There are two issues when trying to build tcl with MinGW w64.

I use the following invocation :

--enable-64bit

1. It fails with EXCEPTION_REGISTRATION issue, which a patch corrected the issue [1]
2. It fails at linkage with zlib with the error undefined reference to "__imp_CoTaskMemFree"

Adding -lole32 to the LIBS variable in the Makefile solved the second problem.

[1]

Has the patch been applied for the next release ?