Determining size of off64_t failed with the following output:
Change Dir: D:/a/1/s/externals/vcpkg/buildtrees/zlib/x64-windows-rel/CMakeFiles/CMakeTmp

Run Build Command(s):C:/Program Files (x86)/Microsoft Visual Studio/2019/Enterprise/Common7/IDE/CommonExtensions/Microsoft/CMake/Ninja/ninja.exe cmTC_ea4a6 && [1/2] Building C object CMakeFiles\cmTC_ea4a6.dir\OFF64_T.c.obj

FAILED: CMakeFiles/cmTC_ea4a6.dir/OFF64_T.c.obj 

C:\PROGRA~2\MICROS~1\2019\ENTERP~1\VC\Tools\MSVC\1429~1.301\bin\Hostx64\x64\cl.exe  /nologo -DHAVE_STDDEF_H -DHAVE_STDINT_H -DHAVE_SYS_TYPES_H -D_LARGEFILE64_SOURCE=1  /nologo /DWIN32 /D_WINDOWS /W3 /utf-8 /MP   /MDd /Zi /Ob0 /Od /RTC1 /showIncludes /FoCMakeFiles\cmTC_ea4a6.dir\OFF64_T.c.obj /FdCMakeFiles\cmTC_ea4a6.dir\ /FS -c D:\a\1\s\externals\vcpkg\buildtrees\zlib\x64-windows-rel\CMakeFiles\CheckTypeSize\OFF64_T.c

D:\a\1\s\externals\vcpkg\buildtrees\zlib\x64-windows-rel\CMakeFiles\CheckTypeSize\OFF64_T.c(29): error C2065: 'off64_t': undeclared identifier
D:\a\1\s\externals\vcpkg\buildtrees\zlib\x64-windows-rel\CMakeFiles\CheckTypeSize\OFF64_T.c(30): error C2065: 'off64_t': undeclared identifier
D:\a\1\s\externals\vcpkg\buildtrees\zlib\x64-windows-rel\CMakeFiles\CheckTypeSize\OFF64_T.c(31): error C2065: 'off64_t': undeclared identifier
D:\a\1\s\externals\vcpkg\buildtrees\zlib\x64-windows-rel\CMakeFiles\CheckTypeSize\OFF64_T.c(32): error C2065: 'off64_t': undeclared identifier
D:\a\1\s\externals\vcpkg\buildtrees\zlib\x64-windows-rel\CMakeFiles\CheckTypeSize\OFF64_T.c(33): error C2065: 'off64_t': undeclared identifier
ninja: build stopped: subcommand failed.



D:/a/1/s/externals/vcpkg/buildtrees/zlib/x64-windows-rel/CMakeFiles/CheckTypeSize/OFF64_T.c:
#include <sys/types.h>
#include <stdint.h>
#include <stddef.h>


#undef KEY
#if defined(__i386)
# define KEY '_','_','i','3','8','6'
#elif defined(__x86_64)
# define KEY '_','_','x','8','6','_','6','4'
#elif defined(__PPC64__)
# define KEY '_','_','P','P','C','6','4','_','_'
#elif defined(__ppc64__)
# define KEY '_','_','p','p','c','6','4','_','_'
#elif defined(__PPC__)
# define KEY '_','_','P','P','C','_','_'
#elif defined(__ppc__)
# define KEY '_','_','p','p','c','_','_'
#elif defined(__aarch64__)
# define KEY '_','_','a','a','r','c','h','6','4','_','_'
#elif defined(__ARM_ARCH_7A__)
# define KEY '_','_','A','R','M','_','A','R','C','H','_','7','A','_','_'
#elif defined(__ARM_ARCH_7S__)
# define KEY '_','_','A','R','M','_','A','R','C','H','_','7','S','_','_'
#endif

#define SIZE (sizeof(off64_t))
static char info_size[] =  {'I', 'N', 'F', 'O', ':', 's','i','z','e','[',
  ('0' + ((SIZE / 10000)%10)),
  ('0' + ((SIZE / 1000)%10)),
  ('0' + ((SIZE / 100)%10)),
  ('0' + ((SIZE / 10)%10)),
  ('0' +  (SIZE    % 10)),
  ']',
#ifdef KEY
  ' ','k','e','y','[', KEY, ']',
#endif
  '\0'};

