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Error on syntactically impossible ===s to undefined #60433

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Error on syntactically impossible ===s to undefined #60433

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8 changes: 8 additions & 0 deletions src/compiler/checker.ts
View file
Original file line number Diff line number Diff line change
@@ -40006,6 +40006,14 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
const eqType = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.EqualsEqualsEqualsToken;
error(errorNode, Diagnostics.This_condition_will_always_return_0_since_JavaScript_compares_objects_by_reference_not_value, eqType ? "false" : "true");
}
const otherUndefinedOp =
(left.kind === SyntaxKind.Identifier && getSymbolAtLocation(left) === undefinedSymbol) ? right :
(right.kind === SyntaxKind.Identifier && getSymbolAtLocation(right) === undefinedSymbol) ? left : undefined;
if (otherUndefinedOp) {
if (getSyntacticNullishnessSemantics(otherUndefinedOp) !== PredicateSemantics.Sometimes) {
error(otherUndefinedOp, Diagnostics.This_binary_expression_is_never_nullish_Are_you_missing_parentheses);
}
}
checkNaNEquality(errorNode, operator, left, right);
reportOperatorErrorUnless((left, right) => isTypeEqualityComparableTo(left, right) || isTypeEqualityComparableTo(right, left));
}
16 changes: 14 additions & 2 deletions tests/baselines/reference/comparisonOperatorWithIdenticalPrimitiveType.errors.txt
View file
Original file line number Diff line number Diff line change
@@ -14,9 +14,13 @@ comparisonOperatorWithIdenticalPrimitiveType.ts(42,11): error TS18050: The value
comparisonOperatorWithIdenticalPrimitiveType.ts(42,19): error TS18050: The value 'null' cannot be used here.
comparisonOperatorWithIdenticalPrimitiveType.ts(43,11): error TS18050: The value 'undefined' cannot be used here.
comparisonOperatorWithIdenticalPrimitiveType.ts(43,24): error TS18050: The value 'undefined' cannot be used here.
comparisonOperatorWithIdenticalPrimitiveType.ts(52,24): error TS2870: This binary expression is never nullish. Are you missing parentheses?
comparisonOperatorWithIdenticalPrimitiveType.ts(61,24): error TS2870: This binary expression is never nullish. Are you missing parentheses?
comparisonOperatorWithIdenticalPrimitiveType.ts(70,25): error TS2870: This binary expression is never nullish. Are you missing parentheses?
comparisonOperatorWithIdenticalPrimitiveType.ts(79,25): error TS2870: This binary expression is never nullish. Are you missing parentheses?


==== comparisonOperatorWithIdenticalPrimitiveType.ts (16 errors) ====
==== comparisonOperatorWithIdenticalPrimitiveType.ts (20 errors) ====
enum E { a, b, c }

var a: number;
@@ -101,6 +105,8 @@ comparisonOperatorWithIdenticalPrimitiveType.ts(43,24): error TS18050: The value
var re5 = e == e;
var re6 = null == null;
var re7 = undefined == undefined;
~~~~~~~~~
!!! error TS2870: This binary expression is never nullish. Are you missing parentheses?

// operator !=
var rf1 = a != a;
@@ -110,6 +116,8 @@ comparisonOperatorWithIdenticalPrimitiveType.ts(43,24): error TS18050: The value
var rf5 = e != e;
var rf6 = null != null;
var rf7 = undefined != undefined;
~~~~~~~~~
!!! error TS2870: This binary expression is never nullish. Are you missing parentheses?
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Why would we get this error here? Surely undefined is always nullish?

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i mean, when it's not ES5, or not the global scope, it could be any value, but presumably TS is ignoring that possibility :-)


