Remove the now-unused @safe(unchecked)

Author: DougGregor

include/swift/AST/Attr.h

@@ -2830,26 +2830,6 @@ class RawLayoutAttr final : public DeclAttribute {
   UNIMPLEMENTED_CLONE(RawLayoutAttr)
 };
 
-class SafeAttr final : public DeclAttribute {
-public:
-  /// The optional message.
-  const StringRef message;
-
-  SafeAttr(SourceLoc atLoc, SourceRange range, StringRef message,
-           bool isImplicit = false)
-      : DeclAttribute(DeclAttrKind::Safe, atLoc, range, isImplicit),
-        message(message) { }
-
-  static bool classof(const DeclAttribute *DA) {
-    return DA->getKind() == DeclAttrKind::Safe;
-  }
-
-  /// Create a copy of this attribute.
-  SafeAttr *clone(ASTContext &ctx) const {
-    return new (ctx) SafeAttr(AtLoc, Range, message, isImplicit());
-  }
-};
-
 class LifetimeAttr final : public DeclAttribute {
   LifetimeEntry *entry;
 

include/swift/AST/Decl.h

@@ -1820,10 +1820,6 @@ struct InheritedEntry : public TypeLoc {
     return getOptions().contains(ProtocolConformanceFlags::Unsafe);
   }
 
-  bool isSafe() const {
-    return getOptions().contains(ProtocolConformanceFlags::Safe);
-  }
-
   bool isSuppressed() const { return IsSuppressed; }
 
   void setOption(ProtocolConformanceFlags flag) {

include/swift/AST/DeclAttr.def

@@ -531,11 +531,7 @@ SIMPLE_DECL_ATTR(_addressableForDependencies, AddressableForDependencies,
   OnNominalType | ABIBreakingToAdd | ABIBreakingToRemove | APIBreakingToAdd | APIBreakingToRemove | UserInaccessible,
   163)
 
-DECL_ATTR(safe, Safe,
-  OnAbstractFunction | OnSubscript | OnVar | OnMacro | OnNominalType |
-  OnExtension | OnTypeAlias | OnImport | UserInaccessible |
-  ABIStableToAdd | ABIStableToRemove | APIBreakingToAdd | APIStableToRemove,
-  164)
+// 164 was the never-shipped @safe attribute and can be reused
 
 DECL_ATTR(abi, ABI,
   OnAbstractFunction | OnVar /* will eventually add types */ | LongAttribute | ABIStableToAdd | ABIStableToRemove | APIStableToAdd | APIStableToRemove,

include/swift/AST/DiagnosticsParse.def

@@ -2111,9 +2111,6 @@ ERROR(parser_new_parser_errors,none,
       "new Swift parser generated errors for code that C++ parser accepted",
        ())
 
-ERROR(safe_attr_unchecked,none,
-      "'@safe' attribute must be written as '@safe(unchecked)'", ())
-
 // MARK: Reference Binding Diagnostics
 ERROR(sil_markuncheckedreferencebinding_requires_attribute,none,
       "mark_unchecked_reference_binding requires an attribute like [inout]", ())

include/swift/AST/DiagnosticsSema.def

@@ -8119,8 +8119,7 @@ GROUPED_WARNING(override_safe_with_unsafe,Unsafe,none,
 
 GROUPED_WARNING(preconcurrency_import_unsafe,Unsafe,none,
       "@preconcurrency import is not memory-safe because it can silently "
-      "introduce data races; use '@safe(unchecked)' to assert that the "
-      "code is memory-safe", ())
+      "introduce data races", ())
 GROUPED_WARNING(unsafe_without_unsafe,Unsafe,none,
       "expression uses unsafe constructs but is not marked with 'unsafe'", ())
 WARNING(no_unsafe_in_unsafe,none,

include/swift/AST/NameLookup.h

@@ -612,21 +612,17 @@ struct InheritedNominalEntry : Located<NominalTypeDecl *> {
   /// The location of the "unsafe" attribute if present.
   SourceLoc unsafeLoc;
 
-  /// The range of the "safe(unchecked)" attribute if present.
-  SourceRange safeRange;
-
   /// Whether this inherited entry was suppressed via "~".
   bool isSuppressed;
 
   InheritedNominalEntry() { }
 
   InheritedNominalEntry(NominalTypeDecl *item, SourceLoc loc,
                         SourceLoc uncheckedLoc, SourceLoc preconcurrencyLoc,
-                        SourceLoc unsafeLoc, SourceRange safeRange,
-                        bool isSuppressed)
+                        SourceLoc unsafeLoc, bool isSuppressed)
       : Located(item, loc), uncheckedLoc(uncheckedLoc),
         preconcurrencyLoc(preconcurrencyLoc), unsafeLoc(unsafeLoc),
-        safeRange(safeRange), isSuppressed(isSuppressed) {}
+        isSuppressed(isSuppressed) {}
 };
 
 /// Retrieve the set of nominal type declarations that are directly

include/swift/AST/ProtocolConformance.h

@@ -659,11 +659,6 @@ class NormalProtocolConformance : public RootProtocolConformance,
     return getOptions().contains(ProtocolConformanceFlags::Unsafe);
   }
 
-  /// Whether this is an "safe(unchecked)" conformance.
-  bool isSafe() const {
-    return getOptions().contains(ProtocolConformanceFlags::Safe);
-  }
-
   /// Determine whether we've lazily computed the associated conformance array
   /// already.
   bool hasComputedAssociatedConformances() const {

include/swift/AST/ProtocolConformanceOptions.h

@@ -31,11 +31,8 @@ enum class ProtocolConformanceFlags {
   /// @unsafe conformance
   Unsafe = 0x04,
 
-  /// @safe(unchecked) conformance
-  Safe = 0x08,
-
   /// @retroactive conformance
-  Retroactive = 0x10,
+  Retroactive = 0x08,
 
   // Note: whenever you add a bit here, update
   // NumProtocolConformanceOptions below.
@@ -52,7 +49,7 @@ inline ProtocolConformanceOptions operator|(
 }
 
 enum : unsigned {
-  NumProtocolConformanceOptions = 5
+  NumProtocolConformanceOptions = 4
 };
 
 } // end namespace swift

include/swift/AST/TypeAttr.def

@@ -61,7 +61,6 @@ SIMPLE_TYPE_ATTR(retroactive, Retroactive)
 SIMPLE_TYPE_ATTR(unchecked, Unchecked)
 SIMPLE_TYPE_ATTR(preconcurrency, Preconcurrency)
 SIMPLE_TYPE_ATTR(unsafe, Unsafe)
-SIMPLE_TYPE_ATTR(safe, Safe)
 SIMPLE_TYPE_ATTR(_local, Local)
 SIMPLE_TYPE_ATTR(_noMetadata, NoMetadata)
 TYPE_ATTR(_opaqueReturnTypeOf, OpaqueReturnTypeOf)

lib/AST/ASTDumper.cpp

@@ -4144,11 +4144,6 @@ class PrintAttribute : public AttributeVisitor<PrintAttribute, void, StringRef>,
     }
     printFoot();
   }
-  void visitSafeAttr(SafeAttr *Attr, StringRef label) {
-    printCommon(Attr, "safe_attr", label);
-    printFieldQuoted(Attr->message, "message");
-    printFoot();
-  }
   void visitSILGenNameAttr(SILGenNameAttr *Attr, StringRef label) {
     printCommon(Attr, "silgen_name_attr", label);
     printFlag(Attr->Raw, "raw");