AST: Remove VarDecl::hasNonPatternBindingInit()

Author: slavapestov

include/swift/AST/Decl.h

@@ -353,18 +353,13 @@ class alignas(1 << DeclAlignInBits) Decl {
     IsStatic : 1
   );
 
-  SWIFT_INLINE_BITFIELD(VarDecl, AbstractStorageDecl, 1+1+1+1+1+1+1,
+  SWIFT_INLINE_BITFIELD(VarDecl, AbstractStorageDecl, 1+1+1+1+1+1,
     /// Encodes whether this is a 'let' binding.
     Introducer : 1,
 
     /// Whether this declaration captures the 'self' param under the same name.
     IsSelfParamCapture : 1,
 
-    /// Whether this vardecl has an initial value bound to it in a way
-    /// that isn't represented in the AST with an initializer in the pattern
-    /// binding.  This happens in cases like "for i in ...", switch cases, etc.
-    HasNonPatternBindingInit : 1,
-
     /// Whether this is a property used in expressions in the debugger.
     /// It is up to the debugger to instruct SIL how to access this variable.
     IsDebuggerVar : 1,
@@ -5115,16 +5110,6 @@ class VarDecl : public AbstractStorageDecl {
       Bits.VarDecl.IsSelfParamCapture = IsSelfParamCapture;
   }
 
-  /// Return true if this vardecl has an initial value bound to it in a way
-  /// that isn't represented in the AST with an initializer in the pattern
-  /// binding.  This happens in cases like "for i in ...", switch cases, etc.
-  bool hasNonPatternBindingInit() const {
-    return Bits.VarDecl.HasNonPatternBindingInit;
-  }
-  void setHasNonPatternBindingInit(bool V = true) {
-    Bits.VarDecl.HasNonPatternBindingInit = V;
-  }
-
   /// Determines if this var has an initializer expression that should be
   /// exposed to clients.
   /// There's a very narrow case when we would: if the decl is an instance

include/swift/AST/Pattern.h

@@ -190,14 +190,6 @@ class alignas(8) Pattern {
 
   bool isNeverDefaultInitializable() const;
 
-  /// Mark all vardecls in this pattern as having non-pattern initial
-  /// values bound into them.
-  void markHasNonPatternBindingInit() {
-    forEachVariable([&](VarDecl *VD) {
-      VD->setHasNonPatternBindingInit();
-    });
-  }
-
   /// Mark all vardecls in this pattern as having an owning statement for
   /// the pattern.
   void markOwnedByStatement(Stmt *S) {

lib/AST/ASTDumper.cpp

@@ -842,8 +842,6 @@ namespace {
       printCommon(VD, "var_decl");
       if (VD->isLet())
         PrintWithColorRAII(OS, DeclModifierColor) << " let";
-      if (VD->hasNonPatternBindingInit())
-        PrintWithColorRAII(OS, DeclModifierColor) << " non_pattern_init";
       if (VD->getAttrs().hasAttribute<LazyAttr>())
         PrintWithColorRAII(OS, DeclModifierColor) << " lazy";
       printStorageImpl(VD);

lib/AST/Decl.cpp

@@ -5408,7 +5408,6 @@ VarDecl::VarDecl(DeclKind kind, bool isStatic, VarDecl::Introducer introducer,
   Bits.VarDecl.IsSelfParamCapture = false;
   Bits.VarDecl.IsDebuggerVar = false;
   Bits.VarDecl.IsLazyStorageProperty = false;
-  Bits.VarDecl.HasNonPatternBindingInit = false;
   Bits.VarDecl.IsPropertyWrapperBackingProperty = false;
   Bits.VarDecl.IsTopLevelGlobal = false;
 }
@@ -5431,26 +5430,21 @@ bool VarDecl::isSettable(const DeclContext *UseDC,
   if (!isLet())
     return supportsMutation();
 
+  //
+  // All the remaining logic handles the special cases where you can
+  // assign a 'let'.
+  //
+
   // Debugger expression 'let's are initialized through a side-channel.
   if (isDebuggerVar())
     return false;
 
-  // We have a 'let'; we must be checking settability from a specific
-  // DeclContext to go on further.
+  // 'let's are only ever settable from a specific DeclContext.
   if (UseDC == nullptr)
     return false;
-
-  // If the decl has a value bound to it but has no PBD, then it is
-  // initialized.
-  if (hasNonPatternBindingInit())
-    return false;
-
-  // Capture list bindings are never settable.
-  if (isCaptureList())
-    return false;
 
-  // Properties in structs/classes are only ever mutable in their designated
-  // initializer(s).
+  // 'let' properties in structs/classes are only ever settable in their
+  // designated initializer(s).
   if (isInstanceMember()) {
     auto *CD = dyn_cast<ConstructorDecl>(UseDC);
     if (!CD) return false;
@@ -5480,7 +5474,12 @@ bool VarDecl::isSettable(const DeclContext *UseDC,
     return true;
   }
 
-  // If the decl has an explicitly written initializer with a pattern binding,
+  // If the 'let' has a value bound to it but has no PBD, then it is
+  // already initializedand not settable.
+  if (getParentPatternBinding() == nullptr)
+    return false;
+
+  // If the 'let' has an explicitly written initializer with a pattern binding,
   // then it isn't settable.
   if (isParentInitialized())
     return false;

lib/Parse/ParseExpr.cpp

@@ -1993,7 +1993,6 @@ ParserResult<Expr> Parser::parseExprStringLiteral() {
                             /*NameLoc=*/SourceLoc(),
                             Context.Id_dollarInterpolation, CurDeclContext);
     InterpolationVar->setImplicit(true);
-    InterpolationVar->setHasNonPatternBindingInit(true);
     InterpolationVar->setUserAccessible(false);
     addToScope(InterpolationVar);
     setLocalDiscriminator(InterpolationVar);

lib/Parse/ParseStmt.cpp

@@ -1129,10 +1129,6 @@ static void parseGuardedPattern(Parser &P, GuardedPattern &result,
       boundDecls.push_back(VD);
     });
 
