csskit_derives: Add peek(skip) attribute - #1266
Merged
Merged
Conversation
Some derive(Peek) calls end up peeking duplicate effective tokens, for example a
generic which also wraps a container generic, e.g.
`Foo<T> { One(T), Many(CommaSeparated<T>) }` would peek `T || CommaSeparated<T>`
which is effectively the same as peeking just `T` (as `CommaSeparated` just
peeks `T` also). This makes `derive(Peek)` leaky, as if we want to optimise a
peek we have to manually implement instead.
This change introduces `peek(skip)` as a variant/field attribute, allowing
`derive(Peek)` to ignore certain fields, this allows us to optimise without
having to drop to a manual impl.
keithamus
enabled auto-merge (squash)
July 5, 2026 15:37
✅ CI passed
|
Merged
github-actions Bot
pushed a commit
that referenced
this pull request
Jul 6, 2026
## [0.0.28] - 2026-07-06 ### Css_ast - csskit_derives: Add peek(skip) attribute (#1266) ([#1266](#1266)) - Regenerate css_ast/src/values from csswg drafts (#1267) ([#1267](#1267)) ### Css_lexer - css_lexer/csskit: Implement LineIndex, precomputing line offsets (#1264) ([#1264](#1264)) ### Csskit - chore(deps): update dependencies (patch) (#1268) ([#1268](#1268)) ### Csskit_vscode - chore(deps): update dependency @types/node to v24.13.2 (#1269) ([#1269](#1269)) - chore(deps): update dependency @types/vscode to v1.125.0 (#1270) ([#1270](#1270)) [forcebuild]
github-actions Bot
pushed a commit
that referenced
this pull request
Jul 6, 2026
## [0.0.28] - 2026-07-06 ### Css_ast - csskit_derives: Add peek(skip) attribute (#1266) ([#1266](#1266)) - Regenerate css_ast/src/values from csswg drafts (#1267) ([#1267](#1267)) ### Css_lexer - css_lexer/csskit: Implement LineIndex, precomputing line offsets (#1264) ([#1264](#1264)) ### Csskit - chore(deps): update dependencies (patch) (#1268) ([#1268](#1268)) ### Csskit_vscode - chore(deps): update dependency @types/node to v24.13.2 (#1269) ([#1269](#1269)) - chore(deps): update dependency @types/vscode to v1.125.0 (#1270) ([#1270](#1270))
keithamus
added a commit
that referenced
this pull request
Jul 7, 2026
Some fields carry no semantic content of their own (e.g. a trailing `)` or `;`), especially as they need to exist to be parsed. Much like #1266 we need to introduce a new `skip` attribute to allow fields to be skipped from codegen. This change does just that: it adds `#[semantic_eq(skip)]` as a new attribute that elides the codegen for that field. This change also adds this annotation in a whole bunch of places. Lastly, in this process, I discovered that semantic_eq wasn't actually correct for some fields (e.g. delims with specific whitespace flags) and so that has also been fixed.
keithamus
added a commit
that referenced
this pull request
Jul 7, 2026
Some fields carry no semantic content of their own (e.g. a trailing `)` or `;`), especially as they need to exist to be parsed. Much like #1266 we need to introduce a new `skip` attribute to allow fields to be skipped from codegen. This change does just that: it adds `#[semantic_eq(skip)]` as a new attribute that elides the codegen for that field. This change also adds this annotation in a whole bunch of places. Lastly, in this process, I discovered that semantic_eq wasn't actually correct for some fields (e.g. delims with specific whitespace flags) and so that has also been fixed.
keithamus
added a commit
that referenced
this pull request
Jul 7, 2026
…#1272) Some fields carry no semantic content of their own (e.g. a trailing `)` or `;`), especially as they need to exist to be parsed. Much like #1266 we need to introduce a new `skip` attribute to allow fields to be skipped from codegen. This change does just that: it adds `#[semantic_eq(skip)]` as a new attribute that elides the codegen for that field. This change also adds this annotation in a whole bunch of places. Lastly, in this process, I discovered that semantic_eq wasn't actually correct for some fields (e.g. delims with specific whitespace flags) and so that has also been fixed.
