Implement Extension Type Feature

[itsjustkevin]

Extension Type feature

Description

Implementation issue for dart-lang/language#2727, extension type; a special kind of type that wraps an existing type into a new static type, without the overhead of a traditional class.

References

• Feature Spec
• Project
• Test Tracking Sheet

Work Items

• [Extension type] Write the spec language#2420
• [Extension type] Language tests #49730
• [Extension type] Co19 tests - add tests co19#1400
• [Extension type] Implement feature in the CFE #49731
• [Extension type] Analyzer implementation #49732
• [Extension type] Tests validating as passing (Tracking via Google Sheet) #49733
• [Extension type] Syntax highlighters implementation #49734
• [Extension type] DDC implementation #49735
• [Extension type] Dart2js implementation #49736
• [Extension type] VM implementation #49737
• [Extension type] Build system support #49738
• [Extension type] Web debugging support #49739
• [Extension type] Core library updates #49740
• [Extension type] Analysis server / IDE support work #49741
• [Extension type] dart_style support dart_style#1129
• [Extension type] dartdoc implementation dartdoc#3123
• [Extension type] Cider support #49742
• [Extension type] Kythe implementation #49743
• [Extension type] Angular compiler implementation #49744
• [Extension type] Intellij implementation #49745
• ☂️ [Extension type] Language feature docs site-www#4177
• [Extension type] VM service protocol support #49746
• [Extension type] VM debugging support #49747
• [Extension type] linter support #58838

[itsjustkevin]

CC: @leafpetersen @kevmoo @sigmundch

[eernstg]

Note that the mechanism is very likely being renamed to 'extension type', cf. dart-lang/language#3182.

[mit-mit]

Updating; the construct has indeed been renamed.