C++23-fix-add-parentheses

[poelmanc]

e.g. [a,b] -> [(a,b)] to avoid confusion with C++23 array subscript operator[] Without these changes, code produces compilation error with the clangcl 15 delivered by MSVC 2022 15.5 Preview with /std:c++latest mode.

[poelmanc]

Footnote: This issue was fixed over in boost/wave already and that author phrased the issue more succinctly:

https://github.com/boostorg/wave/pull/148/commits/ef2d7d830bc7141b7272faf59bd8163db8297f92

The comma operator is deprecated inside of square brackets The fix is simple: add a layer of parentheses

[jeremy-murphy]

Thanks! Once the CI is green, I'll merge it.

[jeremy-murphy]

Thanks, @poelmanc !