As part of my masters in linguistics, I am taking a course on the subject of irony. We were given examples of sentences that are most likely ironic, as the English sentence “he is not exceptionally smart” (which has the structure “he is not exceptionally X”). This does not mean literally that he is smart at an exceptional level, but rather, ironically, that he is very stupid.

Are there similar constructions in French, preferably ones that involve superlative and negation?

Here is a paper (PDF format) of my professor about the subject for those who are interested in elaboration on the subject.