* Avoid weak vtables by providing a private virtual member function
* Add warning Wweak-vtables to clang when FMT_PEDANTIC is on
* Add defaulted copy and move operations to format_error and system_error
Compiler generated copy operations are deprecated and move operations
are not generated altogether.
* Add warning Wdeprecated to clang when FMT_PEDANTIC is on
* Fix undefined in core-test
Fixes "reference binding to null pointer" in BufferTest.Ctor
buffer.operator[] attempts to return a reference to `buffer.ptr_[0]` when `ptr_`
in `mock_buffer<int> buffer` is null.
* Fix undefined in printf-test
Fixes "signed integer overflow" in PrintfTest.Length
This occurs in `TestLength<long long>("ll")`, since its minimum value minus one
does not fit in long long.
* Fix undefined in printf %0$
Printf counts arguments from 1.
Fixes "shift exponent -4 is negative" in PrintfTest.InvalidArgIndex.
`do_get` is called with index -1 when `basic_printf_context.arg` is called with
id 4294967295 when basic_printf_context::get_arg subtracts 1 from arg_index 0 in
the format string "%0$d".
Address enhancement request #1322.
The overload is provided in `ranges` (original `fmt::join` exists
currently in `format.h` for historical reasons.
Tests for prvalue and lvalue tuple arguments as well as the empty
tuple are provided in `ranges-test.cc`.
string_view_metadata was introduced to make compiled format relocatable.
However, format string compilation is an optimization and therefore
adding overhead and extra complexity for relocation is undesirable.
In most cases the string will be either static or outlive compilation
and formatting and if it doesn't, it's possible to make compiled
representation relocatale by other means.
