Slightly less conservative check in isConstraintPosition (microsoft#46526)

* Slight adjustment to check in isConstraintPosition

* Add regression test

Author: ahejlsberg

src/compiler/checker.ts

@@ -24758,7 +24758,7 @@ 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) {

tests/baselines/reference/controlFlowGenericTypes.errors.txt

@@ -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;
+        }
+    }
 

tests/baselines/reference/controlFlowGenericTypes.js

@@ -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]
@@ -343,3 +363,8 @@ var SqlTable = /** @class */ (function () {
     };
     return SqlTable;
 }());
+function update(control, key, value) {
+    if (control !== undefined) {
+        control[key] = value;
+    }
+}

tests/baselines/reference/controlFlowGenericTypes.symbols

@@ -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))
+    }
+}
+

tests/baselines/reference/controlFlowGenericTypes.types

@@ -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]
+    }
+}
+

tests/cases/conformance/controlFlow/controlFlowGenericTypes.ts

@@ -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;
+    }
+}