Enable 'BorrowingSwitch' feature.

jckarter · jckarter · commit 10f9289ef84b · 2024-05-14T07:31:59.000-07:00
diff --git a/include/swift/AST/DiagnosticsParse.def b/include/swift/AST/DiagnosticsParse.def
@@ -984,7 +984,7 @@ ERROR(extra_var_in_multiple_pattern_list,none,
 ERROR(let_pattern_in_immutable_context,none,
       "'let' pattern cannot appear nested in an already immutable context", ())
 WARNING(borrowing_syntax_change,none,
-      "'_borrowing' spelling is deprecated; use 'borrowing' without the underscore", ())
+        "'borrowing' in pattern matches is deprecated; use 'let'", ())
 ERROR(borrowing_subpattern_unsupported,none,
       "'borrowing' pattern modifier must be directly applied to pattern variable name", ())
 ERROR(specifier_must_have_type,none,
diff --git a/include/swift/Basic/Features.def b/include/swift/Basic/Features.def
@@ -197,6 +197,7 @@ UPCOMING_FEATURE(RegionBasedIsolation, 414, 6)
 UPCOMING_FEATURE(DynamicActorIsolation, 423, 6)
 UPCOMING_FEATURE(NonfrozenEnumExhaustivity, 192, 6)
 UPCOMING_FEATURE(GlobalActorIsolatedTypesUsability, 0434, 6)
+UPCOMING_FEATURE(BorrowingSwitch, 432, 6)
 
 // Swift 7
 UPCOMING_FEATURE(ExistentialAny, 335, 7)
@@ -354,9 +355,6 @@ EXPERIMENTAL_FEATURE(GroupActorErrors, true)
 // Allow for the 'transferring' keyword to be applied to arguments and results.
 SUPPRESSIBLE_EXPERIMENTAL_FEATURE(TransferringArgsAndResults, true)
 
-// Allow for `switch` of noncopyable values to be borrowing or consuming.
-EXPERIMENTAL_FEATURE(BorrowingSwitch, true)
-
 // Enable explicit isolation of closures.
 EXPERIMENTAL_FEATURE(ClosureIsolation, true)
 
diff --git a/lib/ASTGen/Sources/ASTGen/SourceFile.swift b/lib/ASTGen/Sources/ASTGen/SourceFile.swift
@@ -60,7 +60,6 @@ extension Parser.ExperimentalFeatures {
     mapFeature(.DoExpressions, to: .doExpressions)
     mapFeature(.NonescapableTypes, to: .nonescapableTypes)
     mapFeature(.TransferringArgsAndResults, to: .transferringArgsAndResults)
-    mapFeature(.BorrowingSwitch, to: .borrowingSwitch)
   }
 }
 
diff --git a/lib/Parse/ParsePattern.cpp b/lib/Parse/ParsePattern.cpp
@@ -1323,45 +1323,41 @@ ParserResult<Pattern> Parser::parseMatchingPattern(bool isExprBasic) {
   
