Commit 30ced404 authored by simonpj@microsoft.com's avatar simonpj@microsoft.com

Improve printing of Orig RdrNames

In Tempate Haskell -ddump-splices, the "after" expression is populated 
with RdrNames, many of which are Orig things.  We used to print these
fully-qualified, but that's a bit heavy.

This patch refactors the code a bit so that the same print-unqualified
mechanism we use for Names also works for RdrNames.  Lots of comments
too, because it took me a while to figure out how it all worked again.
parent a99906e5
......@@ -63,7 +63,7 @@ module Name (
NamedThing(..),
getSrcLoc, getSrcSpan, getOccString,
pprInfixName, pprPrefixName,
pprInfixName, pprPrefixName, pprModulePrefix,
-- Re-export the OccName stuff
module OccName
......@@ -396,23 +396,16 @@ pprName (Name {n_sort = sort, n_uniq = u, n_occ = occ})
pprExternal :: PprStyle -> Unique -> Module -> OccName -> Bool -> BuiltInSyntax -> SDoc
pprExternal sty uniq mod occ is_wired is_builtin
| codeStyle sty = ppr mod <> char '_' <> ppr_z_occ_name occ
| codeStyle sty = ppr mod <> char '_' <> ppr_z_occ_name occ
-- In code style, always qualify
-- ToDo: maybe we could print all wired-in things unqualified
-- in code style, to reduce symbol table bloat?
| debugStyle sty = ppr mod <> dot <> ppr_occ_name occ
<> braces (hsep [if is_wired then ptext (sLit "(w)") else empty,
pprNameSpaceBrief (occNameSpace occ),
pprUnique uniq])
| BuiltInSyntax <- is_builtin = ppr_occ_name occ
-- never qualify builtin syntax
| NameQual modname <- qual_name = ppr modname <> dot <> ppr_occ_name occ
-- see HscTypes.mkPrintUnqualified and Outputable.QualifyName:
| NameNotInScope1 <- qual_name = ppr mod <> dot <> ppr_occ_name occ
| NameNotInScope2 <- qual_name = ppr (modulePackageId mod) <> char ':' <>
ppr (moduleName mod) <> dot <> ppr_occ_name occ
| otherwise = ppr_occ_name occ
where qual_name = qualName sty mod occ
| debugStyle sty = ppr mod <> dot <> ppr_occ_name occ
<> braces (hsep [if is_wired then ptext (sLit "(w)") else empty,
pprNameSpaceBrief (occNameSpace occ),
pprUnique uniq])
| BuiltInSyntax <- is_builtin = ppr_occ_name occ -- Never qualify builtin syntax
| otherwise = pprModulePrefix sty mod occ <> ppr_occ_name occ
pprInternal :: PprStyle -> Unique -> OccName -> SDoc
pprInternal sty uniq occ
......@@ -435,6 +428,18 @@ pprSystem sty uniq occ
-- is unlikely to be informative (like 's'),
-- so print the unique
pprModulePrefix :: PprStyle -> Module -> OccName -> SDoc
-- Print the "M." part of a name, based on whether it's in scope or not
-- See Note [Printing original names] in HscTypes
pprModulePrefix sty mod occ
= case qualName sty mod occ of -- See Outputable.QualifyName:
NameQual modname -> ppr modname <> dot -- Name is in scope
NameNotInScope1 -> ppr mod <> dot -- Not in scope
NameNotInScope2 -> ppr (modulePackageId mod) <> colon -- Module not in
<> ppr (moduleName mod) <> dot -- scope eithber
_otherwise -> empty
ppr_underscore_unique :: Unique -> SDoc
-- Print an underscore separating the name from its unique
-- But suppress it if we aren't printing the uniques anyway
......
......@@ -251,7 +251,7 @@ instance Outputable RdrName where
ppr (Exact name) = ppr name
ppr (Unqual occ) = ppr occ
ppr (Qual mod occ) = ppr mod <> dot <> ppr occ
ppr (Orig mod occ) = ppr mod <> dot <> ppr occ
ppr (Orig mod occ) = getPprStyle (\sty -> pprModulePrefix sty mod occ <> ppr occ)
instance OutputableBndr RdrName where
pprBndr _ n
......
......@@ -54,8 +54,9 @@ module HscTypes (
-- * Interactive context
InteractiveContext(..), emptyInteractiveContext,
icPrintUnqual, mkPrintUnqualified, extendInteractiveContext,
icPrintUnqual, extendInteractiveContext,
substInteractiveContext,
mkPrintUnqualified, pprModulePrefix,
-- * Interfaces
ModIface(..), mkIfaceWarnCache, mkIfaceHashCache, mkIfaceFixCache,
......@@ -1202,6 +1203,8 @@ substInteractiveContext ictxt@InteractiveContext{ic_tmp_ids=ids} subst =
%* *
%************************************************************************
Note [Printing original names]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Deciding how to print names is pretty tricky. We are given a name
P:M.T, where P is the package name, M is the defining module, and T is
the occurrence name, and we have to decide in which form to display
......@@ -1211,19 +1214,24 @@ Ideally we want to display the name in the form in which it is in
scope. However, the name might not be in scope at all, and that's
where it gets tricky. Here are the cases:
1. T uniquely maps to P:M.T ---> "T"
2. there is an X for which X.T uniquely maps to P:M.T ---> "X.T"
3. there is no binding for "M.T" ---> "M.T"
4. otherwise ---> "P:M.T"
3 and 4 apply when P:M.T is not in scope. In these cases we want to
refer to the name as "M.T", but "M.T" might mean something else in the
current scope (e.g. if there's an "import X as M"), so to avoid
confusion we avoid using "M.T" if there's already a binding for it.
There's one further subtlety: if the module M cannot be imported
because it is not exposed by any package, then we must refer to it as
"P:M". This is handled by the qual_mod component of PrintUnqualified.
1. T uniquely maps to P:M.T ---> "T" NameUnqual
2. There is an X for which X.T
uniquely maps to P:M.T ---> "X.T" NameQual X
3. There is no binding for "M.T" ---> "M.T" NameNotInScope1
4. Otherwise ---> "P:M.T" NameNotInScope2
(3) and (4) apply when the entity P:M.T is not in the GlobalRdrEnv at
all. In these cases we still want to refer to the name as "M.T", *but*
"M.T" might mean something else in the current scope (e.g. if there's
an "import X as M"), so to avoid confusion we avoid using "M.T" if
there's already a binding for it. Instead we write P:M.T.
There's one further subtlety: in case (3), what if there are two
things around, P1:M.T and P2:M.T? Then we don't want to print both of
them as M.T! However only one of the modules P1:M and P2:M can be
exposed (say P2), so we use M.T for that, and P1:M.T for the other one.
This is handled by the qual_mod component of PrintUnqualified, inside
the (ppr mod) of case (3), in Name.pprModulePrefix
\begin{code}
-- | Creates some functions that work out the best ways to format
......
......@@ -129,6 +129,7 @@ data Depth = AllTheWay
-- in source code, names are qualified by ModuleNames.
type QueryQualifyName = Module -> OccName -> QualifyName
-- See Note [Printing original names] in HscTypes
data QualifyName -- given P:M.T
= NameUnqual -- refer to it as "T"
| NameQual ModuleName -- refer to it as "X.T" for the supplied X
......
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