[Refactoring] Add async refactorings

Adds three refactorings intended to help users migrate their existing
code to use the new async language features:
  1. Convert call to use async alternative
  2. Convert function to async
  3. Add async alternative function

A function is considered to have an async alternative if it has a void
return type and has a void returning closure as its last parameter. A
method to explicitly mark functions as having an async alternative may
be added to make this more accurate in the future (required for eg.
a warning about a call to the non-async version of a function in an
async context).

(1) converts a call to use the new `await` async language syntax. If the
async alternative throws, it will also add `try`. The closure itself is
hoisted out of the call, see the comments on
`AsyncConversionStringBuilder` for specifics.

(2) converts a whole function to `async`, using (1) to convert any calls
in the function to their async alternatives. (3) is similar to (2), but
instead *adds* a function and replaces calls to its
completion/handler/callback closure parameter with `return` or `throws`.

Resolves rdar://68254700

Author: bnbarham

include/swift/AST/DiagnosticsRefactoring.def

@@ -54,5 +54,23 @@ WARNING(mismatched_rename, none, "the name at the given location cannot be renam
 
 ERROR(no_insert_position, none, "cannot find inserting position", ())
 
+ERROR(missing_callback_arg, none, "cannot refactor as callback closure argument missing", ())
+
+ERROR(mismatched_callback_args, none, "cannot refactor as callback arguments do not match declaration", ())
+
+ERROR(unknown_callback_conditions, none, "cannot refactor complex if conditions", ())
+
+ERROR(mixed_callback_conditions, none, "cannot refactor mixed nil and not-nil conditions", ())
+
+ERROR(callback_multiple_bound_names, none, "cannot refactor when multiple names bound to single declaration, had '%0' and found '%1'", (StringRef, StringRef))
+
+ERROR(callback_with_fallthrough, none, "cannot refactor switch with fallthrough", ())
+
+ERROR(callback_with_default, none, "cannot refactor switch with default case", ())
+
+ERROR(callback_multiple_case_items, none, "cannot refactor switch using a case with multiple items", ())
+
+ERROR(callback_where_case_item, none, "cannot refactor switch using a case with where clause", ())
+
 #define UNDEFINE_DIAGNOSTIC_MACROS
 #include "DefineDiagnosticMacros.h"

include/swift/AST/KnownStdlibTypes.def

@@ -91,4 +91,6 @@ KNOWN_STDLIB_TYPE_DECL(KeyedEncodingContainer, NominalTypeDecl, 1)
 KNOWN_STDLIB_TYPE_DECL(KeyedDecodingContainer, NominalTypeDecl, 1)
 KNOWN_STDLIB_TYPE_DECL(RangeReplaceableCollection, ProtocolDecl, 1)
 
+KNOWN_STDLIB_TYPE_DECL(Result, NominalTypeDecl, 2)
+
 #undef KNOWN_STDLIB_TYPE_DECL

include/swift/IDE/RefactoringKinds.def

@@ -54,6 +54,12 @@ CURSOR_REFACTORING(MemberwiseInitLocalRefactoring, "Generate Memberwise Initiali
 
 CURSOR_REFACTORING(AddEquatableConformance, "Add Equatable Conformance", add.equatable.conformance)
 
+CURSOR_REFACTORING(ConvertCallToAsyncAlternative, "Convert Call to Async Alternative", convert.call-to-async)
+
+CURSOR_REFACTORING(ConvertToAsync, "Convert Function to Async", convert.func-to-async)
+
+CURSOR_REFACTORING(AddAsyncAlternative, "Add Async Alternative", add.async-alternative)
+
 RANGE_REFACTORING(ExtractExpr, "Extract Expression", extract.expr)
 
 RANGE_REFACTORING(ExtractFunction, "Extract Method", extract.function)

include/swift/IDE/Utils.h

@@ -559,10 +559,9 @@ class SourceEditJsonConsumer : public SourceEditConsumer {
 
 /// Outputs replacements to `OS` in the form
 /// ```
-/// // </path/to/file> [startLine:startCol, endLine:endCol)
+/// // </path/to/file> startLine:startCol -> endLine:endCol
+/// replacement
 /// text
-/// to
-/// replace
 ///
 /// ```
 class SourceEditTextConsumer : public SourceEditConsumer {