[InterfaceGen] Print property initializers in resilient, fixed-layout types (#19619)

Augment the ASTPrinter to print the name and text of initializer expressions if
a property has an initializer and the type is @_fixed_layout and resides in a resilient module, and serialize the text for partial modules.

With this change, all .swiftinterface files in the project (except for SwiftLang) compile to swiftmodules on macOS.

rdar://43774580
rdar://43812188

Author: Harlan

include/swift/AST/Decl.h

@@ -1864,76 +1864,114 @@ class ExtensionRange {
 /// Pattern and Initialization expression.  The pattern is always present, but
 /// the initializer can be null if there is none.
 class PatternBindingEntry {
-  Pattern *ThePattern;
-
-  /// The location of the equal '=' token.
-  SourceLoc EqualLoc;
-
   enum class Flags {
     Checked = 1 << 0,
     Removed = 1 << 1,
-    Lazy    = 1 << 2,
+    Lazy    = 1 << 2
+  };
+  llvm::PointerIntPair<Pattern *, 3, OptionSet<Flags>> PatternAndFlags;
+
+  struct ExprAndEqualLoc {
+    // When the initializer is removed we don't actually clear the pointer
+    // because we might need to get initializer's source range. Since the
+    // initializer is ASTContext-allocated it is safe.
+    Expr *Node;
+    /// The location of the equal '=' token.
+    SourceLoc EqualLoc;
   };
 
-  // When the initializer is removed we don't actually clear the pointer
-  // because we might need to get initializer's source range. Since the
-  // initializer is ASTContext-allocated it is safe.
-  llvm::PointerIntPair<Expr *, 3, OptionSet<Flags>> InitAndFlags;
+  union {
+    /// The initializer expression and its '=' token loc.
+    ExprAndEqualLoc InitExpr;
+
+    /// The text of the initializer expression if deserialized from a module.
+    StringRef InitStringRepresentation;
+  };
 
   /// The initializer context used for this pattern binding entry.
-  DeclContext *InitContext = nullptr;
+  llvm::PointerIntPair<DeclContext *, 1, bool> InitContextAndIsText;
 
   friend class PatternBindingInitializer;
 
 public:
   PatternBindingEntry(Pattern *P, SourceLoc EqualLoc, Expr *E,
                       DeclContext *InitContext)
-      : ThePattern(P), EqualLoc(EqualLoc), InitAndFlags(E, {}),
-        InitContext(InitContext) {}
+    : PatternAndFlags(P, {}), InitExpr({E, EqualLoc}),
+      InitContextAndIsText({InitContext, false}) {
+  }
 
-  Pattern *getPattern() const { return ThePattern; }
-  void setPattern(Pattern *P) { ThePattern = P; }
+  Pattern *getPattern() const { return PatternAndFlags.getPointer(); }
+  void setPattern(Pattern *P) { PatternAndFlags.setPointer(P); }
   Expr *getInit() const {
-    return (InitAndFlags.getInt().contains(Flags::Removed))
-      ? nullptr : InitAndFlags.getPointer();
+    if (PatternAndFlags.getInt().contains(Flags::Removed) ||
+        InitContextAndIsText.getInt())
+      return nullptr;
+    return InitExpr.Node;
   }
   Expr *getNonLazyInit() const {
     return isInitializerLazy() ? nullptr : getInit();
   }
   SourceRange getOrigInitRange() const;
   void setInit(Expr *E);
 
+  /// Gets the text of the initializer expression, stripping out inactive
+  /// branches of any #ifs inside the expression.
+  StringRef getInitStringRepresentation(SmallVectorImpl<char> &scratch) const;
+
+  /// Sets the initializer string representation to the string that was
+  /// deserialized from a partial module.
+  void setInitStringRepresentation(StringRef str) {
+    InitStringRepresentation = str;
+    InitContextAndIsText.setInt(true);
+  }
+
+  /// Whether this pattern entry can generate a string representation of its
+  /// initializer expression.
+  bool hasInitStringRepresentation() const;
+
   /// Retrieve the location of the equal '=' token.
-  SourceLoc getEqualLoc() const { return EqualLoc; }
+  SourceLoc getEqualLoc() const {
+    return InitContextAndIsText.getInt() ? SourceLoc() : InitExpr.EqualLoc;
+  }
 
   /// Set the location of the equal '=' token.
-  void setEqualLoc(SourceLoc equalLoc) { EqualLoc = equalLoc; }
+  void setEqualLoc(SourceLoc equalLoc) {
+    assert(!InitContextAndIsText.getInt() &&
+           "cannot set equal loc for textual initializer");
+    InitExpr.EqualLoc = equalLoc;
+  }
 
