intersect duh

Author: Andarist

src/compiler/checker.ts

@@ -19173,7 +19173,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
 
     function getPropertyTypeForIndexType(originalObjectType: Type, objectType: Type, indexType: Type, fullIndexType: Type, accessNode: ElementAccessExpression | IndexedAccessTypeNode | PropertyName | BindingName | SyntheticExpression | undefined, accessFlags: AccessFlags) {
         if (indexType.flags & TypeFlags.Substitution) {
-            indexType = (indexType as SubstitutionType).baseType;
+            indexType = getSubstitutionIntersection(indexType as SubstitutionType);
         }
         const accessExpression = accessNode && accessNode.kind === SyntaxKind.ElementAccessExpression ? accessNode : undefined;
         const propName = accessNode && isPrivateIdentifier(accessNode) ? undefined : getPropertyNameFromIndex(indexType, accessNode);

tests/baselines/reference/nonGenericIndexedAccessInConditionalTrueBranch1.symbols

@@ -37,3 +37,9 @@ type E = "k" extends keyof C ? C["k" | "other"] : never;
 >C : Symbol(C, Decl(nonGenericIndexedAccessInConditionalTrueBranch1.ts, 6, 46))
 >C : Symbol(C, Decl(nonGenericIndexedAccessInConditionalTrueBranch1.ts, 6, 46))
 
+type F = keyof C extends "k" ? C[keyof C] : never;
+>F : Symbol(F, Decl(nonGenericIndexedAccessInConditionalTrueBranch1.ts, 14, 56))
+>C : Symbol(C, Decl(nonGenericIndexedAccessInConditionalTrueBranch1.ts, 6, 46))
+>C : Symbol(C, Decl(nonGenericIndexedAccessInConditionalTrueBranch1.ts, 6, 46))
+>C : Symbol(C, Decl(nonGenericIndexedAccessInConditionalTrueBranch1.ts, 6, 46))
+

tests/baselines/reference/nonGenericIndexedAccessInConditionalTrueBranch1.types

@@ -39,3 +39,7 @@ type E = "k" extends keyof C ? C["k" | "other"] : never;
 >E : boolean | symbol
 >  : ^^^^^^^^^^^^^^^^
 
+type F = keyof C extends "k" ? C[keyof C] : never;
+>F : never
+>  : ^^^^^
+

tests/cases/compiler/nonGenericIndexedAccessInConditionalTrueBranch1.ts

@@ -16,3 +16,4 @@ type C = {
 
 type D = "k" extends keyof C ? C["k"] : never;
 type E = "k" extends keyof C ? C["k" | "other"] : never;
+type F = keyof C extends "k" ? C[keyof C] : never;