   // The `borrowing` modifier is a contextual keyword, so it's only accepted
   // directly applied to a binding name, as in `case .foo(borrowing x)`.
-  if (Context.LangOpts.hasFeature(Feature::BorrowingSwitch)) {
-    if ((Tok.isContextualKeyword("_borrowing")
-         || Tok.isContextualKeyword("borrowing"))
-        && peekToken().isAny(tok::identifier, tok::kw_self, tok::dollarident,
-                             tok::code_complete)
-        && !peekToken().isAtStartOfLine()) {
-      if (Tok.isContextualKeyword("_borrowing")) {
-        diagnose(Tok.getLoc(),
-                 diag::borrowing_syntax_change)
-          .fixItReplace(Tok.getLoc(), "borrowing");
-      }
-
-      Tok.setKind(tok::contextual_keyword);
-      SourceLoc borrowingLoc = consumeToken();
-      
-      // If we have `case borrowing x.`, `x(`, `x[`, or `x<` then this looks
-      // like an attempt to include a subexpression under a `borrowing`
-      // binding, which isn't yet supported.
-      if (peekToken().isAny(tok::period, tok::period_prefix, tok::l_paren,
-                            tok::l_square)
-          || (peekToken().isAnyOperator() && peekToken().getText().equals("<"))) {
-
-        // Diagnose the unsupported production.
-        diagnose(Tok.getLoc(),
-                 diag::borrowing_subpattern_unsupported);
-        
-        // Recover by parsing as if it was supported.
-        return parseMatchingPattern(isExprBasic);
-      }
-      Identifier name;
-      SourceLoc nameLoc = consumeIdentifier(name,
-                                            /*diagnoseDollarPrefix*/ false);
-      auto namedPattern = createBindingFromPattern(nameLoc, name,
-                                             VarDecl::Introducer::Borrowing);
-      auto bindPattern = new (Context) BindingPattern(
-        borrowingLoc, VarDecl::Introducer::Borrowing, namedPattern);
+  if ((Tok.isContextualKeyword("_borrowing")
+       || Tok.isContextualKeyword("borrowing"))
+      && peekToken().isAny(tok::identifier, tok::kw_self, tok::dollarident,
+                           tok::code_complete)
+      && !peekToken().isAtStartOfLine()) {
+    diagnose(Tok.getLoc(),
+             diag::borrowing_syntax_change)
+      .fixItReplace(Tok.getLoc(), "let");
+
+    Tok.setKind(tok::contextual_keyword);
+    SourceLoc borrowingLoc = consumeToken();
+    
+    // If we have `case borrowing x.`, `x(`, `x[`, or `x<` then this looks
+    // like an attempt to include a subexpression under a `borrowing`
+    // binding, which isn't yet supported.
+    if (peekToken().isAny(tok::period, tok::period_prefix, tok::l_paren,
+                          tok::l_square)
+        || (peekToken().isAnyOperator() && peekToken().getText().equals("<"))) {
+
+      // Diagnose the unsupported production.
+      diagnose(Tok.getLoc(),
+               diag::borrowing_subpattern_unsupported);
       
-      return makeParserResult(bindPattern);
+      // Recover by parsing as if it was supported.
+      return parseMatchingPattern(isExprBasic);
     }
+    Identifier name;
+    SourceLoc nameLoc = consumeIdentifier(name,
+                                          /*diagnoseDollarPrefix*/ false);
+    auto namedPattern = createBindingFromPattern(nameLoc, name,
+                                           VarDecl::Introducer::Borrowing);
+    auto bindPattern = new (Context) BindingPattern(
+      borrowingLoc, VarDecl::Introducer::Borrowing, namedPattern);
+    
+    return makeParserResult(bindPattern);
   }
 
   // matching-pattern ::= 'is' type
@@ -1442,14 +1438,12 @@ Parser::parseMatchingPatternAsBinding(PatternBindingState newState,
 }
 
 bool Parser::isOnlyStartOfMatchingPattern() {
-  if (Context.LangOpts.hasFeature(Feature::BorrowingSwitch)) {
-    if ((Tok.isContextualKeyword("_borrowing")
-         || Tok.isContextualKeyword("borrowing"))
-        && peekToken().isAny(tok::identifier, tok::kw_self, tok::dollarident,
-                             tok::code_complete)
-        && !peekToken().isAtStartOfLine()) {
-      return true;
-    }
+  if ((Tok.isContextualKeyword("_borrowing")
+       || Tok.isContextualKeyword("borrowing"))
+      && peekToken().isAny(tok::identifier, tok::kw_self, tok::dollarident,
+                           tok::code_complete)
+      && !peekToken().isAtStartOfLine()) {
+    return true;
   }
 
   return Tok.isAny(tok::kw_var, tok::kw_let, tok::kw_is) ||
diff --git a/lib/Sema/MiscDiagnostics.cpp b/lib/Sema/MiscDiagnostics.cpp
@@ -4575,18 +4575,6 @@ diagnoseMoveOnlyPatternMatchSubject(ASTContext &C,
       || !subjectType->isNoncopyable()) {
     return;
   }
-
-  // A bare reference to, or load from, a move-only binding must be consumed.
-  subjectExpr = subjectExpr->getSemanticsProvidingExpr();
-  if (auto load = dyn_cast<LoadExpr>(subjectExpr)) {
-    subjectExpr = load->getSubExpr()->getSemanticsProvidingExpr();
-  }
-  if (!C.LangOpts.hasFeature(Feature::BorrowingSwitch)
-      && isa<DeclRefExpr>(subjectExpr)) {
-    C.Diags.diagnose(subjectExpr->getLoc(),
-                           diag::move_only_pattern_match_not_consumed)
-      .fixItInsert(subjectExpr->getStartLoc(), "consume ");
-  }
 }
 
