This is something C linters have been catching probably since there have been C linters, either from looking for that specific pattern (a lone equals sign in a conditional) or by "inventing" the notion of a boolean type long before C had one and then pretending that only comparison operators had such a type.

Needless to say, the better class of compiler catches this fine. gcc 9 does with -Wall and makes it an error with -Werror. Ditto clang 9. (Look at me giving version numbers as if this were recent. Any non-antediluvian C compiler worth using will do the same.) My point is, any reasonable build would at least pop up some errors for this, making it appear amateurish to me.