   /// Retrieve the initializer as it was written in the source.
-  Expr *getInitAsWritten() const { return InitAndFlags.getPointer(); }
+  Expr *getInitAsWritten() const {
+    return InitContextAndIsText.getInt() ? nullptr : InitExpr.Node;
+  }
 
   bool isInitializerChecked() const {
-    return InitAndFlags.getInt().contains(Flags::Checked);
+    return PatternAndFlags.getInt().contains(Flags::Checked);
   }
   void setInitializerChecked() {
-    InitAndFlags.setInt(InitAndFlags.getInt() | Flags::Checked);
+    PatternAndFlags.setInt(PatternAndFlags.getInt() | Flags::Checked);
   }
 
   bool isInitializerLazy() const {
-    return InitAndFlags.getInt().contains(Flags::Lazy);
+    return PatternAndFlags.getInt().contains(Flags::Lazy);
   }
   void setInitializerLazy() {
-    InitAndFlags.setInt(InitAndFlags.getInt() | Flags::Lazy);
+    PatternAndFlags.setInt(PatternAndFlags.getInt() | Flags::Lazy);
   }
 
   // Return the first variable initialized by this pattern.
   VarDecl *getAnchoringVarDecl() const;
 
   // Retrieve the declaration context for the initializer.
-  DeclContext *getInitContext() const { return InitContext; }
+  DeclContext *getInitContext() const {
+    return InitContextAndIsText.getPointer();
+  }
 
   /// Override the initializer context.
-  void setInitContext(DeclContext *dc) { InitContext = dc; }
+  void setInitContext(DeclContext *dc) {
+    InitContextAndIsText.setPointer(dc);
+  }
 
   /// Retrieve the source range covered by this pattern binding.
   ///
@@ -2007,6 +2045,10 @@ class PatternBindingDecl final : public Decl,
     return const_cast<PatternBindingDecl*>(this)->getMutablePatternList();
   }
 
+  void setInitStringRepresentation(unsigned i, StringRef str) {
+    getMutablePatternList()[i].setInitStringRepresentation(str);
+  }
+
   Expr *getInit(unsigned i) const {
     return getPatternList()[i].getInit();
   }
@@ -2039,7 +2081,8 @@ class PatternBindingDecl final : public Decl,
 
   /// Return the PatternEntry (a pattern + initializer pair) for the specified
   /// VarDecl.
-  PatternBindingEntry getPatternEntryForVarDecl(const VarDecl *VD) const {
+  const PatternBindingEntry &getPatternEntryForVarDecl(
+    const VarDecl *VD) const {
     return getPatternList()[getPatternEntryIndexForVarDecl(VD)];
   }
 
@@ -2097,7 +2140,7 @@ class PatternBindingDecl final : public Decl,
   static bool classof(const Decl *D) {
     return D->getKind() == DeclKind::PatternBinding;
   }
-  
+
 private:
   MutableArrayRef<PatternBindingEntry> getMutablePatternList() {
     // Pattern entries are tail allocated.
@@ -4606,6 +4649,14 @@ class VarDecl : public AbstractStorageDecl {
     return nullptr;
   }
 
+  // Return whether this VarDecl has an initial value, either by checking
+  // if it has an initializer in its parent pattern binding or if it has
+  // the @_hasInitialValue attribute.
+  bool hasInitialValue() const {
+    return getAttrs().hasAttribute<HasInitialValueAttr>() ||
+           getParentInitializer();
+  }
+
   VarDecl *getOverriddenDecl() const {
     return cast_or_null<VarDecl>(AbstractStorageDecl::getOverriddenDecl());
   }
@@ -4687,6 +4738,13 @@ class VarDecl : public AbstractStorageDecl {
   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
+  /// member with an initializer expression and the parent type is
+  /// @_fixed_layout and resides in a resilient module.
+  bool isInitExposedToClients() const;
 
