Affected subclause: [format.string.std]
Change: Restrict types of formatting arguments
used as
width or
precision in
a
std-format-spec. Rationale: Disallow types that do not have useful or portable semantics as
a formatting width or precision
. Effect on original feature: Valid C++ 2020 code that passes a boolean or character type as
arg-id becomes invalid
. For example:
std::format("{:*^{}}", "", true);
std::format("{:*^{}}", "", '1');