Use export list of Main module in function TcRnDriver.hs:check_main (Fix #16453)

- Provide the export list of the `Main` module as parameter to the
  `compiler/typecheck/TcRnDriver.hs:check_main` function.
- Instead of `lookupOccRn_maybe` call the function `lookupInfoOccRn`.
  It returns the list `mains_all` of all the main functions in scope.
- Select from this list `mains_all` all `main` functions that are in
  the export list of the `Main` module.
- If this new list contains exactly one single `main` function, then
  typechecking continues.
- Otherwise issue an appropriate error message.

19 files changed, 51 insertions, 0 deletions

diff --git a/testsuite/tests/typecheck/should_fail/T16453E1.hs b/testsuite/tests/typecheck/should_fail/T16453E1.hs
new file mode 100644
index 0000000000..3e910dd453
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T16453E1.hs
@@ -0,0 +1,2 @@
+module Main where
+import T16453T
diff --git a/testsuite/tests/typecheck/should_fail/T16453E1.stderr b/testsuite/tests/typecheck/should_fail/T16453E1.stderr
new file mode 100644
index 0000000000..d435ab8e1e
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T16453E1.stderr
@@ -0,0 +1,2 @@
+T16453E1.hs:1:1: error:
+    The IO action ‘main’ is not defined in module ‘Main’
diff --git a/testsuite/tests/typecheck/should_fail/T16453E2.hs b/testsuite/tests/typecheck/should_fail/T16453E2.hs
new file mode 100644
index 0000000000..d27e2e6c41
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T16453E2.hs
@@ -0,0 +1,3 @@
+module Main (T16453T.main, T16453S.main) where
+import T16453T
+import T16453S
diff --git a/testsuite/tests/typecheck/should_fail/T16453E2.stderr b/testsuite/tests/typecheck/should_fail/T16453E2.stderr
new file mode 100644
index 0000000000..4999d60cc7
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T16453E2.stderr
@@ -0,0 +1,9 @@
+T16453E2.hs:1:1:
+    Ambiguous occurrence ‘main’
+    It could refer to
+       either ‘T16453T.main’,
+              imported from ‘T16453T’ at T16453E2.hs:2:1-14
+              (and originally defined at T16453T.hs:2:1-4)
+           or ‘T16453S.main’,
+              imported from ‘T16453S’ at T16453E2.hs:3:1-14
+              (and originally defined at T16453S.hs:2:1-4)
diff --git a/testsuite/tests/typecheck/should_fail/T16453S.hs b/testsuite/tests/typecheck/should_fail/T16453S.hs
new file mode 100644
index 0000000000..c9e966dca9
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T16453S.hs
@@ -0,0 +1,2 @@
+module T16453S where
+main = putStrLn "T16453S"
diff --git a/testsuite/tests/typecheck/should_fail/T16453T.hs b/testsuite/tests/typecheck/should_fail/T16453T.hs
new file mode 100644
index 0000000000..98ea6255f7
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T16453T.hs
@@ -0,0 +1,2 @@
+module T16453T where
+main = putStrLn "T16453T"
diff --git a/testsuite/tests/typecheck/should_fail/all.T b/testsuite/tests/typecheck/should_fail/all.T
index 60e50ca241..4f8f08ed85 100644
--- a/testsuite/tests/typecheck/should_fail/all.T
+++ b/testsuite/tests/typecheck/should_fail/all.T
@@ -516,6 +516,10 @@ test('T16255', normal, compile_fail, [''])
 test('T16204c', normal, compile_fail, [''])
 test('T16394', normal, compile_fail, [''])
 test('T16414', normal, compile_fail, [''])
+test('T16453E1', extra_files(['T16453T.hs', 'T16453S.hs']), multimod_compile_fail,
+    ['T16453E1.hs', '-v0'])
+test('T16453E2', extra_files(['T16453T.hs', 'T16453S.hs']),
+    multimod_compile_fail, ['T16453E2.hs', '-v0'])
 test('T16456', normal, compile_fail, ['-fprint-explicit-foralls'])
 test('T16627', normal, compile_fail, [''])
 test('T502', normal, compile_fail, [''])
diff --git a/testsuite/tests/typecheck/should_run/T16453M0.hs b/testsuite/tests/typecheck/should_run/T16453M0.hs
new file mode 100644
index 0000000000..08ace5d99e
--- /dev/null
+++ b/testsuite/tests/typecheck/should_run/T16453M0.hs
@@ -0,0 +1,3 @@
+module Main where
+import T16453T
+main = putStrLn "T16453M0"
