From 1a3615102993e9f017a44b903ff2277a38a171a8 Mon Sep 17 00:00:00 2001
From: Eric Huss <eric@huss.org>
Date: Sat, 16 May 2020 15:03:57 -0700
Subject: [PATCH] Update tuple index token.
---
src/expressions/enum-variant-expr.md | 2 +-
src/expressions/struct-expr.md | 2 +-
src/expressions/tuple-expr.md | 2 +-
src/patterns.md | 2 +-
src/tokens.md | 36 +++++++++++++++++++++-------
5 files changed, 31 insertions(+), 13 deletions(-)
diff --git a/src/expressions/enum-variant-expr.md b/src/expressions/enum-variant-expr.md
index edaee7942..961d654ce 100644
--- a/src/expressions/enum-variant-expr.md
+++ b/src/expressions/enum-variant-expr.md
@@ -41,7 +41,7 @@ Enum variant expressions have the same syntax, behavior, and restrictions as [st
expressions][structs], except they do not support base update with the `..` syntax.
[IDENTIFIER]: ../identifiers.md
-[TUPLE_INDEX]: ../tokens.md#integer-literals
+[TUPLE_INDEX]: ../tokens.md#tuple-index
[_Expression_]: ../expressions.md
[_PathInExpression_]: ../paths.md#paths-in-expressions
[structs]: struct-expr.md
diff --git a/src/expressions/struct-expr.md b/src/expressions/struct-expr.md
index baeba7b8a..a56d0c7de 100644
--- a/src/expressions/struct-expr.md
+++ b/src/expressions/struct-expr.md
@@ -140,7 +140,7 @@ expressions].
[IDENTIFIER]: ../identifiers.md
[Inner attributes]: ../attributes.md
-[TUPLE_INDEX]: ../tokens.md#integer-literals
+[TUPLE_INDEX]: ../tokens.md#tuple-index
[_Expression_]: ../expressions.md
[_InnerAttribute_]: ../attributes.md
[_PathInExpression_]: ../paths.md#paths-in-expressions
diff --git a/src/expressions/tuple-expr.md b/src/expressions/tuple-expr.md
index b979a4f5f..0236d0553 100644
--- a/src/expressions/tuple-expr.md
+++ b/src/expressions/tuple-expr.md
@@ -55,7 +55,7 @@ assert_eq!(unit_x.0, 1.0);
```
[Inner attributes]: ../attributes.md
-[TUPLE_INDEX]: ../tokens.md#integer-literals
+[TUPLE_INDEX]: ../tokens.md#tuple-index
[_Expression_]: ../expressions.md
[_InnerAttribute_]: ../attributes.md
[attributes on block expressions]: block-expr.md#attributes-on-block-expressions
diff --git a/src/patterns.md b/src/patterns.md
index ae6ef08cf..47131d45c 100644
--- a/src/patterns.md
+++ b/src/patterns.md
@@ -481,7 +481,7 @@ Reference patterns are always irrefutable.
> `..`
[_OuterAttribute_]: attributes.md
-[TUPLE_INDEX]: tokens.md#integer-literals
+[TUPLE_INDEX]: tokens.md#tuple-index
Struct patterns match struct values that match all criteria defined by its subpatterns.
They are also used to [destructure](#destructuring) a struct.
diff --git a/src/tokens.md b/src/tokens.md
index 0b0c29cf8..d7cc47052 100644
--- a/src/tokens.md
+++ b/src/tokens.md
@@ -329,10 +329,6 @@ literal_. The grammar for recognizing the two kinds of literals is mixed.
> DEC_LITERAL :\
> DEC_DIGIT (DEC_DIGIT|`_`)<sup>\*</sup>
>
-> TUPLE_INDEX :\
-> `0`
-> | NON_ZERO_DEC_DIGIT DEC_DIGIT<sup>\*</sup>
->
> BIN_LITERAL :\
> `0b` (BIN_DIGIT|`_`)<sup>\*</sup> BIN_DIGIT (BIN_DIGIT|`_`)<sup>\*</sup>
>
@@ -348,8 +344,6 @@ literal_. The grammar for recognizing the two kinds of literals is mixed.
>
> DEC_DIGIT : [`0`-`9`]
>
-> NON_ZERO_DEC_DIGIT : [`1`-`9`]
->
> HEX_DIGIT : [`0`-`9` `a`-`f` `A`-`F`]
>
> INTEGER_SUFFIX :\
@@ -360,9 +354,6 @@ An _integer literal_ has one of four forms:
* A _decimal literal_ starts with a *decimal digit* and continues with any
mixture of *decimal digits* and _underscores_.
-* A _tuple index_ is either `0`, or starts with a *non-zero decimal digit* and
- continues with zero or more decimal digits. Tuple indexes are used to refer
- to the fields of [tuples], [tuple structs], and [tuple variants].
* A _hex literal_ starts with the character sequence `U+0030` `U+0078`
(`0x`) and continues as any mixture (with at least one digit) of hex digits
and underscores.
@@ -442,6 +433,33 @@ a single integer literal.
[unary minus operator]: expressions/operator-expr.md#negation-operators
+#### Tuple index
+
+> **<sup>Lexer</sup>**\
+> TUPLE_INDEX: \
+> INTEGER_LITERAL
+
+A tuple index is used to refer to the fields of [tuples], [tuple structs], and
+[tuple variants].
+
+Tuple indices are compared with the literal token directly. Tuple indices
+start with `0` and each successive index increments the value by `1` as a
+decimal value. Thus, only decimal values will match, and the value must not
+have any extra `0` prefix characters.
+
+```rust,compile_fail
+let example = ("dog", "cat", "horse");
+let dog = example.0;
+let cat = example.1;
+// The following examples are invalid.
+let cat = example.01; // ERROR no field named `01`
+let horse = example.0b10; // ERROR no field named `0b10`
+```
+
+> **Note**: The tuple index may include an `INTEGER_SUFFIX`, but this is not
+> intended to be valid, and may be removed in a future version. See
+> <https://github.com/rust-lang/rust/issues/60210> for more information.
+
#### Floating-point literals
> **<sup>Lexer</sup>**\