If a base class can be formatted, it is assumed
that the hierarchy can be formatted from the base
class. The idiom is not uncommon with ostreams.

Similar to the Pullrequest #539, `_SECURE_SCL` caused the same  `warning C4574: '_SECURE_SCL' is defined to be '0': did you mean to use '#if _SECURE_SCL'`.  `_SECURE_SCL` is defined in the `MSVC/14.10.25017/include/yvals.h` by Microsoft itself

`FMT_USE_USER_DEFINED_LITERALS` macro expands to `defined()` which is undefined behavior.

For the consumer it should not matter if fmt has been added to the
project as subdirectory or via find_package. With the alias targets
the library can be always imported via fmt::fmt.

Each instantiation of ArgArray template uses sizeof operator, which
returns a std::size_t value. GCC 7.1 warns about invalid conversion
(error: conversion to ‘unsigned int’ from ‘long unsigned
int’ may alter its value [-Werror=conversion]).

Revert #456 because it causes issues for known types (#495) and is not C++98-compatible.

* printf.h fixed to compile clean - need to check whether this is the right
thing to do

* fix warnings and errors in test compiles with BUILD_SHARED_LIBS

* did requested changes and added one change to allow all tests to succeed
in windows DLL

Fixes #505.

i test the the code on https://gcc.godbolt.org/, and only gcc 4.7 works,
gcc 4.6 fail to complie

With Sphinx 1.5, this is needed by searchtools.js to display the source
snippets (see sphinx-doc/sphinx#2454).

With earlier Sphinx versions, this is a no-op because the undefined variable
will evaluate to an empty string.

Fix Visual Studio 2017 new warning (C4244: 'argument': conversion from 'int' to 'const char', possible loss of data)

Fixes #491 (and probably #480) Before, the put-area of the custom streambuf
implementation was (sometimes) incorrectly extended beyond the writeable buffer.
The new implementation is in some cases not as efficient as the old, but avoids
to write into uninitialized memory.