// operator ===
var rg1 = a === a;
@@ -119,6 +127,8 @@ comparisonOperatorWithIdenticalPrimitiveType.ts(43,24): error TS18050: The value
var rg5 = e === e;
var rg6 = null === null;
var rg7 = undefined === undefined;
~~~~~~~~~
!!! error TS2870: This binary expression is never nullish. Are you missing parentheses?

// operator !==
var rh1 = a !== a;
@@ -127,4 +137,6 @@ comparisonOperatorWithIdenticalPrimitiveType.ts(43,24): error TS18050: The value
var rh4 = d !== d;
var rh5 = e !== e;
var rh6 = null !== null;
var rh7 = undefined !== undefined;
var rh7 = undefined !== undefined;
~~~~~~~~~
!!! error TS2870: This binary expression is never nullish. Are you missing parentheses?
74 changes: 74 additions & 0 deletions tests/baselines/reference/conditionalOperatorConditionIsBooleanType.errors.txt
View file
Original file line number Diff line number Diff line change
@@ -0,0 +1,74 @@
conditionalOperatorConditionIsBooleanType.ts(36,1): error TS2870: This binary expression is never nullish. Are you missing parentheses?
conditionalOperatorConditionIsBooleanType.ts(38,1): error TS2870: This binary expression is never nullish. Are you missing parentheses?
conditionalOperatorConditionIsBooleanType.ts(59,23): error TS2870: This binary expression is never nullish. Are you missing parentheses?


==== conditionalOperatorConditionIsBooleanType.ts (3 errors) ====
//Cond ? Expr1 : Expr2, Cond is of boolean type, Expr1 and Expr2 have the same type
var condBoolean: boolean;

var exprAny1: any;
var exprBoolean1: boolean;
var exprNumber1: number;
var exprString1: string;
var exprIsObject1: Object;

var exprAny2: any;
var exprBoolean2: boolean;
var exprNumber2: number;
var exprString2: string;
var exprIsObject2: Object;

//Cond is a boolean type variable
condBoolean ? exprAny1 : exprAny2;
condBoolean ? exprBoolean1 : exprBoolean2;
condBoolean ? exprNumber1 : exprNumber2;
condBoolean ? exprString1 : exprString2;
condBoolean ? exprIsObject1 : exprIsObject2;
condBoolean ? exprString1 : exprBoolean1; // union

//Cond is a boolean type literal
true ? exprAny1 : exprAny2;
false ? exprBoolean1 : exprBoolean2;
true ? exprNumber1 : exprNumber2;
false ? exprString1 : exprString2;
true ? exprIsObject1 : exprIsObject2;
true ? exprString1 : exprBoolean1; // union

//Cond is a boolean type expression
!true ? exprAny1 : exprAny2;
typeof "123" == "string" ? exprBoolean1 : exprBoolean2;
2 > 1 ? exprNumber1 : exprNumber2;
null === undefined ? exprString1 : exprString2;
~~~~
!!! error TS2870: This binary expression is never nullish. Are you missing parentheses?
true || false ? exprIsObject1 : exprIsObject2;
null === undefined ? exprString1 : exprBoolean1; // union
~~~~
!!! error TS2870: This binary expression is never nullish. Are you missing parentheses?

//Results shoud be same as Expr1 and Expr2
var resultIsAny1 = condBoolean ? exprAny1 : exprAny2;
var resultIsBoolean1 = condBoolean ? exprBoolean1 : exprBoolean2;
var resultIsNumber1 = condBoolean ? exprNumber1 : exprNumber2;
var resultIsString1 = condBoolean ? exprString1 : exprString2;
var resultIsObject1 = condBoolean ? exprIsObject1 : exprIsObject2;
var resultIsStringOrBoolean1 = condBoolean ? exprString1 : exprBoolean1; // union

var resultIsAny2 = true ? exprAny1 : exprAny2;
var resultIsBoolean2 = false ? exprBoolean1 : exprBoolean2;
var resultIsNumber2 = true ? exprNumber1 : exprNumber2;
var resultIsString2 = false ? exprString1 : exprString2;
var resultIsObject2 = true ? exprIsObject1 : exprIsObject2;
var resultIsStringOrBoolean2 = true ? exprString1 : exprBoolean1; // union
var resultIsStringOrBoolean3 = false ? exprString1 : exprBoolean1; // union

