From the README:

Zigft is a small library that lets you perform function transform in Zig. Consisting of just two files, it’s designed to be used in source form. Simply download the file you need from this repo, place it in your src directory, and import it into your own code.

Here’s one of the examples given:

const std = @import("std");
const fn_transform = @import("./fn-transform.zig");

fn attachDebugOutput(comptime func: anytype, comptime name: []const u8) @TypeOf(func) {
    const FT = @TypeOf(func);
    const fn_info = @typeInfo(FT).@"fn";
    const ns = struct {
        inline fn call(args: std.meta.ArgsTuple(FT)) fn_info.return_type.? {
            std.debug.print("{s}: {any}\n", .{ name, args });
            return @call(.auto, func, args);
        }
    };
    return fn_transform.spreadArgs(ns.call, fn_info.calling_convention);
}

pub fn main() void {
    const ns = struct {
        fn hello(a: i32, b: i32) void {
            std.debug.print("sum = {d}\n", .{a + b});
        }
    };
    const func = attachDebugOutput(ns.hello, "hello");
    func(123, 456);
}