Give helpful advice when a fully qualified name is not in scope

This implements #11071. It needs to thread through a GlobalRdrEnv
corresponding to the export list of the module if its exports were not
restricted.

A refactoring of ImportedModsVal into a proper data type follows.

Differential Revision: https://phabricator.haskell.org/D1462

13 files changed, 118 insertions, 13 deletions

diff --git a/testsuite/tests/rename/prog002/rename.prog002.stderr b/testsuite/tests/rename/prog002/rename.prog002.stderr
index b9dbf7f54a..01ab86946e 100644
--- a/testsuite/tests/rename/prog002/rename.prog002.stderr
+++ b/testsuite/tests/rename/prog002/rename.prog002.stderr
@@ -1,2 +1,5 @@
 
-rnfail037.hs:8:7: Not in scope: data constructor ‘Rn037Help.C’
+rnfail037.hs:8:7: error:
+    Not in scope: data constructor ‘Rn037Help.C’
+    Perhaps you want to remove ‘C’ from the explicit hiding list
+    in the import of ‘Rn037Help’ (rnfail037.hs:4:1-28).
diff --git a/testsuite/tests/rename/should_fail/T10781.stderr b/testsuite/tests/rename/should_fail/T10781.stderr
index 5d4dc3c098..d86f0d1beb 100644
--- a/testsuite/tests/rename/should_fail/T10781.stderr
+++ b/testsuite/tests/rename/should_fail/T10781.stderr
@@ -1,2 +1,4 @@
 
-T10781.hs:12:5: error: Not in scope: ‘Foo._name’
+T10781.hs:12:5: error:
+    Not in scope: ‘Foo._name’
+    No module named ‘Foo’ is imported.
diff --git a/testsuite/tests/rename/should_fail/T11071.hs b/testsuite/tests/rename/should_fail/T11071.hs
new file mode 100644
index 0000000000..ad31bc0c80
--- /dev/null
+++ b/testsuite/tests/rename/should_fail/T11071.hs
@@ -0,0 +1,28 @@
+module T11071 where
+
+import Data.List (lines)
+import qualified Data.Map as M ()
+import qualified Data.IntMap as M ()
+import qualified Data.IntMap as M () -- just to see if this confused the code
+
+import qualified Data.Ord as Ord hiding (Down)
+
+import qualified Data.Map as M' hiding (size, filter)
+import qualified Data.Map as M' hiding (size)
+import qualified Data.IntMap as M' hiding (size)
+import qualified System.IO as M' () -- unrelated
+
+ignore :: a -> IO ()
+ignore = const (return ())
+
+main = do
+    ignore NoSuchModule.foo  -- no such module
+    ignore Data.List.foobar  -- does not exist (one import)
+    ignore M.foobar          -- does not exist (two imports)
+    ignore M'.foobar         -- does not exist (three imports)
+    ignore Data.List.sort    -- needs import
+    ignore Data.List.unlines -- needs import, similar to imported
+    ignore M.size            -- multiple modules to import from
+    ignore M.valid           -- only one module to import from
+    ignore Ord.Down          -- explicit hiding
+    ignore M'.size           -- hidden and/or missing in import list
diff --git a/testsuite/tests/rename/should_fail/T11071.stderr b/testsuite/tests/rename/should_fail/T11071.stderr
new file mode 100644
index 0000000000..e3d5e30377
--- /dev/null
+++ b/testsuite/tests/rename/should_fail/T11071.stderr
@@ -0,0 +1,53 @@
+
+T11071.hs:19:12: error:
+    Not in scope: ‘NoSuchModule.foo’
+    No module named ‘NoSuchModule’ is imported.
+
+T11071.hs:20:12: error:
+    Not in scope: ‘Data.List.foobar’
+    Module ‘Data.List’ does not export ‘foobar’.
+
+T11071.hs:21:12: error:
+    Not in scope: ‘M.foobar’
+    Neither ‘Data.Map’ nor ‘Data.IntMap’ exports ‘foobar’.
+
+T11071.hs:22:12: error:
+    Not in scope: ‘M'.foobar’
+    Neither ‘Data.Map’, ‘Data.IntMap’ nor ‘System.IO’ exports ‘foobar’.
+
+T11071.hs:23:12: error:
+    Not in scope: ‘Data.List.sort’
+    Perhaps you want to add ‘sort’ to the import list in the import of
+    ‘Data.List’ (T11071.hs:3:1-24).
+
+T11071.hs:24:12: error:
+    Not in scope: ‘Data.List.unlines’
+    Perhaps you meant ‘Data.List.lines’ (imported from Data.List)
+    Perhaps you want to add ‘unlines’ to the import list
+    in the import of ‘Data.List’ (T11071.hs:3:1-24).
+
+T11071.hs:25:12: error:
+    Not in scope: ‘M.size’
+    Perhaps you want to add ‘size’ to one of these import lists:
+      ‘Data.Map’ (T11071.hs:4:1-33)
+      ‘Data.IntMap’ (T11071.hs:5:1-36)
+
+T11071.hs:26:12: error:
+    Not in scope: ‘M.valid’
+    Perhaps you meant one of these:
+      ‘M'.valid’ (imported from Data.Map),
+      ‘M'.valid’ (imported from Data.Map)
+    Perhaps you want to add ‘valid’ to the import list in the import of
+    ‘Data.Map’ (T11071.hs:4:1-33).
+
+T11071.hs:27:12: error:
+    Not in scope: data constructor ‘Ord.Down’
+    Perhaps you want to remove ‘Down’ from the explicit hiding list
+    in the import of ‘Data.Ord’ (T11071.hs:8:1-46).
+
+T11071.hs:28:12: error:
+    Not in scope: ‘M'.size’
+    Perhaps you want to remove ‘size’ from the hiding clauses
+    in one of these imports:
+      ‘Data.Map’ (T11071.hs:10:1-53)
+      ‘Data.IntMap’ (T11071.hs:12:1-48)
diff --git a/testsuite/tests/rename/should_fail/T2901.stderr b/testsuite/tests/rename/should_fail/T2901.stderr
index b240139bd8..d5a2247ce1 100644
--- a/testsuite/tests/rename/should_fail/T2901.stderr
+++ b/testsuite/tests/rename/should_fail/T2901.stderr
@@ -1,4 +1,7 @@
 
