Package keys (for linking/type equality) separated from package IDs.

This patch set makes us no longer assume that a package key is a human
readable string, leaving Cabal free to "do whatever it wants" to allocate
keys; we'll look up the PackageId in the database to display to the user.
This also means we have a new level of qualifier decisions to make at the
package level, and rewriting some Safe Haskell error reporting code to DTRT.

Additionally, we adjust the build system to use a new ghc-cabal output
Make variable PACKAGE_KEY to determine library names and other things,
rather than concatenating PACKAGE/VERSION as before.

Adds a new `-this-package-key` flag to subsume the old, erroneously named
`-package-name` flag, and `-package-key` to select packages by package key.

RFC: The md5 hashes are pretty tough on the eye, as far as the file
system is concerned :(

ToDo: safePkg01 test had its output updated, but the fix is not really right:
the rest of the dependencies are truncated due to the fact the we're only
grepping a single line, but ghc-pkg is wrapping its output.

ToDo: In a later commit, update all submodules to stop using -package-name
and use -this-package-key.  For now, we don't do it to avoid submodule
explosion.

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Test Plan: validate

Reviewers: simonpj, simonmar, hvr, austin

Subscribers: simonmar, relrod, carter

Differential Revision: https://phabricator.haskell.org/D80

1 files changed, 1 insertions, 0 deletions

diff --git a/testsuite/tests/cabal/T1750A.pkg b/testsuite/tests/cabal/T1750A.pkg
index 9bda51eea0..3f4a96e22b 100644
--- a/testsuite/tests/cabal/T1750A.pkg
+++ b/testsuite/tests/cabal/T1750A.pkg
@@ -1,4 +1,5 @@
 name: T1750A
 version: 1
 id: T1750A-1-XXX
+key: T1750A-1
 depends: T1750B-1-XXX