Add in `-fwarn-trustworthy-safe` flag.

This warns when a module marked as `-XTrustworthy` could have been
inferred as safe instead.

8 files changed, 49 insertions, 3 deletions

diff --git a/testsuite/tests/safeHaskell/check/pkg01/ImpSafe01.hs b/testsuite/tests/safeHaskell/check/pkg01/ImpSafe01.hs
index deb0d57f8d..107881b2d8 100644
--- a/testsuite/tests/safeHaskell/check/pkg01/ImpSafe01.hs
+++ b/testsuite/tests/safeHaskell/check/pkg01/ImpSafe01.hs
@@ -1,6 +1,6 @@
 {-# LANGUAGE Safe #-}
 {-# LANGUAGE NoImplicitPrelude #-}
-module ImpSafe ( MyWord ) where
+module ImpSafe01 ( MyWord ) where
 
 -- While Data.Word is safe it imports trustworthy
 -- modules in base, hence base needs to be trusted.
diff --git a/testsuite/tests/safeHaskell/check/pkg01/ImpSafe02.hs b/testsuite/tests/safeHaskell/check/pkg01/ImpSafe02.hs
index deb0d57f8d..c6ba0968d0 100644
--- a/testsuite/tests/safeHaskell/check/pkg01/ImpSafe02.hs
+++ b/testsuite/tests/safeHaskell/check/pkg01/ImpSafe02.hs
@@ -1,6 +1,6 @@
 {-# LANGUAGE Safe #-}
 {-# LANGUAGE NoImplicitPrelude #-}
-module ImpSafe ( MyWord ) where
+module ImpSafe02 ( MyWord ) where
 
 -- While Data.Word is safe it imports trustworthy
 -- modules in base, hence base needs to be trusted.
diff --git a/testsuite/tests/safeHaskell/check/pkg01/ImpSafe03.hs b/testsuite/tests/safeHaskell/check/pkg01/ImpSafe03.hs
new file mode 100644
index 0000000000..485e9e238c
--- /dev/null
+++ b/testsuite/tests/safeHaskell/check/pkg01/ImpSafe03.hs
@@ -0,0 +1,8 @@
+{-# LANGUAGE Trustworthy #-}
+module Main where
+
+import safe Prelude
+import safe ImpSafe03_A
+
+main = putStrLn "test"
+
diff --git a/testsuite/tests/safeHaskell/check/pkg01/ImpSafe03.stderr b/testsuite/tests/safeHaskell/check/pkg01/ImpSafe03.stderr
new file mode 100644
index 0000000000..2fdf45ce13
--- /dev/null
+++ b/testsuite/tests/safeHaskell/check/pkg01/ImpSafe03.stderr
@@ -0,0 +1,4 @@
+[2 of 2] Compiling Main             ( ImpSafe03.hs, ImpSafe03.o )
+
+<no location info>:
+    The package (bytestring-0.10.4.0) is required to be trusted but it isn't!
diff --git a/testsuite/tests/safeHaskell/check/pkg01/ImpSafe03_A.hs b/testsuite/tests/safeHaskell/check/pkg01/ImpSafe03_A.hs
new file mode 100644
index 0000000000..06f5d39754
--- /dev/null
+++ b/testsuite/tests/safeHaskell/check/pkg01/ImpSafe03_A.hs
@@ -0,0 +1,8 @@
+{-# LANGUAGE Trustworthy #-}
+module ImpSafe03_A where
+
+import safe Prelude
+import safe qualified Data.ByteString.Char8 as BS
+
+s = BS.pack "Hello World"
+
diff --git a/testsuite/tests/safeHaskell/check/pkg01/ImpSafe04.hs b/testsuite/tests/safeHaskell/check/pkg01/ImpSafe04.hs
new file mode 100644
index 0000000000..3a8882905f
--- /dev/null
+++ b/testsuite/tests/safeHaskell/check/pkg01/ImpSafe04.hs
@@ -0,0 +1,13 @@
+{-# LANGUAGE Trustworthy #-}
+{-# LANGUAGE NoImplicitPrelude #-}
+module ImpSafe04 ( MyWord ) where
+
+-- While Data.Word is safe it imports trustworthy
+-- modules in base, hence base needs to be trusted.
+-- Note: Worthwhile giving out better error messages for cases
+-- like this if I can.
+import safe Data.Word
+import System.IO.Unsafe
+
+type MyWord = Word
+
diff --git a/testsuite/tests/safeHaskell/check/pkg01/ImpSafe04.stderr b/testsuite/tests/safeHaskell/check/pkg01/ImpSafe04.stderr
new file mode 100644
index 0000000000..50a12e027b
--- /dev/null
+++ b/testsuite/tests/safeHaskell/check/pkg01/ImpSafe04.stderr
@@ -0,0 +1,4 @@
+
+ImpSafe04.hs:9:1:
+    Data.Word: Can't be safely imported!
+    The package (base-4.8.0.0) the module resides in isn't trusted.
diff --git a/testsuite/tests/safeHaskell/check/pkg01/all.T b/testsuite/tests/safeHaskell/check/pkg01/all.T
index f121b99add..e1ed80dd7c 100644
--- a/testsuite/tests/safeHaskell/check/pkg01/all.T
+++ b/testsuite/tests/safeHaskell/check/pkg01/all.T
@@ -51,6 +51,15 @@ test('ImpSafe01', normal, compile_fail, ['-fpackage-trust -distrust base'])
 # Succeed since we don't enable package trust
 test('ImpSafe02', normal, compile, ['-distrust base'])
 
+# Fail since we don't trust base of bytestring
+test('ImpSafe03', normal, multi_compile_fail,
+  ['ImpSafe03 -trust base -distrust bytestring', [
+   ('ImpSafe03_A.hs', ' -trust base -trust bytestring')
+  ], '-fpackage-trust' ])
+
+# Fail same as ImpSafe01 but testing with -XTrustworthy now
+test('ImpSafe04', normal, compile_fail, ['-fpackage-trust -distrust base'])
+
 test('ImpSafeOnly01',
      [pre_cmd('$MAKE -s --no-print-directory mkPackageDatabase.ImpSafeOnly01 ' + make_args),
       clean_cmd('$MAKE -s --no-print-directory cleanPackageDatabase.ImpSafeOnly01')],
@@ -95,7 +104,7 @@ test('ImpSafeOnly07',
       clean_cmd('$MAKE -s --no-print-directory cleanPackageDatabase.ImpSafeOnly07'),
       normalise_errmsg_fun(normaliseBytestringPackage)],
      compile_fail,
-     ['-fpackage-trust -package-db pdb.ImpSafeOnly07/local.db -trust safePkg01'])
+     ['-fpackage-trust -package-db pdb.ImpSafeOnly07/local.db -trust safePkg01 -distrust bytestring'])
 test('ImpSafeOnly08',
      [pre_cmd('$MAKE -s --no-print-directory mkPackageDatabase.ImpSafeOnly08 ' + make_args),
       clean_cmd('$MAKE -s --no-print-directory cleanPackageDatabase.ImpSafeOnly08'),