replace leading _ for private symbols with keyword hide

examples/packages/hidden_valid/app/a.bro

@@ -1,14 +1,27 @@
-_Thing :: struct {
+hide helper func() i32 {
+	thing Thing = Thing { value = value }
+	return thing.value
+}
+
+hide Thing :: struct {
 	value i32
 }
 
-_value :: 1
-
-_helper func() i32 {
-	thing _Thing = _Thing { value = _value }
-	return thing.value
+hide Local_Union :: union {
+	value i32
 }
 
+hide Local_Enum :: enum {
+	value
+}
+
+hide Local_Opaque :: opaque
+hide Local_Distinct :: distinct i32
+hide Local_Alias :: alias i32
+
+hide value :: 1
+hide mutable_value i32 = 1
+
 _foreign c_func() i32 {
 	return 1
 }
@@ -17,6 +30,15 @@ _C_Record :: c_struct {
 	value c_int
 }
 
-from_a func() i32 {
-	return _helper()
+hide local_foreign c_func() i32 {
+	return 1
+}
+
+hide Local_C_Record :: c_struct {
+	value c_int
+}
+
+from_a func() i32 {
+	record Local_C_Record = Local_C_Record { value = 0 }
+	return helper() + local_foreign() + i32(record.value)
 }

examples/packages/hidden_valid/app/b.bro

@@ -1,14 +1,37 @@
-_Thing :: struct {
+import "../dep"
+
+hide Thing :: struct {
 	value i32
 }
 
-_value :: 2
+hide Local_Union :: union {
+	value i32
+}
 
-_helper func() i32 {
-	thing _Thing = _Thing { value = _value }
+hide Local_Enum :: enum {
+	value
+}
+
+hide Local_Opaque :: opaque
+hide Local_Distinct :: distinct i32
+hide Local_Alias :: alias i32
+
+hide value :: 2
+hide mutable_value i32 = 2
+
+hide helper func() i32 {
+	thing Thing = Thing { value = value }
 	return thing.value
 }
 
+hide local_foreign c_func() i32 {
+	return 1
+}
+
+hide Local_C_Record :: c_struct {
+	value c_int
+}
+
 Box :: struct {
 	_value i32
 }
@@ -16,5 +39,5 @@ Box :: struct {
 from_b func(_input i32) i32 {
 	_local Box = Box { _value = _input }
 	record _C_Record = _C_Record { value = 0 }
-	return _helper() + _local._value + _foreign() + i32(record.value)
+	return helper() + _local._value + _foreign() + i32(record.value) + dep._visible()
 }

examples/packages/hidden_valid/dep/dep.bro

@@ -0,0 +1,3 @@
+_visible func() i32 {
+	return 1
+}