x/tools/go/analysis: running the same analysis with different sets of flags

[dominikh]

By convention, analyses are provided as singletons in package variables, a la var Analysis = &analysis.Analyzer{...}. Furthermore, analysis.Analyzer stores a flag.FlagSet for providing options to the analysis. However, this combination of singleton and FlagSet makes it difficult to run one analysis multiple times concurrently with different options. This becomes especially problematic when multiple independent tools coexist in the same address space and want to use the same analysis with different options, as they won't be coordinating with each other.

As far as I am aware, there is no suitable workaround.

/cc @matloob

[bcmills]

CC @ianthehat