Thinning and renaming modules from packages on the command line.

Summary:
This patch set adds support for extra syntax on -package and related
arguments which allow you to thin and rename modules from a package.
For example, this argument:

    -package "base (Data.Bool as Bam, Data.List)"

adds two more modules into scope, Bam and Data.List, without adding
any of base's other modules to scope.

These flags are additive: so, for example, saying:

    -hide-all-packages -package base -package "base (Data.Bool as Bam)"

will provide both the normal bindings for modules in base, as well as
the module Bam.

There is also a new debug flag -ddump-mod-map which prints the state
of the module mapping database.  H = hidden, E = exposed (so for
example EH says the module in question is exported, but in a hidden
package.)

Module suggestions have been minorly overhauled to work better with reexports:
if you have -package "base (Data.Bool as Bam)" and mispell Bam, GHC
will suggest "Did you mean Bam (defined via package flags to be
base:Data.Bool)"; and generally you will get more accurate information.
Also, fix a bug where we suggest the -package flag when we really need
the -package-key flag.

NB: The renaming afforded here does *not* affect what wired in
symbols GHC generates.  (But it does affect implicit prelude!)

ToDo: add 'hiding' functionality, to make it easier to support the alternative
prelude use-case.

ToDo: Cabal support

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

Test Plan: new tests and validate

Reviewers: simonpj, simonmar, hvr, austin

Subscribers: simonmar, relrod, ezyang, carter

Differential Revision: https://phabricator.haskell.org/D113

GHC Trac Issues: #9375

20 files changed, 138 insertions, 1 deletions

diff --git a/testsuite/tests/ghci/scripts/T5979.stderr b/testsuite/tests/ghci/scripts/T5979.stderr
index fe6e012603..bbdba12305 100644
--- a/testsuite/tests/ghci/scripts/T5979.stderr
+++ b/testsuite/tests/ghci/scripts/T5979.stderr
@@ -1,4 +1,7 @@
 
