straight-A student
A student who achieves the highest grades in all subjects; a common term in educational contexts.
He graduated as a straight-A student.
優等生 is a more general term for an honor student or top student, while 全優の学生 specifically emphasizes straight A's across all subjects.
Compound of 全 (all) + 優 (excellent) + の (possessive particle) + 学生 (student). The exact historical derivation is uncertain, but the phrase is a straightforward modern construction.