Sema: fix for 61440 (lib/AST/GenericEnvironment) no generic environment provided for type with type parameter

Author: jreference

lib/Sema/MiscDiagnostics.cpp

@@ -2575,9 +2575,9 @@ static bool fixItOverrideDeclarationTypesImpl(
       });
     }
 
-    auto resultType = subscript->getDeclContext()->mapTypeIntoContext(
-        subscript->getElementInterfaceType());
-    auto baseResultType = baseSubscript->getDeclContext()->mapTypeIntoContext(
+    auto resultType =
+        subscript->mapTypeIntoContext(subscript->getElementInterfaceType());
+    auto baseResultType = baseSubscript->mapTypeIntoContext(
         baseSubscript->getElementInterfaceType());
     fixedAny |= checkType(resultType, ParamDecl::Specifier::Default,
                           baseResultType, ParamDecl::Specifier::Default,

test/Sema/generic-subscript.swift

@@ -0,0 +1,44 @@
+// RUN: %target-typecheck-verify-swift
+
+
+protocol P
+{
+    subscript<Value>(x:Value) -> Int // expected-note {{protocol requires subscript with type '<Value> (Value) -> Int'; do you want to add a stub?}}
+    {
+        get 
+    } 
+}
+
+struct S:P // expected-error {{type 'S' does not conform to protocol 'P'}}
+{
+    subscript<Value>(x:Int) -> Value // expected-note {{candidate has non-matching type '<Value> (Int) -> Value'}}
+    {
+    } // expected-error {{missing return in subscript expected to return 'Value'}}
+}
+
+
+
+struct S2:P 
+{
+    subscript<Value>(x:Value) -> Int 
+    {
+			return 123;
+    } 
+}
+
+protocol P2
+{
+    subscript(x:Int) -> Int 
+    {
+        get 
+    } 
+}
+
+struct S3:P2
+{
+    subscript(x:Int) -> Int
+    {
+        return x;
+    } 
+}
+