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

6 files changed, 32 insertions, 4 deletions

diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index 85ed3ba7db..d6778ecf39 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -610,11 +610,8 @@ void NamedDecl::ClearLinkageCache() {
 }
 
 Linkage NamedDecl::getLinkage() const {
-  if (HasCachedLinkage) {
-    assert(Linkage(CachedLinkage) ==
-           getLVForDecl(this, true).linkage());
+  if (HasCachedLinkage)
     return Linkage(CachedLinkage);
-  }
 
   CachedLinkage = getLVForDecl(this, true).linkage();
   HasCachedLinkage = 1;
diff --git a/lib/Serialization/ASTReaderDecl.cpp b/lib/Serialization/ASTReaderDecl.cpp
index c2ace30782..64b33b066b 100644
--- a/lib/Serialization/ASTReaderDecl.cpp
+++ b/lib/Serialization/ASTReaderDecl.cpp
@@ -526,6 +526,8 @@ void ASTDeclReader::VisitFunctionDecl(FunctionDecl *FD) {
   FD->HasImplicitReturnZero = Record[Idx++];
   FD->IsConstexpr = Record[Idx++];
   FD->HasSkippedBody = Record[Idx++];
+  FD->HasCachedLinkage = true;
+  FD->CachedLinkage = Record[Idx++];
   FD->EndRangeLoc = ReadSourceLocation(Record, Idx);
 
   switch ((FunctionDecl::TemplatedKind)Record[Idx++]) {
@@ -908,6 +910,8 @@ void ASTDeclReader::VisitVarDecl(VarDecl *VD) {
   VD->VarDeclBits.CXXForRangeDecl = Record[Idx++];
   VD->VarDeclBits.ARCPseudoStrong = Record[Idx++];
   VD->VarDeclBits.IsConstexpr = Record[Idx++];
+  VD->HasCachedLinkage = true;
+  VD->CachedLinkage = Record[Idx++];
   
   // Only true variables (not parameters or implicit parameters) can be merged.
   if (VD->getKind() == Decl::Var)
diff --git a/lib/Serialization/ASTWriterDecl.cpp b/lib/Serialization/ASTWriterDecl.cpp
index c2e1513586..3795e21bdf 100644
--- a/lib/Serialization/ASTWriterDecl.cpp
+++ b/lib/Serialization/ASTWriterDecl.cpp
@@ -330,6 +330,7 @@ void ASTDeclWriter::VisitFunctionDecl(FunctionDecl *D) {
   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 @@ void ASTDeclWriter::VisitVarDecl(VarDecl *D) {
   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 @@ void ASTWriter::WriteDeclsBlockAbbrevs() {
   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 @@ void ASTWriter::WriteDeclsBlockAbbrevs() {
   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
diff --git a/test/Modules/Inputs/cxx-linkage-cache.h b/test/Modules/Inputs/cxx-linkage-cache.h
new file mode 100644
index 0000000000..df82927976
--- /dev/null
+++ b/test/Modules/Inputs/cxx-linkage-cache.h
@@ -0,0 +1,11 @@
+// Reduced from a crash encountered with a modularized libc++, where
+// we would try to compute the linkage of a declaration before we
+// finish loading the relevant pieces of it.
+inline namespace D {
+  template<class>
+  struct U {
+    friend bool f(const U &);
+  };
+
+  template class U<int>;
+}
diff --git a/test/Modules/Inputs/module.map b/test/Modules/Inputs/module.map
index f219036e21..53f2fd65d3 100644
--- a/test/Modules/Inputs/module.map
+++ b/test/Modules/Inputs/module.map
@@ -179,3 +179,7 @@ module cxx_many_overloads {
 module cxx_inline_namespace {
   header "cxx-inline-namespace.h"
 }
+
+module cxx_linkage_cache {
+  header "cxx-linkage-cache.h"
+}
diff --git a/test/Modules/cxx-linkage-cache.cpp b/test/Modules/cxx-linkage-cache.cpp
new file mode 100644
index 0000000000..296cc8034f
--- /dev/null
+++ b/test/Modules/cxx-linkage-cache.cpp
@@ -0,0 +1,8 @@
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -x objective-c++ -fmodules -fmodules-cache-path=%t -I %S/Inputs %s -verify -std=c++11
+
+@import cxx_linkage_cache;
+
+T x; // expected-error {{unknown type name 'T'}}
+D::U<int> u;
+bool b = f(u);