| Bug #91955 | 8.0 broke plugin API for C | ||
|---|---|---|---|
| Submitted: | 9 Aug 2018 19:06 | Modified: | 9 Nov 2018 3:44 |
| Reporter: | Laurynas Biveinis (OCA) | Email Updates: | |
| Status: | Closed | Impact on me: | |
| Category: | MySQL Server: Documentation | Severity: | S3 (Non-critical) |
| Version: | 8.0 | OS: | Any |
| Assigned to: | CPU Architecture: | Any | |
[10 Aug 2018 5:15]
Laurynas Biveinis
Then In file included from /Users/laurynas/percona/mysql-server/include/mysql/plugin.h:76: In file included from /Users/laurynas/percona/mysql-server/include/mysql/services.h:28: In file included from /Users/laurynas/percona/mysql-server/include/mysql/service_command.h:32: /Users/laurynas/percona/mysql-server/include/mysql/com_data.h:64:3: error: must use 'struct' tag to refer to type 'PS_PARAM' PS_PARAM *parameters; ^ struct ... and many more errors in that header
[10 Aug 2018 5:40]
Laurynas Biveinis
In file included from /Users/laurynas/percona/mysql-server/include/mysql/plugin.h:76:
In file included from /Users/laurynas/percona/mysql-server/include/mysql/services.h:28:
In file included from /Users/laurynas/percona/mysql-server/include/mysql/service_command.h:33:
/Users/laurynas/percona/mysql-server/include/mysql/service_srv_session.h:47:8: error: expected identifier or '('
extern "C" struct srv_session_service_st {
^
[10 Aug 2018 5:42]
Laurynas Biveinis
In file included from /Users/laurynas/percona/mysql-server/include/mysql/plugin.h:76:
In file included from /Users/laurynas/percona/mysql-server/include/mysql/services.h:28:
In file included from /Users/laurynas/percona/mysql-server/include/mysql/service_command.h:35:
/Users/laurynas/percona/mysql-server/include/decimal.h:58:38: error: must use 'struct' tag to refer to type 'decimal_t'
int string2decimal(const char *from, decimal_t *to, char **end);
^
struct
[10 Aug 2018 8:55]
Laurynas Biveinis
After some mechanical fixes we bump into service_rules_table.h, which is a completely C++ header.
[15 Aug 2018 14:37]
Steinar Gunderson
Writing plugins in C is not supported. Reassigning to documentation so this can be made clear.
[16 Aug 2018 5:30]
MySQL Verification Team
Hello Laurynas, Thank you for the report and feedback! Verifying this as a doc issue per Steinar's last note. regards, Umesh
[9 Nov 2018 3:44]
Paul DuBois
Posted by developer: Correct, plugins now must be compiled as C++ code, as of MySQL 8.0.13. I added a changelog entry for Bug#26781567: Previously, MySQL plugins could be written in C or C++. MySQL header files used by plugins now contain C++ code, which means that plugins must be written in C++, not C. Also updated https://dev.mysql.com/doc/refman/8.0/en/writing-plugins-overview.html to list conditions for plugin writing.
Description: Unless I'm missing something, 8.0 broke ability to build C plugins. A plugin source file (written in C) includes include/mysql/plugin.h, which further includes status_var.h, and there we find struct SHOW_VAR { ... }; ... typedef int (*mysql_show_var_func)(MYSQL_THD, SHOW_VAR *, char *); ... resulting in /Users/laurynas/percona/mysql-server/include/mysql/status_var.h:90:47: error: must use 'struct' tag to refer to type 'SHOW_VAR' typedef int (*mysql_show_var_func)(MYSQL_THD, SHOW_VAR *, char *); ^ struct with clang at least. This appears to be introduced by - commit 545b168a5b8966cd4a35386dfcafd31f35e080a7 Author: Steinar H. Gunderson <steinar.gunderson@oracle.com> Date: Wed Sep 13 12:57:13 2017 +0200 Bug #26781567: REMOVE C LEGACY Replace the final typedefs to st_* and *_st structs. Note in particular that st_mysql_show_var was called sometimes SHOW_VAR and sometimes STATUS_VAR (by way of duplicated forward-declaring typedefs). This patch changes it so that it's universally SHOW_VAR, which seems to match better with the original type name. Change-Id: Ide483ceac31284d909c42adb46496308dd4d4f85 How to repeat: See above Suggested fix: Add that struct tag Have a small test C plugin in-tree to avoid regressions in the future, as already suggested in bug 89288