Accidentally Turing-Complete
Some things were not supposed to be
Turing-complete.
This is a collection of such accidents.
Stuff which is somehow limited
(stack overflows, arbitrary configuration, etc)
is still considered Turing complete,
since all "physical" Turing machines are resource limited.
C++ Templates
Although they were initially not supposed to,
C++ templates are Turing-complete.
For proof look at this
paper (pdf).
TypeScript Type System
In a very similar fashion to C++,
the type system of TypeScript can be used to...
Read more at beza1e1.tuxen.de