Cannot use variables inside geometry construtors

-- Define 2 simple points

SET @p1=POINT(1, 1), @p2=POINT(2,2);

-- Check their types

SELECT ST_GEOMETRYTYPE(@p1), ST_GEOMETRYTYPE(@p2);

-- Try to create a multipoint without variables - works as expected

SELECT MULTIPOINT(POINT(1, 1), POINT(2, 2));

-- Try to create a multipoint with variables - Fail

SELECT MULTIPOINT(@p1, @p2);

-- Fail with message Illegal non geometric '@`p1`' value found during parsing