Errors inside macro redefinitions are reported with wrong source locations.

Try uncommenting only {$error 1}, then only {$error 2}, then only {$error 3} in the code below.

{$mode objfpc} {$macro on}

begin
{$define write_something :=
	write('A');
	{2} write('B');
// {$error 1}
	write('C');}
	write_something

// {$undef write_something} // does not help

{$define write_something :=
	write('D');
	write('E');
// {$error 2}
	write('F');}
	write_something

{$define write_something_else :=
	write('G');
	write('H');
// {$error 3}
	write('I');}
	write_something_else
end.

{$error 2} is reported with the wrong location (marked as {2}), as if it was counted from the start of the first write_something definition instead of the actual. {$undef write_something} does not help. Renaming the macro does, but is usually not an option.