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auto merge of #16175 : EduardoBautista/rust/fix-guessing-game-appearing-early, r=steveklabnik 

Solves: https://github.com/rust-lang/rust/issues/16162
This commit is contained in:
bors 2014-08-02 12:06:09 +00:00
parent 1b44c5b0eb 69267b1e1d
commit 5bad333fec
1 changed files with 14 additions and 14 deletions
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src/doc/guide.md
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@ -449,9 +449,9 @@ let x;
...we'll get an error:
```{ignore}
src/guessing_game.rs:2:9: 2:10 error: cannot determine a type for this local variable: unconstrained type
src/guessing_game.rs:2 let x;
^
src/hello_world.rs:2:9: 2:10 error: cannot determine a type for this local variable: unconstrained type
src/hello_world.rs:2 let x;
^
```
Giving it a type will compile, though:
@ -460,7 +460,7 @@ Giving it a type will compile, though:
let x: int;
```
Let's try it out. Change your `src/guessing_game.rs` file to look like this:
Let's try it out. Change your `src/hello_world.rs` file to look like this:
```{rust}
fn main() {
@ -474,10 +474,10 @@ You can use `cargo build` on the command line to build it. You'll get a warning,
but it will still print "Hello, world!":
```{ignore,notrust}
Compiling guessing_game v0.1.0 (file:/home/you/projects/guessing_game)
src/guessing_game.rs:2:9: 2:10 warning: unused variable: `x`, #[warn(unused_variable)] on by default
src/guessing_game.rs:2 let x: int;
^
Compiling hello_world v0.1.0 (file:/home/you/projects/hello_world)
src/hello_world.rs:2:9: 2:10 warning: unused variable: `x`, #[warn(unused_variable)] on by default
src/hello_world.rs:2 let x: int;
^
```
Rust warns us that we never use the variable binding, but since we never use it,
@ -496,16 +496,16 @@ And try to build it. You'll get an error:
```{bash}
$ cargo build
Compiling guessing_game v0.1.0 (file:/home/you/projects/guessing_game)
src/guessing_game.rs:4:39: 4:40 error: use of possibly uninitialized variable: `x`
src/guessing_game.rs:4 println!("The value of x is: {}", x);
^
Compiling hello_world v0.1.0 (file:/home/you/projects/hello_world)
src/hello_world.rs:4:39: 4:40 error: use of possibly uninitialized variable: `x`
src/hello_world.rs:4 println!("The value of x is: {}", x);
^
note: in expansion of format_args!
<std macros>:2:23: 2:77 note: expansion site
<std macros>:1:1: 3:2 note: in expansion of println!
src/guessing_game.rs:4:5: 4:42 note: expansion site
src/hello_world.rs:4:5: 4:42 note: expansion site
error: aborting due to previous error
Could not execute process `rustc src/guessing_game.rs --crate-type bin --out-dir /home/you/projects/guessing_game/target -L /home/you/projects/guessing_game/target -L /home/you/projects/guessing_game/target/deps` (status=101)
Could not execute process `rustc src/hello_world.rs --crate-type bin --out-dir /home/you/projects/hello_world/target -L /home/you/projects/hello_world/target -L /home/you/projects/hello_world/target/deps` (status=101)
```
Rust will not let us use a value that has not been initialized. So why let us