ch03-02-data-types - mistaken description of the code snippet

[MaksimDanilau]

In the Invalid Array Element Access section there is a phrase:

The compilation didn’t produce any errors, but the program resulted in a runtime error and didn’t exit successfully.

But according to the code snippet above in the book exactly compiling stage is producing the error.

Also, I've tried to run the build locally.

❯ cargo build
   Compiling variables v0.1.0 (/Users/maksim/Projects/Rust/variables)
error: this operation will panic at runtime
 --> src/main.rs:8:5
  |
8 |     a[10];
  |     ^^^^^ index out of bounds: the length is 3 but the index is 10
  |
  = note: `#[deny(unconditional_panic)]` on by default

error: aborting due to previous error

error: could not compile `variables`

To learn more, run the command again with --verbose.

Is there a mistake in the book? Is it my misunderstanding?

[carols10cents]

Yes, the compiler got smarter and the book was incorrect. See this issue and this PR. The book has been fixed, but the fix hasn't ridden the Rust release trains to stable yet. You can read the new text at https://doc.rust-lang.org/nightly/book/ch03-02-data-types.html#invalid-array-element-access (note nightly in the URL instead of stable).

Thanks!

[MaksimDanilau]

@carols10cents Great!

My bad, I've not found the same issue. Thanks for nightly tip!