AST: Add AbstractFunctionDecl::isSynthesized() flag

Author: slavapestov

include/swift/AST/Decl.h

@@ -367,7 +367,7 @@ class alignas(1 << DeclAlignInBits) Decl {
     DefaultArgumentResilienceExpansion : 1
   );
 
-  SWIFT_INLINE_BITFIELD(AbstractFunctionDecl, ValueDecl, 3+8+5+1+1+1+1+1,
+  SWIFT_INLINE_BITFIELD(AbstractFunctionDecl, ValueDecl, 3+8+5+1+1+1+1+1+1,
     /// \see AbstractFunctionDecl::BodyKind
     BodyKind : 3,
 
@@ -390,7 +390,11 @@ class alignas(1 << DeclAlignInBits) Decl {
     HasComputedNeedsNewVTableEntry : 1,
 
     /// The ResilienceExpansion to use for default arguments.
-    DefaultArgumentResilienceExpansion : 1
+    DefaultArgumentResilienceExpansion : 1,
+
+    /// Whether this member was synthesized as part of a derived
+    /// protocol conformance.
+    Synthesized : 1
   );
 
   SWIFT_INLINE_BITFIELD(FuncDecl, AbstractFunctionDecl, 1+2+1+1+2,
@@ -5253,6 +5257,14 @@ class AbstractFunctionDecl : public GenericContext, public ValueDecl {
     return Bits.AbstractFunctionDecl.NeedsNewVTableEntry;
   }
 
+  bool isSynthesized() const {
+    return Bits.AbstractFunctionDecl.Synthesized;
+  }
+
+  void setSynthesized(bool value = true) {
+    Bits.AbstractFunctionDecl.Synthesized = value;
+  }
+
 private:
   void computeNeedsNewVTableEntry();
 

lib/Sema/DerivedConformanceCodable.cpp

@@ -750,6 +750,7 @@ static FuncDecl *deriveEncodable_encode(TypeChecker &tc, Decl *parentDecl,
                                       TypeLoc::withoutLoc(returnType),
                                       target);
   encodeDecl->setImplicit();
+  encodeDecl->setSynthesized();
   encodeDecl->setBodySynthesizer(deriveBodyEncodable_encode);
 
   // This method should be marked as 'override' for classes inheriting Encodable
@@ -1084,6 +1085,7 @@ static ValueDecl *deriveDecodable_init(TypeChecker &tc, Decl *parentDecl,
                                            SourceLoc(), selfDecl, paramList,
                                            /*GenericParams=*/nullptr, target);
   initDecl->setImplicit();
+  initDecl->setSynthesized();
   initDecl->setBodySynthesizer(deriveBodyDecodable_init);
 
   // This constructor should be marked as `required` for non-final classes.