Do not catch exceptions of polymorphic type by value, as that requires the
compiler to slice the exceptions.  Catching them by reference allows the
compiler to emit more efficient code.

--- monotone-1.1/src/dates.cc.orig	2014-05-04 03:15:16.000000000 -0600
+++ monotone-1.1/src/dates.cc	2020-06-30 12:15:35.765139561 -0600
@@ -652,7 +652,7 @@ date_t::date_t(string const & s)
 
       d = our_timegm(t);
     }
-  catch (std::out_of_range)
+  catch (std::out_of_range &)
     {
       E(false, origin::user,
         F("unrecognized date (monotone only understands ISO 8601 format)"));
--- monotone-1.1/src/key_packet.cc.orig	2014-05-04 03:15:17.000000000 -0600
+++ monotone-1.1/src/key_packet.cc	2020-06-30 12:14:15.581206185 -0600
@@ -139,7 +139,7 @@ namespace
         }
       // since we do not want to prompt for a password to decode it finally,
       // we ignore all other exceptions
-      catch (Botan::Invalid_Argument) {}
+      catch (Botan::Invalid_Argument &) {}
     }
     void validate_no_more_args(istringstream & iss) const
     {
--- monotone-1.1/src/key_store.cc.orig	2014-05-04 03:15:17.000000000 -0600
+++ monotone-1.1/src/key_store.cc	2020-06-30 12:14:36.965188418 -0600
@@ -622,7 +622,7 @@ key_store_state::decrypt_private_key(key
             break;
           }
 #if BOTAN_VERSION_CODE >= BOTAN_VERSION_CODE_FOR(1,9,4)
-        catch (Botan::Invalid_Argument)
+        catch (Botan::Invalid_Argument &)
 #else
         catch (Botan::Exception & e)
 #endif
--- monotone-1.1/src/network/session.cc.orig	2014-05-04 03:15:17.000000000 -0600
+++ monotone-1.1/src/network/session.cc	2020-06-30 12:15:10.949160179 -0600
@@ -362,7 +362,7 @@ bool session::do_work(transaction_guard
                                              % errmsg.substr(4));
                           }
                       }
-                    catch (boost::bad_lexical_cast)
+                    catch (boost::bad_lexical_cast &)
                       { // ok, so it wasn't a number
                       }
                   }
--- monotone-1.1/src/option.cc.orig	2014-05-04 03:15:17.000000000 -0600
+++ monotone-1.1/src/option.cc	2020-06-30 12:12:46.420100297 -0600
@@ -522,7 +522,7 @@ void concrete_option_set::from_command_l
                     o.resetter();
                 }
             }
-          catch (boost::bad_lexical_cast)
+          catch (boost::bad_lexical_cast &)
             {
               throw bad_arg(o.longname, arg);
             }
@@ -567,7 +567,7 @@ void concrete_option_set::from_key_value
                 o.resetter();
             }
         }
-      catch (boost::bad_lexical_cast)
+      catch (boost::bad_lexical_cast &)
         {
           throw bad_arg(o.longname, value);
         }
--- monotone-1.1/src/packet.cc.orig	2014-05-04 03:15:17.000000000 -0600
+++ monotone-1.1/src/packet.cc	2020-06-30 12:13:54.197195613 -0600
@@ -192,9 +192,9 @@ namespace
       // since we do not want to prompt for a password to decode it finally,
       // we ignore all other exceptions
 #if BOTAN_VERSION_CODE >= BOTAN_VERSION_CODE_FOR(1,9,11)
-      catch (Passphrase_Required) {}
+      catch (Passphrase_Required &) {}
 #else
-      catch (Botan::Invalid_Argument) {}
+      catch (Botan::Invalid_Argument &) {}
 #endif
     }
     void validate_certname(string const & cn) const
--- monotone-1.1/src/paths.hh.orig	2014-05-04 03:15:17.000000000 -0600
+++ monotone-1.1/src/paths.hh	2020-06-30 12:12:29.845076986 -0600
@@ -424,7 +424,7 @@ bool safe_compose(T const & p, char cons
       result = p / path_component(s);
       return true;
     }
-  catch (std::logic_error)
+  catch (std::logic_error &)
     {
       report_failed_path_composition(p, s, isdir);
       return false;
--- monotone-1.1/src/sanity.cc.orig	2020-06-30 09:32:43.994207307 -0600
+++ monotone-1.1/src/sanity.cc	2020-06-30 12:13:32.165164632 -0600
@@ -433,13 +433,13 @@ sanity::gasp()
           (*i)->gasp(tmp);
           out << tmp;
         }
-      catch (logic_error)
+      catch (logic_error &)
         {
           out << tmp;
           out << "<caught logic_error>\n";
           L(FL("ignoring error trigged by saving work set to debug log"));
         }
-      catch (recoverable_failure)
+      catch (recoverable_failure &)
         {
           out << tmp;
           out << "<caught informative_failure>\n";