title: Building the Windows Universal C Runtime
body: <p>I am trying to build the Universal C Runtime that comes with the Windows 10 SDK.</p>
  
  <p>I created a project and added source code from this directory:</p>
  
  <p>%ProgramFiles(x86)%\Windows Kits\10\Source\10.0.16299.0\ucrt</p>
  
  <p>I encountered errors. I followed and fixed the trail of errors. But eventually I got errors about overloaded functions and missing headers that don't seem to exist on my computer:</p>
  
  <pre><code>(ClCompile target) -&gt;
    C:\Program Files (x86)\Windows Kits\10\Source\10.0.16299.0\ucrt\inc\corecrt_internal.h(102): error C2556: '__crt_stat
  e_management::dual_state_global&lt;int&gt; *__p__fmode(void)': overloaded function differs only by return type from 'int *__p
  __fmode(void)' [C:\src\ucrt\build\time.vcxproj]
    C:\Program Files (x86)\Windows Kits\10\Source\10.0.16299.0\ucrt\inc\corecrt_internal.h(102): error C2371: '__p__fmode
  ': redefinition; different basic types [C:\src\ucrt\build\time.vcxproj]
    C:\Program Files (x86)\Windows Kits\10\Source\10.0.16299.0\ucrt\inc\corecrt_internal.h(1920): fatal error C1083: Cann
  ot open include file: 'corecrt_internal_state_isolation.h': No such file or directory [C:\src\ucrt\build\ti
  me.vcxproj]
    C:\Program Files (x86)\Windows Kits\10\Source\10.0.16299.0\ucrt\inc\corecrt_internal.h(102): error C2556: '__crt_stat
  e_management::dual_state_global&lt;int&gt; *__p__fmode(void)': overloaded function differs only by return type from 'int *__p
  __fmode(void)' [C:\src\ucrt\build\time.vcxproj]
    C:\Program Files (x86)\Windows Kits\10\Source\10.0.16299.0\ucrt\inc\corecrt_internal.h(102): error C2371: '__p__fmode
  ': redefinition; different basic types [C:\src\ucrt\build\time.vcxproj]
    C:\Program Files (x86)\Windows Kits\10\Source\10.0.16299.0\ucrt\inc\corecrt_internal.h(1920): fatal error C1083: Cann
  ot open include file: 'corecrt_internal_state_isolation.h': No such file or directory [C:\src\ucrt\build\ti
  me.vcxproj]
    C:\Program Files (x86)\Windows Kits\10\Source\10.0.16299.0\ucrt\inc\corecrt_internal.h(102): error C2556: '__crt_stat
  e_management::dual_state_global&lt;int&gt; *__p__fmode(void)': overloaded function differs only by return type from 'int *__p
  __fmode(void)' [C:\src\ucrt\build\time.vcxproj]
    C:\Program Files (x86)\Windows Kits\10\Source\10.0.16299.0\ucrt\inc\corecrt_internal.h(102): error C2371: '__p__fmode
  ': redefinition; different basic types [C:\src\ucrt\build\time.vcxproj]
    C:\Program Files (x86)\Windows Kits\10\Source\10.0.16299.0\ucrt\inc\corecrt_internal.h(1920): fatal error C1083: Cann
  ot open include file: 'corecrt_internal_state_isolation.h': No such file or directory [C:\src\ucrt\build\ti
  me.vcxproj]
    C:\Program Files (x86)\Windows Kits\10\Source\10.0.16299.0\ucrt\inc\corecrt_internal.h(102): error C2556: '__crt_stat
  e_management::dual_state_global&lt;int&gt; *__p__fmode(void)': overloaded function differs only by return type from 'int *__p
  __fmode(void)' [C:\src\ucrt\build\time.vcxproj]
    C:\Program Files (x86)\Windows Kits\10\Source\10.0.16299.0\ucrt\inc\corecrt_internal.h(102): error C2371: '__p__fmode
  ': redefinition; different basic types [C:\src\ucrt\build\time.vcxproj]
    C:\Program Files (x86)\Windows Kits\10\Source\10.0.16299.0\ucrt\inc\corecrt_internal.h(1920): fatal error C1083: Cann
  ot open include file: 'corecrt_internal_state_isolation.h': No such file or directory [C:\src\ucrt\build\ti
  me.vcxproj]
    C:\Program Files (x86)\Windows Kits\10\Source\10.0.16299.0\ucrt\inc\corecrt_internal.h(102): error C2556: '__crt_stat
  e_management::dual_state_global&lt;int&gt; *__p__fmode(void)': overloaded function differs only by return type from 'int *__p
  __fmode(void)' [C:\src\ucrt\build\time.vcxproj]
  ...
  </code></pre>
  
  <p>I wasn't able to find any documentation about building the Universal C Runtime.</p>
  
  <p>Am I on the wrong track? Any advice is appreciated.</p>