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2 changes: 1 addition & 1 deletion standard/conversions.md
Original file line number Diff line number Diff line change
Expand Up @@ -345,7 +345,7 @@ In all cases, the rules ensure that a conversion is executed as a boxing convers

### 10.2.13 Implicit tuple conversions

An implicit conversion exists from a tuple expression `E` to a tuple type `T` if `E` has the same arity as `T` and an implicit conversion exists from each element in `E` to the corresponding element type in `T`. The conversion is performed by creating an instance of `T`’s corresponding `System.ValueTuple<...>` type, and initializing each of its fields in order from left to right by evaluating the corresponding tuple element expression of `E`, converting it to the corresponding element type of `T` using the implicit conversion found, and initializing the field with the result.
An implicit conversion exists from an expression `E` with a tuple type `S` to a tuple type `T` if `S` has the same arity as `T` and an implicit conversion exists from each element type in `S` to the corresponding element type in `T`.
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I think I'm following, but just checking. Is there a tuple type S for every tuple expression? For instance, does (default, default) have a tuple type S in:

(object, object) x = (default, default);


If an element name in the tuple expression does not match a corresponding element name in the tuple type, a warning shall be issued.

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6 changes: 3 additions & 3 deletions standard/expressions.md
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Expand Up @@ -33,12 +33,12 @@ An ***instance accessor*** is a property access on an instance, an event access

### 12.2.2 Values of expressions

Most of the constructs that involve an expression ultimately require the expression to denote a ***value***. In such cases, if the actual expression denotes a namespace, a type, a method group, or nothing, a compile-time error occurs. However, if the expression denotes a property access, an indexer access, or a variable, the value of the property, indexer, or variable is implicitly substituted:
Most of the constructs that involve an expression ultimately require the expression to denote a ***value***. In such cases, if the actual expression denotes a namespace, a type, a method group, or nothing, a compile-time error occurs. However, if the expression denotes a property access, an indexer access, a tuple, or a variable, the value of the property, indexer, tuple, or variable is implicitly substituted:
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Why do we mention tuple expressions here, but we don't mention other kinds of expressions such as object creation expressions, array creation expressions, lambda expressions, and so on?


- The value of a variable is simply the value currently stored in the storage location identified by the variable. A variable shall be considered definitely assigned ([§9.4](variables.md#94-definite-assignment)) before its value can be obtained, or otherwise a compile-time error occurs.
- The value of a property access expression is obtained by invoking the get accessor of the property. If the property has no get accessor, a compile-time error occurs. Otherwise, a function member invocation ([§12.6.6](expressions.md#1266-function-member-invocation)) is performed, and the result of the invocation becomes the value of the property access expression.
- The value of an indexer access expression is obtained by invoking the get accessor of the indexer. If the indexer has no get accessor, a compile-time error occurs. Otherwise, a function member invocation ([§12.6.6](expressions.md#1266-function-member-invocation)) is performed with the argument list associated with the indexer access expression, and the result of the invocation becomes the value of the indexer access expression.
- The value of a tuple expression is obtained by applying an implicit tuple conversion ([§10.2.13](conversions.md#10213-implicit-tuple-conversions)) to the type of the tuple expression. It is an error to obtain the value of a tuple expression that does not have a type.
- The value of a tuple expression is the value obtained by evaluating the tuple expression (§12.8.6). It is an error to obtain the value of a tuple expression that does not have a type.

## 12.3 Static and Dynamic Binding

Expand Down Expand Up @@ -1611,7 +1611,7 @@ A tuple expression has a type if and only if each of its element expressions `Ei

A tuple expression is evaluated by evaluating each of its element expressions in order from left to right.

A tuple value can be obtained from a tuple expression by converting it to a tuple type ([§10.2.13](conversions.md#10213-implicit-tuple-conversions)), by reclassifying it as a value ([§12.2.2](expressions.md#1222-values-of-expressions))) or by making it the target of a deconstructing assignment ([§12.21.2](expressions.md#12212-simple-assignment)).
A tuple value is obtained from a tuple expression by evaluating it and storing the result in corresponding `System.ValueTuple<...>` type, and initializing each of its fields in order from left to right by evaluating the corresponding tuple element expression of `E`, converting it to the corresponding element type of `T` using the implicit conversion found, and initializing the field with the result.
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System.ValueTuple isn't mentioned anywhere else in this file. Shouldn't we be a bit more specific? There are wrinkles in how tuples map to the ValueTuple types. For instance, a tuple type (T1, T2, T3, T4, T5, T6, T7, T8) must be represented as nested ValueTuples, because the TRest type argument of a tuple must always itself be a nested tuple: ValueTuple<T1, T2, T3, T4, T5, T6, T7, ValueTuple<T8>>

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I see that conversions.md does mention ValueTuple<...> a few times, but it doesn't explain the required recursive encoding.


> *Example*:
>
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