'openssl/err.h': No such file or directory

To rectify the 'openssl/err.h': No such file or directory error encountered while using aioquic on Windows, follow these steps:

1. Environment Variable Configuration:
   1. Identify OpenSSL Installation Directories:
      • Execute choco list openssl to locate the installation directory, typically found at C:\ProgramData\chocolatey\lib\openssl\tools\mingw64\include.
      • Find the library directory at C:\ProgramData\chocolatey\lib\openssl\tools\mingw64\lib.
   2. Set Environment Variables:
      • Open an elevated command prompt.
      • Set the INCLUDE variable to point to the OpenSSL include directory:

      setx INCLUDE "C:\ProgramData\chocolatey\lib\openssl\tools\mingw64\include" /M
      

      • Set the LIB variable to point to the OpenSSL library directory:

      setx LIB "C:\ProgramData\chocolatey\lib\openssl\tools\mingw64\lib" /M
      

      • Close and reopen the command prompt for changes to take effect.
2. Compiler Flags:

   If setting environment variables alone is insufficient, explicitly specify compiler flags during installation:

   pip install -e . CFLAGS=-I/path/to/openssl/include LDFLAGS=-L/path/to/openssl/lib
   

   Replace /path/to/openssl/include and /path/to/openssl/lib with the actual directories.

3. Reinstall OpenSSL:

   Consider uninstalling and reinstalling OpenSSL using Chocolatey to ensure proper directory structure and environment variables:

   choco uninstall openssl
   choco install openssl