Currently -Xcc options are serialized in Swift modules, but they are
not saved as attributes to the DW_TAG_module representing the imported
clang module. This patch saves all *user-specified* -D macros there,
but it does not save any macros that are added by the ClangImporter
itself.
<rdar://problem/31990102>
Some APIs that expected a String now expect a Substring and vice
versa. To ease the transition, emit fix-its on conversion errors
between these types that the migrator can pick up.
When converting from Substring -> String, suggest wrapping in
`String.init`.
When converting from String -> Substring, suggest appending the
void subscript `[]`. (This isn't implemented yet so this is
hidden behind a flag).
This can possibly be generalized later when converting between
some sequence and its subsequence, such as Array and ArraySlice,
for example.
rdar://problem/31665649
rdar://problem/31666638
The warnings about deprecated @objc inference in Swift 3 mode can be a
bit annoying; and are mostly relevant to the migration workflow. Make
the warning emission a three-state switch:
* None (the default): don't warn about these issues.
* Minimal (-warn-swift3-objc-inference-minimal): warn about direct
uses of @objc entrypoints and provide "@objc" Fix-Its for them.
* Complete (-warn-swift3-objc-inference-complete): warn about all
cases where Swift 3 infers @objc but Swift 4 will not.
Fixes rdar://problem/31922278.
Based on recommendations in SE-0160, there are two migration workflows:
- Conservative: Maintain @objc visibility that was inferred in Swift 3
by adding @objc to all declarations that were implicitily visible to
the Objective-C runtime. This is invoked in the migrator by adding the
-migrate-keep-objc-visibility flag.
- Minimal: Only declarations that must be visible to Objective-C based
on their uses (or in cases like dynamic vars) are migrated.
rdar://problem/31876357
I had set up the driver to invoke a separate frontend invocation with
the "update code" mode. We sort of did this last release, except we
forked to the swift-update binary instead. This is causing problems with
testing in Xcode.
Instead, let's perform a single compile and add the remap file as an
additional output during normal compiles. The driver, seeing
-update-code, will add -emit-remap-file-path $PATH to the -c frontend
invocation.
rdar://problem/31857580
These data files are installed into runtime resource directory so that migrator can pick them automatically according to specific platforms. To support testing, a front-end option -api-diff-data-file can be used to specify the data file to use and it will overwrite the default ones from resource directory.
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
Track the types we've seen instead of the type declarations we've
passed through, which eliminates some holes relating to generic types.
Detect infinite expansions by imposing an arbitrary limit.
Fixes rdar://30355804
If the -enable-experimental-subclass-existentials staging flag
is on, resolveType() now allows protocol compositions to contain
class types. It also diagnoses if a composition has more than one
superclass requirement.
Also, change diagnostics that talked about 'protocol composition'
to 'protocol-constrained type'.
Since such types can now contain a superclass constraint, it's not
correct to call them protocol composition.
"Protocol-constrained type" isn't quite accurate either because
'Any' has no protocols, and 'AnyObject' will have no protocols but
a general class constraint; but those are edge cases which won't
come up in these diagnostics.