 // Perform MiscDiagnostics on Switch Statements.
diff --git a/stdlib/public/core/CMakeLists.txt b/stdlib/public/core/CMakeLists.txt
@@ -315,7 +315,7 @@ list(APPEND swift_stdlib_compile_flags "-Xfrontend" "-enable-experimental-concis
 list(APPEND swift_stdlib_compile_flags "-enable-experimental-feature" "Macros")
 list(APPEND swift_stdlib_compile_flags "-enable-experimental-feature" "FreestandingMacros")
 list(APPEND swift_stdlib_compile_flags "-enable-experimental-feature" "Extern")
-list(APPEND swift_stdlib_compile_flags "-enable-experimental-feature" "BorrowingSwitch")
+list(APPEND swift_stdlib_compile_flags "-enable-experimental-feature" "BitwiseCopyable")
 
 if("${SWIFT_NATIVE_SWIFT_TOOLS_PATH}" STREQUAL "")
   set(swift_bin_dir "${CMAKE_BINARY_DIR}/bin")
diff --git a/test/Interpreter/moveonly_linkedlist_2_simple.swift b/test/Interpreter/moveonly_linkedlist_2_simple.swift
@@ -1,13 +1,12 @@
 // RUN: %target-swift-emit-irgen                             \
 // RUN:     -parse-as-library                                \
 // RUN:     -enable-builtin-module                           \
-// RUN:     -enable-experimental-feature BorrowingSwitch     \
 // RUN:     %s                                               \
 // RUN: |                                                    \
 // RUN: %FileCheck %s --check-prefix=CHECK-IR
-// RUN: %target-run-simple-swift(-parse-as-library -enable-builtin-module -enable-experimental-feature BorrowingSwitch -Xfrontend -sil-verify-all) | %FileCheck %s
-// RUN: %target-run-simple-swift(-O -parse-as-library -enable-builtin-module -enable-experimental-feature BorrowingSwitch -Xfrontend -sil-verify-all) | %FileCheck %s
-// RUN: %target-run-simple-swift(-O -parse-as-library -enable-builtin-module -enable-experimental-feature BorrowingSwitch -Xfrontend -sil-verify-all -Xfrontend -enable-ossa-modules) | %FileCheck %s
+// RUN: %target-run-simple-swift(-parse-as-library -enable-builtin-module -Xfrontend -sil-verify-all) | %FileCheck %s
+// RUN: %target-run-simple-swift(-O -parse-as-library -enable-builtin-module -Xfrontend -sil-verify-all) | %FileCheck %s
+// RUN: %target-run-simple-swift(-O -parse-as-library -enable-builtin-module -Xfrontend -sil-verify-all -Xfrontend -enable-ossa-modules) | %FileCheck %s
 
 // REQUIRES: executable_test
 
diff --git a/test/Interpreter/moveonly_swiftskell.swift b/test/Interpreter/moveonly_swiftskell.swift
@@ -6,8 +6,7 @@
 // RUN:    -module-name Swiftskell \
 // RUN:    -parse-as-library \
 // RUN:    %S/../Inputs/Swiftskell.swift -c -o %t/Swiftskell.o \
-// RUN:   -enable-experimental-feature NonescapableTypes \
-// RUN:   -enable-experimental-feature BorrowingSwitch
+// RUN:   -enable-experimental-feature NonescapableTypes
 
