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Clean up E0070 long explanation

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GuillaumeGomez committed Nov 25, 2019
1 parent ef35980 commit 1bd28b1087b067df4037cbbe2f48db7776e3deaa
Showing with 20 additions and 18 deletions.
  1. +20 −18 src/librustc_error_codes/error_codes/E0070.md
@@ -1,41 +1,43 @@
The left-hand side of an assignment operator must be a place expression. A
place expression represents a memory location and can be a variable (with
optional namespacing), a dereference, an indexing expression or a field
reference.
An assignment operator was used on a non-place expression.

More details can be found in the [Expressions] section of the Reference.

[Expressions]: https://doc.rust-lang.org/reference/expressions.html#places-rvalues-and-temporaries

Now, we can go further. Here are some erroneous code examples:
Erroneous code examples:

```compile_fail,E0070
struct SomeStruct {
x: i32,
y: i32
y: i32,
}
const SOME_CONST : i32 = 12;
const SOME_CONST: i32 = 12;
fn some_other_func() {}
fn some_function() {
SOME_CONST = 14; // error : a constant value cannot be changed!
1 = 3; // error : 1 isn't a valid place!
some_other_func() = 4; // error : we cannot assign value to a function!
SomeStruct.x = 12; // error : SomeStruct a structure name but it is used
// like a variable!
SOME_CONST = 14; // error: a constant value cannot be changed!
1 = 3; // error: 1 isn't a valid place!
some_other_func() = 4; // error: we cannot assign value to a function!
SomeStruct::x = 12; // error: SomeStruct a structure name but it is used
// like a variable!
}
```

The left-hand side of an assignment operator must be a place expression. A
place expression represents a memory location and can be a variable (with
optional namespacing), a dereference, an indexing expression or a field
reference.

More details can be found in the [Expressions] section of the Reference.

[Expressions]: https://doc.rust-lang.org/reference/expressions.html#places-rvalues-and-temporaries

And now let's give working examples:

```
struct SomeStruct {
x: i32,
y: i32
y: i32,
}
let mut s = SomeStruct {x: 0, y: 0};
let mut s = SomeStruct { x: 0, y: 0 };
s.x = 3; // that's good !

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