDs : boolean
+>newID : string
+>seenIDs : { [key: string]: string; }
+
+      return newID;
+>newID : string
+    }
+  }
+  throw Error("heat death of the universe");
+>Error("heat death of the universe") : Error
+>Error : ErrorConstructor
+>"heat death of the universe" : "heat death of the universe"
+}
+
+function uniqueID_54790_2(id: string | number, seenIDs: object) {
+>uniqueID_54790_2 : (id: string | number, seenIDs: object) => void
+>id : string | number
+>seenIDs : object
+
+  id = "a";
+>id = "a" : "a"
+>id : string | number
+>"a" : "a"
+
+  for (let i = 1; i < 3; i++) {
+>i : number
+>1 : 1
+>i < 3 : boolean
+>i : number
+>3 : 3
+>i++ : number
+>i : number
+
+    const newID = `${id}`;
+>newID : string
+>`${id}` : string
+>id : string
+
+    if (newID in seenIDs) {
+>newID in seenIDs : boolean
+>newID : string
+>seenIDs : object
+    }
+  }
+}
+
+function uniqueID_54790_3(id: string | number, seenIDs: object) {
+>uniqueID_54790_3 : (id: string | number, seenIDs: object) => void
+>id : string | number
+>seenIDs : object
+
+  id = "a";
+>id = "a" : "a"
+>id : string | number
+>"a" : "a"
+
+  for (let i = 1; i < 3; i++) {
+>i : number
+>1 : 1
+>i < 3 : boolean
+>i : number
+>3 : 3
+>i++ : number
+>i : number
+
+    const newID = id;
+>newID : string
+>id : string
+
+    if (newID in seenIDs) {
+>newID in seenIDs : boolean
+>newID : string
+>seenIDs : object
+    }
+  }
+}
+

tests/cases/conformance/controlFlow/controlFlowInOperator.ts

@@ -24,3 +24,42 @@ if (a in c) {
 if (d in c) {
     c; // never
 }
+
+// repro from https://github.com/microsoft/TypeScript/issues/54790
+
+function uniqueID_54790(
+  id: string | undefined,
+  seenIDs: { [key: string]: string }
+): string {
+  if (id === undefined) {
+    id = "1";
+  }
+  if (!(id in seenIDs)) {
+    return id;
+  }
+  for (let i = 1; i < Number.MAX_VALUE; i++) {
+    const newID = `${id}-${i}`;
+    if (!(newID in seenIDs)) {
+      return newID;
+    }
+  }
+  throw Error("heat death of the universe");
+}
+
+function uniqueID_54790_2(id: string | number, seenIDs: object) {
+  id = "a";
+  for (let i = 1; i < 3; i++) {
+    const newID = `${id}`;
+    if (newID in seenIDs) {
+    }
+  }
+}
+
+function uniqueID_54790_3(id: string | number, seenIDs: object) {
+  id = "a";
+  for (let i = 1; i < 3; i++) {
+    const newID = id;
+    if (newID in seenIDs) {
+    }
+  }
+}