6 files changed, 26 insertions, 1 deletions
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 5fb3af61908..7db98d59923 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2161,6 +2161,8 @@ def err_declspec_thread_on_thread_variable : Error<
   "thread-local storage specifier">;
 def err_attribute_dll_not_extern : Error<
   "%q0 must have external linkage when declared %q1">;
+def err_attribute_dll_thread_local : Error<
+  "%q0 cannot be thread local when declared %q1">;
 def warn_attribute_invalid_on_definition : Warning<
   "'%0' attribute cannot be specified on a definition">,
   InGroup<IgnoredAttributes>;
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 03dd2a7093c..c3c436d8e31 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -9534,8 +9534,11 @@ Sema::FinalizeDeclaration(Decl *ThisDecl) {
     }
   }
 
+  // Grab the dllimport or dllexport attribute off of the VarDecl.
+  const InheritableAttr *DLLAttr = getDLLAttr(VD);
+
   // Imported static data members cannot be defined out-of-line.
-  if (const DLLImportAttr *IA = VD->getAttr<DLLImportAttr>()) {
+  if (const auto *IA = dyn_cast_or_null<DLLImportAttr>(DLLAttr)) {
     if (VD->isStaticDataMember() && VD->isOutOfLine() &&
         VD->isThisDeclarationADefinition()) {
       // We allow definitions of dllimport class template static data members
@@ -9556,6 +9559,14 @@ Sema::FinalizeDeclaration(Decl *ThisDecl) {
     }
   }
 
+  // dllimport/dllexport variables cannot be thread local, their TLS index
+  // isn't exported with the variable.
+  if (DLLAttr && VD->getTLSKind()) {
+    Diag(VD->getLocation(), diag::err_attribute_dll_thread_local) << VD
+                                                                  << DLLAttr;
+    VD->setInvalidDecl();
+  }
+
   if (UsedAttr *Attr = VD->getAttr<UsedAttr>()) {
     if (!Attr->isInherited() && !VD->isThisDeclarationADefinition()) {
       Diag(Attr->getLocation(), diag::warn_attribute_ignored) << Attr;
diff --git a/clang/test/Sema/dllexport.c b/clang/test/Sema/dllexport.c
index 6c71ad82987..76b6f6dc5a0 100644
--- a/clang/test/Sema/dllexport.c
+++ b/clang/test/Sema/dllexport.c
@@ -49,6 +49,9 @@ __declspec(dllexport) extern int GlobalRedecl4; // expected-warning{{redeclarati
 // External linkage is required.
 __declspec(dllexport) static int StaticGlobal; // expected-error{{'StaticGlobal' must have external linkage when declared 'dllexport'}}
 
+// Thread local variables are invalid.
+__declspec(dllexport) __thread int ThreadLocalGlobal; // expected-error{{'ThreadLocalGlobal' cannot be thread local when declared 'dllexport'}}
+
 // Export in local scope.
 void functionScope() {
   __declspec(dllexport)        int LocalVarDecl; // expected-error{{'LocalVarDecl' must have external linkage when declared 'dllexport'}}
diff --git a/clang/test/Sema/dllimport.c b/clang/test/Sema/dllimport.c
index d64c85953d0..1b111077b62 100644
--- a/clang/test/Sema/dllimport.c
+++ b/clang/test/Sema/dllimport.c
@@ -77,6 +77,9 @@ __declspec(dllimport) extern int GlobalRedecl5; // expected-warning{{redeclarati
 // External linkage is required.
 __declspec(dllimport) static int StaticGlobal; // expected-error{{'StaticGlobal' must have external linkage when declared 'dllimport'}}
 
+// Thread local variables are invalid.
+__declspec(dllimport) __thread int ThreadLocalGlobal; // expected-error{{'ThreadLocalGlobal' cannot be thread local when declared 'dllimport'}}
+
 // Import in local scope.
 __declspec(dllimport) float LocalRedecl1; // expected-note{{previous definition is here}}
 __declspec(dllimport) float LocalRedecl2; // expected-note{{previous definition is here}}
diff --git a/clang/test/SemaCXX/dllexport.cpp b/clang/test/SemaCXX/dllexport.cpp
index df87c737865..5d688944095 100644
--- a/clang/test/SemaCXX/dllexport.cpp
+++ b/clang/test/SemaCXX/dllexport.cpp
@@ -64,6 +64,9 @@ namespace ns { __declspec(dllexport) int ExternalGlobal; }
 __declspec(dllexport) auto InternalAutoTypeGlobal = Internal(); // expected-error{{'InternalAutoTypeGlobal' must have external linkage when declared 'dllexport'}}
 __declspec(dllexport) auto ExternalAutoTypeGlobal = External();
 
+// Thread local variables are invalid.
+__declspec(dllexport) __thread int ThreadLocalGlobal; // expected-error{{'ThreadLocalGlobal' cannot be thread local when declared 'dllexport'}}
+
 // Export in local scope.
 void functionScope() {
   __declspec(dllexport)        int LocalVarDecl; // expected-error{{'LocalVarDecl' must have external linkage when declared 'dllexport'}}
diff --git a/clang/test/SemaCXX/dllimport.cpp b/clang/test/SemaCXX/dllimport.cpp
index d0e88368fc3..1ba25dbbc5c 100644
--- a/clang/test/SemaCXX/dllimport.cpp
+++ b/clang/test/SemaCXX/dllimport.cpp
@@ -86,6 +86,9 @@ namespace ns { __declspec(dllimport) int ExternalGlobal; }
 __declspec(dllimport) auto InternalAutoTypeGlobal = Internal(); // expected-error{{'InternalAutoTypeGlobal' must have external linkage when declared 'dllimport'}}
                                                                 // expected-error@-1{{definition of dllimport data}}
 
+// Thread local variables are invalid.
+__declspec(dllimport) __thread int ThreadLocalGlobal; // expected-error{{'ThreadLocalGlobal' cannot be thread local when declared 'dllimport'}}
+
 // Import in local scope.
 __declspec(dllimport) float LocalRedecl1; // expected-note{{previous definition is here}}
 __declspec(dllimport) float LocalRedecl2; // expected-note{{previous definition is here}}