var resultIsAny3 = !true ? exprAny1 : exprAny2;
var resultIsBoolean3 = typeof "123" == "string" ? exprBoolean1 : exprBoolean2;
var resultIsNumber3 = 2 > 1 ? exprNumber1 : exprNumber2;
var resultIsString3 = null === undefined ? exprString1 : exprString2;
~~~~
!!! error TS2870: This binary expression is never nullish. Are you missing parentheses?
var resultIsObject3 = true || false ? exprIsObject1 : exprIsObject2;
var resultIsStringOrBoolean4 = typeof "123" === "string" ? exprString1 : exprBoolean1; // union

23 changes: 23 additions & 0 deletions tests/baselines/reference/conditionalOperatorConditionIsBooleanType.types
View file
Original file line number Diff line number Diff line change
@@ -8,6 +8,7 @@ var condBoolean: boolean;

var exprAny1: any;
>exprAny1 : any
> : ^^^

var exprBoolean1: boolean;
>exprBoolean1 : boolean
@@ -27,6 +28,7 @@ var exprIsObject1: Object;

var exprAny2: any;
>exprAny2 : any
> : ^^^

var exprBoolean2: boolean;
>exprBoolean2 : boolean
@@ -47,10 +49,13 @@ var exprIsObject2: Object;
//Cond is a boolean type variable
condBoolean ? exprAny1 : exprAny2;
>condBoolean ? exprAny1 : exprAny2 : any
> : ^^^
>condBoolean : boolean
> : ^^^^^^^
>exprAny1 : any
> : ^^^
>exprAny2 : any
> : ^^^

condBoolean ? exprBoolean1 : exprBoolean2;
>condBoolean ? exprBoolean1 : exprBoolean2 : boolean
@@ -105,10 +110,13 @@ condBoolean ? exprString1 : exprBoolean1; // union
//Cond is a boolean type literal
true ? exprAny1 : exprAny2;
>true ? exprAny1 : exprAny2 : any
> : ^^^
>true : true
> : ^^^^
>exprAny1 : any
> : ^^^
>exprAny2 : any
> : ^^^

false ? exprBoolean1 : exprBoolean2;
>false ? exprBoolean1 : exprBoolean2 : boolean
@@ -163,12 +171,15 @@ true ? exprString1 : exprBoolean1; // union
//Cond is a boolean type expression
!true ? exprAny1 : exprAny2;
>!true ? exprAny1 : exprAny2 : any
> : ^^^
>!true : boolean
> : ^^^^^^^
>true : true
> : ^^^^
>exprAny1 : any
> : ^^^
>exprAny2 : any
> : ^^^

typeof "123" == "string" ? exprBoolean1 : exprBoolean2;
>typeof "123" == "string" ? exprBoolean1 : exprBoolean2 : boolean
@@ -241,11 +252,15 @@ null === undefined ? exprString1 : exprBoolean1; // union
//Results shoud be same as Expr1 and Expr2
var resultIsAny1 = condBoolean ? exprAny1 : exprAny2;
>resultIsAny1 : any
> : ^^^
>condBoolean ? exprAny1 : exprAny2 : any
> : ^^^
>condBoolean : boolean
> : ^^^^^^^
>exprAny1 : any
> : ^^^
>exprAny2 : any
> : ^^^

var resultIsBoolean1 = condBoolean ? exprBoolean1 : exprBoolean2;
>resultIsBoolean1 : boolean
@@ -309,11 +324,15 @@ var resultIsStringOrBoolean1 = condBoolean ? exprString1 : exprBoolean1; // unio

var resultIsAny2 = true ? exprAny1 : exprAny2;
>resultIsAny2 : any
> : ^^^
>true ? exprAny1 : exprAny2 : any
> : ^^^
>true : true
> : ^^^^
>exprAny1 : any
> : ^^^
>exprAny2 : any
> : ^^^

var resultIsBoolean2 = false ? exprBoolean1 : exprBoolean2;
>resultIsBoolean2 : boolean
@@ -389,13 +408,17 @@ var resultIsStringOrBoolean3 = false ? exprString1 : exprBoolean1; // union

var resultIsAny3 = !true ? exprAny1 : exprAny2;
>resultIsAny3 : any
> : ^^^
>!true ? exprAny1 : exprAny2 : any
> : ^^^
>!true : boolean
> : ^^^^^^^
>true : true
> : ^^^^
>exprAny1 : any
> : ^^^
>exprAny2 : any
> : ^^^

var resultIsBoolean3 = typeof "123" == "string" ? exprBoolean1 : exprBoolean2;
>resultIsBoolean3 : boolean
11 changes: 10 additions & 1 deletion tests/baselines/reference/equalityStrictNulls.errors.txt
View file
Original file line number Diff line number Diff line change
@@ -1,10 +1,13 @@
equalityStrictNulls.ts(37,22): error TS2870: This binary expression is never nullish. Are you missing parentheses?
equalityStrictNulls.ts(39,22): error TS2870: This binary expression is never nullish. Are you missing parentheses?
equalityStrictNulls.ts(41,9): error TS2870: This binary expression is never nullish. Are you missing parentheses?
equalityStrictNulls.ts(59,13): error TS18050: The value 'undefined' cannot be used here.
equalityStrictNulls.ts(61,13): error TS18050: The value 'undefined' cannot be used here.
equalityStrictNulls.ts(63,14): error TS18050: The value 'undefined' cannot be used here.
equalityStrictNulls.ts(65,14): error TS18050: The value 'undefined' cannot be used here.


==== equalityStrictNulls.ts (4 errors) ====
==== equalityStrictNulls.ts (7 errors) ====
function f1(x: string) {
if (x == undefined) {
}
@@ -42,10 +45,16 @@ equalityStrictNulls.ts(65,14): error TS18050: The value 'undefined' cannot be us

function f2() {
if (undefined == undefined) {
~~~~~~~~~
!!! error TS2870: This binary expression is never nullish. Are you missing parentheses?
}
if (undefined == null) {
~~~~
!!! error TS2870: This binary expression is never nullish. Are you missing parentheses?
}
if (null == undefined) {
~~~~
!!! error TS2870: This binary expression is never nullish. Are you missing parentheses?
}
if (null == null) {
}
5 changes: 4 additions & 1 deletion tests/baselines/reference/functionImplementationErrors.errors.txt
View file
Original file line number Diff line number Diff line change
@@ -2,9 +2,10 @@ functionImplementationErrors.ts(25,16): error TS2355: A function whose declared
functionImplementationErrors.ts(30,17): error TS2373: Parameter 'n' cannot reference identifier 'm' declared after it.
functionImplementationErrors.ts(35,17): error TS2373: Parameter 'n' cannot reference identifier 'm' declared after it.
functionImplementationErrors.ts(40,1): error TS2839: This condition will always return 'false' since JavaScript compares objects by reference, not value.
functionImplementationErrors.ts(40,15): error TS2870: This binary expression is never nullish. Are you missing parentheses?


