diff options
| -rw-r--r-- | src/doc/tarpl/checked-uninit.md | 23 | ||||
| -rw-r--r-- | src/doc/tarpl/other-reprs.md | 2 |
2 files changed, 24 insertions, 1 deletions
diff --git a/src/doc/tarpl/checked-uninit.md b/src/doc/tarpl/checked-uninit.md index 65bffd7d09f..8b03cd497b7 100644 --- a/src/doc/tarpl/checked-uninit.md +++ b/src/doc/tarpl/checked-uninit.md @@ -68,6 +68,29 @@ fn main() { } ``` +Of course, while the analysis doesn't consider actual values, it does +have a relatively sophisticated understanding of dependencies and control +flow. For instance, this works: + +```rust +let x: i32; + +loop { + // Rust doesn't understand that this branch will be taken unconditionally, + // because it relies on actual values. + if true { + // But it does understand that it will only be taken once because + // we *do* unconditionally break out of it. Therefore `x` doesn't + // need to be marked as mutable. + x = 0; + break; + } +} +// It also knows that it's impossible to get here without reaching the break. +// And therefore that `x` must be initialized here! +println!("{}", x); +``` + If a value is moved out of a variable, that variable becomes logically uninitialized if the type of the value isn't Copy. That is: diff --git a/src/doc/tarpl/other-reprs.md b/src/doc/tarpl/other-reprs.md index d4c6134c543..26e0192a536 100644 --- a/src/doc/tarpl/other-reprs.md +++ b/src/doc/tarpl/other-reprs.md @@ -47,7 +47,7 @@ discriminant. On non-C-like enums, this will inhibit certain optimizations like the null- pointer optimization. -These reprs have no affect on a struct. +These reprs have no effect on a struct. |