builder begin_cell() pure asm "NEWC";

global int g;

(builder) f_pure() pure {
    var g;  // strange, but this doesn't make a variable local, it still refers to a global one
    builder b = begin_cell();
    g = g + 1;
    return b;
}

int main() {
    g = 0;
    f_pure();
    return g;
}

{-
@compilation_should_fail
@stderr
"""
An impure operation in a pure function
g = g + 1;
"""
-}