-T2901.hs:6:5: Not in scope: data constructor ‘F.Foo’
+T2901.hs:6:5: error:
+    Not in scope: data constructor ‘F.Foo’
+    No module named ‘F’ is imported.
 
-T2901.hs:6:13: ‘F.field’ is not a (visible) constructor field name
+T2901.hs:6:13: error:
+    ‘F.field’ is not a (visible) constructor field name
diff --git a/testsuite/tests/rename/should_fail/T5657.stderr b/testsuite/tests/rename/should_fail/T5657.stderr
index aa5f870b7b..5663b900d9 100644
--- a/testsuite/tests/rename/should_fail/T5657.stderr
+++ b/testsuite/tests/rename/should_fail/T5657.stderr
@@ -1,5 +1,7 @@
 
-T5657.hs:3:8: Not in scope: ‘LT..’
+T5657.hs:3:8: error:
+    Not in scope: ‘LT..’
+    No module named ‘LT’ is imported.
 
-T5657.hs:3:8:
+T5657.hs:3:8: error:
     A section must be enclosed in parentheses thus: (LT.. GT)
diff --git a/testsuite/tests/rename/should_fail/T5892b.stderr b/testsuite/tests/rename/should_fail/T5892b.stderr
index 994ea78c11..0f93c21f68 100644
--- a/testsuite/tests/rename/should_fail/T5892b.stderr
+++ b/testsuite/tests/rename/should_fail/T5892b.stderr
@@ -1,2 +1,4 @@
 
