basic fix for aliased variables CFA

src/compiler/checker.ts

@@ -22235,11 +22235,24 @@ namespace ts {
  && (source as MetaProperty).name.escapedText === (target as MetaProperty).name.escapedText;
  case SyntaxKind.Identifier:
  case SyntaxKind.PrivateIdentifier:
- return isThisInTypeQuery(source) ?
- target.kind === SyntaxKind.ThisKeyword :
- target.kind === SyntaxKind.Identifier && getResolvedSymbol(source as Identifier) === getResolvedSymbol(target as Identifier) ||
- (target.kind === SyntaxKind.VariableDeclaration || target.kind === SyntaxKind.BindingElement) &&
- getExportSymbolOfValueSymbolIfExported(getResolvedSymbol(source as Identifier)) === getSymbolOfNode(target);
+ if (isThisInTypeQuery(source)) {
+ return target.kind === SyntaxKind.ThisKeyword;
+ }
+ // Debug.assert(isIdentifier(source) || isPrivateIdentifier(source));
+ if (target.kind === SyntaxKind.Identifier
+ && getResolvedSymbol(source as Identifier) === getResolvedSymbol(target as Identifier)
+ || (target.kind === SyntaxKind.VariableDeclaration || target.kind === SyntaxKind.BindingElement)
+ && getExportSymbolOfValueSymbolIfExported(getResolvedSymbol(source as Identifier)) === getSymbolOfNode(target)
+ ) {
+ return true;
+ }
+ else {
+ const access = getPropertyAccess(source as Identifier);
+ if (access) {
+ return isMatchingReference(isAccessExpression(access) ? access.expression : access.parent.parent.initializer!, target);
+ }
+ }
+ return false;
  case SyntaxKind.ThisKeyword:
  return target.kind === SyntaxKind.ThisKeyword;
  case SyntaxKind.SuperKeyword:
@@ -23714,7 +23727,7 @@ namespace ts {
  }
 
  // @ts-ignore
- function __isMatchingReferenceDiscriminant(expr: Expression, computedType: Type) {
+ function _isMatchingReferenceDiscriminant(expr: Expression, computedType: Type) {
  const type = declaredType.flags & TypeFlags.Union ? declaredType : computedType;
  if (!(type.flags & TypeFlags.Union) || !isAccessExpression(expr)) {
  return false;
@@ -24033,6 +24046,7 @@ namespace ts {
  }
 
  /**
+ * Assume there is variable `foo` whose type is `A`, try to get the final type of foo.property1.proerty2...
  * @param type Assume this should be just the type of 'reference'
  * @param expressionWithOutKeyword an expression without any keyword. "typeof root.a" is not acceptable.
  */
@@ -24051,8 +24065,10 @@ namespace ts {
  const nonCallExpressionWithOutKeyword = expressionWithOutKeyword;
 
  // check some condition, if not meet, it means we could not handle this confition for now.
- if (nonCallExpressionWithOutKeyword.kind !== SyntaxKind.BindingElement && nonCallExpressionWithOutKeyword.kind !== SyntaxKind.Identifier && !isAccessExpression(nonCallExpressionWithOutKeyword)) {// || (<AccessExpression>expressionWithOutKeyword).expression.kind === SyntaxKind.ThisKeyword) {
- // ATTENTION: binding element is not handled!!!!!!!!!!!!!!!
+ if (nonCallExpressionWithOutKeyword.kind !== SyntaxKind.Identifier && nonCallExpressionWithOutKeyword.kind !== SyntaxKind.BindingElement && !isAccessExpression(nonCallExpressionWithOutKeyword)) {// || (<AccessExpression>expressionWithOutKeyword).expression.kind === SyntaxKind.ThisKeyword) {
+ // if (nonCallExpressionWithOutKeyword.kind === SyntaxKind.BindingElement) {
+ // debugger;
+ // }
  return undefined;
  }
 
