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Welcome to Software Development on Codidact!

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Q&A What might happen if I ignore warning?

Warnings most often mean "here is a bug which will likely cause your program to crash or misbehave". They do not mean "here's something that you can optionally fix when you can spare the time". See...

posted 2y ago by Lundin‭  ·  edited 2y ago by Lundin‭

Answer
#2: Post edited by user avatar Lundin‭ · 2021-08-31T10:12:41Z (over 2 years ago)
  • Warnings most often mean "here is a bug which will likely cause your program to crash or misbehave". They do _not_ mean "here's something that you can optionally fix when you can spare the time". See [What must a C compiler do when it finds an error?](https://software.codidact.com/posts/277340)
  • In your specific case, ignoring the warning leads to undefined behavior, meaning anything can happen. For example runaway code, crashes caused by stack corruption/wrong calling convention, wrong results calculated on garbage values, code getting incorrectly optimized and parts of it removed etc etc. [What is undefined behavior and how does it work?](https://software.codidact.com/posts/277486)
  • Warnings most often mean "here is a bug which will likely cause your program to crash or misbehave". They do _not_ mean "here's something that you can optionally fix when you can spare the time". See [What must a C compiler do when it finds an error?](https://software.codidact.com/posts/277340)
  • In your specific case, ignoring the warning leads to undefined behavior, meaning anything can happen. This is mentioned in the C standard C17 6.9.1/12:
  • > If the } that terminates a function is reached, and the value of the function call is used by the caller, the behavior is undefined.
  • For example runaway code, crashes caused by stack corruption/wrong calling convention, wrong results calculated on garbage values, code getting incorrectly optimized and parts of it removed etc etc. [What is undefined behavior and how does it work?](https://software.codidact.com/posts/277486)
#1: Initial revision by user avatar Lundin‭ · 2021-08-31T10:09:55Z (over 2 years ago)
Warnings most often mean "here is a bug which will likely cause your program to crash or misbehave". They do _not_ mean "here's something that you can optionally fix when you can spare the time". See [What must a C compiler do when it finds an error?](https://software.codidact.com/posts/277340)

In your specific case, ignoring the warning leads to undefined behavior, meaning anything can happen. For example runaway code, crashes caused by stack corruption/wrong calling convention, wrong results calculated on garbage values, code getting incorrectly optimized and parts of it removed etc etc. [What is undefined behavior and how does it work?](https://software.codidact.com/posts/277486)