I am trying to install libgmp sources as I am trying to build some other source that requires gmp.h.In Cygwin setup-x86_64.exe I Search for gmp and it finds the libgmp line which says 6.1.2-1  Keep on the left, n/a under Bin? , and empty checkbox under Src?.I check the checkbox and proceed and it appears to install something and succeed. However, gmp.h doesn't appear anywhere under /usr/include (or anywhere else that I can find); and when I run setup-x86_64.exe again, the Src box is unchecked.What's going wrong? I have tried with a few other libraries too, in all cases the source doesn't seem to appear and the Src checkbox resets next time the setup is run.
Installing source package has no effect
cygwin