no merge: add some debugging for linux.

Author: zoecarver

lib/ClangImporter/ImportDecl.cpp

@@ -3923,6 +3923,17 @@ namespace {
       auto dc = Impl.importDeclContextOf(
           decl, importedName.getEffectiveContext());
 
+#ifndef NDEBUG
+      if (dc == nullptr) {
+        llvm::dbgs() << "No decl context!\n";
+        llvm::dbgs() << "Decl: " << importedName.getDeclName().getBaseIdentifier().str() << "\n";
+        llvm::dbgs() << "Decl: "; decl->dump();
+        llvm::dbgs() << "Efective ctx: "; importedName.getEffectiveContext().DC->dumpAsDecl();
+        llvm::dbgs() << "Decl ctx: "; decl->getDeclContext()->dumpAsDecl();
+        llvm_unreachable("");
+      }
+#endif
+      
       SmallVector<GenericTypeParamDecl *, 4> genericParams;
       for (auto &param : *decl->getTemplateParameters()) {
         auto genericParamDecl =