[AST] Sink 'part of explicit cast' down into ImplicitCastExpr

Summary:
As discussed in IRC with @rsmith, it is slightly not good to keep that in the `CastExpr` itself:
Given the explicit cast, which is represented in AST as an `ExplicitCastExpr` + `ImplicitCastExpr`'s,
only the  `ImplicitCastExpr`'s will be marked as `PartOfExplicitCast`, but not the `ExplicitCastExpr` itself.
Thus, it is only ever `true` for `ImplicitCastExpr`'s, so we don't need to write/read/dump it for `ExplicitCastExpr`'s.

We don't need to worry that we write the `PartOfExplicitCast` in PCH after `CastExpr::path_iterator`,
since the `ExprImplicitCastAbbrev` is only used when the `NumBaseSpecs == 0`, i.e. there is no 'path'.

Reviewers: rsmith, rjmccall, erichkeane, aaron.ballman

Reviewed By: rsmith, erichkeane

Subscribers: vsk, cfe-commits, rsmith

Tags: #clang

Differential Revision: https://reviews.llvm.org/D49838

llvm-svn: 338108

2 files changed, 2 insertions, 2 deletions

diff --git a/clang/lib/Serialization/ASTReaderStmt.cpp b/clang/lib/Serialization/ASTReaderStmt.cpp
index ee03b6def02..d9d780b25b3 100644
--- a/clang/lib/Serialization/ASTReaderStmt.cpp
+++ b/clang/lib/Serialization/ASTReaderStmt.cpp
@@ -723,7 +723,6 @@ void ASTStmtReader::VisitCastExpr(CastExpr *E) {
   assert(NumBaseSpecs == E->path_size());
   E->setSubExpr(Record.readSubExpr());
   E->setCastKind((CastKind)Record.readInt());
-  E->setIsPartOfExplicitCast(Record.readInt());
   CastExpr::path_iterator BaseI = E->path_begin();
   while (NumBaseSpecs--) {
     auto *BaseSpec = new (Record.getContext()) CXXBaseSpecifier;
@@ -770,6 +769,7 @@ ASTStmtReader::VisitBinaryConditionalOperator(BinaryConditionalOperator *E) {
 
 void ASTStmtReader::VisitImplicitCastExpr(ImplicitCastExpr *E) {
   VisitCastExpr(E);
+  E->setIsPartOfExplicitCast(Record.readInt());
 }
 
 void ASTStmtReader::VisitExplicitCastExpr(ExplicitCastExpr *E) {
diff --git a/clang/lib/Serialization/ASTWriterStmt.cpp b/clang/lib/Serialization/ASTWriterStmt.cpp
index 79156dcc5ce..3efb6482dd4 100644
--- a/clang/lib/Serialization/ASTWriterStmt.cpp
+++ b/clang/lib/Serialization/ASTWriterStmt.cpp
@@ -665,7 +665,6 @@ void ASTStmtWriter::VisitCastExpr(CastExpr *E) {
   Record.push_back(E->path_size());
   Record.AddStmt(E->getSubExpr());
   Record.push_back(E->getCastKind()); // FIXME: stable encoding
-  Record.push_back(E->getIsPartOfExplicitCast());
 
   for (CastExpr::path_iterator
          PI = E->path_begin(), PE = E->path_end(); PI != PE; ++PI)
@@ -714,6 +713,7 @@ ASTStmtWriter::VisitBinaryConditionalOperator(BinaryConditionalOperator *E) {
 
 void ASTStmtWriter::VisitImplicitCastExpr(ImplicitCastExpr *E) {
   VisitCastExpr(E);
+  Record.push_back(E->isPartOfExplicitCast());
 
   if (E->path_size() == 0)
     AbbrevToUse = Writer.getExprImplicitCastAbbrev();