[indic-generator] Add a couple comments

src/gen-indic-table.py

@@ -243,15 +243,18 @@ for k,new_cat in category_overrides.items():
   data[k] = (new_cat, pos, block)
 
 # We only expect position for certain types
+positioned_categories = ('CM', 'SM', 'RS', 'H', 'M')
 for k, (cat, pos, block) in data.items():
-  if cat not in ('CM', 'SM', 'RS', 'H', 'M'):
+  if cat not in positioned_categories:
     pos = 'END'
     data[k] = (cat, pos, block)
 
 # Position overrides are more complicated
 
+# Keep in sync with CONSONANT_FLAGS in the shaper
+consonant_categories = ('C', 'CS', 'Ra','CM', 'V', 'PLACEHOLDER', 'DOTTEDCIRCLE')
 for k, (cat, pos, block) in data.items():
-  if cat in ('C', 'CS', 'Ra','CM', 'V', 'PLACEHOLDER', 'DOTTEDCIRCLE'):
+  if cat in consonant_categories:
     pos = 'BASE_C'
     data[k] = (cat, pos, block)
 

src/hb-ot-shaper-indic.hh

@@ -78,7 +78,9 @@ enum indic_category_t {
  *
  * We treat Vowels and placeholders as if they were consonants.  This is safe because Vowels
  * cannot happen in a consonant syllable.  The plus side however is, we can call the
- * consonant syllable logic from the vowel syllable function and get it all right! */
+ * consonant syllable logic from the vowel syllable function and get it all right!
+ *
+ * Keep in sync with consonant_categories in the generator. */
 #define CONSONANT_FLAGS (FLAG (OT_C) | FLAG (OT_CS) | FLAG (OT_Ra) | MEDIAL_FLAGS | FLAG (OT_V) | FLAG (OT_PLACEHOLDER) | FLAG (OT_DOTTEDCIRCLE))
 #define JOINER_FLAGS (FLAG (OT_ZWJ) | FLAG (OT_ZWNJ))