Open array parameter accepts non-array var

[riwu]

Interesting issue. I have tried this and found that FPC 3.0.0 generates a compile error "Assignments to formal parameters and arrays are not possible", but the error does not appear if the call to f is made from within a while loop. Odd.

{$mode objfpc}
procedure f(arr: array of ShortInt);
begin
  while true do //uncommenting the while makes the difference
    f(arr[0]);
end;

This is the error i'm getting.
Like what others mentioned, it only happens at O2 and above.

Here's my version: http://i.imgur.com/N79ZWM8.png

Lpi config:

Code: [Select]

<?xml version="1.0" encoding="UTF-8"?>
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[skalogryz]

let's do something stupid then:

Code: Pascal  [Select][+][-]

1. procedure f(arr: array of Integer); overload;
2. begin
3.   {$OPTIMIZATION OFF}
4.   //while true do  
5.     f(arr[0]);
6.   {$OPTIMIZATION DEFAULT}
7. end;
8.  

[Handoko]

I performed the test again on Win7, and these are what I found:

- Compile won't fail on optimization level 0 and level 1.
- Compile fails on optimization level 2, 3, 4.
- {$OPTIMIZATION OFF} makes no difference.

[Thaddy]

After some research this is also the case on arm. It seems a bug in the high level optimizer at level 2 or higher.
I had to bring the conditionals to surround the begin end; block.

Code: Pascal  [Select][+][-]

1. procedure f(arr: array of Integer); overload;
2. {$PUSH}{...$OPTIMIZATION OFF}
3. begin
4.  
5.   //while true do  
6.     f(arr[0]);
7. end;
8. {$POP}
9.  

Renders:

Code: [Select]

fpc -CX -XXs -O4 tests.pas
Free Pascal Compiler version 3.1.1-r35333 [2017/01/26] for arm
Copyright (c) 1993-2017 by Florian Klaempfl and others
Target OS: Linux for ARMHF
Compiling tests.pas
tests.pas(5,1) Error: Assignments to formal parameters and open arrays are not possible
tests.pas(16) Fatal: There were 1 errors compiling module, stopping
Fatal: Compilation aborted
Error: /usr/local/bin/ppcarm returned an error exitcode
And this code:

Code: Pascal  [Select][+][-]

1. program tests;
2. {$mode delphi}
3. procedure f(arr: array of Integer); overload;
4. {$PUSH}{$OPTIMIZATION OFF}
5. begin
6.   //while true do  
7.     f(arr[0]);
8. end;
9. {$POP}
10.  
11. var
12.   a : integer;
13. begin
14.   f(a);
15. end.

Renders:

Code: [Select]

fpc -CX -XXs -O4 tests.pas
Free Pascal Compiler version 3.1.1-r35333 [2017/01/26] for arm
Copyright (c) 1993-2017 by Florian Klaempfl and others
Target OS: Linux for ARMHF
Compiling tests.pas
tests.pas(14,6) Warning: Variable "a" does not seem to be initialized
Linking testsFinally this code:

Code: Pascal  [Select][+][-]

1. program tests;
2. {$mode delphi}
3. procedure f(arr: array of Integer); overload;
4. {$PUSH}{.....$OPTIMIZATION OFF}
5. begin
6.   while true do  
7.     f(arr[0]);
8. end;
9. {$POP}
10.  
11. var
12.   a : integer;
13. begin
14.   f(a);
15. end.

Renders:

Code: [Select]

fpc -CX -XXs -O4 tests.pas
Free Pascal Compiler version 3.1.1-r35333 [2017/01/26] for arm
Copyright (c) 1993-2017 by Florian Klaempfl and others
Target OS: Linux for ARMHF
Compiling tests.pas
tests.pas(14,6) Warning: Variable "a" does not seem to be initialized
Linking tests