[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.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@317308 91177308-0d34-0410-b5e6-96231b3b80d8

7 files changed, 102 insertions, 16 deletions

diff --git a/include/clang/Lex/Preprocessor.h b/include/clang/Lex/Preprocessor.h
index 4f211a3eb6..5e847effdc 100644
--- a/include/clang/Lex/Preprocessor.h
+++ b/include/clang/Lex/Preprocessor.h
@@ -286,6 +286,23 @@ class Preprocessor {
   /// This is used when loading a precompiled preamble.
   std::pair<int, bool> SkipMainFilePreamble;
 
+public:
+  struct PreambleSkipInfo {
+    PreambleSkipInfo(SourceLocation HashTokenLoc, SourceLocation IfTokenLoc,
+                     bool FoundNonSkipPortion, bool FoundElse,
+                     SourceLocation ElseLoc)
+        : HashTokenLoc(HashTokenLoc), IfTokenLoc(IfTokenLoc),
+          FoundNonSkipPortion(FoundNonSkipPortion), FoundElse(FoundElse),
+          ElseLoc(ElseLoc) {}
+
+    SourceLocation HashTokenLoc;
+    SourceLocation IfTokenLoc;
+    bool FoundNonSkipPortion;
+    bool FoundElse;
+    SourceLocation ElseLoc;
+  };
+
+private:
   class PreambleConditionalStackStore {
     enum State {
       Off = 0,
@@ -319,6 +336,12 @@ class Preprocessor {
 
     bool hasRecordedPreamble() const { return !ConditionalStack.empty(); }
 
+    bool reachedEOFWhileSkipping() const { return SkipInfo.hasValue(); }
+
+    void clearSkipInfo() { SkipInfo.reset(); }
+
+    llvm::Optional<PreambleSkipInfo> SkipInfo;
+
   private:
     SmallVector<PPConditionalInfo, 4> ConditionalStack;
     State ConditionalStackState;
@@ -1839,7 +1862,7 @@ private:
   /// \p FoundElse is false, then \#else directives are ok, if not, then we have
   /// already seen one so a \#else directive is a duplicate.  When this returns,
   /// the caller can lex the first valid token.
-  void SkipExcludedConditionalBlock(const Token &HashToken,
+  void SkipExcludedConditionalBlock(SourceLocation HashTokenLoc,
                                     SourceLocation IfTokenLoc,
                                     bool FoundNonSkipPortion, bool FoundElse,
                                     SourceLocation ElseLoc = SourceLocation());
@@ -2019,9 +2042,15 @@ public:
     PreambleConditionalStack.setStack(s);
   }
 
-  void setReplayablePreambleConditionalStack(ArrayRef<PPConditionalInfo> s) {
+  void setReplayablePreambleConditionalStack(ArrayRef<PPConditionalInfo> s,
+                                             llvm::Optional<PreambleSkipInfo> SkipInfo) {
     PreambleConditionalStack.startReplaying();
     PreambleConditionalStack.setStack(s);
+    PreambleConditionalStack.SkipInfo = SkipInfo;
+  }
+
+  llvm::Optional<PreambleSkipInfo> getPreambleSkipInfo() const {
+    return PreambleConditionalStack.SkipInfo;
   }
 
 private:
diff --git a/lib/Lex/PPDirectives.cpp b/lib/Lex/PPDirectives.cpp
index f9a97505bf..ca3e70fd10 100644
--- a/lib/Lex/PPDirectives.cpp
+++ b/lib/Lex/PPDirectives.cpp
@@ -350,7 +350,7 @@ void Preprocessor::CheckEndOfDirective(const char *DirType, bool EnableMacros) {
 /// If ElseOk is true, then \#else directives are ok, if not, then we have
 /// already seen one so a \#else directive is a duplicate.  When this returns,
 /// the caller can lex the first valid token.
-void Preprocessor::SkipExcludedConditionalBlock(const Token &HashToken,
+void Preprocessor::SkipExcludedConditionalBlock(SourceLocation HashTokenLoc,
                                                 SourceLocation IfTokenLoc,
                                                 bool FoundNonSkipPortion,
                                                 bool FoundElse,
@@ -358,8 +358,11 @@ void Preprocessor::SkipExcludedConditionalBlock(const Token &HashToken,
   ++NumSkipped;
   assert(!CurTokenLexer && CurPPLexer && "Lexing a macro, not a file?");
 
-  CurPPLexer->pushConditionalLevel(IfTokenLoc, /*isSkipping*/false,
-                                 FoundNonSkipPortion, FoundElse);
+  if (PreambleConditionalStack.reachedEOFWhileSkipping())
+    PreambleConditionalStack.clearSkipInfo();
+  else
+    CurPPLexer->pushConditionalLevel(IfTokenLoc, /*isSkipping*/ false,
+                                     FoundNonSkipPortion, FoundElse);
 
   if (CurPTHLexer) {
     PTHSkipExcludedConditionalBlock();
@@ -385,6 +388,9 @@ void Preprocessor::SkipExcludedConditionalBlock(const Token &HashToken,
       // We don't emit errors for unterminated conditionals here,
       // Lexer::LexEndOfFile can do that propertly.
       // Just return and let the caller lex after this #include.
+      if (PreambleConditionalStack.isRecording())
+        PreambleConditionalStack.SkipInfo.emplace(
+            HashTokenLoc, IfTokenLoc, FoundNonSkipPortion, FoundElse, ElseLoc);
       break;
     }
 
