Show minimal complete definitions in ghci (#10847)

Show the minimal complete definition on :info in ghci. They
are shown like MINIMAL pragmas in code. If the minimal complete
definition is empty or only a specific method from a class is
requested, nothing is shown.

Reviewed By: simonpj, austin, thomie

Differential Revision: https://phabricator.haskell.org/D1241

11 files changed, 24 insertions, 0 deletions

diff --git a/testsuite/tests/driver/sigof01/sigof01i2.stdout b/testsuite/tests/driver/sigof01/sigof01i2.stdout
index ac15dcfa1e..1ee81c10d2 100644
--- a/testsuite/tests/driver/sigof01/sigof01i2.stdout
+++ b/testsuite/tests/driver/sigof01/sigof01i2.stdout
@@ -1,5 +1,6 @@
 class Foo a where
   foo :: a -> a
+  {-# MINIMAL foo #-}
 data T = A.T
 mkT :: T
 x :: Bool
diff --git a/testsuite/tests/ghci/prog008/ghci.prog008.stdout b/testsuite/tests/ghci/prog008/ghci.prog008.stdout
index 99e63a1b14..df6767bb84 100644
--- a/testsuite/tests/ghci/prog008/ghci.prog008.stdout
+++ b/testsuite/tests/ghci/prog008/ghci.prog008.stdout
@@ -2,7 +2,9 @@ class C a b where
   c1 :: Num b => a -> b

   c2 :: (Num b, Show b) => a -> b

   c3 :: a1 -> b

+  {-# MINIMAL c1, c2, c3 #-}

 class C a b where

   c1 :: Num b => a -> b

   c2 :: (Num b, Show b) => a -> b

   c3 :: forall a1. a1 -> b

+  {-# MINIMAL c1, c2, c3 #-}
\ No newline at end of file
diff --git a/testsuite/tests/ghci/scripts/T9181.stdout b/testsuite/tests/ghci/scripts/T9181.stdout
index 7e8b95af80..3ea130d177 100644
--- a/testsuite/tests/ghci/scripts/T9181.stdout
+++ b/testsuite/tests/ghci/scripts/T9181.stdout
@@ -7,8 +7,10 @@ type family CmpNat (a :: Nat) (b :: Nat) :: Ordering
 type family CmpSymbol (a :: Symbol) (b :: Symbol) :: Ordering
 class KnownNat (n :: Nat) where
   natSing :: SNat n
+  {-# MINIMAL natSing #-}
 class KnownSymbol (n :: Symbol) where
   symbolSing :: SSymbol n
+  {-# MINIMAL symbolSing #-}
 data SomeNat where
   SomeNat :: KnownNat n => (Proxy n) -> SomeNat
 data SomeSymbol where
diff --git a/testsuite/tests/ghci/scripts/ghci008.stdout b/testsuite/tests/ghci/scripts/ghci008.stdout
index 9a1bcf7551..eb057ca4bd 100644
--- a/testsuite/tests/ghci/scripts/ghci008.stdout
+++ b/testsuite/tests/ghci/scripts/ghci008.stdout
@@ -27,6 +27,9 @@ class (RealFrac a, Floating a) => RealFloat a where
   isNegativeZero :: a -> Bool

   isIEEE :: a -> Bool

   atan2 :: a -> a -> a

+  {-# MINIMAL floatRadix, floatDigits, floatRange, decodeFloat,

+              encodeFloat, isNaN, isInfinite, isDenormalized, isNegativeZero,

+              isIEEE #-}

   	-- Defined in ‘GHC.Float’

 instance RealFloat Float -- Defined in ‘GHC.Float’

 instance RealFloat Double -- Defined in ‘GHC.Float’

diff --git a/testsuite/tests/ghci/scripts/ghci025.stdout b/testsuite/tests/ghci/scripts/ghci025.stdout
index e5b5bc34b7..fc9bd6e2b1 100644
--- a/testsuite/tests/ghci/scripts/ghci025.stdout
+++ b/testsuite/tests/ghci/scripts/ghci025.stdout
@@ -9,6 +9,7 @@ class C a b where
   c2 :: (N b, S b) => a -> b

   c3 :: a1 -> b

   c4 :: a1 -> b

+  {-# MINIMAL c1, c2, c3, c4 #-}

 c1 :: (C a b, N b) => a -> b

 c2 :: (C a b, N b, S b) => a -> b

 c3 :: C a b => forall a. a -> b

@@ -30,6 +31,7 @@ class Applicative m => Monad (m :: * -> *) where
   (>>) :: m a -> m b -> m b

   return :: a -> m a

   fail :: String -> m a

+  {-# MINIMAL (>>=) #-}

 -- imported via Data.Maybe

 catMaybes :: [Maybe a] -> [a]

