fix: run_hipcc.cmake spirv platform branch + regression test

tests/post-install/FindHIPLegacySpirvTarget/CMakeLists.txt

@@ -0,0 +1,9 @@
+cmake_minimum_required(VERSION 3.16 FATAL_ERROR)
+project(FindHIPLegacySpirvTarget LANGUAGES CXX)
+find_package(HIP REQUIRED)
+# Force compilation through run_hipcc.cmake (same as SeisSol's Device submodule)
+set_source_files_properties(foo.hip PROPERTIES HIP_SOURCE_PROPERTY_FORMAT 1)
+# SHARED triggers --shared -Xcompiler '-fPIC' in HIP_NVCC_FLAGS, which clang
+# cannot understand when run_hipcc.cmake falls through to the nvcc branch
+hip_add_library(foo SHARED foo.hip)
+set_property(TARGET foo PROPERTY HIP_ARCHITECTURES OFF)

tests/post-install/FindHIPLegacySpirvTarget/foo.hip

@@ -0,0 +1,3 @@
+#include <hip/hip_runtime.h>
+__global__ void k() {}
+int main() { return 0; }

tests/post-install/cmake-tests.bash

@@ -41,6 +41,24 @@ make VERBOSE=1
 echo "Success"
 echo
 
+echo "### Check legacy FindHIP cmake integration on SPIR-V platform (run_hipcc.cmake spirv branch)"
+# Regression test: when HIP_PLATFORM=spirv, run_hipcc.cmake must use the clang
+# branch, not the nvcc branch. The nvcc branch inserts '--compiler-options -fPIC'
+# which clang does not understand, causing compilation to fail.
+setup-test-dir
+cmake @CMAKE_CURRENT_SOURCE_DIR@/FindHIPLegacySpirvTarget \
+      -DCMAKE_PREFIX_PATH=@CMAKE_INSTALL_PREFIX@ \
+      -DCMAKE_MODULE_PATH=@CMAKE_INSTALL_PREFIX@/lib/cmake/hip \
+      -DCMAKE_CXX_COMPILER=${CXX}
+# Build only the compilation step (linking requires hipcc_cmake_linker_helper, tested separately).
+# run_hipcc.cmake names the output file foo_generated_foo.hip.o
+ninja -v "CMakeFiles/foo.dir/foo_generated_foo.hip.o" 2>&1 | tee build.log
+if grep -qF "''-fPIC''" build.log; then
+    echo "FAIL: NVCC-style quoted -fPIC found — run_hipcc.cmake spirv branch missing"
+    exit 1
+fi
+if [ ! -f CMakeFiles/foo.dir/foo_generated_foo.hip.o ]; then
+    echo "FAIL: foo_generated_foo.hip.o was not produced — compilation failed"
 echo "### check CMake-CUDA"
 setup-test-dir