diff --git a/lldb/tools/lldb-dap/DAP.cpp b/lldb/tools/lldb-dap/DAP.cpp
index 9361ba968e9c..1f49d70ab3ac 100644
--- a/lldb/tools/lldb-dap/DAP.cpp
+++ b/lldb/tools/lldb-dap/DAP.cpp
@@ -722,6 +722,7 @@ bool DAP::HandleObject(const protocol::Message &M) {
                              case protocol::eResponseMessageNotStopped:
                                return "notStopped";
                              }
+                             llvm_unreachable("unknown response message kind.");
                            }),
                        *resp->message);
       }
diff --git a/lldb/tools/lldb-dap/Protocol/ProtocolBase.cpp b/lldb/tools/lldb-dap/Protocol/ProtocolBase.cpp
index 87fd0df018b6..af63cc803e54 100644
--- a/lldb/tools/lldb-dap/Protocol/ProtocolBase.cpp
+++ b/lldb/tools/lldb-dap/Protocol/ProtocolBase.cpp
@@ -284,6 +284,7 @@ bool fromJSON(const json::Value &Params, Message &PM, json::Path P) {
     PM = std::move(evt);
     return true;
   }
+  llvm_unreachable("unhandled message type request.");
 }
 
 json::Value toJSON(const Message &M) {
diff --git a/lldb/tools/lldb-dap/Protocol/ProtocolTypes.cpp b/lldb/tools/lldb-dap/Protocol/ProtocolTypes.cpp
index d1dd9ad9c5fe..f4f0bf8dcea8 100644
--- a/lldb/tools/lldb-dap/Protocol/ProtocolTypes.cpp
+++ b/lldb/tools/lldb-dap/Protocol/ProtocolTypes.cpp
@@ -69,6 +69,7 @@ json::Value toJSON(const ColumnType &T) {
   case eColumnTypeTimestamp:
     return "unixTimestampUTC";
   }
+  llvm_unreachable("unhandled column type.");
 }
 
 json::Value toJSON(const ColumnDescriptor &CD) {
@@ -95,6 +96,7 @@ json::Value toJSON(const ChecksumAlgorithm &CA) {
   case eChecksumAlgorithmTimestamp:
     return "timestamp";
   }
+  llvm_unreachable("unhandled checksum algorithm.");
 }
 
 json::Value toJSON(const BreakpointModeApplicability &BMA) {
@@ -108,6 +110,7 @@ json::Value toJSON(const BreakpointModeApplicability &BMA) {
   case eBreakpointModeApplicabilityInstruction:
     return "instruction";
   }
+  llvm_unreachable("unhandled breakpoint mode applicability.");
 }
 
 json::Value toJSON(const BreakpointMode &BM) {
@@ -200,6 +203,7 @@ static llvm::StringLiteral ToString(AdapterFeature feature) {
   case eAdapterFeatureTerminateDebuggee:
     return "supportTerminateDebuggee";
   }
+  llvm_unreachable("unhandled adapter feature.");
 }
 
 json::Value toJSON(const Capabilities &C) {