Bug #25146: Some warnings/errors not shown when using --show-warnings

In several cases, an error when processing the query would cause mysql to
return to the top level without printing warnings.  Fix is to always
print any available warnings before returning to the top level.


client/mysql.cc:
  In com_go(), ensure that warnings are printed even if an error
  occurred when processing the query.  Before this patch, an error
  in several places would return to the top level without printing
  associated warnings.
  
  Attempt to avoid printing the warning, though, if it's a duplicate
  of mysql_error() for the connection handle.
mysql-test/r/mysql.result:
  Add test for bug 25146
mysql-test/t/mysql.test:
  Add test for bug 25146

client/mysql.cc

@@ -2126,33 +2126,26 @@ com_go(String *buffer,char *line __attribute__((unused)))
   }
 #endif
 
-  if (error)
-  {
-    executing_query= 0;
-    buffer->length(0); // Remove query on error
-    return error;
-  }
-  error=0;
   buffer->length(0);
 
+  if (error)
+    goto end;
+
   do
   {
     if (quick)
     {
       if (!(result=mysql_use_result(&mysql)) && mysql_field_count(&mysql))
       {
-        executing_query= 0;
-        return put_error(&mysql);
+        error= put_error(&mysql);
+        goto end;
       }
     }
     else
     {
       error= mysql_store_result_for_lazy(&result);
       if (error)
-      {
-        executing_query= 0;
-        return error;
-      }
+        goto end;
     }
 
     if (verbose >= 3 || !opt_silent)
@@ -2229,12 +2222,10 @@ com_go(String *buffer,char *line __attribute__((unused)))
   if (err >= 1)
     error= put_error(&mysql);
 
+end:
+
   if (show_warnings == 1 && warnings >= 1) /* Show warnings if any */
-  {
-    init_pager();
     print_warnings();
-    end_pager();
-  }
 
   if (!error && !status.batch && 
       (mysql.server_status & SERVER_STATUS_DB_DROPPED))
@@ -2658,6 +2649,9 @@ static void print_warnings()
   MYSQL_RES    *result;
   MYSQL_ROW    cur;
   my_ulonglong num_rows;
+  
+  /* Save current error before calling "show warnings" */
+  uint error= mysql_errno(&mysql);
 
   /* Get the warnings */
   query= "show warnings";
@@ -2666,16 +2660,28 @@ static void print_warnings()
 
   /* Bail out when no warnings */
   if (!(num_rows= mysql_num_rows(result)))
-  {
-    mysql_free_result(result);
-    return;
-  }
+    goto end;
+
+  cur= mysql_fetch_row(result);
+
+  /*
+    Don't print a duplicate of the current error.  It is possible for SHOW
+    WARNINGS to return multiple errors with the same code, but different
+    messages.  To be safe, skip printing the duplicate only if it is the only
+    warning.
+  */
+  if (!cur || num_rows == 1 && error == (uint) strtoul(cur[1], NULL, 10))
+    goto end;
 
   /* Print the warnings */
-  while ((cur= mysql_fetch_row(result)))
+  init_pager();
+  do
   {
     tee_fprintf(PAGER, "%s (Code %s): %s\n", cur[0], cur[1], cur[2]);
-  }
+  } while ((cur= mysql_fetch_row(result)));
+  end_pager();
+
+end:
   mysql_free_result(result);
 }
 

mysql-test/r/mysql.result

@@ -180,3 +180,10 @@ ERROR at line 1: DELIMITER cannot contain a backslash character
 1
 End of 5.0 tests
 WARNING: --server-arg option not supported in this configuration.
+Warning (Code 1286): Unknown table engine 'nonexistent'
+Warning (Code 1266): Using storage engine MyISAM for table 't2'
+Warning (Code 1286): Unknown table engine 'nonexistent'
+Warning (Code 1266): Using storage engine MyISAM for table 't2'
+Error (Code 1050): Table 't2' already exists
+drop tables t1, t2;
+End of tests

mysql-test/t/mysql.test

@@ -290,3 +290,21 @@ remove_file $MYSQLTEST_VARDIR/tmp/bug21412.sql;
 --disable_query_log
 --exec $MYSQL --server-arg=no-defaults test -e "quit"
 --enable_query_log
+
+#
+# Bug #25146: Some warnings/errors not shown when using --show-warnings
+#
+
+# This one should succeed with no warnings
+--exec $MYSQL --show-warnings test -e "create table t1 (id int)"
+
+# This should succeed, with warnings about conversion from nonexistent engine
+--exec $MYSQL --show-warnings test -e "create table t2 (id int) engine=nonexistent"
+
+# This should fail, with warnings as well
+--error 1
+--exec $MYSQL --show-warnings test -e "create table t2 (id int) engine=nonexistent"
+
+drop tables t1, t2;
+
+--echo End of tests