[Ipopt] IPOPT and MinGW/MSYS

[John Pye]

Hi all

Just trying to build IPOPT 3.8.1 on MinGW/MSYS. Previously I had no 
trouble with this, and built an ipopt.dll DLL that I had shipped with 
our product (which is GPL licensed, BTW!). I think this may previously 
have been with version 3.8.0 or earlier.

Anyway, with the latest version, it seems that I can no longer use 
'--enable-shared' to produce a DLL. The following error is returned:

> configure: WARNING: On Msys, shared objects are not supported. I'm 
> disabling you
> r choice.

I don't understand this: MSYS most definitely does support shared 
objects (SOs aka DLLs), so why is my choice being disabled? We'd be very 
keen to have a DLL version of IPOPT available to us, because it means we 
can make it a drop-in optional component (dlopen-able) if we so choose.

Next, I get the following error, which it is requested I tell you about. 
I can confirm that windows.h exists, and I have been able to use it with 
some other code that I've been working on recently.

> checking whether the linear solver loader should be compiled... yes
> checking windows.h usability... no
> checking windows.h presence... yes
> configure: WARNING: windows.h: present but cannot be compiled
> configure: WARNING: windows.h:     check for missing prerequisite headers?
> configure: WARNING: windows.h: see the Autoconf documentation
> configure: WARNING: windows.h:     section "Present But Cannot Be 
> Compiled"
> configure: WARNING: windows.h: proceeding with the preprocessor's result
> configure: WARNING: windows.h: in the future, the compiler will take 
> precedence
> configure: WARNING:     ## 
> -----------------------------------------------------
> ----- ##
> configure: WARNING:     ## Report this to 
> http://projects.coin-or.org/Ipopt/newt
> icket ##
> configure: WARNING:     ## 
> -----------------------------------------------------
> ----- ##
> checking for windows.h... yes
> checking dlfcn.h usability... no
> checking dlfcn.h presence... no

Cheers
JP