Can a spellcasting Fighter use the Action Surge ability to cast two spells (not cantrips) in one turn?
Answers to this question assume they can not, however, nothing in the rules explicitly restricts that. The only restriction described is the "bonus action" paragraph (PHB, page 202):
A spell cast with a bonus action is especially swift. You must use a bonus action on your turn to cast the spell, provided that you haven’t already taken a bonus action this turn. You can’t cast another spell during the same turn, except for a cantrip with a casting time of 1 action.
But it is related to the bonus action, isn't it?
A follow-up question - what if the Fighter casts a Bonus Action spell with a cantrip, then takes the Action Surge, and then casts any "normal" (not a cantrip) spell? Will it contradict the "you can’t cast another spell during the same turn" part?