github-actions Bot
pushed a commit
that referenced
this pull request
Jul 7, 2026
## [0.0.28] - 2026-07-07 ### Css_ast - csskit_derives: Add peek(skip) attribute (#1266) ([#1266](#1266)) - Regenerate css_ast/src/values from csswg drafts (#1267) ([#1267](#1267)) - css_parse/csskit_derives: Add semantic_eq(skip) to derive(SemanticEq) (#1272) ([#1272](#1272)) ### Css_lexer - css_lexer/csskit: Implement LineIndex, precomputing line offsets (#1264) ([#1264](#1264)) ### Csskit - chore(deps): update dependencies (patch) (#1268) ([#1268](#1268)) ### Csskit_vscode - chore(deps): update dependency @types/node to v24.13.2 (#1269) ([#1269](#1269)) - chore(deps): update dependency @types/vscode to v1.125.0 (#1270) ([#1270](#1270)) [forcebuild]
github-actions Bot
pushed a commit
that referenced
this pull request
Jul 7, 2026
## [0.0.28] - 2026-07-07 ### Css_ast - csskit_derives: Add peek(skip) attribute (#1266) ([#1266](#1266)) - Regenerate css_ast/src/values from csswg drafts (#1267) ([#1267](#1267)) - css_parse/csskit_derives: Add semantic_eq(skip) to derive(SemanticEq) (#1272) ([#1272](#1272)) ### Css_lexer - css_lexer/csskit: Implement LineIndex, precomputing line offsets (#1264) ([#1264](#1264)) ### Csskit - chore(deps): update dependencies (patch) (#1268) ([#1268](#1268)) ### Csskit_vscode - chore(deps): update dependency @types/node to v24.13.2 (#1269) ([#1269](#1269)) - chore(deps): update dependency @types/vscode to v1.125.0 (#1270) ([#1270](#1270))
github-actions Bot
pushed a commit
that referenced
this pull request
Jul 8, 2026
## [0.0.28] - 2026-07-08 ### Css_ast - csskit_derives: Add peek(skip) attribute (#1266) ([#1266](#1266)) - Regenerate css_ast/src/values from csswg drafts (#1267) ([#1267](#1267)) - css_parse/csskit_derives: Add semantic_eq(skip) to derive(SemanticEq) (#1272) ([#1272](#1272)) ### Css_lexer - css_lexer/csskit: Implement LineIndex, precomputing line offsets (#1264) ([#1264](#1264)) ### Csskit - chore(deps): update dependencies (patch) (#1268) ([#1268](#1268)) ### Csskit_vscode - chore(deps): update dependency @types/node to v24.13.2 (#1269) ([#1269](#1269)) - chore(deps): update dependency @types/vscode to v1.125.0 (#1270) ([#1270](#1270)) - chore(deps): update dependency typescript to v7 (#1273) ([#1273](#1273)) [forcebuild]
github-actions Bot
pushed a commit
that referenced
this pull request
Jul 8, 2026
## [0.0.28] - 2026-07-08 ### Css_ast - csskit_derives: Add peek(skip) attribute (#1266) ([#1266](#1266)) - Regenerate css_ast/src/values from csswg drafts (#1267) ([#1267](#1267)) - css_parse/csskit_derives: Add semantic_eq(skip) to derive(SemanticEq) (#1272) ([#1272](#1272)) ### Css_lexer - css_lexer/csskit: Implement LineIndex, precomputing line offsets (#1264) ([#1264](#1264)) ### Csskit - chore(deps): update dependencies (patch) (#1268) ([#1268](#1268)) ### Csskit_vscode - chore(deps): update dependency @types/node to v24.13.2 (#1269) ([#1269](#1269)) - chore(deps): update dependency @types/vscode to v1.125.0 (#1270) ([#1270](#1270)) - chore(deps): update dependency typescript to v7 (#1273) ([#1273](#1273))
github-actions Bot
pushed a commit
that referenced
this pull request
Jul 9, 2026
