refactor: allow not having a `default` case for enum

Problem: The style guide states that all switch statements that are not conditional on an enum must have a `default` case, but does not give any explicit guideline for switch statements that are conditional on enums. As a result, a `default` case is added in many enum switch statements, even when the switch statement is exhaustive. This is not ideal because it removes the ability to have compiler errors to easily detect unchanged switch statements when a new possible value for an enum is added.

Solution: Add explicit guidelines for switch statements that are conditional on an enum, clarifying that a `default` case is not necessary if the switch statement is exhaustive. Also refactor pre-existing code with unnecessary `default` cases.

1 files changed, 1 insertions, 2 deletions

diff --git a/src/nvim/drawscreen.c b/src/nvim/drawscreen.c
index 98077364a0..ca70c1f4ef 100644
--- a/src/nvim/drawscreen.c
+++ b/src/nvim/drawscreen.c
@@ -738,9 +738,8 @@ int win_get_bordertext_col(int total_col, int text_width, AlignTextPos align)
     return (total_col - text_width) / 2 + 1;
   case kAlignRight:
     return total_col - text_width + 1;
-  default:
-    abort();
   }
+  UNREACHABLE;
 }
 
 static void win_redr_border(win_T *wp)