@@ -24067,7 +24083,7 @@ namespace ts {
  // 1. type A is { a: undefined }.
  // 2. type B is { a: never }.
  // Now we have `type C = { a: {innerType: 1} }`
- // for case 1, create `type X = A|C`, it should be filtered through optional chain, and not cause any error although A.a does not have any inner type. Like `root.a?.innerType` is valid.
+ // for case 1, create `type X = A|C`, it should be filtered through optional chain, and not cause any error, although A.a does not have any inner type. Like `root.a?.innerType` is valid.
  // for case 2, it is similar, and we do not even need optional chain. Like `root.a.innerType`
 
  let propertyTypeArray: NarrowDeepPropertyInfo[] | undefined;
@@ -24084,27 +24100,45 @@ namespace ts {
 
  return propertyTypeArray;
 
+ // Assume reference is a
  // If expression is a, return []
  // If expression is a.b["c"].d(), return ["b","c","d"]
+ // If element is BindingElement 'const x = a.b.c', return ["b", "c"]
+ // If element is BindingElement 'const { c: x } = a.b', return ["b", "c"]
  // NOTE: If element expression is not known in compile progress like a.b[f()].d, the result would be undefined
+ // NOTE: Binding element is restricted for now: reference must be more "expanded" than node, which might be a binding element. See this example:
+ // const tmp1 = root.a.b; const { b : tmp2 } = root.a;
+ // if (tmp1.c.d === "A") root.a.b // root would be narrowed
+ // if (root.a.b.c.d === "A") tmp1.c.d // however, tmp1 would not be narrowed for now
+ // The result is similar for tmp2
  // //NOTE: this function need improvement, ElementAccessExpression argument might could be known in compile time, like "1"+"2", we should check "12" in the path, but how to get the value?
- function tryGetPropertyPathsOfReferenceFromExpression(expressionOri: Expression, reference: Node): PathInfo[] | undefined {
+ function tryGetPropertyPathsOfReferenceFromExpression(node: Expression | BindingElement, reference: Node): PathInfo[] | undefined {
  const properties = [];
- let expr: Expression = expressionOri;
- while (isAccessExpression(expr)) {
- if (isMatchingReference(reference, expr)) {
- return properties;
- }
- const propName = getAccessedPropertyName(expr);
+ let exprOrBindingElemenr: BindingElement | Expression | undefined = node;
+ let access: Expression | undefined;
+
+ while (exprOrBindingElemenr && !isMatchingReference(reference, currentNode()) && (isAccessExpression(exprOrBindingElemenr) || isBindingElement(exprOrBindingElemenr))) {
+ const propName = getAccessedPropertyName(exprOrBindingElemenr);
  if (!propName) {
  return undefined;
  }
- properties.unshift({ path: propName, isOptionalChain: isOptionalChain(expr) });
- expr = expr.expression;
+ properties.unshift({ path: propName, isOptionalChain: isOptionalChain(exprOrBindingElemenr) });
+ access = isBindingElement(exprOrBindingElemenr) ? exprOrBindingElemenr.parent.parent.initializer : exprOrBindingElemenr.expression;
+ if (!access) {
+ return undefined;
+ }
+ exprOrBindingElemenr = getPropertyAccess(access);
  }
- if (isMatchingReference(reference, expr)) {
+
+ if (isMatchingReference(reference, currentNode())) {
  return properties;
  }
+
+ function currentNode() {
+ if (exprOrBindingElemenr) return exprOrBindingElemenr;
+ if (access) return access;
+ throw new Error("Never");
+ }
  }
 
  function getPropertyTypeFromTypeAccordingToPath(constituentType: Type, pathInfos: PathInfo[], isCallExpression: boolean): NarrowDeepPropertyInfo | undefined {

tests/baselines/reference/destructuringControlFlow.types

@@ -63,34 +63,34 @@ function f2(obj: [number, string] | null[]) {
 >obj[0] : number | null
 >obj : [number, string] | null[]
 >0 : 0
->obj[1] : string
->obj : [number, string]
+>obj[1] : string | null
+>obj : [number, string] | null[]
 >1 : 1
 
  let c0 = obj[0]; // number
 >c0 : number
 >obj[0] : number
->obj : [number, string]
+>obj : [number, string] | null[]
 >0 : 0
 
  let c1 = obj[1]; // string
 >c1 : string
 >obj[1] : string
->obj : [number, string]
+>obj : [number, string] | null[]
 >1 : 1
 
  let [d0, d1] = obj;
 >d0 : number
 >d1 : string
->obj : [number, string]
+>obj : [number, string] | null[]
 
