Progress on pure functions

4 messages · 1 person · 8-12-2023 – 8-17-2023

J. Gareth Moreton 4

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J. Gareth Moreton8-12-2023 17:14 UTC

Hi everyone,

So I'm still working on pure functions and have pushed some merge requests that are indirectly related to it, mostly simplifying the node tree so it can more easily be collapsed into simple assignments (what pure functions should simplify to). Negative testing is still limited, but I have stumbled across one potential problem. Using the following code example:

program pure1a;
{$MODE OBJFPC}
{$COPERATORS ON}
function Factorial(N: Cardinal): Cardinal; pure;
   var
     X: Integer;
   begin
     Result := 1;
     for X := N downto 2 do
       Result *= X;
   end;
begin
   WriteLn(Factorial(32));
end.

For those not familiar with the factorial function, the result increases in value very quickly to the point that 13! > 2^32 (LongWord), 21! > 2^64 (QWord) and 70! > 10^100 (a googol), so 32! is guaranteed to overflow.

Having not really handled this eventuality just yet, I decided to see what happens when the compiler runs it as is:

pure1a.pp(15,24) Warning: Range check error while evaluating constants
(6227020800 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(27048749056 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(19184179200 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(32068960256 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(34071216128 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-288522240 must be between 0 and 4294967295)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(4006445056 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-5193400320 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-898433024 must be between 0 and 4294967295)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(3396534272 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-17070227456 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-2102132736 must be between 0 and 4294967295)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(2192834560 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-44144787456 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-1195114496 must be between 0 and 4294967295)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(3099852800 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-26292518912 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-522715136 must be between 0 and 4294967295)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(3772252160 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-12022448128 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(20698890240 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-775946240 must be between 0 and 4294967295)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(3519021056 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-19398656000 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(53980692480 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-1853882368 must be between 0 and 4294967295)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(2441084928 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-50054823936 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(41573941248 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-1375731712 must be between 0 and 4294967295)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(2919235584 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-39896219648 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-1241513984 must be between 0 and 4294967295)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(3053453312 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-37245419520 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(43687870464 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(23622320128 must be between -2147483648 and 2147483647)
pure1a.pp(15,24) Warning: Range check error while evaluating constants
(-2147483648 must be between 0 and 4294967295)

Not an ideal cascade of warnings. I figured it might be better to throw an error instead, so during the processing of pure functions, I enforced range and overflow checking:

pure1a.pp(15,24) Error: Range check error while evaluating constants (6227020800 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (27048749056 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (19184179200 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (32068960256 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (34071216128 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-288522240 must be between 0 and 4294967295)
pure1a.pp(15,24) Error: Range check error while evaluating constants (4006445056 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-5193400320 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-898433024 must be between 0 and 4294967295)
pure1a.pp(15,24) Error: Range check error while evaluating constants (3396534272 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-17070227456 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (2192834560 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-2102132736 must be between 0 and 4294967295)
pure1a.pp(15,24) Error: Range check error while evaluating constants (2192834560 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-44144787456 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-1195114496 must be between 0 and 4294967295)
pure1a.pp(15,24) Error: Range check error while evaluating constants (3099852800 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-26292518912 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-522715136 must be between 0 and 4294967295)
pure1a.pp(15,24) Error: Range check error while evaluating constants (3772252160 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-12022448128 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (20698890240 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-775946240 must be between 0 and 4294967295)
pure1a.pp(15,24) Error: Range check error while evaluating constants (3519021056 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-19398656000 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (53980692480 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-1853882368 must be between 0 and 4294967295)
pure1a.pp(15,24) Error: Range check error while evaluating constants (2441084928 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-50054823936 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (41573941248 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-1375731712 must be between 0 and 4294967295)
pure1a.pp(15,24) Error: Range check error while evaluating constants (2919235584 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-39896219648 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-1241513984 must be between 0 and 4294967295)
pure1a.pp(15,24) Error: Range check error while evaluating constants (3053453312 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-37245419520 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (43687870464 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (23622320128 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-2147483648 must be between 0 and 4294967295)
pure1a.pp(17) Fatal: There were 39 errors compiling module, stopping Fatal: Compilation aborted

This is not much better and is very unhelpful and untidy in an error log. Since the node tree is expanded during pure function analysis (in this case, the for-loop is unrolled) and each node points to the function call, each compiler message thus points here. Ideally there should only be one warning/error message, but since these messages are generated elsewhere in the node compilation process, it's not that easy to catch it and drop out the instant an error is thrown.

