Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
1.1k views
in Technique[技术] by (71.8m points)

rust - How to suppress "function is never used" warning for a function used by tests?

I'm writing a program in Rust and I have some tests for it. I wrote a helper function for these tests, but whenever I build using cargo build it warns me that the function is never used:

warning: function is never used: ... #[warn(dead_code)] on by default

How I can mark this function as used so as not to get the warnings?

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

Specific question

How I can mark this function as used so as not to get the warnings?

The Rust compiler runs many lints to warn you about possible issues in your code and the dead_code lint is one of them. It can be very useful in pointing out mistakes when code is complete, but may also be a nuisance at earlier stages. Often, this can be solved by either deleting unused code, or by marking a public method. However, all lints can be turned off by allowing them, and your error message (#[warn(dead_code)] on by default) contains the name of the lint you could disable.

#[allow(dead_code)]
fn my_unused_function() {}

Alternative for testing

I wrote a helper function for these tests, but whenever I build using cargo build it warns me that the function is never used.

This happens to be a special case, which is that code that is only used for testing isn't needed in the real executable and should probably not be included.

In order to optionally disable compilation of test code, you can mark it accordingly using the cfg attribute with the test profile.

#[cfg(test)]
fn my_test_specific_function() {}

When marked in this way, the compiler knows to ignore the method during compilation. This is similar to commonly used ifdef usage in other languages like C or C++, where you are telling a preprocessor to ignore the enclosed code unless TESTING is defined.

#ifdef TESTING
...
#endif

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...