  ([c0, c1] = obj);
->([c0, c1] = obj) : [number, string]
->[c0, c1] = obj : [number, string]
+>([c0, c1] = obj) : [number, string] | null[]
+>[c0, c1] = obj : [number, string] | null[]
 >[c0, c1] : [number, string]
 >c0 : number
 >c1 : string
->obj : [number, string]
+>obj : [number, string] | null[]
  }
 }
 

tests/baselines/reference/discriminatedUnionTypes2.errors.txt

@@ -2,10 +2,9 @@ tests/cases/conformance/types/union/discriminatedUnionTypes2.ts(27,30): error TS
  Object literal may only specify known properties, and 'c' does not exist in type '{ a: null; b: string; }'.
 tests/cases/conformance/types/union/discriminatedUnionTypes2.ts(32,11): error TS2339: Property 'b' does not exist on type '{ a: 0; b: string; } | { a: T; c: number; }'.
  Property 'b' does not exist on type '{ a: T; c: number; }'.
-tests/cases/conformance/types/union/discriminatedUnionTypes2.ts(132,11): error TS2339: Property 'value' does not exist on type 'never'.
 
 
-==== tests/cases/conformance/types/union/discriminatedUnionTypes2.ts (3 errors) ====
+==== tests/cases/conformance/types/union/discriminatedUnionTypes2.ts (2 errors) ====
  function f10(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
  if (x.kind === false) {
  x.a;
@@ -144,8 +143,6 @@ tests/cases/conformance/types/union/discriminatedUnionTypes2.ts(132,11): error T
  }
  else {
  x.value; // Error, x is never
- ~~~~~
-!!! error TS2339: Property 'value' does not exist on type 'never'.
  }
  }
 

tests/baselines/reference/discriminatedUnionTypes2.symbols

@@ -367,7 +367,9 @@ function foo1(x: RuntimeValue & { type: 'number' }) {
  }
  else {
  x.value; // Error, x is never
+>x.value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 122, 23))
 >x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 126, 14))
+>value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 122, 23))
  }
 }
 

tests/baselines/reference/discriminatedUnionTypes2.types

@@ -380,9 +380,9 @@ function foo1(x: RuntimeValue & { type: 'number' }) {
  }
  else {
  x.value; // Error, x is never
->x.value : any
->x : never
->value : any
+>x.value : number
+>x : { type: "number"; value: number; } & { type: "number"; }
+>value : number
  }
 }
 

tests/baselines/reference/discriminatedUnionTypes3.errors.txt

@@ -1,7 +1,22 @@
-tests/cases/conformance/types/union/discriminatedUnionTypes3.ts(59,11): error TS2339: Property 's' does not exist on type 'T'.
+tests/cases/conformance/types/union/discriminatedUnionTypes3.ts(13,15): error TS2339: Property 'x' does not exist on type 'X | Y'.
+ Property 'x' does not exist on type 'Y'.
+tests/cases/conformance/types/union/discriminatedUnionTypes3.ts(16,15): error TS2339: Property 'y' does not exist on type 'X | Y'.
+ Property 'y' does not exist on type 'X'.
+tests/cases/conformance/types/union/discriminatedUnionTypes3.ts(34,11): error TS2339: Property 'x' does not exist on type 'X | Y'.
+ Property 'x' does not exist on type 'Y'.
+tests/cases/conformance/types/union/discriminatedUnionTypes3.ts(36,11): error TS2339: Property 'y' does not exist on type 'X | Y'.
+ Property 'y' does not exist on type 'X'.
+tests/cases/conformance/types/union/discriminatedUnionTypes3.ts(42,11): error TS2339: Property 'x' does not exist on type 'X | W'.
