Please, fix commit message subject. Then LGTM.

> On 4 Feb 2019, at 20:05, Ivan Koptelov <ivan.koptelov@tarantool.org> wrote:
> 
> On 04/02/2019 18:28, n.pettik wrote:
>>> On 4 Feb 2019, at 17:44, Ivan Koptelov <ivan.koptelov@tarantool.org> <mailto:ivan.koptelov@tarantool.org> wrote:
>>> 
>>> Adds error raise in case of CHECK constraint declared with ON
>>> CONFLICT REPLACE action. Before the patch such option was
>>> forbidden, but if a user tried to create space with such constraint,
>>> this attempt failed silently.
>>> 
>> What is more, now all on conflict actions are ignored for check
>> constraints. So lets simply fix parser to disallow this clause.
>> It is quite easy: all you need is to remove onconf rule after CHECK
>> keyword:
>> 
>>    319	tcons ::= CHECK LP expr(E) RP onconf.
>>    320	                                 {sql_add_check_constraint(pParse,&E);}
> Thank you for the idea, done.
> 
> --
>  src/box/sql/parse.y         |  2 +-
>  test/sql-tap/check.test.lua | 37 ++++++++++++++++++++++++++++++++++++-
>  2 files changed, 37 insertions(+), 2 deletions(-)
> 
> diff --git a/src/box/sql/parse.y b/src/box/sql/parse.y
> index 8e21b6fca..a5fe7c0a7 100644
> --- a/src/box/sql/parse.y
> +++ b/src/box/sql/parse.y
> @@ -316,7 +316,7 @@ tcons ::= UNIQUE LP sortlist(X) RP.
>                                   {sql_create_index(pParse,0,0,X,0,
>                                                     SORT_ORDER_ASC,false,
>                                                     SQL_INDEX_TYPE_CONSTRAINT_UNIQUE);}
> -tcons ::= CHECK LP expr(E) RP onconf.
> +tcons ::= CHECK LP expr(E) RP .
>                                   {sql_add_check_constraint(pParse,&E);}
>  tcons ::= FOREIGN KEY LP eidlist(FA) RP
>            REFERENCES nm(T) eidlist_opt(TA) refargs(R) defer_subclause_opt(D). {
> diff --git a/test/sql-tap/check.test.lua b/test/sql-tap/check.test.lua
> index 1f369fb02..7960204bc 100755
> --- a/test/sql-tap/check.test.lua
> +++ b/test/sql-tap/check.test.lua
> @@ -1,6 +1,6 @@
>  #!/usr/bin/env tarantool
>  test = require("sqltester")
> -test:plan(58)
> +test:plan(61)
>  
>  --!./tcltestrunner.lua
>  -- 2005 November 2
> @@ -772,5 +772,40 @@ test:do_execsql_test(
>          -- </8.1>
>      })
>  
> +-- gh-3345 : the test checks that ON CONFLICT REPLACE
> +-- is not allowed for CHECK constraint.
> +test:do_catchsql_test(
> +    9.1,
> +    [[
> +        CREATE TABLE t101 (a INT primary key, b INT, CHECK(b < 10)
> +        ON CONFLICT REPLACE)
> +    ]], {
> +        -- <9.1>
> +        1, "keyword \"ON\" is reserved"
> +        -- </9.1>
> +    })
> +
> +test:do_catchsql_test(
> +    9.2,
> +    [[
> +        CREATE TABLE t101 (a INT primary key, b INT, CHECK(b < 10)
> +        ON CONFLICT ABORT)
> +    ]], {
> +        -- <9.2>
> +        1, "keyword \"ON\" is reserved"
> +        -- </9.2>
> +    })
> +
> +test:do_catchsql_test(
> +    9.3,
> +    [[
> +        CREATE TABLE t101 (a INT primary key, b INT, CHECK(b < 10)
> +        ON CONFLICT ROLLBACK)
> +    ]], {
> +        -- <9.3>
> +        1, "keyword \"ON\" is reserved"
> +        -- </9.3>
> +    })
> +
>  test:finish_test()
>  
> -- 
> 2.14.3 (Apple Git-98)
> 
>