Why is this an issue?

To simplify reviews and changes, a file should not mix entity/package/configuration declarations.

How to fix it

Code examples

Noncompliant code example

my_file.vhd
entity my_entity is
end;

package my_package is
end;

Compliant solution

my_entity.vhd
entity my_entity is
end;

my_package.vhd
package my_package is
end;