Fix configure detection.
authorTamar Christina <tamar@zhox.com>
Sat, 13 Aug 2016 15:27:30 +0000 (16:27 +0100)
committerTamar Christina <tamar@zhox.com>
Sun, 14 Aug 2016 17:40:05 +0000 (18:40 +0100)
commit18f06878ed5d8cb0cf366a876f2bfea29647e5f0
tree844fc82ad11a1cd1c5dcb9b504b57751752ba192
parent7ad3b49161587f937facd1852742cc3fbaf1ffce
Fix configure detection.

Summary:
GHC's configure script seems to normalize the values returned from config.guess.
So for Windows it turns x86_64-pc-mingw64 into x86_64-unknown-mingw32.
These mangled names are stored in the values $BuildPlatform, $HostPlatform
and $TargetPlatform.

However further down the file when the comparison is done between the stage0
compiler and the host the normalized versions are not used.
So when normalization actually changes the triple this check will fail.

Not sure why it's worked for all this time.. Nor if this is the right fix?
Does it still work for cross compiling correctly?

Test Plan: ./configure

Reviewers: hvr, austin, thomie, bgamari, erikd

Reviewed By: erikd

Subscribers: erikd, #ghc_windows_task_force

Differential Revision: https://phabricator.haskell.org/D2452

GHC Trac Issues: #12487
configure.ac