Warning regarding redefinition of __HIP_PLATFORM_AMD__

[Paul Hargrove]

Recently, CI builds on OLCF's Frontier with --enable-hip have begun to produce the following (harmless) warning from every application compile:

<command-line>: warning: "__HIP_PLATFORM_AMD__" redefined
<command-line>: note: this is the location of the previous definition

This is due to relatively recent behavior in which the cc and CC compiler wrappers in the Cray Programming Environment pass -D__HIP_PLATFORM_AMD__. Since such a option is implicitly a definition to 1, this is a conflict with UPC++'s definition (by upcxx or upcxx-meta) to a (historically necessary) empty value.

[Paul Hargrove]

Ideally, our configure script would probe CXX for any definition is provides for __HIP_PLATFORM_AMD__ and either match it or omit our definition.

In the meantime:

• Users may choose to safely ignore this warning
• Users may edit the Makefile generated by configure, prior to running make, to remove the conflicting definition (if you need clearer instructions, then this approach is probably not for you).