for example with a U_ILLEGAL_ARGUMENT_ERROR since PR #2813
in some cases where the implementation may have
returned with a misleading U_BUFFER_OVERFLOW_ERROR
It's not uncommon for code for Windows to use the _MSC_VER preprocessor
macro to identify that it's being compiled for Windows so it's also not
uncommon for compilers other than the real MSVC compiler to also set
this to be able to compile such code.
It's also not possible to use _MSC_VER to determine whether the C++
standard library implementation used is the Microsoft STL.
Clang will however refuse to instantiate a template with a forward
declared type, so the code that currently does this needs to be moved to
after the type has been properly defined, which in turn makes MSVC warn
that those templates aren't instantiated, so those warnings need to be
disabled, but then the disabling of warning C4661 doesn't work any
longer (for some unknown reason) but this can be resolved by properly
deleting the non-existent operators instead of disabling the warning.
Previously, there were separate overrides for the options and
attributes parsing methods in the parser that were used in different
context. (Options can appear in Operator and Markup, while attributes
can appear in Expression and Markup.)
This is a refactoring that eliminates this duplicated code.
To enable it, a builder is added for the internal OptionMap type.
Separately, this patch also explicitly deletes copy constructors
and copy assignment operators for all Builder classes; a bug in an
earlier version of this patch caused me to notice this hadn't been
done. Also explicitly deletes move constructors/assignment operators
with the exception of OptionMap::Builder (OptionMap is non-public,
so that shouldn't cause confusion).
The implementation was keeping a cache of FormatterFactory
objects so that subsequent calls to the same formatter re-use the
same object.
The problem is that this is unsafe, because
`MFFunctionRegistry::getFormatter()` returns a non-const `FormatterFactory*`;
so if the caller deleted the resulting pointer, the formatter cache
would contain a dangling pointer.
This optimization was added because of an ICU4J test that checked for
the presence of the optimization. However, for separate reasons
(making `adoptFormatter()` actually adopt its argument), this test
was already removed.
The caching could be re-added later if that optimization is needed,
but for now, remove it (also, no tests were checking for its presence).
