From 320cc3c60b575fa49e49a21619472f01b8890049 Mon Sep 17 00:00:00 2001
From: Michael Davidsaver <mdavidsaver@gmail.com>
Date: Tue, 29 Sep 2020 13:27:27 -0700
Subject: [PATCH] shared_vector_convert<>() fix convert of empty array

Empty arrays can be untyped, but this doesn't matter.
---
 src/misc/pv/sharedVector.h        | 6 +++++-
 testApp/misc/testSharedVector.cpp | 5 ++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/misc/pv/sharedVector.h b/src/misc/pv/sharedVector.h
index fa426a7..28322d3 100644
--- a/src/misc/pv/sharedVector.h
+++ b/src/misc/pv/sharedVector.h
@@ -837,9 +837,13 @@ namespace detail {
             typedef typename meta::strip_const<TO>::type to_t;
             ScalarType stype = src.original_type(),
                        dtype = (ScalarType)ScalarTypeID<TO>::value;
-            if(stype==dtype) {
+            if(src.empty()) {
+                return shared_vector<TO>();
+
+            } else if(stype==dtype) {
                 // no convert needed
                 return shared_vector<TO>(src, detail::_shared_vector_cast_tag());
+
             } else {
                 // alloc and convert
                 shared_vector<to_t> ret(src.size()/ScalarTypeFunc::elementSize(stype));
diff --git a/testApp/misc/testSharedVector.cpp b/testApp/misc/testSharedVector.cpp
index b0d5416..e2b52ef 100644
--- a/testApp/misc/testSharedVector.cpp
+++ b/testApp/misc/testSharedVector.cpp
@@ -474,6 +474,9 @@ void testVectorConvert()
     testOk1(ints.unique());
     testOk1(strings.size()==ints.size());
     testOk1(strings.at(0)=="42");
+
+    testDiag("convert empty array");
+    testOk1(pvd::shared_vector_convert<double>(pvd::shared_vector<pvd::int32>()).empty());
 }
 
 void testWeak()
@@ -695,7 +698,7 @@ void testCXX11Init()
 
 MAIN(testSharedVector)
 {
-    testPlan(191);
+    testPlan(192);
     testDiag("Tests for shared_vector");
 
     testDiag("sizeof(shared_vector<pvd::int32>)=%lu",