From eadaf06f0c0a4f18d4b207ba0486847941587256 Mon Sep 17 00:00:00 2001
From: Kenneth Moreland <kmorel@sandia.gov>
Date: Fri, 26 Mar 2021 15:42:45 -0600
Subject: [PATCH] Set what string in Error::SetMessage

`vtkm::cont::Error` inherits from `std::exception`. As such, it has a
special `what` string that reports an error message in a standard way.
This is particularly useful when a `vtkm::cont::Error` exception remains
uncaught because the system will print the `what` string before
crashing.

Unfortunately, the `what` string was only being set in the `Error`
constructor that took a message. That is a problem for subclasses like
`ErrorCuda` that used the default constructor and then used
`SetMessage`. The `what` string did not get set in this case.

Change the behavior to capture the stack trace in the default
constructor and update the `what` string if a subclass uses
`SetMessage`.
---
 vtkm/cont/Error.h | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/vtkm/cont/Error.h b/vtkm/cont/Error.h
index 15e56e44d..9929fcfbf 100644
--- a/vtkm/cont/Error.h
+++ b/vtkm/cont/Error.h
@@ -56,7 +56,12 @@ public:
   bool GetIsDeviceIndependent() const { return this->IsDeviceIndependent; }
 
 protected:
-  Error() {}
+  Error()
+    : StackTrace(vtkm::cont::GetStackTrace(1))
+    , What("Undescribed error\n" + StackTrace)
+    , IsDeviceIndependent(false)
+  {
+  }
   Error(const std::string& message, bool is_device_independent = false)
     : Message(message)
     , StackTrace(vtkm::cont::GetStackTrace(1))
@@ -65,7 +70,11 @@ protected:
   {
   }
 
-  void SetMessage(const std::string& message) { this->Message = message; }
+  void SetMessage(const std::string& message)
+  {
+    this->Message = message;
+    this->What = this->Message + "\n" + this->StackTrace;
+  }
 
 private:
   std::string Message;