[c++2a] P0683R1: Permit default member initializers for bit-fields.

This would be trivial, except that our in-memory and serialized representations
for FieldDecls assumed that this can't happen.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@311867 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 23 insertions, 22 deletions

diff --git a/lib/Serialization/ASTReaderDecl.cpp b/lib/Serialization/ASTReaderDecl.cpp
index 085341571c..37cce8f507 100644
--- a/lib/Serialization/ASTReaderDecl.cpp
+++ b/lib/Serialization/ASTReaderDecl.cpp
@@ -1219,16 +1219,17 @@ void ASTDeclReader::VisitObjCPropertyImplDecl(ObjCPropertyImplDecl *D) {
 void ASTDeclReader::VisitFieldDecl(FieldDecl *FD) {
   VisitDeclaratorDecl(FD);
   FD->Mutable = Record.readInt();
-  if (int BitWidthOrInitializer = Record.readInt()) {
-    FD->InitStorage.setInt(
-          static_cast<FieldDecl::InitStorageKind>(BitWidthOrInitializer - 1));
-    if (FD->InitStorage.getInt() == FieldDecl::ISK_CapturedVLAType) {
-      // Read captured variable length array.
-      FD->InitStorage.setPointer(Record.readType().getAsOpaquePtr());
-    } else {
-      FD->InitStorage.setPointer(Record.readExpr());
-    }
+
+  if (auto ISK = static_cast<FieldDecl::InitStorageKind>(Record.readInt())) {
+    FD->InitStorage.setInt(ISK);
+    FD->InitStorage.setPointer(ISK == FieldDecl::ISK_CapturedVLAType
+                                   ? Record.readType().getAsOpaquePtr()
+                                   : Record.readExpr());
   }
+
+  if (auto *BW = Record.readExpr())
+    FD->setBitWidth(BW);
+
   if (!FD->getDeclName()) {
     if (FieldDecl *Tmpl = ReadDeclAs<FieldDecl>())
       Reader.getContext().setInstantiatedFromUnnamedFieldDecl(FD, Tmpl);
diff --git a/lib/Serialization/ASTWriterDecl.cpp b/lib/Serialization/ASTWriterDecl.cpp
index ec21ca2276..c13c528d23 100644
--- a/lib/Serialization/ASTWriterDecl.cpp
+++ b/lib/Serialization/ASTWriterDecl.cpp
@@ -849,17 +849,16 @@ void ASTDeclWriter::VisitObjCPropertyImplDecl(ObjCPropertyImplDecl *D) {
 void ASTDeclWriter::VisitFieldDecl(FieldDecl *D) {
   VisitDeclaratorDecl(D);
   Record.push_back(D->isMutable());
-  if (D->InitStorage.getInt() == FieldDecl::ISK_BitWidthOrNothing &&
-      D->InitStorage.getPointer() == nullptr) {
-    Record.push_back(0);
-  } else if (D->InitStorage.getInt() == FieldDecl::ISK_CapturedVLAType) {
-    Record.push_back(D->InitStorage.getInt() + 1);
-    Record.AddTypeRef(
-        QualType(static_cast<Type *>(D->InitStorage.getPointer()), 0));
-  } else {
-    Record.push_back(D->InitStorage.getInt() + 1);
-    Record.AddStmt(static_cast<Expr *>(D->InitStorage.getPointer()));
-  }
+
+  FieldDecl::InitStorageKind ISK = D->InitStorage.getInt();
+  Record.push_back(ISK);
+  if (ISK == FieldDecl::ISK_CapturedVLAType)
+    Record.AddTypeRef(QualType(D->getCapturedVLAType(), 0));
+  else if (ISK)
+    Record.AddStmt(D->getInClassInitializer());
+
+  Record.AddStmt(D->getBitWidth());
+
   if (!D->getDeclName())
     Record.AddDeclRef(Context.getInstantiatedFromUnnamedFieldDecl(D));
 
@@ -873,6 +872,7 @@ void ASTDeclWriter::VisitFieldDecl(FieldDecl *D) {
       !D->isModulePrivate() &&
       !D->getBitWidth() &&
       !D->hasInClassInitializer() &&
+      !D->hasCapturedVLAType() &&
       !D->hasExtInfo() &&
       !ObjCIvarDecl::classofKind(D->getKind()) &&
       !ObjCAtDefsFieldDecl::classofKind(D->getKind()) &&
@@ -1741,7 +1741,7 @@ void ASTWriter::WriteDeclAbbrevs() {
   Abv->Add(BitCodeAbbrevOp(0));                       // hasExtInfo
   // FieldDecl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isMutable
-  Abv->Add(BitCodeAbbrevOp(0));                       //getBitWidth
+  Abv->Add(BitCodeAbbrevOp(0));                       // InitStyle
   // Type Source Info
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
@@ -1774,7 +1774,7 @@ void ASTWriter::WriteDeclAbbrevs() {
   Abv->Add(BitCodeAbbrevOp(0));                       // hasExtInfo
   // FieldDecl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isMutable
-  Abv->Add(BitCodeAbbrevOp(0));                       //getBitWidth
+  Abv->Add(BitCodeAbbrevOp(0));                       // InitStyle
   // ObjC Ivar
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // getAccessControl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // getSynthesize