From daf7c398df5a6251fda38ce6e3e5773e6fe3e70b Mon Sep 17 00:00:00 2001
From: Stephen Nicholas Swatman <stephen.nicholas.swatman@cern.ch>
Date: Mon, 1 Jul 2024 13:39:37 +0200
Subject: [PATCH] Deduplicate `empty.sycl` file

The current setup uses `try_compile` on the source file `empty.sycl`
twice, which leads to the following error when using Ninja, enabling
SYCL, and having the tests enabled:

```
error: sycl/cmake/empty.sycl is defined as an output multiple times
```

This commit takes the path of least resistance and clones the file into
`empty_ubsan.sycl` so that these compile tests no longer collide.
---
 tests/sycl/CMakeLists.txt         |  2 +-
 tests/sycl/cmake/empty_ubsan.sycl | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)
 create mode 100644 tests/sycl/cmake/empty_ubsan.sycl

diff --git a/tests/sycl/CMakeLists.txt b/tests/sycl/CMakeLists.txt
index 64178a16..43b70991 100644
--- a/tests/sycl/CMakeLists.txt
+++ b/tests/sycl/CMakeLists.txt
@@ -25,7 +25,7 @@ vecmem_add_test( sycl
 include( CheckCXXCompilerFlag )
 check_cxx_compiler_flag( "-fsanitize=undefined" VECMEM_HAVE_UBSAN )
 vecmem_check_sycl_code_compiles( VECMEM_HAVE_SYCL_UBSAN
-   "${CMAKE_CURRENT_SOURCE_DIR}/../../sycl/cmake/empty.sycl"
+   "${CMAKE_CURRENT_SOURCE_DIR}/cmake/empty_ubsan.sycl"
    CMAKE_FLAGS -DCOMPILE_DEFINITIONS=-fsanitize=undefined )
 if( VECMEM_HAVE_UBSAN AND VECMEM_HAVE_SYCL_UBSAN )
    target_compile_options( vecmem_test_sycl PRIVATE "-fsanitize=undefined" )
diff --git a/tests/sycl/cmake/empty_ubsan.sycl b/tests/sycl/cmake/empty_ubsan.sycl
new file mode 100644
index 00000000..64abc9c6
--- /dev/null
+++ b/tests/sycl/cmake/empty_ubsan.sycl
@@ -0,0 +1,13 @@
+/* VecMem project, part of the ACTS project (R&D line)
+ *
+ * (c) 2024 CERN for the benefit of the ACTS project
+ *
+ * Mozilla Public License Version 2.0
+ */
+
+// SYCL include(s).
+#include <CL/sycl.hpp>
+
+int main() {
+    return 0;
+}