patch 8.2.2097: Vim9: using :silent! when calling a function prevents abort

Problem:    Vim9: using :silent! when calling a function prevents abortng that
            function.
Solution:   Add emsg_silent_def and did_emsg_def.

src/globals.h

@@ -230,6 +230,8 @@ EXTERN int	did_endif INIT(= FALSE);    // just had ":endif"
 EXTERN int	did_emsg;		    // set by emsg() when the message
 					    // is displayed or thrown
 #ifdef FEAT_EVAL
+EXTERN int	did_emsg_def;		    // set by emsg() when emsg_silent
+					    // is set before calling a function
 EXTERN int	did_emsg_cumul;		    // cumulative did_emsg, increased
 					    // when did_emsg is reset.
 EXTERN int	called_vim_beep;	    // set if vim_beep() is called
@@ -1134,6 +1136,10 @@ EXTERN int	is_export INIT(= FALSE);    // :export {cmd}
 
 EXTERN int	msg_silent INIT(= 0);	// don't print messages
 EXTERN int	emsg_silent INIT(= 0);	// don't print error messages
+#ifdef FEAT_EVAL
+EXTERN int	emsg_silent_def INIT(= 0);  // value of emsg_silent when a :def
+					    // function is called
+#endif
 EXTERN int	emsg_noredir INIT(= 0);	// don't redirect error messages
 EXTERN int	cmd_silent INIT(= FALSE); // don't echo the command line
 

src/message.c

@@ -697,6 +697,12 @@ emsg_core(char_u *s)
 		}
 		redir_write(s, -1);
 	    }
+#ifdef FEAT_EVAL
+	    // Only increment did_emsg_def when :silent! wasn't used inside the
+	    // :def function.
+	    if (emsg_silent == emsg_silent_def)
+		++did_emsg_def;
+#endif
 #ifdef FEAT_JOB_CHANNEL
 	    ch_log(NULL, "ERROR silent: %s", (char *)s);
 #endif

src/testdir/test_vim9_func.vim

@@ -1784,6 +1784,22 @@ def Test_reset_did_emsg()
   delfunc! g:Func
 enddef
 
+def Test_abort_with_silent_call()
+  var lines =<< trim END
+      vim9script
+      g:result = 'none'
+      def Func()
+        g:result += 3
+        g:result = 'yes'
+      enddef
+      # error is silenced, but function aborts on error
+      silent! Func()
+      assert_equal('none', g:result)
+      unlet g:result
+  END
+  CheckScriptSuccess(lines)
+enddef
+
 def Test_continues_with_silent_error()
   var lines =<< trim END
       vim9script

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2097,
 /**/
     2096,
 /**/

src/vim9execute.c

@@ -851,6 +851,8 @@ call_def_function(
     msglist_T	*private_msg_list = NULL;
     cmdmod_T	save_cmdmod;
     int		restore_cmdmod = FALSE;
+    int		save_emsg_silent_def = emsg_silent_def;
+    int		save_did_emsg_def = did_emsg_def;
     int		trylevel_at_start = trylevel;
     int		orig_funcdepth;
 
@@ -1021,6 +1023,11 @@ call_def_function(
     // Do turn errors into exceptions.
     suppress_errthrow = FALSE;
 
+    // When ":silent!" was used before calling then we still abort the
+    // function.  If ":silent!" is used in the function then we don't.
+    emsg_silent_def = emsg_silent;
+    did_emsg_def = 0;
+
     // Decide where to start execution, handles optional arguments.
     init_instr_idx(ufunc, argc, &ectx);
 
@@ -3008,8 +3015,10 @@ func_return:
 
 on_error:
 	// Jump here for an error that does not require aborting execution.
-	// If "emsg_silent" is set then ignore the error.
-	if (did_emsg_cumul + did_emsg == did_emsg_before && emsg_silent)
+	// If "emsg_silent" is set then ignore the error, unless it was set
+	// when calling the function.
+	if (did_emsg_cumul + did_emsg == did_emsg_before
+					   && emsg_silent && did_emsg_def == 0)
 	    continue;
 on_fatal_error:
 	// Jump here for an error that messes up the stack.
@@ -3056,6 +3065,8 @@ failed:
 	undo_cmdmod(&cmdmod);
 	cmdmod = save_cmdmod;
     }
+    emsg_silent_def = save_emsg_silent_def;
+    did_emsg_def += save_did_emsg_def;
 
 failed_early:
     // Free all local variables, but not arguments.