David Farler 303a3e5824 Start the Migrator library ...

The Swift 4 Migrator is invoked through either the driver and frontend
with the -update-code flag.

The basic pipeline in the frontend is:

- Perform some list of syntactic fixes (there are currently none).
- Perform N rounds of sema fix-its on the primary input file, currently
  set to 7 based on prior migrator seasons.  Right now, this is just set
  to take any fix-it suggested by the compiler.
- Emit a replacement map file, a JSON file describing replacements to a
  file that Xcode knows how to understand.

Currently, the Migrator maintains a history of migration states along
the way for debugging purposes.

- Add -emit-remap frontend option
  This will indicate the EmitRemap frontend action.
- Don't fork to a separte swift-update binary.
  This is going to be a mode of the compiler, invoked by the same flags.
- Add -disable-migrator-fixits option
  Useful for debugging, this skips the phase in the Migrator that
  automatically applies fix-its suggested by the compiler.
- Add -emit-migrated-file-path option
  This is used for testing/debugging scenarios. This takes the final
  migration state's output text and writes it to the file specified
  by this option.
- Add -dump-migration-states-dir

  This dumps all of the migration states encountered during a migration
  run for a file to the given directory. For example, the compiler
  fix-it migration pass dumps the input file, the output file, and the
  remap file between the two.

  State output has the following naming convention:
  ${Index}-${MigrationPassName}-${What}.${extension}, such as:
  1-FixitMigrationState-Input.swift

rdar://problem/30926261

2017-04-17 16:25:02 -07:00

60 KiB

Raw Blame History

View Raw