 fromJust :: Maybe a -> a

@@ -50,6 +52,7 @@ Nothing :: Maybe a
 class Eq a where

   (==) :: a -> a -> Bool

   (/=) :: a -> a -> Bool

+  {-# MINIMAL (==) | (/=) #-}

 -- imported via Prelude, T

 Prelude.length :: Foldable t => forall a. t a -> Int

 -- imported via T

@@ -68,6 +71,7 @@ class C a b where
   c2 :: (N b, S b) => a -> b

   c3 :: a1 -> b

   c4 :: a1 -> b

+  {-# MINIMAL c1, c2, c3, c4 #-}

 c1 :: (C a b, N b) => a -> b

 c2 :: (C a b, N b, S b) => a -> b

 c3 :: C a b => forall a. a -> b

@@ -82,6 +86,7 @@ class C a b where
   c2 :: (N b, S b) => a -> b

   c3 :: forall a1. a1 -> b

   c4 :: forall a1. a1 -> b

+  {-# MINIMAL c1, c2, c3, c4 #-}

 c1 :: forall a b. (C a b, N b) => a -> b

 c2 :: forall a b. (C a b, N b, S b) => a -> b

 c3 :: forall a b. C a b => forall a. a -> b

diff --git a/testsuite/tests/indexed-types/should_compile/T3017.stderr b/testsuite/tests/indexed-types/should_compile/T3017.stderr
index cffbf700a6..2d2187c5a7 100644
--- a/testsuite/tests/indexed-types/should_compile/T3017.stderr
+++ b/testsuite/tests/indexed-types/should_compile/T3017.stderr
@@ -7,6 +7,7 @@ TYPE CONSTRUCTORS
     type family Elem c :: * open

     empty :: c

     insert :: Elem c -> c -> c

+    {-# MINIMAL empty, insert #-}

   data ListColl a = L [a]

     Promotable

 COERCION AXIOMS

diff --git a/testsuite/tests/rename/should_fail/rnfail055.stderr b/testsuite/tests/rename/should_fail/rnfail055.stderr
index 4611e867ec..d87054e926 100644
--- a/testsuite/tests/rename/should_fail/rnfail055.stderr
+++ b/testsuite/tests/rename/should_fail/rnfail055.stderr
@@ -87,8 +87,10 @@ RnFail055.hs-boot:28:1: error:
     Main module: class C2 a b where
                    m2 :: a -> b
                    m2' :: a -> b
+                   {-# MINIMAL m2, m2' #-}
     Boot file:   class C2 a b where
                    m2 :: a -> b
+                   {-# MINIMAL m2 #-}
     The methods do not match: There are different numbers of methods
 
 RnFail055.hs-boot:29:1: error:
diff --git a/testsuite/tests/roles/should_compile/Roles14.stderr b/testsuite/tests/roles/should_compile/Roles14.stderr
index 230603cf09..bb61133ce0 100644
--- a/testsuite/tests/roles/should_compile/Roles14.stderr
+++ b/testsuite/tests/roles/should_compile/Roles14.stderr
@@ -3,6 +3,7 @@ TYPE CONSTRUCTORS
   type role C2 representational
   class C2 a where
     meth2 :: a -> a
+    {-# MINIMAL meth2 #-}
 COERCION AXIOMS
   axiom Roles12.NTCo:C2 :: C2 a = a -> a
 Dependent modules: []
diff --git a/testsuite/tests/roles/should_compile/Roles3.stderr b/testsuite/tests/roles/should_compile/Roles3.stderr
index 93cafc0c94..6f25b63691 100644
--- a/testsuite/tests/roles/should_compile/Roles3.stderr
+++ b/testsuite/tests/roles/should_compile/Roles3.stderr
@@ -2,13 +2,17 @@ TYPE SIGNATURES
 TYPE CONSTRUCTORS
   class C1 a where
     meth1 :: a -> a
+    {-# MINIMAL meth1 #-}
   class C2 a b where
     meth2 :: a ~ b => a -> b
+    {-# MINIMAL meth2 #-}
   class C3 a b where
     type family F3 b :: * open
     meth3 :: a -> F3 b -> F3 b
+    {-# MINIMAL meth3 #-}
   class C4 a b where
     meth4 :: a -> F4 b -> F4 b
+    {-# MINIMAL meth4 #-}
   type family F4 a :: * open
   type Syn1 a = F4 a
   type Syn2 a = [a]
diff --git a/testsuite/tests/roles/should_compile/Roles4.stderr b/testsuite/tests/roles/should_compile/Roles4.stderr
index 109a2bb96f..0113869e42 100644
--- a/testsuite/tests/roles/should_compile/Roles4.stderr
+++ b/testsuite/tests/roles/should_compile/Roles4.stderr
@@ -2,8 +2,10 @@ TYPE SIGNATURES
 TYPE CONSTRUCTORS
   class C1 a where
     meth1 :: a -> a
+    {-# MINIMAL meth1 #-}
   class C3 a where
     meth3 :: a -> Syn1 a
+    {-# MINIMAL meth3 #-}
   type Syn1 a = [a]
 COERCION AXIOMS
   axiom Roles4.NTCo:C1 :: C1 a = a -> a
diff --git a/testsuite/tests/typecheck/should_compile/tc231.stderr b/testsuite/tests/typecheck/should_compile/tc231.stderr
index fb011c66c5..5503eaf295 100644
--- a/testsuite/tests/typecheck/should_compile/tc231.stderr
+++ b/testsuite/tests/typecheck/should_compile/tc231.stderr
@@ -11,6 +11,7 @@ TYPE CONSTRUCTORS
     Promotable
   class Zork s a b | a -> b where
     huh :: Q s a chain -> ST s ()
+    {-# MINIMAL huh #-}
 COERCION AXIOMS
   axiom NTCo:Zork ::
       Zork s a b = forall chain. Q s a chain -> ST s ()