Work correctly on unconstrained types.

DanielRosenwasser · web-flow · commit 891aa24350e6 · 2022-04-05T23:33:55.000Z
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -25345,7 +25345,7 @@ namespace ts {
                     someType(type, isGenericTypeWithUnionConstraint) ||
                     ((type.flags & TypeFlags.Instantiable) && contextualType && isEmptyObjectType(contextualType))
                 );
-            return substituteConstraints ? mapType(type, t => t.flags & TypeFlags.Instantiable ? getBaseConstraintOrType(t) : t) : type;
+            return substituteConstraints ? mapType(type, t => t.flags & TypeFlags.Instantiable ? getBaseConstraintOfType(t) || unknownType : t) : type;
         }
 
         function isExportOrExportExpression(location: Node) {

Original file line number	Diff line number	Diff line change
`@@ -25345,7 +25345,7 @@ namespace ts {`
`25345`	`25345`	`someType(type, isGenericTypeWithUnionConstraint) \|\|`
`25346`	`25346`	`((type.flags & TypeFlags.Instantiable) && contextualType && isEmptyObjectType(contextualType))`
`25347`	`25347`	`);`
`25348`		`- return substituteConstraints ? mapType(type, t => t.flags & TypeFlags.Instantiable ? getBaseConstraintOrType(t) : t) : type;`
	`25348`	`+ return substituteConstraints ? mapType(type, t => t.flags & TypeFlags.Instantiable ? getBaseConstraintOfType(t) \|\| unknownType : t) : type;`
`25349`	`25349`	`}`
`25350`	`25350`
`25351`	`25351`	`function isExportOrExportExpression(location: Node) {`