Fix for Trac #15611: Scope errors lie about what modules are imported.

Summary:
For the error message:
    Not in scope X.Y
    Module X does not export Y
    No module named ‘X’ is imported:
there are 2 cases, where we don't show the last "no module named is imported" line:
1. If the module X has been imported.
2. If the module X is the current module. There are 2 subcases:

   2.1 If the unknown module name is in a input source file,
       then we can use the getModule function to get the current module name.

   2.2 If the unknown module name has been entered by the user in GHCi,
       then the getModule function returns something like "interactive:Ghci1",
       and we have to check the current module in the last added entry of
       the HomePackageTable.

Test Plan: make test TESTS="T15611a T15611b"

Reviewers: monoidal, hvr, thomie, dfeuer, bgamari, DavidEichmann

Reviewed By: monoidal, DavidEichmann

Subscribers: rwbarton, carter

GHC Trac Issues: #15611

Differential Revision: https://phabricator.haskell.org/D5284

1 files changed, 2 insertions, 0 deletions

diff --git a/testsuite/tests/rename/should_fail/T15611a.hs b/testsuite/tests/rename/should_fail/T15611a.hs
new file mode 100644
index 0000000000..df1bb2f08c
--- /dev/null
+++ b/testsuite/tests/rename/should_fail/T15611a.hs
@@ -0,0 +1,2 @@
+main :: IO ()
+main = Main.foo