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Niches#3334

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joshtriplett wants to merge 49 commits intorust-lang:masterrust-lang/rfcs:masterfrom joshtriplett:nichejoshtriplett/rfcs:nicheCopy head branch name to clipboard

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Commits on Oct 23, 2022

• Niches

  joshtriplett

  committed
  e62830c

• Niche is RFC 3334

  joshtriplett

  committed
  2947255

• Forbid structs with generic parameters affecting the non-ZST field

  joshtriplett

  committed
  26b01d6

• Fix typo

  joshtriplett

  committed
  f1b671a

• Further clarify the non-guarantees about multiple niche values

  joshtriplett

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  74fee72

• Further clarify non-support for negative values at this time

  joshtriplett

  committed
  ae13802

• Specify two's-complement specifically

  joshtriplett

  committed
  ae3671a

• Discuss mapping to unsigned integer representation

  joshtriplett

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  f4b0631

• Alternatives: Add pattern-based syntax

  joshtriplett

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  132d1f8

• Reorder some of the reference-level explanation to group similar things

  joshtriplett

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  7a1b2e4

• Further clarify round-trip via bytes

  joshtriplett

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  422dcd9

• Add note about non_exhaustive.

  joshtriplett

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  825d29c

Commits on Oct 24, 2022

• Drop support for having ZST fields

  Show description for 1a36e03
  joshtriplett

  committed
  1a36e03

• Add future possibility of structs with ZST fields

  joshtriplett

  committed
  ffd1965

• Guarantee that adding a niche doesn't change storage size

  Show description for 9816724
  joshtriplett

  committed
  9816724

• Only allow simple field types

  joshtriplett

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  ca5970e

• Future possibilities: fields of reference type

  joshtriplett

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  eaf6327

• Future possibilities: mention interaction with read-only fields

  joshtriplett

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  bb5b5b9

• Consistently use "struct" rather than "structure"

  joshtriplett

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  93d4707

• Future possibilities: change derive(TryInto) to derive(TryFrom)

  joshtriplett

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  4559ee9

• Add language to reference section about unsafe vs safe operations

  joshtriplett

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  5b03ea2

• Add information to the guide-level section on typical operations

  joshtriplett

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  b8bcfda

• Consistently use "niche" rather than "invalid" except when explaining "niche"

  joshtriplett

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  c3c6154

• Future possibilities: safe writes of compile-time constants

  joshtriplett

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  bb1a8ec

• Clarify language regarding compile-time constants and verification

  joshtriplett

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  ad9bf34

• Explicitly allow niche to appear inside cfg_attr

  joshtriplett

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  f16a730

• Alternatives: Add detailed discussion of niche-on-field vs niche-on-struct

  joshtriplett

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  ee9359f

• Explicitly allow inclusive and exclusive ranges

  joshtriplett

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  08bb5b4

• Note that the compiler may be able to perform additional optimizations

  joshtriplett

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  77069e6

• Discuss pattern matching

  joshtriplett

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  58d3b9e

• Explicitly allow open-ended ranges.

  joshtriplett

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  d5966c6

• Future possibilities: add niches affecting pattern-matching exhaustiveness

  joshtriplett

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  c18bee3

• Explicitly allow construction or writing from const code

  joshtriplett

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  627df7f

• Note that #[niche(...)] would be forward-compatible with a pattern syntax

  joshtriplett

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  5109f44

• Discuss interaction with derive(Default)

  joshtriplett

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  f77eb45

• Note that a derive(TryFrom) would also avoid duplicating the range

  joshtriplett

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  5965de8

• Mention C and C++ bitfields

  joshtriplett

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  811024a

• Note why we don't support bool

  joshtriplett

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  014d504

• Add Ada as precedent

  joshtriplett

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  4856096

• Discuss how we can handle derive(Default)

  joshtriplett

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  bb38342

• Explicitly conflict with repr(packed)

  joshtriplett

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  c20796c

• Alternative regarding derive(Default)

  joshtriplett

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  7f27700

• Discuss mutable references in more detail

  joshtriplett

  committed
  b8e0397

Commits on Oct 25, 2022

• s/primitive integer type/built-in integer type/

  joshtriplett

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  48d1c22

• s/either zero or one/at most one/

  joshtriplett

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  6cf4c4e

• Clarify what else adding a niche *doesn't* change (alignment, other ABI details)

  joshtriplett

  committed
  a011965

• Remove a resolved question

  joshtriplett

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  ea1bd10

• Rework the RFC to use values of the field type: negative numbers and floats

  Show description for 5358cb5
  joshtriplett

  committed
  5358cb5

Commits on Oct 26, 2022

• Rephrase descriptions of ranges

  joshtriplett

  committed
  08244e0