-    // Now that we have them, mark them as being initialized without a PBD.
-    for (auto VD : boundDecls)
-      VD->setHasNonPatternBindingInit();
-
     // Parse the optional 'where' guard.
     parseWhereGuard(P, result, status, parsingContext, isExprBasic);
   } else {
@@ -1178,10 +1174,6 @@ static void parseGuardedPattern(Parser &P, GuardedPattern &result,
         status.setIsParseError();
       }
     }
-    
-    for (auto VD : repeatedDecls) {
-      VD->setHasNonPatternBindingInit();
-    }
 
     // Parse the optional 'where' guard, with this particular pattern's bound
     // vars in scope.
@@ -1544,7 +1536,6 @@ Parser::parseStmtConditionElement(SmallVectorImpl<StmtConditionElement> &result,
     setLocalDiscriminator(VD);
     if (VD->hasName())
       addToScope(VD);
-    VD->setHasNonPatternBindingInit();
   });
   return Status;
 }
@@ -2034,7 +2025,6 @@ ParserResult<CaseStmt> Parser::parseStmtCatch() {
       auto *vNew = new (Context) VarDecl(
           /*IsStatic*/ false, vOld->getIntroducer(),
           vOld->getNameLoc(), vOld->getName(), vOld->getDeclContext());
-      vNew->setHasNonPatternBindingInit();
       vNew->setImplicit();
       Result[i] = vNew;
     }
@@ -2145,9 +2135,6 @@ ParserResult<Stmt> Parser::parseStmtForEach(LabeledStmtInfo LabelInfo) {
     parseToken(tok::kw_in, InLoc, diag::expected_foreach_in);
   }
 
-  // Bound variables all get their initial values from the generator.
-  pattern.get()->markHasNonPatternBindingInit();
-
   if (IsCStyleFor) {
     // Skip until start of body part.
     if (Tok.is(tok::l_paren)) {
@@ -2381,7 +2368,6 @@ parseStmtCase(Parser &P, SourceLoc &CaseLoc,
       auto *vNew = new (P.Context) VarDecl(
           /*IsStatic*/ false, vOld->getIntroducer(),
           vOld->getNameLoc(), vOld->getName(), vOld->getDeclContext());
-      vNew->setHasNonPatternBindingInit();
       vNew->setImplicit();
       Result[i] = vNew;
     }

lib/SILGen/SILGenDecl.cpp

@@ -470,10 +470,6 @@ class LetValueInitialization : public Initialization {
     assert(!isa<ParamDecl>(vd)
            && "should not bind function params on this path");
     if (vd->getParentPatternBinding() && !vd->getParentInitializer()) {
-      // This value is uninitialized (and unbound) if it has a pattern binding
-      // decl, with no initializer value.
-      assert(!vd->hasNonPatternBindingInit() && "Bound values aren't uninit!");
-      
       // If this is a let-value without an initializer, then we need a temporary
       // buffer.  DI will make sure it is only assigned to once.
       needsTemporaryBuffer = true;

lib/Sema/CSGen.cpp

@@ -2166,7 +2166,7 @@ namespace {
         // FIXME: This should be handled in the solver, not here.
         //
         // Otherwise, create a new type variable.
-        if (!var->hasNonPatternBindingInit() &&
+        if (var->getParentPatternBinding() &&
             !var->hasAttachedPropertyWrapper() &&
             optionality != ReferenceOwnershipOptionality::Required) {
           if (auto boundExpr = locator.trySimplifyToExpr()) {

lib/Sema/DerivedConformanceComparable.cpp

@@ -146,7 +146,6 @@ deriveBodyComparable_enum_hasAssociatedValues_lt(AbstractFunctionDecl *ltDecl, v
         auto *vNew = new (C) VarDecl(
             /*IsStatic*/ false, vOld->getIntroducer(),
             vOld->getNameLoc(), vOld->getName(), vOld->getDeclContext());
-        vNew->setHasNonPatternBindingInit();
         vNew->setImplicit();
         copy[i] = vNew;
       }

lib/Sema/DerivedConformanceEquatableHashable.cpp

@@ -207,7 +207,6 @@ deriveBodyEquatable_enum_hasAssociatedValues_eq(AbstractFunctionDecl *eqDecl,
         auto *vNew = new (C) VarDecl(
             /*IsStatic*/ false, vOld->getIntroducer(),
             vOld->getNameLoc(), vOld->getName(), vOld->getDeclContext());
-        vNew->setHasNonPatternBindingInit();
         vNew->setImplicit();
         copy[i] = vNew;
       }
@@ -732,7 +731,6 @@ deriveBodyHashable_enum_hasAssociatedValues_hashInto(
         auto *vNew = new (C) VarDecl(
             /*IsStatic*/ false, vOld->getIntroducer(),
             vOld->getNameLoc(), vOld->getName(), vOld->getDeclContext());
-        vNew->setHasNonPatternBindingInit();
         vNew->setImplicit();
         copy[i] = vNew;
       }