C++ incomprehensible compiler errors

Question

I got a pretty simple task to do. Write a class that defines time. For some reason, in one of the functions I get an error, that I do not understand. I searched for a solution with no success, so in the end I decided post it here. time.h ``` class time { private: int _hours; int _minutes; float _seconds; bool checkHours(int hours); bool checkMinutes(int minutes); bool checkSeconds(float seconds); public: time(int hours=0, int minutes=0, float seconds=0); time(const time & tm); ~time(); void hours(int hours); int hours() const; void minutes(int minutes); int minutes() const; void seconds(float seconds); float seconds() const; void operator=(time tm); bool operator==(time tm); void print(); time getTimeFromUser(); float getTimeAsFractionOfTheDay(time tm); ``` }; and time.cpp ``` #include #include "time.h" bool time::checkHours(int hours) { return hours>=0 && hours<24; } bool time::checkMinutes(int MS) { return MS>=0 && MS<60; } bool time::checkSeconds(float MS) { return MS>=0…

Accepted Answer

As it turns out, you are the victim of a subtle bug.

`time` is a function declared in the system header `time.h`, which is getting included in your program via `iostream`. When you declare `time time::getTimeFromUser()`, the compiler sees the return value and thinks you mean the function time!

`clang` makes this obvious with its error:

```
time.cpp:122:1: error: must use 'class' tag to refer to type 'time' in this scope
time time::getTimeFromUser()
^
class 
/usr/include/time.h:133:8: note: class 'time' is hidden by a non-type declaration of 'time' here
time_t time(time_t *);
       ^
```

The fix is to define that particular function like this:

```
class time time::getTimeFromUser() {
    ...
}
```

Or, if using C++11,

```
auto time::getTimeFromUser() -> time {
    ...
}
```

C++ incomprehensible compiler errors

Solution

Problem