So to ask. If during analysis an overflow/range check error occurs, how do you think it should be handled? And does anyone have tips on how to program the compiler to immediately stop processing if a single error is found or to otherwise suppress subsequent messages that point to the same file location?

Kit

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J. Gareth Moreton8-16-2023 03:02 UTC

to J. Gareth Moreton

So managed to stop the cascade in a fairly clean way (it detects the difference in ErrorCount, marks the call node as erroneous and flags "codegenerror"), and it seems to work.

pure1a.pp(15,24) Error: Range check error while evaluating constants (6227020800 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: At least 1 error(s) occurred during the purity analysis of subroutine "Factorial".
pure1a.pp(17) Fatal: There were 2 errors compiling module, stopping Fatal: Compilation aborted

The message says "at least X error(s)" because other errors may get masked.

My recursive version of the factorial function doesn't quite simplify properly yet (it compiles successfully, but the call is a regular call and a warning is generated):

pure1b.pp(15,23) Warning: Subroutine "Factorial" is not eligible to be a pure function due to the following reason: analysis did not produce simple assignment.

Being a warning, this cascades and is generated multiple times (the number of times depends on how deep the recursion goes). I'll work on suppressing the cascade too since when this warning is triggered, the "pure" flag is removed from the subroutine.

Currently the "analysis did not produce simple assignment" part is a hard-coded string and not a part of errore.msg, for exmaple, so there may need to be a way to adapt this to be multi-lingual.

