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Slightly less conservative check in isConstraintPosition #46526

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Merged
merged 2 commits into from
Oct 26, 2021
Merged

Slightly less conservative check in isConstraintPosition #46526

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cec8d52
Slight adjustment to check in isConstraintPosition
ahejlsberg Oct 25, 2021
042debb
Add regression test
ahejlsberg Oct 25, 2021
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2 changes: 1 addition & 1 deletion src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -24755,7 +24755,7 @@ namespace ts {
return parent.kind === SyntaxKind.PropertyAccessExpression ||
parent.kind === SyntaxKind.CallExpression && (parent as CallExpression).expression === node ||
parent.kind === SyntaxKind.ElementAccessExpression && (parent as ElementAccessExpression).expression === node &&
!(isGenericTypeWithoutNullableConstraint(type) && isGenericIndexType(getTypeOfExpression((parent as ElementAccessExpression).argumentExpression)));
!(someType(type, isGenericTypeWithoutNullableConstraint) && isGenericIndexType(getTypeOfExpression((parent as ElementAccessExpression).argumentExpression)));
}

function isGenericTypeWithUnionConstraint(type: Type) {
Expand Down
20 changes: 20 additions & 0 deletions tests/baselines/reference/controlFlowGenericTypes.errors.txt
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Expand Up @@ -220,4 +220,24 @@ tests/cases/conformance/controlFlow/controlFlowGenericTypes.ts(168,9): error TS2
this.validateRow(row);
}
}

// Repro from #46495

interface Button {
type: "button";
text: string;
}

interface Checkbox {
type: "checkbox";
isChecked: boolean;
}

type Control = Button | Checkbox;

function update<T extends Control, K extends keyof T>(control : T | undefined, key: K, value: T[K]): void {
if (control !== undefined) {
control[key] = value;
}
}

25 changes: 25 additions & 0 deletions tests/baselines/reference/controlFlowGenericTypes.js
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Expand Up @@ -190,6 +190,26 @@ class SqlTable<T> {
this.validateRow(row);
}
}

// Repro from #46495

interface Button {
type: "button";
text: string;
}

interface Checkbox {
type: "checkbox";
isChecked: boolean;
}

type Control = Button | Checkbox;

function update<T extends Control, K extends keyof T>(control : T | undefined, key: K, value: T[K]): void {
if (control !== undefined) {
control[key] = value;
}
}


//// [controlFlowGenericTypes.js]
Expand Down Expand Up @@ -343,3 +363,8 @@ var SqlTable = /** @class */ (function () {
};
return SqlTable;
}());
function update(control, key, value) {
if (control !== undefined) {
control[key] = value;
}
}
52 changes: 52 additions & 0 deletions tests/baselines/reference/controlFlowGenericTypes.symbols
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Expand Up @@ -574,3 +574,55 @@ class SqlTable<T> {
}
}

// Repro from #46495

interface Button {
>Button : Symbol(Button, Decl(controlFlowGenericTypes.ts, 190, 1))

type: "button";
>type : Symbol(Button.type, Decl(controlFlowGenericTypes.ts, 194, 18))

text: string;
>text : Symbol(Button.text, Decl(controlFlowGenericTypes.ts, 195, 19))
}

interface Checkbox {
>Checkbox : Symbol(Checkbox, Decl(controlFlowGenericTypes.ts, 197, 1))

type: "checkbox";
>type : Symbol(Checkbox.type, Decl(controlFlowGenericTypes.ts, 199, 20))

isChecked: boolean;
>isChecked : Symbol(Checkbox.isChecked, Decl(controlFlowGenericTypes.ts, 200, 21))
}

type Control = Button | Checkbox;
>Control : Symbol(Control, Decl(controlFlowGenericTypes.ts, 202, 1))
>Button : Symbol(Button, Decl(controlFlowGenericTypes.ts, 190, 1))
>Checkbox : Symbol(Checkbox, Decl(controlFlowGenericTypes.ts, 197, 1))

function update<T extends Control, K extends keyof T>(control : T | undefined, key: K, value: T[K]): void {
>update : Symbol(update, Decl(controlFlowGenericTypes.ts, 204, 33))
>T : Symbol(T, Decl(controlFlowGenericTypes.ts, 206, 16))
>Control : Symbol(Control, Decl(controlFlowGenericTypes.ts, 202, 1))
>K : Symbol(K, Decl(controlFlowGenericTypes.ts, 206, 34))
>T : Symbol(T, Decl(controlFlowGenericTypes.ts, 206, 16))
>control : Symbol(control, Decl(controlFlowGenericTypes.ts, 206, 54))
>T : Symbol(T, Decl(controlFlowGenericTypes.ts, 206, 16))
>key : Symbol(key, Decl(controlFlowGenericTypes.ts, 206, 78))
>K : Symbol(K, Decl(controlFlowGenericTypes.ts, 206, 34))
>value : Symbol(value, Decl(controlFlowGenericTypes.ts, 206, 86))
>T : Symbol(T, Decl(controlFlowGenericTypes.ts, 206, 16))
>K : Symbol(K, Decl(controlFlowGenericTypes.ts, 206, 34))

if (control !== undefined) {
>control : Symbol(control, Decl(controlFlowGenericTypes.ts, 206, 54))
>undefined : Symbol(undefined)

control[key] = value;
>control : Symbol(control, Decl(controlFlowGenericTypes.ts, 206, 54))
>key : Symbol(key, Decl(controlFlowGenericTypes.ts, 206, 78))
>value : Symbol(value, Decl(controlFlowGenericTypes.ts, 206, 86))
}
}

41 changes: 41 additions & 0 deletions tests/baselines/reference/controlFlowGenericTypes.types
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Expand Up @@ -542,3 +542,44 @@ class SqlTable<T> {
}
}

// Repro from #46495

interface Button {
type: "button";
>type : "button"

text: string;
>text : string
}

interface Checkbox {
type: "checkbox";
>type : "checkbox"

isChecked: boolean;
>isChecked : boolean
}

type Control = Button | Checkbox;
>Control : Control

function update<T extends Control, K extends keyof T>(control : T | undefined, key: K, value: T[K]): void {
>update : <T extends Control, K extends keyof T>(control: T | undefined, key: K, value: T[K]) => void
>control : T | undefined
>key : K
>value : T[K]

if (control !== undefined) {
>control !== undefined : boolean
>control : T | undefined
>undefined : undefined

control[key] = value;
>control[key] = value : T[K]
>control[key] : T[K]
>control : T
>key : K
>value : T[K]
}
}

20 changes: 20 additions & 0 deletions tests/cases/conformance/controlFlow/controlFlowGenericTypes.ts
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Expand Up @@ -191,3 +191,23 @@ class SqlTable<T> {
this.validateRow(row);
}
}

// Repro from #46495

interface Button {
type: "button";
text: string;
}

interface Checkbox {
type: "checkbox";
isChecked: boolean;
}

type Control = Button | Checkbox;

function update<T extends Control, K extends keyof T>(control : T | undefined, key: K, value: T[K]): void {
if (control !== undefined) {
control[key] = value;
}
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Can a subsequent else if discriminate between Button and Checkbox, or are we now stuck with T?

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In a subsequent else if the type of control would be undefined. But if you mean a subsequent if inside the block, then yes:

if (control !== undefined) {          // Type of control is T | undefined
    control[key] = value;             // Type of control is T
    if (control.type === "button") {  // Type of control is Control
        control.text;                 // Type of control is Button
    }
}

}