New upstream version 1.53.0+dfsg1

[rustc.git] / src / doc / reference / src / expressions / array-expr.md

diff --git a/src/doc/reference/src/expressions/array-expr.md b/src/doc/reference/src/expressions/array-expr.md
index 2659b229e8ea3d9e8a30503188915f9c36ab3523..5f50f09cb476049fe38bf7572076b1a7cfb5f128 100644 (file)
--- a/src/doc/reference/src/expressions/array-expr.md
+++ b/src/doc/reference/src/expressions/array-expr.md
@@ -10,21 +10,28 @@
 > &nbsp;&nbsp; &nbsp;&nbsp; [_Expression_] ( `,` [_Expression_] )<sup>\*</sup> `,`<sup>?</sup>\
 > &nbsp;&nbsp; | [_Expression_] `;` [_Expression_]
 
-An _[array] expression_ can be written by enclosing zero or more comma-separated expressions of uniform type in square brackets.
+*Array expressions* construct [arrays][array].
+Array expressions come in two forms.
+
+The first form lists out every value in the array.
+The syntax for this form is a comma-separated list of expressions of uniform type enclosed in square brackets.
 This produces an array containing each of these values in the order they are written.
 
-Alternatively there can be exactly two expressions inside the brackets, separated by a semicolon.
-The expression after the `;` must have type `usize` and be a [constant expression], such as a [literal] or a [constant item].
-`[a; b]` creates an array containing `b` copies of the value of `a`.
-If the expression after the semicolon has a value greater than 1 then this requires that the type of `a` is [`Copy`], or `a` must be a path to a constant item.
+The syntax for the second form is two expressions separated by a semicolon (`;`) enclosed in square brackets.
+The expression before the `;` is called the *repeat operand*.
+The expression after the `;` is called the *length operand*.
+It must have type `usize` and be a [constant expression], such as a [literal] or a [constant item].
+An array expression of this form creates an array with the length of the value of the legnth operand with each element a copy of the repeat operand.
+That is, `[a; b]` creates an array containing `b` copies of the value of `a`.
+If the length operand has a value greater than 1 then this requires that the type of the repeat operand is [`Copy`] or that it must be a [path] to a constant item.
 
-When the repeat expression `a` is a constant item, it is evaluated `b` times.
-If `b` is 0, the constant item is not evaluated at all.
-For expressions that are not a constant item, it is evaluated exactly once, and then the result is copied `b` times.
+When the repeat operand is a constant item, it is evaluated the length operand's value times.
+If that value is `0`, then the constant item is not evaluated at all.
+For expressions that are not a constant item, it is evaluated exactly once, and then the result is copied the length operand's value times.
 
 <div class="warning">
 
-Warning: In the case where `b` is 0, and `a` is a non-constant item, there is currently a bug in `rustc` where the value `a` is evaluated but not dropped, thus causing a leak.
+Warning: In the case where the length operand is 0, and the repeat operand is a non-constant item, there is currently a bug in `rustc` where the value `a` is evaluated but not dropped, thus causing a leak.
 See [issue #74836](https://github.com/rust-lang/rust/issues/74836).
 
 </div>
@@ -49,7 +56,7 @@ const EMPTY: Vec<i32> = Vec::new();
 > _IndexExpression_ :\
 > &nbsp;&nbsp; [_Expression_] `[` [_Expression_] `]`
 
-[Array] and [slice]-typed expressions can be indexed by writing a square-bracket-enclosed expression of type `usize` (the index) after them.
+[Array] and [slice]-typed values can be indexed by writing a square-bracket-enclosed expression of type `usize` (the index) after them.
 When the array is mutable, the resulting [memory location] can be assigned to.
 
 For other types an index expression `a[b]` is equivalent to `*std::ops::Index::index(&a, b)`, or `*std::ops::IndexMut::index_mut(&mut a, b)` in a mutable place expression context.
@@ -91,4 +98,5 @@ The array index expression can be implemented for types other than arrays and sl
 [constant item]: ../items/constant-items.md
 [literal]: ../tokens.md#literals
 [memory location]: ../expressions.md#place-expressions-and-value-expressions
+[path]: path-expr.md
 [slice]: ../types/slice.md