   /// Is this a special debugger variable?
   bool isDebuggerVar() const { return Bits.VarDecl.IsDebuggerVar; }

include/swift/Serialization/ModuleFile.h

@@ -887,6 +887,9 @@ class ModuleFile
 
   /// Reads inlinable body text from \c DeclTypeCursor, if present.
   Optional<StringRef> maybeReadInlinableBodyText();
+
+  /// Reads pattern initializer text from \c DeclTypeCursor, if present.
+  Optional<StringRef> maybeReadPatternInitializerText();
 };
 
 template <typename T, typename RawData>

include/swift/Serialization/ModuleFormat.h

@@ -55,7 +55,7 @@ const uint16_t VERSION_MAJOR = 0;
 /// describe what change you made. The content of this comment isn't important;
 /// it just ensures a conflict if two people change the module format.
 /// Don't worry about adhering to the 80-column limit for this line.
-const uint16_t VERSION_MINOR = 450; // Last change: don't serialize requirement environment
+const uint16_t VERSION_MINOR = 451; // Last change: pattern initializer text
 
 using DeclIDField = BCFixed<31>;
 
@@ -1478,7 +1478,8 @@ namespace decls_block {
   using PatternBindingInitializerLayout = BCRecordLayout<
     PATTERN_BINDING_INITIALIZER_CONTEXT,
     DeclIDField, // parent pattern binding decl
-    BCVBR<3>     // binding index in the pattern binding decl
+    BCVBR<3>,    // binding index in the pattern binding decl
+    BCBlob       // initializer text, if present
   >;
 
   using DefaultArgumentInitializerLayout = BCRecordLayout<

lib/AST/ASTPrinter.cpp

@@ -842,26 +842,35 @@ void PrintAST::printAttributes(const Decl *D) {
   if (Options.SkipAttributes)
     return;
 
-  // Don't print a redundant 'final' if we are printing a 'static' decl.
+  // Save the current number of exclude attrs to restore once we're done.
   unsigned originalExcludeAttrCount = Options.ExcludeAttrList.size();
-  if (Options.PrintImplicitAttrs &&
-      D->getDeclContext()->getSelfClassDecl() &&
-      getCorrectStaticSpelling(D) == StaticSpellingKind::KeywordStatic) {
-    Options.ExcludeAttrList.push_back(DAK_Final);
-  }
 
-  // Don't print any contextual decl modifiers.
-  // We will handle 'mutating' and 'nonmutating' separately.
-  if (Options.PrintImplicitAttrs && isa<AccessorDecl>(D)) {
+  if (Options.PrintImplicitAttrs) {
+
+    // Don't print a redundant 'final' if we are printing a 'static' decl.
+    if (D->getDeclContext()->getSelfClassDecl() &&
+        getCorrectStaticSpelling(D) == StaticSpellingKind::KeywordStatic) {
+      Options.ExcludeAttrList.push_back(DAK_Final);
+    }
+
+    // Don't print @_hasInitialValue if we're printing an initializer
+    // expression.
+    if (auto vd = dyn_cast<VarDecl>(D)) {
+      if (vd->isInitExposedToClients())
+        Options.ExcludeAttrList.push_back(DAK_HasInitialValue);
+    }
+
+    // Don't print any contextual decl modifiers.
+    // We will handle 'mutating' and 'nonmutating' separately.
+    if (isa<AccessorDecl>(D)) {
 #define EXCLUDE_ATTR(Class) Options.ExcludeAttrList.push_back(DAK_##Class);
 #define CONTEXTUAL_DECL_ATTR(X, Class, Y, Z) EXCLUDE_ATTR(Class)
 #define CONTEXTUAL_SIMPLE_DECL_ATTR(X, Class, Y, Z) EXCLUDE_ATTR(Class)
 #define CONTEXTUAL_DECL_ATTR_ALIAS(X, Class) EXCLUDE_ATTR(Class)
 #include "swift/AST/Attr.def"
-  }
+    }
 
-  // If the declaration is implicitly @objc, print the attribute now.
-  if (Options.PrintImplicitAttrs) {
+    // If the declaration is implicitly @objc, print the attribute now.
     if (auto VD = dyn_cast<ValueDecl>(D)) {
       if (VD->isObjC() && !VD->getAttrs().hasAttribute<ObjCAttr>()) {
         Printer.printAttrName("@objc");
@@ -899,7 +908,10 @@ void PrintAST::printPattern(const Pattern *pattern) {
     recordDeclLoc(decl, [&]{
       if (Options.OmitNameOfInaccessibleProperties &&
           contributesToParentTypeStorage(decl) &&
-          !isPublicOrUsableFromInline(decl))
+          !isPublicOrUsableFromInline(decl) &&
+          // FIXME: We need to figure out a way to generate an entry point
+          //        for the initializer expression without revealing the name.
+          !decl->hasInitialValue())
         Printer << "_";
       else
         Printer.printName(named->getBoundName());
@@ -2045,7 +2057,7 @@ void PrintAST::visitPatternBindingDecl(PatternBindingDecl *decl) {
   }
 
