Fix a bug reduced from a crash when trying to use modules with libc++. We check
the linkage of functions and variables while merging declarations from modules,
and we don't necessarily have enough of the rest of the AST loaded at that
point to allow us to compute linkage, so serialize it instead.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174943 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Serialization/ASTWriterDecl.cpp b/lib/Serialization/ASTWriterDecl.cpp
index c2e1513..3795e21 100644
--- a/lib/Serialization/ASTWriterDecl.cpp
+++ b/lib/Serialization/ASTWriterDecl.cpp
@@ -330,6 +330,7 @@
   Record.push_back(D->hasImplicitReturnZero());
   Record.push_back(D->isConstexpr());
   Record.push_back(D->HasSkippedBody);
+  Record.push_back(D->getLinkage());
   Writer.AddSourceLocation(D->getLocEnd(), Record);
 
   Record.push_back(D->getTemplatedKind());
@@ -682,6 +683,7 @@
   Record.push_back(D->isCXXForRangeDecl());
   Record.push_back(D->isARCPseudoStrong());
   Record.push_back(D->isConstexpr());
+  Record.push_back(D->getLinkage());
 
   if (D->getInit()) {
     Record.push_back(!D->isInitKnownICE() ? 1 : (D->isInitICE() ? 3 : 2));
@@ -1505,6 +1507,7 @@
   Abv->Add(BitCodeAbbrevOp(0));                       // isCXXForRangeDecl
   Abv->Add(BitCodeAbbrevOp(0));                       // isARCPseudoStrong
   Abv->Add(BitCodeAbbrevOp(0));                       // isConstexpr
+  Abv->Add(BitCodeAbbrevOp(0));                       // Linkage
   Abv->Add(BitCodeAbbrevOp(0));                       // HasInit
   Abv->Add(BitCodeAbbrevOp(0));                   // HasMemberSpecializationInfo
   // ParmVarDecl
@@ -1584,6 +1587,7 @@
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isCXXForRangeDecl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isARCPseudoStrong
   Abv->Add(BitCodeAbbrevOp(0));                         // isConstexpr
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 2)); // Linkage
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // HasInit
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // HasMemberSpecInfo
   // Type Source Info