4 files changed, 44 insertions, 9 deletions
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 426237711ec..7ecd95ea204 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -2003,6 +2003,8 @@ void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D) {
     GV->setDLLStorageClass(llvm::GlobalVariable::DLLImportStorageClass);
   else if (D->hasAttr<DLLExportAttr>())
     GV->setDLLStorageClass(llvm::GlobalVariable::DLLExportStorageClass);
+  else
+    GV->setDLLStorageClass(llvm::GlobalVariable::DefaultStorageClass);
 
   if (Linkage == llvm::GlobalVariable::CommonLinkage)
     // common vars aren't constant even if declared const.
@@ -2338,6 +2340,12 @@ void CodeGenModule::EmitGlobalFunctionDefinition(GlobalDecl GD,
   // declarations).
   auto *Fn = cast<llvm::Function>(GV);
   setFunctionLinkage(GD, Fn);
+  if (D->hasAttr<DLLImportAttr>())
+    GV->setDLLStorageClass(llvm::GlobalVariable::DLLImportStorageClass);
+  else if (D->hasAttr<DLLExportAttr>())
+    GV->setDLLStorageClass(llvm::GlobalVariable::DLLExportStorageClass);
+  else
+    GV->setDLLStorageClass(llvm::GlobalVariable::DefaultStorageClass);
 
   // FIXME: this is redundant with part of setFunctionDefinitionAttributes
   setGlobalVisibility(Fn, D);
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 734a01e2e30..fe5981121fe 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -5185,6 +5185,14 @@ static void checkDLLAttributeRedeclaration(Sema &S, NamedDecl *OldDecl,
     S.Diag(OldImportAttr->getLocation(), diag::note_previous_attribute);
     OldDecl->dropAttr<DLLImportAttr>();
     NewDecl->dropAttr<DLLImportAttr>();
+  } else if (IsInline && OldImportAttr &&
+             !S.Context.getTargetInfo().getCXXABI().isMicrosoft()) {
+    // In MinGW, seeing a function declared inline drops the dllimport attribute.
+    OldDecl->dropAttr<DLLImportAttr>();
+    NewDecl->dropAttr<DLLImportAttr>();
+    S.Diag(NewDecl->getLocation(),
+           diag::warn_dllimport_dropped_from_inline_function)
+        << NewDecl << OldImportAttr;
   }
 }
 
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index f6a89d73c5e..1b04e52f150 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -3999,6 +3999,16 @@ static void handleDLLAttr(Sema &S, Decl *D, const AttributeList &A) {
     return;
   }
 
+  if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
+    if (FD->isInlined() && A.getKind() == AttributeList::AT_DLLImport &&
+        !S.Context.getTargetInfo().getCXXABI().isMicrosoft()) {
+      // MinGW doesn't allow dllimport on inline functions.
+      S.Diag(A.getRange().getBegin(), diag::warn_attribute_ignored_on_inline)
+          << A.getName();
+      return;
+    }
+  }
+
   unsigned Index = A.getAttributeSpellingListIndex();
   Attr *NewAttr = A.getKind() == AttributeList::AT_DLLExport
                       ? (Attr *)S.mergeDLLExportAttr(D, A.getRange(), Index)
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index e7171831f63..031edf1515b 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -4655,7 +4655,9 @@ static void checkDLLAttribute(Sema &S, CXXRecordDecl *Class) {
     // Don't inherit dll attribute until the template is instantiated.
     return;
 
-  bool ClassExported = ClassAttr->getKind() == attr::DLLExport;
+  // The class is either imported or exported.
+  const bool ClassExported = ClassAttr->getKind() == attr::DLLExport;
+  const bool ClassImported = !ClassExported;
 
   // Force declaration of implicit members so they can inherit the attribute.
   S.ForceDeclarationOfImplicitMembers(Class);
@@ -4674,15 +4676,22 @@ static void checkDLLAttribute(Sema &S, CXXRecordDecl *Class) {
     if (!VD && !MD)
       continue;
 
-    // Don't process deleted methods.
-    if (MD && MD->isDeleted())
-      continue;
+    if (MD) {
+      // Don't process deleted methods.
+      if (MD->isDeleted())
+        continue;
 
-    if (MD && MD->isMoveAssignmentOperator() && !ClassExported &&
-        MD->isInlined()) {
-      // Current MSVC versions don't export the move assignment operators, so
-      // don't attempt to import them if we have a definition.
-      continue;
+      if (MD->isMoveAssignmentOperator() && ClassImported && MD->isInlined()) {
+        // Current MSVC versions don't export the move assignment operators, so
+        // don't attempt to import them if we have a definition.
+        continue;
+      }
+
+      if (MD->isInlined() && ClassImported &&
+          !S.Context.getTargetInfo().getCXXABI().isMicrosoft()) {
+        // MinGW does not import inline functions.
+        continue;
+      }
     }
 
     if (!getDLLAttr(Member)) {