==== functionImplementationErrors.ts (4 errors) ====
==== functionImplementationErrors.ts (5 errors) ====
// FunctionExpression with no return type annotation with multiple return statements with unrelated types
var f1 = function () {
return '';
@@ -52,6 +53,8 @@ functionImplementationErrors.ts(40,1): error TS2839: This condition will always
// Should be error but isn't
undefined === function (): number {
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~
!!! error TS2870: This binary expression is never nullish. Are you missing parentheses?
throw undefined;
~~~~~~~~~~~~~~~~~~~~
var x = 4;
5 changes: 4 additions & 1 deletion tests/baselines/reference/functionImplementations.errors.txt
View file
Original file line number Diff line number Diff line change
@@ -1,8 +1,9 @@
functionImplementations.ts(85,5): error TS2403: Subsequent variable declarations must have the same type. Variable 'a' must be of type 'any', but here has type 'Base'.
functionImplementations.ts(90,1): error TS2839: This condition will always return 'false' since JavaScript compares objects by reference, not value.
functionImplementations.ts(90,15): error TS2870: This binary expression is never nullish. Are you missing parentheses?


==== functionImplementations.ts (2 errors) ====
==== functionImplementations.ts (3 errors) ====
// FunctionExpression with no return type annotation and no return statement returns void
var v: void = function () { } ();

@@ -97,6 +98,8 @@ functionImplementations.ts(90,1): error TS2839: This condition will always retur
// FunctionExpression with non -void return type annotation with a single throw statement
undefined === function (): number {
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~
!!! error TS2870: This binary expression is never nullish. Are you missing parentheses?
throw undefined;
~~~~~~~~~~~~~~~~~~~~
};
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