#ifdef __CLASSIC_C__
int main(argc, argv) int argc; char *argv[];
#else
int main(int argc, char *argv[])
#endif
{
  int require = 0;
  require += info_size[argc];
  (void)argv;
  return require;
}


Determining if the function fseeko exists failed with the following output:
Change Dir: D:/a/1/s/externals/vcpkg/buildtrees/zlib/x64-windows-rel/CMakeFiles/CMakeTmp

Run Build Command(s):C:/Program Files (x86)/Microsoft Visual Studio/2019/Enterprise/Common7/IDE/CommonExtensions/Microsoft/CMake/Ninja/ninja.exe cmTC_eba15 && [1/2] Building C object CMakeFiles\cmTC_eba15.dir\CheckFunctionExists.c.obj

[2/2] Linking C executable cmTC_eba15.exe

FAILED: cmTC_eba15.exe 

cmd.exe /C "cd . && "C:\Program Files\CMake\bin\cmake.exe" -E vs_link_exe --intdir=CMakeFiles\cmTC_eba15.dir --rc=C:\PROGRA~2\WI3CF2~1\10\bin\100220~1.0\x64\rc.exe --mt=C:\PROGRA~2\WI3CF2~1\10\bin\100220~1.0\x64\mt.exe --manifests  -- C:\PROGRA~2\MICROS~1\2019\ENTERP~1\VC\Tools\MSVC\1429~1.301\bin\Hostx64\x64\link.exe /nologo CMakeFiles\cmTC_eba15.dir\CheckFunctionExists.c.obj  /out:cmTC_eba15.exe /implib:cmTC_eba15.lib /pdb:cmTC_eba15.pdb /version:0.0 /machine:x64  /debug /INCREMENTAL /subsystem:console  kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib && cd ."

LINK Pass 1: command "C:\PROGRA~2\MICROS~1\2019\ENTERP~1\VC\Tools\MSVC\1429~1.301\bin\Hostx64\x64\link.exe /nologo CMakeFiles\cmTC_eba15.dir\CheckFunctionExists.c.obj /out:cmTC_eba15.exe /implib:cmTC_eba15.lib /pdb:cmTC_eba15.pdb /version:0.0 /machine:x64 /debug /INCREMENTAL /subsystem:console kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib /MANIFEST /MANIFESTFILE:CMakeFiles\cmTC_eba15.dir/intermediate.manifest CMakeFiles\cmTC_eba15.dir/manifest.res" failed (exit code 1120) with the following output:
CheckFunctionExists.c.obj : error LNK2019: unresolved external symbol fseeko referenced in function main

cmTC_eba15.exe : fatal error LNK1120: 1 unresolved externals

ninja: build stopped: subcommand failed.




Determining if the include file unistd.h exists failed with the following output:
Change Dir: D:/a/1/s/externals/vcpkg/buildtrees/zlib/x64-windows-rel/CMakeFiles/CMakeTmp

Run Build Command(s):C:/Program Files (x86)/Microsoft Visual Studio/2019/Enterprise/Common7/IDE/CommonExtensions/Microsoft/CMake/Ninja/ninja.exe cmTC_5529f && [1/2] Building C object CMakeFiles\cmTC_5529f.dir\CheckIncludeFile.c.obj

FAILED: CMakeFiles/cmTC_5529f.dir/CheckIncludeFile.c.obj 

C:\PROGRA~2\MICROS~1\2019\ENTERP~1\VC\Tools\MSVC\1429~1.301\bin\Hostx64\x64\cl.exe  /nologo   /nologo /DWIN32 /D_WINDOWS /W3 /utf-8 /MP   /MDd /Zi /Ob0 /Od /RTC1 /showIncludes /FoCMakeFiles\cmTC_5529f.dir\CheckIncludeFile.c.obj /FdCMakeFiles\cmTC_5529f.dir\ /FS -c D:\a\1\s\externals\vcpkg\buildtrees\zlib\x64-windows-rel\CMakeFiles\CMakeTmp\CheckIncludeFile.c

D:\a\1\s\externals\vcpkg\buildtrees\zlib\x64-windows-rel\CMakeFiles\CMakeTmp\CheckIncludeFile.c(1): fatal error C1083: Cannot open include file: 'unistd.h': No such file or directory
ninja: build stopped: subcommand failed.