## [0.0.28] - 2026-07-09 ### Css_ast - csskit_derives: Add peek(skip) attribute (#1266) ([#1266](#1266)) - Regenerate css_ast/src/values from csswg drafts (#1267) ([#1267](#1267)) - css_parse/csskit_derives: Add semantic_eq(skip) to derive(SemanticEq) (#1272) ([#1272](#1272)) - css_ast: Implement various shape functions for clip-path, etc (#1275) ([#1275](#1275)) - css_ast: Use blocks for Container & Style at rules (#1276) ([#1276](#1276)) ### Css_lexer - css_lexer/csskit: Implement LineIndex, precomputing line offsets (#1264) ([#1264](#1264)) ### Csskit - chore(deps): update dependencies (patch) (#1268) ([#1268](#1268)) ### Csskit_vscode - chore(deps): update dependency @types/node to v24.13.2 (#1269) ([#1269](#1269)) - chore(deps): update dependency @types/vscode to v1.125.0 (#1270) ([#1270](#1270)) - chore(deps): update dependency typescript to v7 (#1273) ([#1273](#1273)) [forcebuild]
github-actions Bot
pushed a commit
that referenced
this pull request
Jul 9, 2026
## [0.0.28] - 2026-07-09 ### Css_ast - csskit_derives: Add peek(skip) attribute (#1266) ([#1266](#1266)) - Regenerate css_ast/src/values from csswg drafts (#1267) ([#1267](#1267)) - css_parse/csskit_derives: Add semantic_eq(skip) to derive(SemanticEq) (#1272) ([#1272](#1272)) - css_ast: Implement various shape functions for clip-path, etc (#1275) ([#1275](#1275)) - css_ast: Use blocks for Container & Style at rules (#1276) ([#1276](#1276)) ### Css_lexer - css_lexer/csskit: Implement LineIndex, precomputing line offsets (#1264) ([#1264](#1264)) ### Csskit - chore(deps): update dependencies (patch) (#1268) ([#1268](#1268)) ### Csskit_vscode - chore(deps): update dependency @types/node to v24.13.2 (#1269) ([#1269](#1269)) - chore(deps): update dependency @types/vscode to v1.125.0 (#1270) ([#1270](#1270)) - chore(deps): update dependency typescript to v7 (#1273) ([#1273](#1273))
github-actions Bot
pushed a commit
that referenced
this pull request
Jul 10, 2026
## [0.0.28] - 2026-07-10 ### Css_ast - csskit_derives: Add peek(skip) attribute (#1266) ([#1266](#1266)) - Regenerate css_ast/src/values from csswg drafts (#1267) ([#1267](#1267)) - css_parse/csskit_derives: Add semantic_eq(skip) to derive(SemanticEq) (#1272) ([#1272](#1272)) - css_ast: Implement various shape functions for clip-path, etc (#1275) ([#1275](#1275)) - css_ast: Use blocks for Container & Style at rules (#1276) ([#1276](#1276)) - css_ast: Add more -moz-meter-* pseudo elements/classes (#1277) ([#1277](#1277)) - css_ast: Refactor and improve `@supports` parsing (#1278) ([#1278](#1278)) - css_ast: Implement fill & stroke (#1279) ([#1279](#1279)) - css_ast: Implement webkit-text-stroek (#1280) ([#1280](#1280)) ### Css_lexer - css_lexer/csskit: Implement LineIndex, precomputing line offsets (#1264) ([#1264](#1264)) ### Csskit - chore(deps): update dependencies (patch) (#1268) ([#1268](#1268)) ### Csskit_vscode - chore(deps): update dependency @types/node to v24.13.2 (#1269) ([#1269](#1269)) - chore(deps): update dependency @types/vscode to v1.125.0 (#1270) ([#1270](#1270)) - chore(deps): update dependency typescript to v7 (#1273) ([#1273](#1273)) [forcebuild]
github-actions Bot
pushed a commit
that referenced
this pull request
Jul 10, 2026
