Re: patch: enhanced get diagnostics statement 2

A couple items for this patch:

The docs state that the variable to receive each diagnostic value needs
to be "of the right data type" but fails to specify what it is.  I think
it'd be good to turn that <itemizedlist> into a table with three
columns: name, type, description.

This seems poor style:

+                               case PLPGSQL_GETDIAG_ERROR_CONTEXT:
+                               case PLPGSQL_GETDIAG_ERROR_DETAIL:
+                               case PLPGSQL_GETDIAG_ERROR_HINT:
+                               case PLPGSQL_GETDIAG_RETURNED_SQLSTATE:
+                               case PLPGSQL_GETDIAG_MESSAGE_TEXT:
+                                   if (!$2)
+                                       ereport(ERROR,
+                                           (errcode(ERRCODE_SYNTAX_ERROR),
+                                            errmsg("EXCEPTION_CONTEXT or EXCEPTION_DETAIL or EXCEPTION_HINT or RETURNED_SQLSTATE or MESSAGE_TEXT are not allowed in current diagnostics statement"),
+                                                    parser_errposition(@1)));
+                                   


I think we could replace this with something like

+                                   if (!$2)
+                                       ereport(ERROR,
+                                           (errcode(ERRCODE_SYNTAX_ERROR),
+                                            errmsg("diagnostic value %s is not allowed in GET CURRENT DIAGNOSTICS statement", stringify(ditem->kind)),


Other than that, and a few grammar fixes in code comments, this seems
good to me.

-- 
Álvaro Herrera <alvherre@commandprompt.com>
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