 // RUN: %target-build-swift -o %t/a.out %s -I %t %t/Swiftskell.o
 // RUN: %target-codesign %t/a.out
diff --git a/test/ModuleInterface/noncopyable_generics.swift b/test/ModuleInterface/noncopyable_generics.swift
@@ -10,7 +10,6 @@
 // RUN: %target-swift-frontend -swift-version 5 -enable-library-evolution -emit-module \
 // RUN:     -enable-experimental-feature SuppressedAssociatedTypes \
 // RUN:     -enable-experimental-feature NonescapableTypes \
-// RUN:     -enable-experimental-feature BorrowingSwitch \
 // RUN:     -o %t/Swiftskell.swiftmodule \
 // RUN:     -emit-module-interface-path %t/Swiftskell.swiftinterface \
 // RUN:     %S/../Inputs/Swiftskell.swift
diff --git a/test/Parse/pattern_borrow_bindings.swift b/test/Parse/pattern_borrow_bindings.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -enable-experimental-feature BorrowingSwitch -typecheck -verify %s
+// RUN: %target-swift-frontend -typecheck -verify %s
 
 struct Payload: ~Copyable {
     var x: Int
@@ -38,16 +38,19 @@ func testBorrowingPatterns(bar: borrowing Bar) {
     case borrowing (): // parses as `borrowing()` as before
         break
 
-    case borrowing x: 
+    case borrowing x: // expected-warning{{'borrowing' in pattern matches is deprecated}} {{10-19=let}}
         useBorrowBar(x)
 
-    case .payload(borrowing x):
+    case .payload(borrowing x): // expected-warning{{'borrowing' in pattern matches is deprecated}} {{19-28=let}}
         useBorrowFoo(x)
 
-    case borrowing x.member: // expected-error{{'borrowing' pattern modifier must be directly applied to pattern variable name}} expected-error{{cannot find 'x' in scope}}
+    case borrowing x.member: // expected-warning{{deprecated}} expected-error{{'borrowing' pattern modifier must be directly applied to pattern variable name}} expected-error{{cannot find 'x' in scope}}
         break
 
-    case _borrowing x: // expected-warning{{'_borrowing' spelling is deprecated}} {{10-20=borrowing}}
+    case borrowing x: // expected-warning{{'borrowing' in pattern matches is deprecated}} {{10-19=let}}
+        useBorrowBar(x)
+
+    case _borrowing x: // expected-warning{{'borrowing' in pattern matches is deprecated}} {{10-20=let}}
         useBorrowBar(x)
 
     default:
diff --git a/test/SILGen/borrowing_switch_return_binding_compat.swift b/test/SILGen/borrowing_switch_return_binding_compat.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-emit-silgen -enable-experimental-feature BorrowingSwitch -verify %s
+// RUN: %target-swift-emit-silgen -verify %s
 func orElse<T: ~Copyable>(
     x: consuming T?,
     defaultValue: @autoclosure () throws -> T?
diff --git a/test/SILGen/borrowing_switch_return_on_all_paths.swift b/test/SILGen/borrowing_switch_return_on_all_paths.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-emit-silgen -enable-experimental-feature BorrowingSwitch -verify %s
+// RUN: %target-swift-emit-silgen -verify %s
 
 struct Box<Wrapped: ~Copyable>: ~Copyable {
     var wrapped: Wrapped {
diff --git a/test/SILGen/borrowing_switch_subjects.swift b/test/SILGen/borrowing_switch_subjects.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-emit-silgen -enable-experimental-feature BorrowingSwitch %s | %FileCheck %s
+// RUN: %target-swift-emit-silgen %s | %FileCheck %s
 
 struct Inner: ~Copyable {}
 
diff --git a/test/SILGen/moveonly_consuming_switch.swift b/test/SILGen/moveonly_consuming_switch.swift
@@ -1,7 +1,6 @@
 // RUN: %target-swift-frontend                                      \
 // RUN:     -emit-silgen                                            \
 // RUN:     %s                                                      \
-// RUN:     -enable-experimental-feature BorrowingSwitch            \
 // RUN: | %FileCheck %s
 
 enum MaybeMaybeVoid<Wrapped: ~Copyable>: ~Copyable {
diff --git a/test/SILOptimizer/lifetime_dependence_optional.swift b/test/SILOptimizer/lifetime_dependence_optional.swift
@@ -2,8 +2,7 @@
 // RUN:   -verify \
 // RUN:   -sil-verify-all \
 // RUN:   -module-name test \
-// RUN:   -enable-experimental-feature NonescapableTypes \
-// RUN:   -enable-experimental-feature BorrowingSwitch
+// RUN:   -enable-experimental-feature NonescapableTypes
 