@@ -554,7 +560,7 @@ void Preprocessor::SkipExcludedConditionalBlock(const Token &HashToken,
 
   if (Callbacks)
     Callbacks->SourceRangeSkipped(
-        SourceRange(HashToken.getLocation(), CurPPLexer->getSourceLocation()),
+        SourceRange(HashTokenLoc, CurPPLexer->getSourceLocation()),
         Tok.getLocation());
 }
 
@@ -2676,7 +2682,8 @@ void Preprocessor::HandleIfdefDirective(Token &Result,
   if (MacroNameTok.is(tok::eod)) {
     // Skip code until we get to #endif.  This helps with recovery by not
     // emitting an error when the #endif is reached.
-    SkipExcludedConditionalBlock(HashToken, DirectiveTok.getLocation(),
+    SkipExcludedConditionalBlock(HashToken.getLocation(),
+                                 DirectiveTok.getLocation(),
                                  /*Foundnonskip*/ false, /*FoundElse*/ false);
     return;
   }
@@ -2725,7 +2732,8 @@ void Preprocessor::HandleIfdefDirective(Token &Result,
                                      /*foundelse*/false);
   } else {
     // No, skip the contents of this block.
-    SkipExcludedConditionalBlock(HashToken, DirectiveTok.getLocation(),
+    SkipExcludedConditionalBlock(HashToken.getLocation(),
+                                 DirectiveTok.getLocation(),
                                  /*Foundnonskip*/ false,
                                  /*FoundElse*/ false);
   }
@@ -2772,7 +2780,7 @@ void Preprocessor::HandleIfDirective(Token &IfToken,
                                    /*foundnonskip*/true, /*foundelse*/false);
   } else {
     // No, skip the contents of this block.
-    SkipExcludedConditionalBlock(HashToken, IfToken.getLocation(),
+    SkipExcludedConditionalBlock(HashToken.getLocation(), IfToken.getLocation(),
                                  /*Foundnonskip*/ false,
                                  /*FoundElse*/ false);
   }
@@ -2837,7 +2845,8 @@ void Preprocessor::HandleElseDirective(Token &Result, const Token &HashToken) {
   }
 
   // Finally, skip the rest of the contents of this block.
-  SkipExcludedConditionalBlock(HashToken, CI.IfLoc, /*Foundnonskip*/ true,
+  SkipExcludedConditionalBlock(HashToken.getLocation(), CI.IfLoc,
+                               /*Foundnonskip*/ true,
                                /*FoundElse*/ true, Result.getLocation());
 }
 
@@ -2881,7 +2890,7 @@ void Preprocessor::HandleElifDirective(Token &ElifToken,
   }
 
   // Finally, skip the rest of the contents of this block.
-  SkipExcludedConditionalBlock(HashToken, CI.IfLoc, /*Foundnonskip*/ true,
-                               /*FoundElse*/ CI.FoundElse,
-                               ElifToken.getLocation());
+  SkipExcludedConditionalBlock(
+      HashToken.getLocation(), CI.IfLoc, /*Foundnonskip*/ true,
+      /*FoundElse*/ CI.FoundElse, ElifToken.getLocation());
 }
diff --git a/lib/Lex/Preprocessor.cpp b/lib/Lex/Preprocessor.cpp
index 65df6a57f1..d80899de8f 100644
--- a/lib/Lex/Preprocessor.cpp
+++ b/lib/Lex/Preprocessor.cpp
@@ -550,6 +550,13 @@ void Preprocessor::replayPreambleConditionalStack() {
            "CurPPLexer is null when calling replayPreambleConditionalStack.");
     CurPPLexer->setConditionalLevels(PreambleConditionalStack.getStack());
     PreambleConditionalStack.doneReplaying();
+    if (PreambleConditionalStack.reachedEOFWhileSkipping())
+      SkipExcludedConditionalBlock(
+          PreambleConditionalStack.SkipInfo->HashTokenLoc,
+          PreambleConditionalStack.SkipInfo->IfTokenLoc,
+          PreambleConditionalStack.SkipInfo->FoundNonSkipPortion,
+          PreambleConditionalStack.SkipInfo->FoundElse,
+          PreambleConditionalStack.SkipInfo->ElseLoc);
   }
 }
 
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 5a3423a3ec..dacdac6658 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/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/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index dec8d8f7d7..3834314109 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/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);
diff --git a/test/Index/preamble-conditionals-inverted.cpp b/test/Index/preamble-conditionals-inverted.cpp
index 1d67ccb61a..f5cf1205e3 100644
--- a/test/Index/preamble-conditionals-inverted.cpp
+++ b/test/Index/preamble-conditionals-inverted.cpp
@@ -3,6 +3,8 @@
 // RUN: | FileCheck %s --implicit-check-not "error:"
 #ifdef FOO_H
 
-void foo();
+void foo() {}
 
 #endif
+
+int foo() { return 0; }
diff --git a/test/Index/preamble-conditionals-skipping.cpp b/test/Index/preamble-conditionals-skipping.cpp
new file mode 100644
index 0000000000..fa5764cd5d
--- /dev/null
+++ b/test/Index/preamble-conditionals-skipping.cpp
@@ -0,0 +1,16 @@
+// RUN: env CINDEXTEST_EDITING=1 c-index-test -test-load-source-reparse 5 \
+// RUN:                                       local -std=c++14 %s 2>&1 \
+// RUN: | FileCheck %s --implicit-check-not "error:"
+
+#ifdef MYCPLUSPLUS
+extern "C" {
+#endif
+
+#ifdef MYCPLUSPLUS
+}
+#endif
+
+int main()
+{
+    return 0;
+}