chore: cleanup.

tasks/ast_codegen/src/layout.rs

@@ -68,8 +68,7 @@ impl KnownLayout {
         self.trailing_pad
     }
 
-    /// number of unused bits scatered throughout layout, this doesn't contain the `trailing_pad`
-    /// bits.
+    /// number of available niches
     #[inline]
     pub fn niches(&self) -> u128 {
         self.niches
@@ -88,7 +87,7 @@ impl KnownLayout {
             self.niches -= 1;
         } else if can_eat_pad && self.trailing_pad() > 0 {
             // consume one byte of padding at the end
-            self.trailing_pad -= 1;
+            self.consume_trailing_pad(1);
             // consume one and add the remaining values of one byte as niches.
             self.niches = (u8::MAX - 1) as u128;
         } else if can_resize {
@@ -97,7 +96,7 @@ impl KnownLayout {
             self.trailing_pad += align;
             self.consume_niches(n, can_eat_pad, can_resize);
         } else {
-            panic!("`consume_bit` called on a layout without enough space.");
+            panic!("`{}` called on a layout without enough space.", stringify!(consume_niches));
         }
     }