@since includes package name (#749)

* Metadoc stores a package name

This means that '@since' annotations can be package aware.

* Get the package name the right way

This should extract the package name for `@since` annotations the
right way. I had to move `modulePackageInfo` around to do this and,
in the process, I took the liberty to update it.

Since it appears that finding the package name is something that can
fail, I added a warning for this case.

* Silence warnings

* Hide package for local 'since' annotations

As discussed, this is still the usual case (and we should avoid being
noisy for it).

Although this commit is large, it is basically only about threading a
'Maybe Package' from 'Haddock.render' all the way to
'Haddock.Backends.Xhtml.DocMarkup.renderMeta'.

* Bump binary interface version

* Add a '--since-qual' option

This controls when to qualify since annotations with the package they
come from. The default is always, but I've left an 'external' variant
where only those annotations coming from outside of the current
package are qualified.

* Make ParserSpec work

* Make Fixtures work

* Use package name even if package version is not available

The @since stuff needs only the package name passed in, so it
makes sense to not be forced to pass in a version too.

3 files changed, 14 insertions, 8 deletions

diff --git a/haddock-library/src/Documentation/Haddock/Doc.hs b/haddock-library/src/Documentation/Haddock/Doc.hs
index 66bd1c97..297d30d6 100644
--- a/haddock-library/src/Documentation/Haddock/Doc.hs
+++ b/haddock-library/src/Documentation/Haddock/Doc.hs
@@ -27,16 +27,16 @@ metaDocAppend (MetaDoc { _meta = m, _doc = d })
               (MetaDoc { _meta = m', _doc = d' }) =
   MetaDoc { _meta = m' `metaAppend` m, _doc = d `docAppend` d' }
 
--- | This is not a monoidal append, it uses '<|>' for the '_version'.
+-- | This is not a monoidal append, it uses '<|>' for the '_version' and
+-- '_package'.
 metaAppend :: Meta -> Meta -> Meta
-metaAppend (Meta { _version = v }) (Meta { _version = v' }) =
-  Meta { _version = v <|> v' }
+metaAppend (Meta v1 p1) (Meta v2 p2) = Meta (v1 <|> v2) (p1 <|> p2)
 
 emptyMetaDoc :: MetaDoc mod id
 emptyMetaDoc = MetaDoc { _meta = emptyMeta, _doc = DocEmpty }
 
 emptyMeta :: Meta
-emptyMeta = Meta { _version = empty }
+emptyMeta = Meta empty empty
 
 docAppend :: DocH mod id -> DocH mod id -> DocH mod id
 docAppend (DocDefList ds1) (DocDefList ds2) = DocDefList (ds1++ds2)
diff --git a/haddock-library/src/Documentation/Haddock/Parser.hs b/haddock-library/src/Documentation/Haddock/Parser.hs
index 6cbc3922..4921b3a7 100644
--- a/haddock-library/src/Documentation/Haddock/Parser.hs
+++ b/haddock-library/src/Documentation/Haddock/Parser.hs
@@ -116,10 +116,13 @@ parse p = either err id . parseOnly (p <* endOfInput)
 
 -- | Main entry point to the parser. Appends the newline character
 -- to the input string.
-parseParas :: String -- ^ String to parse
+parseParas :: Maybe Package
+           -> String -- ^ String to parse
            -> MetaDoc mod Identifier
-parseParas input = case parseParasState input of
-  (state, a) -> MetaDoc { _meta = Meta { _version = parserStateSince state }
+parseParas pkg input = case parseParasState input of
+  (state, a) -> MetaDoc { _meta = Meta { _version = parserStateSince state
+                                       , _package = pkg
+                                       }
                         , _doc = a
                         }
 
diff --git a/haddock-library/src/Documentation/Haddock/Types.hs b/haddock-library/src/Documentation/Haddock/Types.hs
index 209f26e8..005ec186 100644
--- a/haddock-library/src/Documentation/Haddock/Types.hs
+++ b/haddock-library/src/Documentation/Haddock/Types.hs
@@ -34,7 +34,9 @@ import Data.Bitraversable
 -- meta-data to comments. We make a structure for this ahead of time
 -- so we don't have to gut half the core each time we want to add such
 -- info.
-newtype Meta = Meta { _version :: Maybe Version } deriving (Eq, Show)
+data Meta = Meta { _version :: Maybe Version
+                 , _package :: Maybe Package
+                 } deriving (Eq, Show)
 
 data MetaDoc mod id =
   MetaDoc { _meta :: Meta
@@ -61,6 +63,7 @@ overDocF :: Functor f => (DocH a b -> f (DocH c d)) -> MetaDoc a b -> f (MetaDoc
 overDocF f d = (\x -> d { _doc = x }) <$> f (_doc d)
 
 type Version = [Int]
+type Package = String
 
 data Hyperlink = Hyperlink
   { hyperlinkUrl   :: String