IRGen: Fix the type of function pointers for signatures with opaque result types

lib/IRGen/GenCall.cpp

@@ -2530,7 +2530,9 @@ class AsyncCallEmission final : public CallEmission {
                                  getCallee().getFunctionPointer().getKind());
 
     return FunctionPointer::createForAsyncCall(
-        calleeFunction, codeAuthInfo, awaitSig, awaitEntrySig.getType());
+        IGF.Builder.CreateBitCast(calleeFunction,
+                                  awaitEntrySig.getType()->getPointerTo()),
+        codeAuthInfo, awaitSig, awaitEntrySig.getType());
   }
 
   SILType getParameterType(unsigned index) override {
@@ -5355,6 +5357,12 @@ llvm::FunctionType *FunctionPointer::getFunctionType() const {
     return cast<llvm::Function>(SecondaryValue)->getFunctionType();
   }
 
+  if (awaitSignature) {
+    assert(llvm::cast<llvm::PointerType>(Value->getType())
+               ->isOpaqueOrPointeeTypeMatches(awaitSignature));
+    return cast<llvm::FunctionType>(awaitSignature);
+  }
+
   // Read the function type off the global or else from the Signature.
   if (auto *constant = dyn_cast<llvm::Constant>(Value)) {
     auto *gv = dyn_cast<llvm::GlobalValue>(Value);
@@ -5377,12 +5385,6 @@ llvm::FunctionType *FunctionPointer::getFunctionType() const {
     return cast<llvm::FunctionType>(gv->getValueType());
   }
 
-  if (awaitSignature) {
-    assert(llvm::cast<llvm::PointerType>(Value->getType())
-               ->isOpaqueOrPointeeTypeMatches(awaitSignature));
-    return cast<llvm::FunctionType>(awaitSignature);
-  }
-
   assert(llvm::cast<llvm::PointerType>(Value->getType())
              ->isOpaqueOrPointeeTypeMatches(Sig.getType()));
   return Sig.getType();

test/IRGen/async.swift

@@ -1,4 +1,5 @@
 // RUN: %target-swift-frontend -primary-file %s -emit-ir  -disable-availability-checking | %FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-%target-ptrsize
+// RUN: %target-swift-frontend -primary-file %s -emit-ir  -disable-availability-checking -enable-library-evolution
 
 // REQUIRES: concurrency
 
@@ -29,3 +30,21 @@ public func testThis(_ task: __owned SomeClass) async {
     print("error")
   }
 }
+
+
+public protocol P {}
+
+struct I : P{
+  var x = 0
+}
+
+public struct S {
+  public func callee() async -> some P {
+    return I()
+  }
+  // We used to assert on this in resilient mode due to mismatch function
+  // pointers.
+  public func caller() async -> some P {
+      return await callee()
+  }
+}