feat(feature): add Validator plugin extension and character-level pre-transform phase#62
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…acter-level pre-transform phase
Introduces two pieces of plumbing in the feature engine that are needed for
out-of-tree plugins (e.g. dingo-mut) to hook into the transpilation pipeline
without the core having to know about them by name:
1. Validator plugin extension (pkg/feature/plugin.go)
- New optional interface `Validator` that any Plugin can implement to run
a post-typecheck pass against the Go AST + go/types Info.
- New `ValidateContext` carrying FileSet, GoFile, TypeInfo, the shared
cross-phase Registry, and the original Dingo filename.
- New `ValidationError` struct (Plugin, Pos, Line, Column, Message) with
an `Error()` method so callers can surface diagnostics through the
usual error machinery.
2. Engine.Validate + Engine.IsEnabled (pkg/feature/engine.go)
- `Engine.Validate(fset, file, info, filename)` walks every enabled
plugin in the same priority order Transform uses (character-level
first, then token-level), collects the slice of `ValidationError`s
each Validator returns, and back-fills the plugin name when the
plugin left it blank.
- `Engine.IsEnabled(name)` exposes the existing internal predicate so
pipeline callers can gate optional phases on a particular plugin's
config without scanning EnabledPluginNames.
3. Pipeline hook (pkg/transpiler/pure_pipeline.go)
- Step 0.5: run `Engine.TransformCharacterLevel` over the raw source
before any built-in transformation. The pipeline does not know which
plugins participate; built-ins and externals look identical.
- Step 3.55: after parsing + typechecking, run `Engine.Validate`. If
any validator reports an error, the pipeline aborts with a
`<plugin> check error at <file>:<line>:<col>: <msg>` diagnostic,
using a generic "validation" label when the plugin did not name
itself.
- The Engine and the feature.EnabledFeatures map are now built once
near the top of the pipeline so both phases share them.
No built-in plugin currently implements `Validator`; this change is the
pure plumbing addition that unblocks the out-of-tree mutability plugin.
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May 18, 2026
…g#62 into fork main Combines all four currently open pull requests against MadAppGang/dingo into the local fork's main so downstream work (e.g. the nodes.go cascade fix) can build on top of all of them without one-by-one branch juggling. The upstream PRs remain unaffected because their base branch is MadAppGang/dingo:main, not bbodi/dingo:main. Included: MadAppGang#59 fix(ast/transform): recognise method receiver param lists for type annotations MadAppGang#60 test(tokenizer): cover ENUM and GUARD keywords at both surfaces MadAppGang#61 fix(ast/enum_parser): allow arbitrary nesting of '*' and '[]' in variant field types MadAppGang#62 feat(feature): add Validator plugin extension and character-level pre-transform phase
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Summary
Adds the plumbing that lets out-of-tree feature plugins (e.g.
dingo-mut) hook into the transpilation pipeline without the core having to know about them by name. No built-in plugin participates yet — this PR is pure infrastructure.1. New
Validatorplugin extension (pkg/feature/plugin.go)Plugincan additionally implementValidatorto run a post-typecheck pass against the Go AST andgo/types.Info.ValidateContextcarriesFileSet,GoFile,TypeInfo, the shared cross-phaseRegistry, and the original Dingo filename.ValidationError(Plugin, Pos, Line, Column, Message) with anError()method so diagnostics flow through the usual error machinery.2.
Engine.Validate+Engine.IsEnabled(pkg/feature/engine.go)Engine.Validate(fset, file, info, filename)walks every enabled plugin in the same priority order asTransform(character-level first, then token-level), collects eachValidator's[]ValidationError, and back-fillsPluginfromp.Name()when the plugin left it blank.Engine.IsEnabled(name)exposes the existing internal predicate so pipeline callers can gate optional phases on a specific plugin's config without scanningEnabledPluginNames.3. Pipeline hook (
pkg/transpiler/pure_pipeline.go)Engine.TransformCharacterLevelover the raw source before any built-in transformation. The pipeline does not know which plugins participate; built-ins and externals look identical from here.Engine.Validate. On the first error the pipeline aborts with<plugin> check error at <file>:<line>:<col>: <msg>, falling back to the literal labelvalidationwhen the plugin did not name itself.Engineand thefeature.EnabledFeaturesmap are constructed once near the top of the pipeline so both phases share them.Why this is split out
The mutability work (separate plugin, separate repo) needs a stable surface to plug into. Landing the plumbing on its own keeps that PR's diff focused on the actual mutability semantics rather than the engine wiring.
Test plan
go build ./...go test ./pkg/feature/... ./pkg/transpiler/...bytes.Index/strings.Index/ regex / byte-offset scans introduced)🤖 Generated with Claude Code