 <no location info>:
     Could not find module ‘Control.Monad.Trans.State’
-    It is not a module in the current program, or in any known package.
+    Perhaps you meant
+      Control.Monad.Trans.State (from transformers-0.4.1.0@trans_ATJ404cg3uBDx7JJZaSn1I)
+      Control.Monad.Trans.Class (from transformers-0.4.1.0@trans_ATJ404cg3uBDx7JJZaSn1I)
+      Control.Monad.Trans.Cont (from transformers-0.4.1.0@trans_ATJ404cg3uBDx7JJZaSn1I)
diff --git a/testsuite/tests/package/Makefile b/testsuite/tests/package/Makefile
new file mode 100644
index 0000000000..9a36a1c5fe
--- /dev/null
+++ b/testsuite/tests/package/Makefile
@@ -0,0 +1,3 @@
+TOP=../..
+include $(TOP)/mk/boilerplate.mk
+include $(TOP)/mk/test.mk
diff --git a/testsuite/tests/package/all.T b/testsuite/tests/package/all.T
new file mode 100644
index 0000000000..cb30949124
--- /dev/null
+++ b/testsuite/tests/package/all.T
@@ -0,0 +1,21 @@
+setTestOpts(only_compiler_types(['ghc']))
+
+hide_all = '-hide-all-packages -XNoImplicitPrelude '
+incr_containers = '-package "containers (Data.Map as Map, Data.Set)" '
+inc_containers = '-package containers '
+incr_ghc = '-package "ghc (HsTypes as MyHsTypes, HsUtils)" '
+inc_ghc = '-package ghc '
+hide_ghc = '-hide-package ghc '
+
+test('package01',  normal, compile,      [hide_all + incr_containers])
+test('package01e', normal, compile_fail, [hide_all + incr_containers])
+test('package02',  normal, compile,      [hide_all + inc_containers + incr_containers])
+test('package03',  normal, compile,      [hide_all + incr_containers + inc_containers])
+test('package04',  normal, compile,      [incr_containers])
+test('package05',  normal, compile,      [incr_ghc + inc_ghc])
+test('package06',  normal, compile,      [incr_ghc])
+test('package06e', normal, compile_fail, [incr_ghc])
+test('package07e', normal, compile_fail, [incr_ghc + inc_ghc + hide_ghc])
+test('package08e', normal, compile_fail, [incr_ghc + hide_ghc])
+test('package09e', normal, compile_fail, ['-package "containers (Data.Map as M, Data.Set as M)"'])
+test('package10',  normal, compile,      ['-hide-all-packages -package "ghc (UniqFM as Prelude)" '])
diff --git a/testsuite/tests/package/package01.hs b/testsuite/tests/package/package01.hs
new file mode 100644
index 0000000000..0fdd41146f
--- /dev/null
+++ b/testsuite/tests/package/package01.hs
@@ -0,0 +1,3 @@
+module Package01 where
+import Map
+import Data.Set
diff --git a/testsuite/tests/package/package01e.hs b/testsuite/tests/package/package01e.hs
new file mode 100644
index 0000000000..946d400f78
--- /dev/null
+++ b/testsuite/tests/package/package01e.hs
@@ -0,0 +1,3 @@
+module Package01e where
+import Data.Map
+import Data.IntMap
diff --git a/testsuite/tests/package/package01e.stderr b/testsuite/tests/package/package01e.stderr
new file mode 100644
index 0000000000..232ec6ce2d
--- /dev/null
+++ b/testsuite/tests/package/package01e.stderr
@@ -0,0 +1,10 @@
+
+package01e.hs:2:1:
+    Failed to load interface for ‘Data.Map’
+    It is a member of the hidden package ‘containers-0.5.5.1’.
+    Use -v to see a list of the files searched for.
+
+package01e.hs:3:1:
+    Failed to load interface for ‘Data.IntMap’
+    It is a member of the hidden package ‘containers-0.5.5.1’.
+    Use -v to see a list of the files searched for.
diff --git a/testsuite/tests/package/package02.hs b/testsuite/tests/package/package02.hs
new file mode 100644
index 0000000000..ea06404935
--- /dev/null
+++ b/testsuite/tests/package/package02.hs
@@ -0,0 +1,5 @@
+module Package02 where
+import Data.Map
+import Map
+import Data.Set
+import Data.IntMap
diff --git a/testsuite/tests/package/package03.hs b/testsuite/tests/package/package03.hs
new file mode 100644
index 0000000000..d81dc3e037
--- /dev/null
+++ b/testsuite/tests/package/package03.hs
@@ -0,0 +1,5 @@
+module Package03 where
+import Data.Map
+import Map
+import Data.Set
+import Data.IntMap
diff --git a/testsuite/tests/package/package04.hs b/testsuite/tests/package/package04.hs
new file mode 100644
index 0000000000..85c2cae05a
--- /dev/null
+++ b/testsuite/tests/package/package04.hs
@@ -0,0 +1,5 @@
+module Package04 where
+import Data.Map
+import Map
+import Data.Set
+import Data.IntMap
diff --git a/testsuite/tests/package/package05.hs b/testsuite/tests/package/package05.hs
new file mode 100644
index 0000000000..3b0069c5d5
--- /dev/null
+++ b/testsuite/tests/package/package05.hs
@@ -0,0 +1,4 @@
+module Package05 where
+import HsTypes
