REVOKE / GRANT visitInfo is incorrect on global grants

[morgo]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

From manual inspection of the code, when GRANT is on . the visitInfo collected the dbName even if it is not applicable:

tidb/planner/core/planbuilder.go

Lines 2268 to 2291 in adfe029

	if dbName == "" {
	dbName = sctx.GetSessionVars().CurrentDB
	}
	vi = appendVisitInfo(vi, mysql.GrantPriv, dbName, tableName, "", nil)
	var allPrivs []mysql.PrivilegeType
	for _, item := range stmt.Privs {
	if item.Priv == mysql.AllPriv {
	switch stmt.Level.Level {
	case ast.GrantLevelGlobal:
	allPrivs = mysql.AllGlobalPrivs
	case ast.GrantLevelDB:
	allPrivs = mysql.AllDBPrivs
	case ast.GrantLevelTable:
	allPrivs = mysql.AllTablePrivs
	}
	break
	}
	vi = appendVisitInfo(vi, item.Priv, dbName, tableName, "", nil)
	}
	for _, priv := range allPrivs {
	vi = appendVisitInfo(vi, priv, dbName, tableName, "", nil)
	}

2. What did you expect to see? (Required)

It should be if dbName == "" && stmt.Level.Level != ast.GrantLevelGlobal {. There are also no tests on visitInfo for GrantLevelGlobal.

3. What did you see instead (Required)

if dbName == "" {
	dbName = sctx.GetSessionVars().CurrentDB
}

4. What is your TiDB version? (Required)

master

[ti-srebot]

Please edit this comment or add a new comment to complete the following information

Bug

This is a bug, but it may not have propagated to users.

1. Root Cause Analysis (RCA) (optional)

2. Symptom (optional)

3. All Trigger Conditions (optional)

4. Workaround (optional)

5. Affected versions

[v4.0.1:v4.0.12], [v5.0.0:v5.0.1]

6. Fixed versions

master

[ti-srebot]

( severity(label) ) fields are empty.