Hello,
As part of my attempts to build some GNU packages with MSVC tools, I also tried
to build them with LLVM tools which can be installed with Visual Studio
(clang-cl.exe and lld-link.exe).
When compiling source files lib/strerror.c and lib/vasnprintf.c (and possibly
some other) the following error occurs:
```
H:/releases/gettext-0.25/libtextstyle/lib/strerror.c(64,7): error: call to
undeclared library function 'sprintf' with type 'int (char *restrict, const
char *restrict, ...)'; ISO C99 and later do not support implicit function
declarations [-Wimplicit-function-declaration]
64 | sprintf (buf, fmt, n);
| ^
H:/releases/gettext-0.25/libtextstyle/lib/strerror.c(64,7): note: include the
header <stdio.h> or explicitly provide a declaration for 'sprintf'
1 error generated.
```
If I pass `-Wno-error=implicit-function-declaration` to make it non-fatal
warning, link will fail:
```
libtextstyle_la-strerror.obj : error LNK2019: unresolved external symbol
sprintf referenced in function libtextstyle_rpl_strerror
libtextstyle_la-vasnprintf.obj : error LNK2001: unresolved external symbol
sprintf
```
or in case of libunistring:
```
libunistring_la-u8-u8-vasnprintf.obj : error LNK2019: unresolved external
symbol sprintf referenced in function u8_u8_vasnprintf
libunistring_la-u8-vasnprintf.obj : error LNK2001: unresolved external symbol
sprintf
libunistring_la-ulc-vasnprintf.obj : error LNK2001: unresolved external symbol
sprintf
libunistring_la-u16-u16-vasnprintf.obj : error LNK2001: unresolved external
symbol sprintf
libunistring_la-u16-vasnprintf.obj : error LNK2001: unresolved external symbol
sprintf
libunistring_la-u32-u32-vasnprintf.obj : error LNK2001: unresolved external
symbol sprintf
libunistring_la-u32-vasnprintf.obj : error LNK2001: unresolved external symbol
sprintf
```
AFAIK, sprintf and friends are defined in Microsoft's header files as inline
functions. There is no real external sprintf and friends.
One notable thing about these source files is that they both contain
```
#undef sprintf
```
However, I do not think that this is the issue. I do not fully understand what
causes it.
I observed this when tried to build gettext and libunstring packages.
- Kirill Makurin
