diagnose and dont crash when unable to find swift_task_deinitOnExecutor

Author: ktoso

include/swift/AST/DiagnosticsSIL.def

@@ -790,6 +790,11 @@ NOTE(box_to_stack_cannot_promote_box_to_stack_due_to_escape_location, none,
 
 WARNING(semantic_function_improper_nesting, none, "'@_semantics' function calls non-'@_semantics' function with nested '@_semantics' calls", ())
 
+// SDK mismatch diagnostics
+ERROR(missing_deinit_on_executor_function, none,
+      "Missing 'swift_task_deinitOnExecutor' function! "
+      "This is likely due to an outdated/incompatible SDK.", ())
+
 // Capture promotion diagnostics
 WARNING(capturepromotion_concurrentcapture_mutation, none,
         "'%0' mutated after capture by sendable closure", (StringRef))

lib/SILGen/SILGenDestructor.cpp

@@ -17,6 +17,7 @@
 #include "SwitchEnumBuilder.h"
 #include "swift/AST/ConformanceLookup.h"
 #include "swift/AST/Decl.h"
+#include "swift/AST/DiagnosticsSIL.h"
 #include "swift/AST/GenericSignature.h"
 #include "swift/AST/SubstitutionMap.h"
 #include "swift/Basic/Assertions.h"
@@ -374,9 +375,8 @@ void SILGenFunction::emitIsolatingDestructor(DestructorDecl *dd) {
     // Get deinitOnExecutor
     FuncDecl *swiftDeinitOnExecutorDecl = SGM.getDeinitOnExecutor();
     if (!swiftDeinitOnExecutorDecl) {
-      llvm::report_fatal_error(
-          "Failed to find swift_task_deinitOnExecutor function decl! "
-          "This is likely due to an outdated/incompatible SDK.");
+      dd->diagnose(diag::missing_deinit_on_executor_function);
+      return;
     }
     SILFunction *swiftDeinitOnExecutorSILFunc = SGM.getFunction(
         SILDeclRef(swiftDeinitOnExecutorDecl, SILDeclRef::Kind::Func),