   bool isFirst = true;
-  for (auto entry : decl->getPatternList()) {
+  for (auto &entry : decl->getPatternList()) {
     if (!shouldPrintPattern(entry.getPattern()))
       continue;
     if (isFirst)
@@ -2065,6 +2077,13 @@ void PrintAST::visitPatternBindingDecl(PatternBindingDecl *decl) {
     if (Options.VarInitializers) {
       // FIXME: Implement once we can pretty-print expressions.
     }
+
+    auto vd = entry.getAnchoringVarDecl();
+    if (entry.hasInitStringRepresentation() &&
+        vd->isInitExposedToClients()) {
+      SmallString<128> scratch;
+      Printer << " = " << entry.getInitStringRepresentation(scratch);
+    }
   }
 }
 

lib/AST/Decl.cpp

@@ -1181,18 +1181,19 @@ unsigned PatternBindingDecl::getPatternEntryIndexForVarDecl(const VarDecl *VD) c
 }
 
 SourceRange PatternBindingEntry::getOrigInitRange() const {
-  auto Init = InitAndFlags.getPointer();
+  auto Init = getInitAsWritten();
   return Init ? Init->getSourceRange() : SourceRange();
 }
 
 void PatternBindingEntry::setInit(Expr *E) {
-  auto F = InitAndFlags.getInt();
+  auto F = PatternAndFlags.getInt();
   if (E) {
-    InitAndFlags.setInt(F - Flags::Removed);
-    InitAndFlags.setPointer(E);
+    PatternAndFlags.setInt(F - Flags::Removed);
   } else {
-    InitAndFlags.setInt(F | Flags::Removed);
+    PatternAndFlags.setInt(F | Flags::Removed);
   }
+  InitExpr.Node = E;
+  InitContextAndIsText.setInt(false);
 }
 
 VarDecl *PatternBindingEntry::getAnchoringVarDecl() const {
@@ -1225,6 +1226,25 @@ SourceRange PatternBindingEntry::getSourceRange(bool omitAccessors) const {
   return SourceRange(startLoc, endLoc);
 }
 
+bool PatternBindingEntry::hasInitStringRepresentation() const {
+  if (InitContextAndIsText.getInt())
+    return !InitStringRepresentation.empty();
+  return getInit() && getInit()->getSourceRange().isValid();
+}
+
+StringRef PatternBindingEntry::getInitStringRepresentation(
+  SmallVectorImpl<char> &scratch) const {
+
+  assert(hasInitStringRepresentation() &&
+         "must check if pattern has string representation");
+
+  if (InitContextAndIsText.getInt() && !InitStringRepresentation.empty())
+    return InitStringRepresentation;
+  auto &sourceMgr = getAnchoringVarDecl()->getASTContext().SourceMgr;
+  auto init = getInit();
+  return extractInlinableText(sourceMgr, init, scratch);
+}
+
 SourceRange PatternBindingDecl::getSourceRange() const {
   SourceLoc startLoc = getStartLoc();
   SourceLoc endLoc = getPatternList().back().getSourceRange().End;
@@ -1279,6 +1299,19 @@ VarDecl *PatternBindingDecl::getSingleVar() const {
   return nullptr;
 }
 
+bool VarDecl::isInitExposedToClients() const {
+  auto parent = dyn_cast<NominalTypeDecl>(getDeclContext());
+  if (!parent) return false;
+  if (!hasInitialValue())
+    return false;
+  if (isStatic())
+    return false;
+  if (!parent->getAttrs().hasAttribute<FixedLayoutAttr>())
+    return false;
+  auto *module = parent->getModuleContext();
+  return module->getResilienceStrategy() == ResilienceStrategy::Resilient;
+}
+
 /// Check whether the given type representation will be
 /// default-initializable.
 static bool isDefaultInitializable(const TypeRepr *typeRepr) {

lib/Sema/TypeCheckConstraints.cpp

@@ -2483,7 +2483,7 @@ bool TypeChecker::typeCheckPatternBinding(PatternBindingDecl *PBD,
   // Add the attribute that preserves the "has an initializer" value across
   // module generation, as required for TBDGen.
   PBD->getPattern(patternNumber)->forEachVariable([&](VarDecl *VD) {
-    if (VD->hasStorage())
+    if (VD->hasStorage() && !VD->getAttrs().hasAttribute<HasInitialValueAttr>())
       VD->getAttrs().add(new (ctx) HasInitialValueAttr(/*IsImplicit=*/true));
   });