[region-isolation] Use the sugared AST type when emitting a TransferNonTransferrable error for passing an argument as a transferrig parameter.

Author: gottesmm

lib/SILOptimizer/Mandatory/TransferNonSendable.cpp

@@ -1042,8 +1042,9 @@ class TransferNonTransferrableDiagnosticInferrer {
       return {UseDiagnosticInfoKind::FunctionArgumentClosure, isolation};
     }
 
-    static UseDiagnosticInfo forFunctionArgumentApplyStronglyTransferred() {
-      return {UseDiagnosticInfoKind::FunctionArgumentApplyStronglyTransferred};
+    static UseDiagnosticInfo forFunctionArgumentApplyStronglyTransferred(Type inferredType) {
+      return {UseDiagnosticInfoKind::FunctionArgumentApplyStronglyTransferred, {},
+        inferredType};
     }
 
     static UseDiagnosticInfo
@@ -1155,8 +1156,14 @@ bool TransferNonTransferrableDiagnosticInferrer::run() {
       if (auto fas = FullApplySite::isa(op->getUser())) {
         if (fas.getArgumentParameterInfo(*op).hasOption(
                 SILParameterInfo::Transferring)) {
+          Type type = op->get()->getType().getASTType();
+          if (auto *inferredArgExpr =
+              inferArgumentExprFromApplyExpr(sourceApply, fas, op)) {
+            type = inferredArgExpr->findOriginalType();
+          }
+
           diagnosticInfo =
-              UseDiagnosticInfo::forFunctionArgumentApplyStronglyTransferred();
+              UseDiagnosticInfo::forFunctionArgumentApplyStronglyTransferred(type);
           return true;
         }
       }
@@ -1283,7 +1290,7 @@ void TransferNonSendableImpl::emitTransferredNonTransferrableDiagnostics() {
       diagnoseError(
           astContext, loc,
           diag::regionbasedisolation_arg_passed_to_strongly_transferred_param,
-          op->get()->getType().getASTType())
+          diagnosticInfo.getType())
           .highlight(op->getUser()->getLoc().getSourceRange());
       break;
     }

test/Concurrency/transfernonsendable_strong_transferring_params.swift

@@ -346,3 +346,9 @@ func testTransferOtherParamClassStructTuple(_ x: transferring Klass, y: KlassWit
   x = y.ns2.1.second // expected-warning {{assigning 'y.ns2.1.second' to transferring parameter 'x' may cause a race}}
   // expected-note @-1 {{'y.ns2.1.second' is a task isolated value that is assigned into transferring parameter 'x'. Transferred uses of 'x' may race with caller uses of 'y.ns2.1.second'}}
 }
+
+func useSugaredTypeNameWhenEmittingTaskIsolationError(_ x: @escaping @MainActor () async -> ()) {
+  func fakeInit(operation: transferring @escaping () async -> ()) {}
+
+  fakeInit(operation: x) // expected-warning {{task isolated value of type '@MainActor () async -> ()' passed as a strongly transferred parameter}}
+}