| # Implementing a new language feature |
| |
| When a new language feature is approved, a tracking issue will be created in |
| order to track the work required in the `analyzer` package. Separate issues are |
| created to track the work in the `analysis_server`, `dartdoc`, and `linter` |
| packages. |
| |
| Below is a template for the list of analyzer features that need to be reviewed |
| to see whether they need to be enhanced in order to work correctly with the new |
| feature. In almost all cases new tests will need to be written to ensure that |
| the feature isn't broken when run over code that uses the new language feature. |
| In some cases, new support will need to be added. |
| |
| ## Add an experiment flag |
| |
| New language features are always implemented behind an experiment flag. |
| |
| If the experiment flag hasn't already been created, add it. |
| |
| In the analyzer packages we almost always immediately enable the experiment flag |
| for all of our tests. This allows us to ensure that existing functionality isn't |
| broken by the implementation of the new feature. The exception to this rule is |
| when there's a language feature that is breaking enough in semantics that the |
| meaning of existing tests would change as a result, in which case we usually |
| have to take a different approach (not described here). |
| |
| The list of enabled features is maintained in the file |
| `pkg/analyzer_utilities/lib/test/experiments/experiments.dart`. |
| |
| ## Template |
| |
| The following is a list of the individual features that need to be considered. |
| The features are listed roughly in dependency order. |
| |
| - [ ] If needed, add an experiment flag |
| - [ ] AST enhancements (`AstBuilder`) |
| - [ ] Resolution of directives |
| - [ ] Element model |
| - [ ] Type system updates |
| - [ ] Summary support |
| - [ ] Resolution |
| - [ ] `ResolutionVisitor` (resolve types) |
| - [ ] `ScopeResolverVisitor` (resolve simple identifiers by scope) |
| - [ ] `ResolverVisitor` (type-based resolution) |
| - [ ] Constant evaluation |
| - [ ] Index and search |
| - [ ] Warnings (annotation-based, unused\*, strict-mode-based, a few others) |
| - [ ] `OverrideVerifier` and `InheritanceOverrideVerifier` (report errors and warnings related to overrides) |
| - [ ] `ErrorVerifier` (report other errors and warnings) |
| - [ ] `FfiVerifier` (report errors and warnings related to FFI) |
| - [ ] Unused elements warnings |
| - [ ] ExitDetector |
| - [ ] NodeLintRegistry |