+ Property 'x' does not exist on type 'W'.
+tests/cases/conformance/types/union/discriminatedUnionTypes3.ts(55,11): error TS2339: Property 's' does not exist on type 'S | T'.
+ Property 's' does not exist on type 'T'.
+tests/cases/conformance/types/union/discriminatedUnionTypes3.ts(56,21): error TS2339: Property 'x' does not exist on type 'X | Y'.
+ Property 'x' does not exist on type 'Y'.
+tests/cases/conformance/types/union/discriminatedUnionTypes3.ts(59,11): error TS2339: Property 's' does not exist on type 'S | T'.
+ Property 's' does not exist on type 'T'.
 
 
-==== tests/cases/conformance/types/union/discriminatedUnionTypes3.ts (1 errors) ====
+==== tests/cases/conformance/types/union/discriminatedUnionTypes3.ts (8 errors) ====
  type A = { type2: "a", a: number }
  type B = { type2: "b", b: number }
  type C = { type2: "c", b: number | string }
@@ -15,9 +30,15 @@ tests/cases/conformance/types/union/discriminatedUnionTypes3.ts(59,11): error TS
  switch (x.type1.type2) {
  case "a":
  x.x // typeof x is X
+ ~
+!!! error TS2339: Property 'x' does not exist on type 'X | Y'.
+!!! error TS2339: Property 'x' does not exist on type 'Y'.
  break;
  case "b":
  x.y // typeof x is Y
+ ~
+!!! error TS2339: Property 'y' does not exist on type 'X | Y'.
+!!! error TS2339: Property 'y' does not exist on type 'X'.
  break;
  }
  }
@@ -36,14 +57,23 @@ tests/cases/conformance/types/union/discriminatedUnionTypes3.ts(59,11): error TS
  function f34(x: X | Y) {
  if (x.type1.type2 === "a") {
  x.x // typeof x is X
+ ~
+!!! error TS2339: Property 'x' does not exist on type 'X | Y'.
+!!! error TS2339: Property 'x' does not exist on type 'Y'.
  } else if (x.type1.type2 === "b") {
  x.y // typeof x is Y
+ ~
+!!! error TS2339: Property 'y' does not exist on type 'X | Y'.
+!!! error TS2339: Property 'y' does not exist on type 'X'.
  }
  }
 
  function f35(x: X | W) {
  if (x.type1?.type2 === "a") {
  x.x
+ ~
+!!! error TS2339: Property 'x' does not exist on type 'X | W'.
+!!! error TS2339: Property 'x' does not exist on type 'W'.
  }
  }
 
@@ -57,12 +87,37 @@ tests/cases/conformance/types/union/discriminatedUnionTypes3.ts(59,11): error TS
  function f37(s: S | T) {
  if (s.sub.type0.type1.type2 === "a") {
  s.s // typeof s is S
+ ~
+!!! error TS2339: Property 's' does not exist on type 'S | T'.
+!!! error TS2339: Property 's' does not exist on type 'T'.
  s.sub.type0.x // type of s.sub.type is X
+ ~
+!!! error TS2339: Property 'x' does not exist on type 'X | Y'.
+!!! error TS2339: Property 'x' does not exist on type 'Y'.
  s.sub.type0.type1.a // type of s.sub.type.type is A
  } else {
  s.s // type error!
  ~
-!!! error TS2339: Property 's' does not exist on type 'T'.
+!!! error TS2339: Property 's' does not exist on type 'S | T'.
+!!! error TS2339: Property 's' does not exist on type 'T'.
  }
  }
+
+ // Repro from #44435
+
+ type Correct = {
+ code: string
+ property: true
+ err: undefined
+ }
+ type Err = {
+ err: `${string} is wrong!`
+ }
+ type SomeReturnType = Correct | Err;
+
+ const example: SomeReturnType = {} as SomeReturnType;
+
+ if (example.err === undefined) {
+ example.property; // true
+ }