From e9a3218a650c15e314916bde4dee30c4e7844155 Mon Sep 17 00:00:00 2001
From: Holly Borla <hborla@apple.com>
Date: Mon, 12 Jun 2023 23:07:21 -0700
Subject: [PATCH] [GenericEnvironment] Don't apply outer context substitutions
 before type.subst in mapTypeIntoContext.

The outer context substitutions are already applied when invoking
QueryInterfaceTypeSubstitutions. Applying the context substitutions
before subst also causes problems because QueryInterfaceTypeSubstitutions
will return a null type if given an archetype, which manifested with
opened pack element environments.

(cherry picked from commit d6fe62542af18b3fa7bbbd91edc1b88d409b96eb)
---
 lib/AST/GenericEnvironment.cpp                    | 1 -
 test/Constraints/pack-expansion-expressions.swift | 8 ++++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/lib/AST/GenericEnvironment.cpp b/lib/AST/GenericEnvironment.cpp
index 88957a6abe737..aecf75826e670 100644
--- a/lib/AST/GenericEnvironment.cpp
+++ b/lib/AST/GenericEnvironment.cpp
@@ -635,7 +635,6 @@ Type GenericEnvironment::mapTypeIntoContext(
   assert((!type->hasArchetype() || type->hasLocalArchetype()) &&
          "already have a contextual type");
 
-  type = maybeApplyOuterContextSubstitutions(type);
   Type result = type.subst(QueryInterfaceTypeSubstitutions(this),
                            lookupConformance,
                            SubstFlags::AllowLoweredTypes |
diff --git a/test/Constraints/pack-expansion-expressions.swift b/test/Constraints/pack-expansion-expressions.swift
index 22de5f7b3b5df..b47a94b2bec48 100644
--- a/test/Constraints/pack-expansion-expressions.swift
+++ b/test/Constraints/pack-expansion-expressions.swift
@@ -552,3 +552,11 @@ do {
     _ = (repeat overloaded(1, each a))
   }
 }
+
+func configure<T, each Element>(
+  _ item: T,
+  with configuration: repeat (ReferenceWritableKeyPath<T, each Element>, each Element)
+) -> T {
+  repeat item[keyPath: (each configuration).0] = (each configuration).1
+  return item
+}