It is notable that this report is against gcc-5, not assigned, and has not been looked at in five years.
There certainly are people who think volatile should mean something for stack variables, but the compiler people very much Do Not Care. So, by the technical wording of Standards, volatile means the same for all variables, in actual compilers (with certain exceptions) it does not.
Well, Richard Biener certainly count as a compiler person (they are heavily involved with the GCC middle end), and they seem to care, although not enough to fix it as the issue if fairly academical in this case.
There certainly are people who think volatile should mean something for stack variables, but the compiler people very much Do Not Care. So, by the technical wording of Standards, volatile means the same for all variables, in actual compilers (with certain exceptions) it does not.