Add test cases for #16615

testsuite/tests/deSugar/should_compile/T16615.hs

+module T16615
+where
+
+f :: Int -> Bool
+f i = if i == 0 then True else g (pred i)
+
+g :: Int -> Bool
+g i = if i == 0 then False else f (pred i)

testsuite/tests/deSugar/should_compile/T16615.stderr

+
+==================== Desugar (after optimization) ====================
+Result size of Desugar (after optimization)
+  = {terms: 36, types: 13, coercions: 0, joins: 0/0}
+
+-- RHS size: {terms: 5, types: 0, coercions: 0, joins: 0/0}
+T16615.$trModule :: GHC.Types.Module
+[LclIdX]
+T16615.$trModule
+  = GHC.Types.Module
+      (GHC.Types.TrNameS "main"#) (GHC.Types.TrNameS "T16615"#)
+
+Rec {
+-- RHS size: {terms: 14, types: 4, coercions: 0, joins: 0/0}
+g :: Int -> Bool
+[LclIdX]
+g = \ (i_a26O :: Int) ->
+      case == @ Int GHC.Classes.$fEqInt i_a26O (GHC.Types.I# 0#) of {
+        False -> f (pred @ Int GHC.Enum.$fEnumInt i_a26O);
+        True -> GHC.Types.False
+      }
+
+-- RHS size: {terms: 14, types: 4, coercions: 0, joins: 0/0}
+f [Occ=LoopBreaker] :: Int -> Bool
+[LclIdX]
+f = \ (i_aWp :: Int) ->
+      case == @ Int GHC.Classes.$fEqInt i_aWp (GHC.Types.I# 0#) of {
+        False -> g (pred @ Int GHC.Enum.$fEnumInt i_aWp);
+        True -> GHC.Types.True
+      }
+end Rec }
+
+
+

testsuite/tests/deSugar/should_compile/all.T

@@ -107,3 +107,4 @@ test('T14773a', normal, compile, ['-Wincomplete-patterns'])
 test('T14773b', normal, compile, ['-Wincomplete-patterns'])
 test('T14815', [], makefile_test, ['T14815'])
 test('T13208', [], makefile_test, ['T13208'])
+test('T16615', normal, compile, ['-ddump-ds'])