From 4a8ada3fb071b70ec70cfc4533de0e1308064e13 Mon Sep 17 00:00:00 2001
From: Dario Rexin <drexin@apple.com>
Date: Thu, 10 Apr 2025 15:13:00 -0700
Subject: [PATCH] [IRGen] Set generic context before getting call emission in
 visitFullApplySite

rdar://149007227

Without the generic context, the result type can't be mapped into the current context, causing the compiler to crash.
---
 lib/IRGen/IRGenSIL.cpp        |  7 ++++---
 test/IRGen/typed_throws.swift | 12 ++++++++++++
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/lib/IRGen/IRGenSIL.cpp b/lib/IRGen/IRGenSIL.cpp
index 18105502da8b9..ba574ae5d7683 100644
--- a/lib/IRGen/IRGenSIL.cpp
+++ b/lib/IRGen/IRGenSIL.cpp
@@ -3850,6 +3850,10 @@ void IRGenSILFunction::visitFullApplySite(FullApplySite site) {
     }
   }
 
+  // Lower the arguments and return value in the callee's generic context.
+  GenericContextScope scope(IGM,
+                            origCalleeType->getInvocationGenericSignature());
+
   Explosion llArgs;
   WitnessMetadata witnessMetadata;
   auto emission = getCallEmissionForLoweredValue(
@@ -3862,9 +3866,6 @@ void IRGenSILFunction::visitFullApplySite(FullApplySite site) {
 
   emission->begin();
 
-  // Lower the arguments and return value in the callee's generic context.
-  GenericContextScope scope(IGM, origCalleeType->getInvocationGenericSignature());
-
   auto &calleeFP = emission->getCallee().getFunctionPointer();
 
   // Allocate space for the coroutine buffer.
diff --git a/test/IRGen/typed_throws.swift b/test/IRGen/typed_throws.swift
index d44b65afd2b14..f4581f0d039e1 100644
--- a/test/IRGen/typed_throws.swift
+++ b/test/IRGen/typed_throws.swift
@@ -359,3 +359,15 @@ struct SomeStruct {
 func someFunc() async throws(SmallError) -> SomeStruct {
     SomeStruct(x: 42, y: 23, z: 25)
 }
+
+// Used to crash the compiler -- https://github.com/swiftlang/swift/issues/80732
+protocol PAssoc<T>: AnyObject {
+    associatedtype T
+    func foo() async throws(SmallError) -> (any PAssoc<T>)
+}
+
+class MyProtocolImpl<T>: PAssoc {
+    func foo() async throws(SmallError) -> (any PAssoc<T>) {
+        fatalError()
+    }
+}