## [0.0.28] - 2026-07-10 ### Css_ast - csskit_derives: Add peek(skip) attribute (#1266) ([#1266](#1266)) - Regenerate css_ast/src/values from csswg drafts (#1267) ([#1267](#1267)) - css_parse/csskit_derives: Add semantic_eq(skip) to derive(SemanticEq) (#1272) ([#1272](#1272)) - css_ast: Implement various shape functions for clip-path, etc (#1275) ([#1275](#1275)) - css_ast: Use blocks for Container & Style at rules (#1276) ([#1276](#1276)) - css_ast: Add more -moz-meter-* pseudo elements/classes (#1277) ([#1277](#1277)) - css_ast: Refactor and improve `@supports` parsing (#1278) ([#1278](#1278)) - css_ast: Implement fill & stroke (#1279) ([#1279](#1279)) - css_ast: Implement webkit-text-stroek (#1280) ([#1280](#1280)) ### Css_lexer - css_lexer/csskit: Implement LineIndex, precomputing line offsets (#1264) ([#1264](#1264)) ### Csskit - chore(deps): update dependencies (patch) (#1268) ([#1268](#1268)) ### Csskit_vscode - chore(deps): update dependency @types/node to v24.13.2 (#1269) ([#1269](#1269)) - chore(deps): update dependency @types/vscode to v1.125.0 (#1270) ([#1270](#1270)) - chore(deps): update dependency typescript to v7 (#1273) ([#1273](#1273))
github-actions Bot
pushed a commit
that referenced
this pull request
Jul 25, 2026
## [0.0.28] - 2026-07-25 ### Other Changes - Chore(deps): update dependencies (patch) (#1300) ([#1300](#1300)) ### Css_ast - csskit_derives: Add peek(skip) attribute (#1266) ([#1266](#1266)) - Regenerate css_ast/src/values from csswg drafts (#1267) ([#1267](#1267)) - css_parse/csskit_derives: Add semantic_eq(skip) to derive(SemanticEq) (#1272) ([#1272](#1272)) - css_ast: Implement various shape functions for clip-path, etc (#1275) ([#1275](#1275)) - css_ast: Use blocks for Container & Style at rules (#1276) ([#1276](#1276)) - css_ast: Add more -moz-meter-* pseudo elements/classes (#1277) ([#1277](#1277)) - css_ast: Refactor and improve `@supports` parsing (#1278) ([#1278](#1278)) - css_ast: Implement fill & stroke (#1279) ([#1279](#1279)) - css_ast: Implement webkit-text-stroek (#1280) ([#1280](#1280)) - css_ast Implement grid functions, track, line, etc (#1281) ([#1281](#1281)) - css_ast/css_parse: Implement ToNormalisedValue trait (#1284) ([#1284](#1284)) - Regenerate css_ast/src/values from csswg drafts (#1285) ([#1285](#1285)) - Regenerate css_ast/src/values from csswg drafts (#1294) ([#1294](#1294)) - csskit_derives: Allow multiple fields to delegate metadata (#1295) ([#1295](#1295)) - css_parse: Reimplement computed value declaration peeking/parsing in DeclarationValue (#1298) ([#1298](#1298)) - css_parse: Refactor BumpBox into generic Arena allocating Box. (#1304) ([#1304](#1304)) - css_parse: Implement an Arena allocated Vec. (#1306) ([#1306](#1306)) - css_ast: Build out substitution function architecture (#1308) ([#1308](#1308)) - css_ast: Use Value/CalcableValue in most manual types (#1309) ([#1309](#1309)) ### Css_feature_data - Regenerate css_ast/src/values from csswg drafts (#1299) ([#1299](#1299)) ### Css_lexer - css_lexer/csskit: Implement LineIndex, precomputing line offsets (#1264) ([#1264](#1264)) - css_lexer: Use a boxed slice in LineIndex, dropping Bumpalo's Vec. (#1305) ([#1305](#1305)) - css_lexer: Implement fearless_simd paths for scanning (#1307) ([#1307](#1307)) ### Css_parse - fuzz: new parser findings 2026-07-13 (#1288) ([#1288](#1288)) - css_parse: Drop CursorSource trait (#1296) ([#1296](#1296)) - css_parse: Drop PreludeList, DeclarationRuleList (#1297) ([#1297](#1297)) ### Csskit - chore(deps): update dependencies (patch) (#1268) ([#1268](#1268)) ### Csskit_derives - csskit_derives: Ensure atom checks properly peek (#1282) ([#1282](#1282)) ### Csskit_spec_generator - csskit_spec_generator: Ensure property atoms includes the extra properties (#1283) ([#1283](#1283)) ### Csskit_vscode - chore(deps): update dependency @types/node to v24.13.2 (#1269) ([#1269](#1269)) - chore(deps): update dependency @types/vscode to v1.125.0 (#1270) ([#1270](#1270)) - chore(deps): update dependency typescript to v7 (#1273) ([#1273](#1273)) - chore(deps): update dependencies (patch) (#1286) ([#1286](#1286)) - chore(deps): update dependency oxlint to v1.69.0 (#1303) ([#1303](#1303)) [forcebuild]
github-actions Bot
