Adds a compile time error if the number of arguments provided to the
format function is larger than the number of braces in the format
string.
Only works in automatic argument indexing mode.
This check deliberately only works for compile-time format string
checking, not at runtime. This is because we don't want existing code to
have unexpected runtime errors after upgrades. There are also scenarios
imaginable where either the arguments or the format string is generated
at runtime, and the ability to have less braces in the format string can
actually be a feature. At the same time, compile-time format calls are
guaranteed to be constant. In other words, having too many arguments will
always mean there's a bug in the code.
The new feature works by adding a on_end_of_string() function to
formatting handlers. This function is called after the whole format
string has been parsed, and needs to be implemented by all parsing
handlers.
0aa4721472