-T5892b.hs:11:7: Not in scope: ‘T5892b.subForest’
+T5892b.hs:11:7: error:
+    Not in scope: ‘T5892b.subForest’
+    No module named ‘T5892b’ is imported.
diff --git a/testsuite/tests/rename/should_fail/all.T b/testsuite/tests/rename/should_fail/all.T
index 48814ec983..66dfeaa916 100644
--- a/testsuite/tests/rename/should_fail/all.T
+++ b/testsuite/tests/rename/should_fail/all.T
@@ -138,3 +138,4 @@ test('T10618', normal, compile_fail, [''])
 test('T10668', normal, compile_fail, [''])
 test('T5001b', normal, compile_fail, [''])
 test('T10781', normal, compile_fail, [''])
+test('T11071', normal, compile_fail, [''])
diff --git a/testsuite/tests/rename/should_fail/rnfail030.stderr b/testsuite/tests/rename/should_fail/rnfail030.stderr
index 5b2cd36358..462dc5fa2c 100644
--- a/testsuite/tests/rename/should_fail/rnfail030.stderr
+++ b/testsuite/tests/rename/should_fail/rnfail030.stderr
@@ -1,2 +1,5 @@
 
-rnfail030.hs:2:21: Not in scope: ‘Data.List.map’
+rnfail030.hs:2:21: error:
+    Not in scope: ‘Data.List.map’
+    Perhaps you want to add ‘map’ to the import list in the import of
+    ‘Data.List’ (rnfail030.hs:3:1-19).
diff --git a/testsuite/tests/rename/should_fail/rnfail031.stderr b/testsuite/tests/rename/should_fail/rnfail031.stderr
index 828d5121c8..95d8ea1561 100644
--- a/testsuite/tests/rename/should_fail/rnfail031.stderr
+++ b/testsuite/tests/rename/should_fail/rnfail031.stderr
@@ -1,2 +1,5 @@
 
-rnfail031.hs:2:21: Not in scope: ‘Data.List.map’
+rnfail031.hs:2:21: error:
+    Not in scope: ‘Data.List.map’
+    Perhaps you want to add ‘map’ to the import list in the import of
+    ‘Data.List’ (rnfail031.hs:3:1-36).
diff --git a/testsuite/tests/rename/should_fail/rnfail032.stderr b/testsuite/tests/rename/should_fail/rnfail032.stderr
index 2169fd502e..70d80a0322 100644
--- a/testsuite/tests/rename/should_fail/rnfail032.stderr
+++ b/testsuite/tests/rename/should_fail/rnfail032.stderr
@@ -1,7 +1,9 @@
 
-rnfail032.hs:2:21:
+rnfail032.hs:2:21: error:
     Not in scope: ‘Data.List.map’
     Perhaps you meant one of these:
       ‘Data.List.zip’ (imported from Data.List),
       ‘Data.List.all’ (imported from Data.List),
       ‘Data.List.and’ (imported from Data.List)
+    Perhaps you want to remove ‘map’ from the explicit hiding list
+    in the import of ‘Data.List’ (rnfail032.hs:3:1-41).
diff --git a/testsuite/tests/rename/should_fail/rnfail033.stderr b/testsuite/tests/rename/should_fail/rnfail033.stderr
index 6b6849d1e5..277b42fb16 100644
--- a/testsuite/tests/rename/should_fail/rnfail033.stderr
+++ b/testsuite/tests/rename/should_fail/rnfail033.stderr
@@ -1,7 +1,9 @@
 
-rnfail033.hs:2:21:
+rnfail033.hs:2:21: error:
     Not in scope: ‘Data.List.map’
     Perhaps you meant one of these:
       ‘Data.List.zip’ (imported from Data.List),
       ‘Data.List.all’ (imported from Data.List),
       ‘Data.List.and’ (imported from Data.List)
+    Perhaps you want to remove ‘map’ from the explicit hiding list
+    in the import of ‘Data.List’ (rnfail033.hs:3:1-31).
diff --git a/testsuite/tests/rename/should_fail/rnfail034.stderr b/testsuite/tests/rename/should_fail/rnfail034.stderr
index 78bc649c29..63e6eb5037 100644
--- a/testsuite/tests/rename/should_fail/rnfail034.stderr
+++ b/testsuite/tests/rename/should_fail/rnfail034.stderr
@@ -1,6 +1,7 @@
 
-rnfail034.hs:4:11: Qualified name in binding position: M.y
+rnfail034.hs:4:11: error: Qualified name in binding position: M.y
 
-rnfail034.hs:4:26:
+rnfail034.hs:4:26: error:
     Not in scope: ‘M.y’
     Perhaps you meant ‘M.g’ (line 4)
+    No module named ‘M’ is imported.