pushed a commit
that referenced
this pull request
Jul 25, 2026
## [0.0.28] - 2026-07-25 ### Other Changes - Chore(deps): update dependencies (patch) (#1300) ([#1300](#1300)) ### Css_ast - csskit_derives: Add peek(skip) attribute (#1266) ([#1266](#1266)) - Regenerate css_ast/src/values from csswg drafts (#1267) ([#1267](#1267)) - css_parse/csskit_derives: Add semantic_eq(skip) to derive(SemanticEq) (#1272) ([#1272](#1272)) - css_ast: Implement various shape functions for clip-path, etc (#1275) ([#1275](#1275)) - css_ast: Use blocks for Container & Style at rules (#1276) ([#1276](#1276)) - css_ast: Add more -moz-meter-* pseudo elements/classes (#1277) ([#1277](#1277)) - css_ast: Refactor and improve `@supports` parsing (#1278) ([#1278](#1278)) - css_ast: Implement fill & stroke (#1279) ([#1279](#1279)) - css_ast: Implement webkit-text-stroek (#1280) ([#1280](#1280)) - css_ast Implement grid functions, track, line, etc (#1281) ([#1281](#1281)) - css_ast/css_parse: Implement ToNormalisedValue trait (#1284) ([#1284](#1284)) - Regenerate css_ast/src/values from csswg drafts (#1285) ([#1285](#1285)) - Regenerate css_ast/src/values from csswg drafts (#1294) ([#1294](#1294)) - csskit_derives: Allow multiple fields to delegate metadata (#1295) ([#1295](#1295)) - css_parse: Reimplement computed value declaration peeking/parsing in DeclarationValue (#1298) ([#1298](#1298)) - css_parse: Refactor BumpBox into generic Arena allocating Box. (#1304) ([#1304](#1304)) - css_parse: Implement an Arena allocated Vec. (#1306) ([#1306](#1306)) - css_ast: Build out substitution function architecture (#1308) ([#1308](#1308)) - css_ast: Use Value/CalcableValue in most manual types (#1309) ([#1309](#1309)) ### Css_feature_data - Regenerate css_ast/src/values from csswg drafts (#1299) ([#1299](#1299)) ### Css_lexer - css_lexer/csskit: Implement LineIndex, precomputing line offsets (#1264) ([#1264](#1264)) - css_lexer: Use a boxed slice in LineIndex, dropping Bumpalo's Vec. (#1305) ([#1305](#1305)) - css_lexer: Implement fearless_simd paths for scanning (#1307) ([#1307](#1307)) ### Css_parse - fuzz: new parser findings 2026-07-13 (#1288) ([#1288](#1288)) - css_parse: Drop CursorSource trait (#1296) ([#1296](#1296)) - css_parse: Drop PreludeList, DeclarationRuleList (#1297) ([#1297](#1297)) ### Csskit - chore(deps): update dependencies (patch) (#1268) ([#1268](#1268)) ### Csskit_derives - csskit_derives: Ensure atom checks properly peek (#1282) ([#1282](#1282)) ### Csskit_spec_generator - csskit_spec_generator: Ensure property atoms includes the extra properties (#1283) ([#1283](#1283)) ### Csskit_vscode - chore(deps): update dependency @types/node to v24.13.2 (#1269) ([#1269](#1269)) - chore(deps): update dependency @types/vscode to v1.125.0 (#1270) ([#1270](#1270)) - chore(deps): update dependency typescript to v7 (#1273) ([#1273](#1273)) - chore(deps): update dependencies (patch) (#1286) ([#1286](#1286)) - chore(deps): update dependency oxlint to v1.69.0 (#1303) ([#1303](#1303))
keithamus
added a commit
that referenced
this pull request
Jul 25, 2026
