[preamble] Also record the "skipping" state of the preprocessor

When a preamble ends in a conditional preprocessor block that is being
skipped, the preprocessor needs to continue skipping that block when
the preamble is used.

This fixes PR34570.

llvm-svn: 317308

2 files changed, 25 insertions, 2 deletions

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 5a3423a3eca..dacdac66586 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -2995,8 +2995,20 @@ ASTReader::ReadASTBlock(ModuleFile &F, unsigned ClientLoadCapabilities) {
 
     case PP_CONDITIONAL_STACK:
       if (!Record.empty()) {
+        unsigned Idx = 0, End = Record.size() - 1;
+        bool ReachedEOFWhileSkipping = Record[Idx++];
+        llvm::Optional<Preprocessor::PreambleSkipInfo> SkipInfo;
+        if (ReachedEOFWhileSkipping) {
+          SourceLocation HashToken = ReadSourceLocation(F, Record, Idx);
+          SourceLocation IfTokenLoc = ReadSourceLocation(F, Record, Idx);
+          bool FoundNonSkipPortion = Record[Idx++];
+          bool FoundElse = Record[Idx++];
+          SourceLocation ElseLoc = ReadSourceLocation(F, Record, Idx);
+          SkipInfo.emplace(HashToken, IfTokenLoc, FoundNonSkipPortion,
+                           FoundElse, ElseLoc);
+        }
         SmallVector<PPConditionalInfo, 4> ConditionalStack;
-        for (unsigned Idx = 0, N = Record.size() - 1; Idx < N; /* in loop */) {
+        while (Idx < End) {
           auto Loc = ReadSourceLocation(F, Record, Idx);
           bool WasSkipping = Record[Idx++];
           bool FoundNonSkip = Record[Idx++];
@@ -3004,7 +3016,7 @@ ASTReader::ReadASTBlock(ModuleFile &F, unsigned ClientLoadCapabilities) {
           ConditionalStack.push_back(
               {Loc, WasSkipping, FoundNonSkip, FoundElse});
         }
-        PP.setReplayablePreambleConditionalStack(ConditionalStack);
+        PP.setReplayablePreambleConditionalStack(ConditionalStack, SkipInfo);
       }
       break;
 
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index dec8d8f7d77..3834314109b 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -2407,6 +2407,17 @@ void ASTWriter::WritePreprocessor(const Preprocessor &PP, bool IsModule) {
 
   if (PP.isRecordingPreamble() && PP.hasRecordedPreamble()) {
     assert(!IsModule);
+    auto SkipInfo = PP.getPreambleSkipInfo();
+    if (SkipInfo.hasValue()) {
+      Record.push_back(true);
+      AddSourceLocation(SkipInfo->HashTokenLoc, Record);
+      AddSourceLocation(SkipInfo->IfTokenLoc, Record);
+      Record.push_back(SkipInfo->FoundNonSkipPortion);
+      Record.push_back(SkipInfo->FoundElse);
+      AddSourceLocation(SkipInfo->ElseLoc, Record);
+    } else {
+      Record.push_back(false);
+    }
     for (const auto &Cond : PP.getPreambleConditionalStack()) {
       AddSourceLocation(Cond.IfLoc, Record);
       Record.push_back(Cond.WasSkipping);