[fpc-devel] Assignment to for..in loop variable

[Alexander Klenin]

Currently, this code:

var
  i: Integer;
  a: array [1..10] of Integer;
...
  for i in a do i += 1;

Is compiled and silently does nothing.

Assignment to the for..in loop variable is currently not supported by
Delphi either:
http://docwiki.embarcadero.com/RADStudio/en/Declarations_and_Statements#Iteration_Over_Containers_Using_For_statements

however, there are some good use cases for this:
http://stackoverflow.com/questions/2246087/delphi-variable-used-in-the-for-in-cannot-be-assigned

So, I have a bug report/feature request:

1) In the current implementation, FPC should at least warn on attempt
to change for..in loop variable
(I assumed that since it compiles, it works, and it cost me much time
to debug this)

2) Ideally, FPC for loop variable should have the same semantics as
var parameter,
so changing it should change the underlying data.

-- 
Alexander S. Klenin