+import MyHsTypes
+import HsUtils
diff --git a/testsuite/tests/package/package06.hs b/testsuite/tests/package/package06.hs
new file mode 100644
index 0000000000..096b81b7ba
--- /dev/null
+++ b/testsuite/tests/package/package06.hs
@@ -0,0 +1,3 @@
+module Package06 where
+import MyHsTypes
+import HsUtils
diff --git a/testsuite/tests/package/package06e.hs b/testsuite/tests/package/package06e.hs
new file mode 100644
index 0000000000..6feaebda62
--- /dev/null
+++ b/testsuite/tests/package/package06e.hs
@@ -0,0 +1,3 @@
+module Package06e where
+import HsTypes
+import UniqFM
diff --git a/testsuite/tests/package/package06e.stderr b/testsuite/tests/package/package06e.stderr
new file mode 100644
index 0000000000..2d4945549e
--- /dev/null
+++ b/testsuite/tests/package/package06e.stderr
@@ -0,0 +1,10 @@
+
+package06e.hs:2:1:
+    Failed to load interface for ‘HsTypes’
+    It is a member of the hidden package ‘ghc’.
+    Use -v to see a list of the files searched for.
+
+package06e.hs:3:1:
+    Failed to load interface for ‘UniqFM’
+    It is a member of the hidden package ‘ghc’.
+    Use -v to see a list of the files searched for.
diff --git a/testsuite/tests/package/package07e.hs b/testsuite/tests/package/package07e.hs
new file mode 100644
index 0000000000..85bb723989
--- /dev/null
+++ b/testsuite/tests/package/package07e.hs
@@ -0,0 +1,5 @@
+module Package07e where
+import MyHsTypes
+import HsTypes
+import HsUtils
+import UniqFM
diff --git a/testsuite/tests/package/package07e.stderr b/testsuite/tests/package/package07e.stderr
new file mode 100644
index 0000000000..6a72a2e89c
--- /dev/null
+++ b/testsuite/tests/package/package07e.stderr
@@ -0,0 +1,20 @@
+
+package07e.hs:2:1:
+    Failed to load interface for ‘MyHsTypes’
+    Perhaps you meant HsTypes (needs flag -package-key ghc)
+    Use -v to see a list of the files searched for.
+
+package07e.hs:3:1:
+    Failed to load interface for ‘HsTypes’
+    It is a member of the hidden package ‘ghc’.
+    Use -v to see a list of the files searched for.
+
+package07e.hs:4:1:
+    Failed to load interface for ‘HsUtils’
+    It is a member of the hidden package ‘ghc’.
+    Use -v to see a list of the files searched for.
+
+package07e.hs:5:1:
+    Failed to load interface for ‘UniqFM’
+    It is a member of the hidden package ‘ghc’.
+    Use -v to see a list of the files searched for.
diff --git a/testsuite/tests/package/package08e.hs b/testsuite/tests/package/package08e.hs
new file mode 100644
index 0000000000..40f814449a
--- /dev/null
+++ b/testsuite/tests/package/package08e.hs
@@ -0,0 +1,5 @@
+module Package08e where
+import MyHsTypes
+import HsTypes
+import HsUtils
+import UniqFM
diff --git a/testsuite/tests/package/package08e.stderr b/testsuite/tests/package/package08e.stderr
new file mode 100644
index 0000000000..a7e8433f7a
--- /dev/null
+++ b/testsuite/tests/package/package08e.stderr
@@ -0,0 +1,20 @@
+
+package08e.hs:2:1:
+    Failed to load interface for ‘MyHsTypes’
+    Perhaps you meant HsTypes (needs flag -package-key ghc)
+    Use -v to see a list of the files searched for.
+
+package08e.hs:3:1:
+    Failed to load interface for ‘HsTypes’
+    It is a member of the hidden package ‘ghc’.
+    Use -v to see a list of the files searched for.
+
+package08e.hs:4:1:
+    Failed to load interface for ‘HsUtils’
+    It is a member of the hidden package ‘ghc’.
+    Use -v to see a list of the files searched for.
+
+package08e.hs:5:1:
+    Failed to load interface for ‘UniqFM’
+    It is a member of the hidden package ‘ghc’.
+    Use -v to see a list of the files searched for.
diff --git a/testsuite/tests/package/package09e.hs b/testsuite/tests/package/package09e.hs
new file mode 100644
index 0000000000..8f08bbd5b2
--- /dev/null
+++ b/testsuite/tests/package/package09e.hs
@@ -0,0 +1,2 @@
+module Package09e where
+import M
diff --git a/testsuite/tests/package/package09e.stderr b/testsuite/tests/package/package09e.stderr
new file mode 100644
index 0000000000..9cd00a2930
--- /dev/null
+++ b/testsuite/tests/package/package09e.stderr
@@ -0,0 +1,5 @@
+
+package09e.hs:2:1:
+    Ambiguous interface for ‘M’:
+      it is bound as Data.Set by a package flag
+      it is bound as Data.Map by a package flag
diff --git a/testsuite/tests/package/package10.hs b/testsuite/tests/package/package10.hs
new file mode 100644
index 0000000000..6db31da664
--- /dev/null
+++ b/testsuite/tests/package/package10.hs
@@ -0,0 +1,2 @@
+module Package10 where
+x = emptyUFM