Add compiler warning for uninitialized variable and fix (#1163)

* Add compiler warning for uninitialized variable and fix

* Add -Wsometimes-uninitialized

* Convert warning to error

[ROCm/rccl commit: b18784d8b8]

projects/rccl/CMakeLists.txt

@@ -598,6 +598,7 @@ endif()
 
 ## Set RCCL compile options
 target_compile_options(rccl PRIVATE -parallel-jobs=12)
+target_compile_options(rccl PRIVATE -Werror=uninitialized -Werror=sometimes-uninitialized)
 target_compile_options(rccl PRIVATE -Wno-format-nonliteral)
 target_compile_options(rccl PRIVATE -fgpu-rdc)               # Generate relocatable device code (required for extern __shared__)
 target_compile_options(rccl PRIVATE -fvisibility=hidden)     # Set symbol visibility to hidden by default

projects/rccl/src/graph/xml.cc

@@ -846,7 +846,7 @@ ncclResult_t ncclTopoFillGpu(struct ncclXml* xml, const char* busId, struct nccl
   NCCLCHECK(xmlSetAttrIfUnset(node, "class", "0x03"));
   NCCLCHECK(ncclTopoGetXmlFromSys(node, xml));
 #if defined(__HIP_PLATFORM_AMD__) || defined(__HCC__) || defined(__HIPCC__)
-  uint32_t devIndex;
+  uint32_t devIndex = 0;
   static int rocmsmiInit = 0;
   if (rocmsmiInit == 0) {
     rocmsmiInit = (rocm_smi_init() != ncclSuccess) ? 2 : 1;