MySQL Bugs: #34883: ft_boolean_syntax cant be assigned from user variable to global var.

Bug #34883	ft_boolean_syntax cant be assigned from user variable to global var.
Submitted:	27 Feb 2008 12:14	Modified:	13 Nov 10:43
Reporter:	Salman Rawala
Status:	Patch pending
Category:	Server: DML	Severity:	S3 (Non-critical)
Version:	5.1.23	OS:	Any
Assigned to:	Sergei Golubchik	Target Version:
Tags:	ft_boolean_syntax
Triage:	Triaged: D4 (Minor)

Description:
When you finally assign temporary initial variable's value to session value, an error
occurs that '' value cannot be set to variable

How to repeat:
Sample Code: 
SELECT @global_start_value;
--Error ER_WRONG_VALUE_FOR_VAR
SET @@global.ft_boolean_syntax = @global_start_value;

Actual Result: 
SELECT @global_start_value;
@global_start_value
+ -><()~*:""&|
SET @@global.ft_boolean_syntax = @global_start_value;
ERROR 42000: Variable 'ft_boolean_syntax' can't be set to the value of ''

Thank you for a bug report. Other variables, e.g. @@global.key_buffer_size, can be set
this way, so it looks like inconsistency.

The manual specifies what values are allowed for ft_boolean_syntax. Empty string is not
one of them.

And this has nothing to do with temporary variables.

So it means that we can not assign temporary variable to ft_boolean_syntax even if the
variable contains the valid value.

SET @global_start_value = @@global.ft_boolean_syntax;
SELECT @global_start_value;
@global_start_value
+ -><()~*:""&|
SET @@global.ft_boolean_syntax = @global_start_value;
ERROR 42000: Variable 'ft_boolean_syntax' can't be set to the value of ''

As we can see that @global_start_value contains valid value but assigning this  variable
is causing the problem.

You're right, sorry for confusion.

Hint: the code uses var->value->str_value.c_ptr(), it should use var->value->val_str()
for an obvious reason. this was copy-pasted all over set_var.cc, all places should be
fixed.

workaround: set the value of the via program code

will be fixed in WL#4738