diff --git a/testsuite/tests/typecheck/should_run/T16453M0.stdout b/testsuite/tests/typecheck/should_run/T16453M0.stdout
new file mode 100644
index 0000000000..e61283f99c
--- /dev/null
+++ b/testsuite/tests/typecheck/should_run/T16453M0.stdout
@@ -0,0 +1 @@
+T16453M0
diff --git a/testsuite/tests/typecheck/should_run/T16453M1.hs b/testsuite/tests/typecheck/should_run/T16453M1.hs
new file mode 100644
index 0000000000..aa240f2c75
--- /dev/null
+++ b/testsuite/tests/typecheck/should_run/T16453M1.hs
@@ -0,0 +1,3 @@
+module Main (T16453T.main)  where
+import T16453T
+main = putStrLn "T16453M1"
diff --git a/testsuite/tests/typecheck/should_run/T16453M1.stdout b/testsuite/tests/typecheck/should_run/T16453M1.stdout
new file mode 100644
index 0000000000..e4dfbcd44f
--- /dev/null
+++ b/testsuite/tests/typecheck/should_run/T16453M1.stdout
@@ -0,0 +1 @@
+T16453T
diff --git a/testsuite/tests/typecheck/should_run/T16453M2.hs b/testsuite/tests/typecheck/should_run/T16453M2.hs
new file mode 100644
index 0000000000..acf4e6791b
--- /dev/null
+++ b/testsuite/tests/typecheck/should_run/T16453M2.hs
@@ -0,0 +1,3 @@
+module Main (Main.main)  where
+import T16453T
+main = putStrLn "T16453M2"
diff --git a/testsuite/tests/typecheck/should_run/T16453M2.stdout b/testsuite/tests/typecheck/should_run/T16453M2.stdout
new file mode 100644
index 0000000000..ab13919690
--- /dev/null
+++ b/testsuite/tests/typecheck/should_run/T16453M2.stdout
@@ -0,0 +1 @@
+T16453M2
diff --git a/testsuite/tests/typecheck/should_run/T16453M3.hs b/testsuite/tests/typecheck/should_run/T16453M3.hs
new file mode 100644
index 0000000000..167d8fde7c
--- /dev/null
+++ b/testsuite/tests/typecheck/should_run/T16453M3.hs
@@ -0,0 +1,3 @@
+module Main (module Main)  where
+import T16453T
+main = putStrLn "T16453M3"
diff --git a/testsuite/tests/typecheck/should_run/T16453M3.stdout b/testsuite/tests/typecheck/should_run/T16453M3.stdout
new file mode 100644
index 0000000000..f0c95103e7
--- /dev/null
+++ b/testsuite/tests/typecheck/should_run/T16453M3.stdout
@@ -0,0 +1 @@
+T16453M3
diff --git a/testsuite/tests/typecheck/should_run/T16453M4.hs b/testsuite/tests/typecheck/should_run/T16453M4.hs
new file mode 100644
index 0000000000..a1ec32bda6
--- /dev/null
+++ b/testsuite/tests/typecheck/should_run/T16453M4.hs
@@ -0,0 +1,3 @@
+module Main (module T16453T)  where
+import T16453T
+main = putStrLn "T16453M4"
diff --git a/testsuite/tests/typecheck/should_run/T16453M4.stdout b/testsuite/tests/typecheck/should_run/T16453M4.stdout
new file mode 100644
index 0000000000..e4dfbcd44f
--- /dev/null
+++ b/testsuite/tests/typecheck/should_run/T16453M4.stdout
@@ -0,0 +1 @@
+T16453T
diff --git a/testsuite/tests/typecheck/should_run/T16453T.hs b/testsuite/tests/typecheck/should_run/T16453T.hs
new file mode 100644
index 0000000000..98ea6255f7
--- /dev/null
+++ b/testsuite/tests/typecheck/should_run/T16453T.hs
@@ -0,0 +1,2 @@
+module T16453T where
+main = putStrLn "T16453T"
diff --git a/testsuite/tests/typecheck/should_run/all.T b/testsuite/tests/typecheck/should_run/all.T
index 512362f1bb..4cd7a1b73c 100755
--- a/testsuite/tests/typecheck/should_run/all.T
+++ b/testsuite/tests/typecheck/should_run/all.T
@@ -135,6 +135,11 @@ test('T14218', normal, compile_and_run, [''])
 test('T14236', normal, compile_and_run, [''])
 test('T14925', normal, compile_and_run, [''])
 test('T14341', normal, compile_and_run, [''])
+test('T16453M0', extra_files(['T16453T.hs']), compile_and_run, [''])
+test('T16453M1', extra_files(['T16453T.hs']), compile_and_run, [''])
+test('T16453M2', extra_files(['T16453T.hs']), compile_and_run, [''])
+test('T16453M3', extra_files(['T16453T.hs']), compile_and_run, [''])
+test('T16453M4', extra_files(['T16453T.hs']), compile_and_run, [''])
 test('UnliftedNewtypesRun', normal, compile_and_run, [''])
 test('UnliftedNewtypesFamilyRun', normal, compile_and_run, [''])
 test('UnliftedNewtypesDependentFamilyRun', normal, compile_and_run, [''])