Add an undocumented and possibly ephemeral ".breakpoint" command to the

command-line shell, to call a no-op routine on which it is convenient to 
set a symbolic debugger breakpoint.

FossilOrigin-Name: 8e2363ad76446e863d03ead91fd621e59d5cb495

src/shell.c

@@ -1562,6 +1562,15 @@ static void sql_trace_callback(void *pArg, const char *z){
   if( f ) fprintf(f, "%s\n", z);
 }
 
+/*
+** A no-op routine that runs with the ".breakpoint" doc-command.  This is
+** a useful spot to set a debugger breakpoint.
+*/
+static void test_breakpoint(void){
+  static int nCall = 0;
+  nCall++;
+}
+
 /*
 ** If an input line begins with "." then invoke this routine to
 ** process that line.
@@ -1641,6 +1650,13 @@ static int do_meta_command(char *zLine, struct callback_data *p){
     bail_on_error = booleanValue(azArg[1]);
   }else
 
+  /* The undocumented ".breakpoint" command causes a call to the no-op
+  ** routine named test_breakpoint().
+  */
+  if( c=='b' && n>=3 && strncmp(azArg[0], "breakpoint", n)==0 ){
+    test_breakpoint();
+  }else
+
   if( c=='d' && n>1 && strncmp(azArg[0], "databases", n)==0 && nArg==1 ){
     struct callback_data data;
     char *zErrMsg = 0;