toperr is not used, but the go compiler itself doesn't detect this
because it's within an anonymous function. However, go/types does
detect this as being unused, which causes any static analysis tools
which uses go/types' type checker to fail with the message "toperr
assigned and not used".

The final result of the benchmarked function is instead assigned to
an exported global variable to ensure the compiler cannot now, nor
in the future optimise away the function calls due to no observable
side effects.

It was chosen to assign the final result, after the benchmark loop,
to the global variable, as this best follows the example set in the
CL https://go-review.googlesource.com/#/c/37195/. As opposed to
having each call to f assign to the global. This also appears to
better align with the original author's intention of toperr.

This change had no observable impact on the benchmark.

Related golang/go#3059.
Related golang/go#8560.

Thanks dominikh for additional clarifications.

Found this by https://github.com/mvdan/unparam

Fixes #136

Signed-off-by: Tibor Benke <[email protected]>

Signed-off-by: TomSweeneyRedHat <[email protected]>

WithMessagef utility function to accompany WithMessage, similar to
exiting Wrapf function accompanying Wrap.

Remove spurious words, add missing words, and smooth out a few
sentences.