## [0.0.28] - 2026-07-25 ### Other Changes - Chore(deps): update dependencies (patch) (#1300) ([#1300](#1300)) ### Css_ast - csskit_derives: Add peek(skip) attribute (#1266) ([#1266](#1266)) - Regenerate css_ast/src/values from csswg drafts (#1267) ([#1267](#1267)) - css_parse/csskit_derives: Add semantic_eq(skip) to derive(SemanticEq) (#1272) ([#1272](#1272)) - css_ast: Implement various shape functions for clip-path, etc (#1275) ([#1275](#1275)) - css_ast: Use blocks for Container & Style at rules (#1276) ([#1276](#1276)) - css_ast: Add more -moz-meter-* pseudo elements/classes (#1277) ([#1277](#1277)) - css_ast: Refactor and improve `@supports` parsing (#1278) ([#1278](#1278)) - css_ast: Implement fill & stroke (#1279) ([#1279](#1279)) - css_ast: Implement webkit-text-stroek (#1280) ([#1280](#1280)) - css_ast Implement grid functions, track, line, etc (#1281) ([#1281](#1281)) - css_ast/css_parse: Implement ToNormalisedValue trait (#1284) ([#1284](#1284)) - Regenerate css_ast/src/values from csswg drafts (#1285) ([#1285](#1285)) - Regenerate css_ast/src/values from csswg drafts (#1294) ([#1294](#1294)) - csskit_derives: Allow multiple fields to delegate metadata (#1295) ([#1295](#1295)) - css_parse: Reimplement computed value declaration peeking/parsing in DeclarationValue (#1298) ([#1298](#1298)) - css_parse: Refactor BumpBox into generic Arena allocating Box. (#1304) ([#1304](#1304)) - css_parse: Implement an Arena allocated Vec. (#1306) ([#1306](#1306)) - css_ast: Build out substitution function architecture (#1308) ([#1308](#1308)) - css_ast: Use Value/CalcableValue in most manual types (#1309) ([#1309](#1309)) ### Css_feature_data - Regenerate css_ast/src/values from csswg drafts (#1299) ([#1299](#1299)) ### Css_lexer - css_lexer/csskit: Implement LineIndex, precomputing line offsets (#1264) ([#1264](#1264)) - css_lexer: Use a boxed slice in LineIndex, dropping Bumpalo's Vec. (#1305) ([#1305](#1305)) - css_lexer: Implement fearless_simd paths for scanning (#1307) ([#1307](#1307)) ### Css_parse - fuzz: new parser findings 2026-07-13 (#1288) ([#1288](#1288)) - css_parse: Drop CursorSource trait (#1296) ([#1296](#1296)) - css_parse: Drop PreludeList, DeclarationRuleList (#1297) ([#1297](#1297)) ### Csskit - chore(deps): update dependencies (patch) (#1268) ([#1268](#1268)) ### Csskit_derives - csskit_derives: Ensure atom checks properly peek (#1282) ([#1282](#1282)) ### Csskit_spec_generator - csskit_spec_generator: Ensure property atoms includes the extra properties (#1283) ([#1283](#1283)) ### Csskit_vscode - chore(deps): update dependency @types/node to v24.13.2 (#1269) ([#1269](#1269)) - chore(deps): update dependency @types/vscode to v1.125.0 (#1270) ([#1270](#1270)) - chore(deps): update dependency typescript to v7 (#1273) ([#1273](#1273)) - chore(deps): update dependencies (patch) (#1286) ([#1286](#1286)) - chore(deps): update dependency oxlint to v1.69.0 (#1303) ([#1303](#1303))
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Some derive(Peek) calls end up peeking duplicate effective tokens, for example a
generic which also wraps a container generic, e.g.
Foo<T> { One(T), Many(CommaSeparated<T>) }would peekT || CommaSeparated<T>which is effectively the same as peeking just
T(asCommaSeparatedjustpeeks
Talso). This makesderive(Peek)leaky, as if we want to optimise apeek we have to manually implement instead.
This change introduces
peek(skip)as a variant/field attribute, allowingderive(Peek)to ignore certain fields, this allows us to optimise withouthaving to drop to a manual impl.