Allow string to enum casting

Signed-off-by: Ketan Umare <[email protected]>

pkg/compiler/validators/typing.go

@@ -40,6 +40,12 @@ func (t trivialChecker) CastsFrom(upstreamType *flyte.LiteralType) bool {
 			return true
 		}
 	}
+	// If t is an enum, it can be created from a string as Enums as just constrained String aliases
+	if t.literalType.GetEnumType() != nil {
+		if upstreamType.GetSimple() == flyte.SimpleType_STRING {
+			return true
+		}
+	}
 
 	// Ignore metadata when comparing types.
 	upstreamTypeCopy := *upstreamType

pkg/compiler/validators/typing_test.go

@@ -86,7 +86,7 @@ func TestSimpleLiteralCasting(t *testing.T) {
 				Type: &core.LiteralType_Simple{Simple: core.SimpleType_STRING},
 			},
 		)
-		assert.True(t, castable, "Integers should be castable to other integers")
+		assert.True(t, castable, "Enum should be castable to string")
 	})
 
 	t.Run("EnumToEnum", func(t *testing.T) {
@@ -102,7 +102,23 @@ func TestSimpleLiteralCasting(t *testing.T) {
 				}},
 			},
 		)
-		assert.True(t, castable, "Integers should be castable to other integers")
+		assert.True(t, castable, "Enum should be castable to Enums if they are identical")
+	})
+
+	t.Run("EnumToEnum", func(t *testing.T) {
+		castable := AreTypesCastable(
+			&core.LiteralType{
+				Type: &core.LiteralType_EnumType{EnumType: &core.EnumType{
+					Values: []string{"x", "y"},
+				}},
+			},
+			&core.LiteralType{
+				Type: &core.LiteralType_EnumType{EnumType: &core.EnumType{
+					Values: []string{"m", "n"},
+				}},
+			},
+		)
+		assert.False(t, castable, "Enum should not be castable to non matching enums")
 	})
 
 	t.Run("StringToEnum", func(t *testing.T) {
@@ -116,7 +132,7 @@ func TestSimpleLiteralCasting(t *testing.T) {
 				}},
 			},
 		)
-		assert.False(t, castable, "Integers should be castable to other integers")
+		assert.True(t, castable, "Strings should be castable to enums - may result in runtime failure")
 	})
 }