#15896: GHC API: add function to allow looking up Name for Located RdrName -------------------------------------+------------------------------------- Reporter: alanz | Owner: (none) Type: task | Status: new Priority: normal | Milestone: 8.6.3 Component: GHC API | Version: 8.6.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): Phab:D5330 | Wiki Page: -------------------------------------+------------------------------------- A tool writer using the GHC API to do a source level change must use the `ParsedSource` as it most closely represents the original source code, and has API Annotations. But the `ParsedSource` only has `RdrName`s in it, and many useful transformations need information from the renamer, the simplest example being renaming a variable in the presence of name shadowing. So we need a way to look up the `Name` corresponding to each `RdrName` in the `ParsedSource`. GHC does have a `GlobalRdrEnv` which is a mapping from `OccName` to a list of elements, each of which has the `Name`. But the `OccName` is only unique wrt its spelling, and so cannot distinguish the name shadowing case. Fortuitously (!), every `RdrName` in the `ParsedSource` is `Located`, and hence has a unique `SrcSpan` associated with it. So, given a `TypecheckedModule`, it is possible to construct a map from the `SrcSpan` of each `Located RdrName` to the corresponding `Name` from the `RenamedSource` (or `TypecheckedSource` for ambiguous record selectors). Introduce this as part of the GHC API. Note: this function has existed in `HaRe` for some time, and is the reason each `RdrName` in the `ParsedSource` is `Located`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15896 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler