Index: lldb/source/Host/common/Terminal.cpp
===================================================================
--- lldb/source/Host/common/Terminal.cpp
+++ lldb/source/Host/common/Terminal.cpp
@@ -77,6 +77,8 @@
   if (enabled)
     fd_termios.c_lflag |= ECHO;
   return SetData(data.get());
+#else
+  llvm_unreachable("GetData() should have returned an error");
 #endif // LLDB_ENABLE_TERMIOS
 }
 
@@ -91,6 +93,8 @@
   if (enabled)
     fd_termios.c_lflag |= ICANON;
   return SetData(data.get());
+#else
+  llvm_unreachable("GetData() should have returned an error");
 #endif // LLDB_ENABLE_TERMIOS
 }
 
@@ -109,6 +113,8 @@
   fd_termios.c_cc[VTIME] = 0;
 
   return SetData(data.get());
+#else
+  llvm_unreachable("GetData() should have returned an error");
 #endif // #if LLDB_ENABLE_TERMIOS
 }
 
@@ -278,6 +284,8 @@
         std::error_code(errno, std::generic_category()),
         "setting output baud rate failed");
   return SetData(data.get());
+#else
+  llvm_unreachable("GetData() should have returned an error");
 #endif // #if LLDB_ENABLE_TERMIOS
 }
 
@@ -301,6 +309,8 @@
         "invalid stop bit count: %d (must be 1 or 2)", stop_bits);
   }
   return SetData(data.get());
+#else
+  llvm_unreachable("GetData() should have returned an error");
 #endif // #if LLDB_ENABLE_TERMIOS
 }
 
@@ -332,6 +342,8 @@
     }
   }
   return SetData(data.get());
+#else
+  llvm_unreachable("GetData() should have returned an error");
 #endif // #if LLDB_ENABLE_TERMIOS
 }
 
@@ -352,6 +364,8 @@
       fd_termios.c_iflag |= PARMRK;
   }
   return SetData(data.get());
+#else
+  llvm_unreachable("GetData() should have returned an error");
 #endif // #if LLDB_ENABLE_TERMIOS
 }
 
@@ -374,6 +388,8 @@
         "hardware flow control is not supported by the platform");
   return llvm::Error::success();
 #endif // defined(CRTSCTS)
+#else
+  llvm_unreachable("GetData() should have returned an error");
 #endif // #if LLDB_ENABLE_TERMIOS
 }