 // REQUIRES: asserts
 // REQUIRES: swift_in_compiler
@@ -58,7 +57,7 @@ extension Nillable where Wrapped: ~Copyable {
     _ transform: (borrowing Wrapped) throws(E) -> U
   ) throws(E) -> U? {
     switch self {
-    case .some(borrowing y):
+    case .some(let y):
       return .some(try transform(y))
     case .none:
       return .none
@@ -82,7 +81,7 @@ extension Nillable where Wrapped: ~Copyable {
     _ transform: (borrowing Wrapped) throws(E) -> U?
   ) throws(E) -> U? {
     switch self {
-    case .some(borrowing y):
+    case .some(let y):
       return try transform(y)
     case .none:
       return .none
diff --git a/test/SILOptimizer/moveonly_addresschecker_diagnostics.swift b/test/SILOptimizer/moveonly_addresschecker_diagnostics.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-emit-sil %s -O -sil-verify-all -verify -enable-experimental-feature BorrowingSwitch -enable-experimental-feature MoveOnlyPartialReinitialization -enable-experimental-feature NoImplicitCopy -enable-experimental-feature MoveOnlyClasses
+// RUN: %target-swift-emit-sil %s -O -sil-verify-all -verify -enable-experimental-feature MoveOnlyPartialReinitialization -enable-experimental-feature NoImplicitCopy -enable-experimental-feature MoveOnlyClasses
 
 //////////////////
 // Declarations //
diff --git a/test/SILOptimizer/moveonly_borrowing_switch.swift b/test/SILOptimizer/moveonly_borrowing_switch.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -emit-sil -verify -enable-experimental-feature BorrowingSwitch %s
+// RUN: %target-swift-frontend -emit-sil -verify %s
 
 struct Payload: ~Copyable {
     var x: Int
diff --git a/test/SILOptimizer/moveonly_borrowing_switch_copyable_subpattern.swift b/test/SILOptimizer/moveonly_borrowing_switch_copyable_subpattern.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -emit-sil -verify -enable-experimental-feature BorrowingSwitch %s
+// RUN: %target-swift-frontend -emit-sil -verify %s
 
 struct Payload: ~Copyable {
     var x: Int
@@ -31,25 +31,7 @@ func test(borrowing foo: borrowing Foo) {
         eat(x)
         nibble(x)
 
-    // `borrowing` match variables impose the no-implicit-copy constraint
-    // like `borrowing` parameters do.
-    case .copyablePayload(borrowing x) // expected-error{{'x' is borrowed and cannot be consumed}}
-      where hungryCondition(x): // expected-note{{consumed here}}
-        eat(x) // expected-note{{consumed here}}
-        nibble(x)
-
-    case .copyablePayload(borrowing x) // expected-error{{'x' is borrowed and cannot be consumed}}
-      where condition(x):
-        eat(x) // expected-note{{consumed here}}
-        nibble(x)
-
-    // Explicit copies are OK.
-    case .copyablePayload(borrowing x)
-      where hungryCondition(copy x):
-        eat(copy x)
-        nibble(x)
-
-    case .copyablePayload(borrowing x):
+    case .copyablePayload(let x):
         nibble(x)
     }
 }
diff --git a/test/SILOptimizer/moveonly_borrowing_switch_load_borrow.swift b/test/SILOptimizer/moveonly_borrowing_switch_load_borrow.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -enable-experimental-feature BorrowingSwitch -emit-sil -verify %s
+// RUN: %target-swift-frontend -emit-sil -verify %s
 
 struct Box<Wrapped: ~Copyable>: ~Copyable {
     init(_ element: consuming Wrapped) { }
diff --git a/test/SILOptimizer/moveonly_borrowing_switch_mode_with_partial_consume.swift b/test/SILOptimizer/moveonly_borrowing_switch_mode_with_partial_consume.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -emit-sil -verify -enable-experimental-feature BorrowingSwitch -parse-as-library %s
+// RUN: %target-swift-frontend -emit-sil -verify -parse-as-library %s
 
 func foo() {
     let node = Node()
diff --git a/test/SILOptimizer/moveonly_borrowing_switch_yield.swift b/test/SILOptimizer/moveonly_borrowing_switch_yield.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -enable-experimental-feature BorrowingSwitch -parse-as-library -O -emit-sil -verify %s
+// RUN: %target-swift-frontend -parse-as-library -O -emit-sil -verify %s
 
 extension List {
     var peek: Element {
diff --git a/test/SILOptimizer/moveonly_consuming_switch.swift b/test/SILOptimizer/moveonly_consuming_switch.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -emit-sil -enable-experimental-feature BorrowingSwitch -verify %s
+// RUN: %target-swift-frontend -emit-sil -verify %s
 
 // TODO: Remove this and just use the real `UnsafeMutablePointer` when
 // noncopyable type support has been upstreamed.
diff --git a/test/SILOptimizer/moveonly_consuming_switch_2.swift b/test/SILOptimizer/moveonly_consuming_switch_2.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -emit-sil -enable-experimental-feature BorrowingSwitch -verify %s
+// RUN: %target-swift-frontend -emit-sil -verify %s
 
 struct Box: ~Copyable {
     let ptr: UnsafeMutablePointer<Int>
diff --git a/test/SILOptimizer/moveonly_objectchecker_diagnostics.swift b/test/SILOptimizer/moveonly_objectchecker_diagnostics.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-emit-sil -enable-experimental-feature BorrowingSwitch -sil-verify-all -verify -enable-experimental-feature MoveOnlyClasses %s
+// RUN: %target-swift-emit-sil -sil-verify-all -verify -enable-experimental-feature MoveOnlyClasses %s
 
 //////////////////
 // Declarations //
diff --git a/test/SILOptimizer/moveonly_trivial_addresschecker_diagnostics.swift b/test/SILOptimizer/moveonly_trivial_addresschecker_diagnostics.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-emit-sil -enable-experimental-feature BorrowingSwitch -enable-experimental-feature MoveOnlyPartialReinitialization -sil-verify-all -verify %s
+// RUN: %target-swift-emit-sil -enable-experimental-feature MoveOnlyPartialReinitialization -sil-verify-all -verify %s
 
 //////////////////
 // Declarations //
diff --git a/test/SILOptimizer/moveonly_trivial_objectchecker_diagnostics.swift b/test/SILOptimizer/moveonly_trivial_objectchecker_diagnostics.swift
@@ -1,4 +1,4 @@
-// RUN: %target-swift-emit-sil -enable-experimental-feature BorrowingSwitch -sil-verify-all -verify %s
+// RUN: %target-swift-emit-sil -sil-verify-all -verify %s
 
 //////////////////
 // Declarations //
diff --git a/validation-test/IRGen/moveonly_partial_consumption_linked_list.swift b/validation-test/IRGen/moveonly_partial_consumption_linked_list.swift
@@ -1,7 +1,6 @@
 // RUN: %target-swift-emit-ir \
 // RUN:     %s \
 // RUN:     -enable-builtin-module \
-// RUN:     -enable-experimental-feature BorrowingSwitch \
 // RUN:     -sil-verify-all \
 // RUN:     -verify
 
diff --git a/validation-test/SILOptimizer/moveonly_partial_consumption_linked_list.swift b/validation-test/SILOptimizer/moveonly_partial_consumption_linked_list.swift
@@ -1,7 +1,6 @@
 // RUN: %target-swift-emit-sil \
 // RUN:     %s \
 // RUN:     -enable-builtin-module \
-// RUN:     -enable-experimental-feature BorrowingSwitch \
 // RUN:     -sil-verify-all \
 // RUN:     -verify
 

Original file line number	Diff line number	Diff line change
`@@ -60,7 +60,6 @@ extension Parser.ExperimentalFeatures {`
`60`	`60`	`mapFeature(.DoExpressions, to: .doExpressions)`
`61`	`61`	`mapFeature(.NonescapableTypes, to: .nonescapableTypes)`
`62`	`62`	`mapFeature(.TransferringArgsAndResults, to: .transferringArgsAndResults)`
`63`		`- mapFeature(.BorrowingSwitch, to: .borrowingSwitch)`
`64`	`63`	`}`
`65`	`64`	`}`
`66`	`65`