Kit

J. Gareth Moreton wrote 216 lines

Hi everyone, So I'm still working on pure functions and have pushed some merge requests that are indirectly related to it, mostly simplifying the node tree so it can more easily be collapsed into simple assignments (what pure functions should simplify to). Negative testing is still limited, but I have stumbled across one potential problem. Using the following code example: program pure1a; {$MODE OBJFPC} {$COPERATORS ON} function Factorial(N: Cardinal): Cardinal; pure; var X: Integer; begin Result := 1; for X := N downto 2 do Result *= X; end; begin WriteLn(Factorial(32)); end. For those not familiar with the factorial function, the result increases in value very quickly to the point that 13! > 2^32 (LongWord), 21! > 2^64 (QWord) and 70! > 10^100 (a googol), so 32! is guaranteed to overflow. Having not really handled this eventuality just yet, I decided to see what happens when the compiler runs it as is: pure1a.pp(15,24) Warning: Range check error while evaluating constants (6227020800 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (27048749056 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (19184179200 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (32068960256 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (34071216128 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-288522240 must be between 0 and 4294967295) pure1a.pp(15,24) Warning: Range check error while evaluating constants (4006445056 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-5193400320 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-898433024 must be between 0 and 4294967295) pure1a.pp(15,24) Warning: Range check error while evaluating constants (3396534272 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-17070227456 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-2102132736 must be between 0 and 4294967295) pure1a.pp(15,24) Warning: Range check error while evaluating constants (2192834560 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-44144787456 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-1195114496 must be between 0 and 4294967295) pure1a.pp(15,24) Warning: Range check error while evaluating constants (3099852800 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-26292518912 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-522715136 must be between 0 and 4294967295) pure1a.pp(15,24) Warning: Range check error while evaluating constants (3772252160 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-12022448128 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (20698890240 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-775946240 must be between 0 and 4294967295) pure1a.pp(15,24) Warning: Range check error while evaluating constants (3519021056 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-19398656000 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (53980692480 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-1853882368 must be between 0 and 4294967295) pure1a.pp(15,24) Warning: Range check error while evaluating constants (2441084928 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-50054823936 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (41573941248 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-1375731712 must be between 0 and 4294967295) pure1a.pp(15,24) Warning: Range check error while evaluating constants (2919235584 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-39896219648 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-1241513984 must be between 0 and 4294967295) pure1a.pp(15,24) Warning: Range check error while evaluating constants (3053453312 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-37245419520 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (43687870464 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (23622320128 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Warning: Range check error while evaluating constants (-2147483648 must be between 0 and 4294967295) Not an ideal cascade of warnings. I figured it might be better to throw an error instead, so during the processing of pure functions, I enforced range and overflow checking: pure1a.pp(15,24) Error: Range check error while evaluating constants (6227020800 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (27048749056 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (19184179200 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (32068960256 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (34071216128 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-288522240 must be between 0 and 4294967295) pure1a.pp(15,24) Error: Range check error while evaluating constants (4006445056 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-5193400320 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-898433024 must be between 0 and 4294967295) pure1a.pp(15,24) Error: Range check error while evaluating constants (3396534272 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-17070227456 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (2192834560 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-2102132736 must be between 0 and 4294967295) pure1a.pp(15,24) Error: Range check error while evaluating constants (2192834560 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-44144787456 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-1195114496 must be between 0 and 4294967295) pure1a.pp(15,24) Error: Range check error while evaluating constants (3099852800 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-26292518912 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-522715136 must be between 0 and 4294967295) pure1a.pp(15,24) Error: Range check error while evaluating constants (3772252160 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-12022448128 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (20698890240 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-775946240 must be between 0 and 4294967295) pure1a.pp(15,24) Error: Range check error while evaluating constants (3519021056 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-19398656000 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (53980692480 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-1853882368 must be between 0 and 4294967295) pure1a.pp(15,24) Error: Range check error while evaluating constants (2441084928 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-50054823936 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (41573941248 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-1375731712 must be between 0 and 4294967295) pure1a.pp(15,24) Error: Range check error while evaluating constants (2919235584 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-39896219648 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-1241513984 must be between 0 and 4294967295) pure1a.pp(15,24) Error: Range check error while evaluating constants (3053453312 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-37245419520 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (43687870464 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (23622320128 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: Range check error while evaluating constants (-2147483648 must be between 0 and 4294967295) pure1a.pp(17) Fatal: There were 39 errors compiling module, stopping Fatal: Compilation aborted This is not much better and is very unhelpful and untidy in an error log. Since the node tree is expanded during pure function analysis (in this case, the for-loop is unrolled) and each node points to the function call, each compiler message thus points here. Ideally there should only be one warning/error message, but since these messages are generated elsewhere in the node compilation process, it's not that easy to catch it and drop out the instant an error is thrown. So to ask. If during analysis an overflow/range check error occurs, how do you think it should be handled? And does anyone have tips on how to program the compiler to immediately stop processing if a single error is found or to otherwise suppress subsequent messages that point to the same file location? Kit _______________________________________________ fpc-devel maillist - https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel

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J. Gareth Moreton8-16-2023 04:05 UTC

to J. Gareth Moreton

Kit

J. Gareth Moreton wrote 254 lines

So managed to stop the cascade in a fairly clean way (it detects the difference in ErrorCount, marks the call node as erroneous and flags "codegenerror"), and it seems to work. pure1a.pp(15,24) Error: Range check error while evaluating constants (6227020800 must be between -2147483648 and 2147483647) pure1a.pp(15,24) Error: At least 1 error(s) occurred during the purity analysis of subroutine "Factorial". pure1a.pp(17) Fatal: There were 2 errors compiling module, stopping Fatal: Compilation aborted The message says "at least X error(s)" because other errors may get masked. My recursive version of the factorial function doesn't quite simplify properly yet (it compiles successfully, but the call is a regular call and a warning is generated): pure1b.pp(15,23) Warning: Subroutine "Factorial" is not eligible to be a pure function due to the following reason: analysis did not produce simple assignment. Being a warning, this cascades and is generated multiple times (the number of times depends on how deep the recursion goes). I'll work on suppressing the cascade too since when this warning is triggered, the "pure" flag is removed from the subroutine. Currently the "analysis did not produce simple assignment" part is a hard-coded string and not a part of errore.msg, for exmaple, so there may need to be a way to adapt this to be multi-lingual. Kit On 12/08/2023 18:14, J. Gareth Moreton via fpc-devel wrote: > Hi everyone, > > So I'm still working on pure functions and have pushed some merge > requests that are indirectly related to it, mostly simplifying the > node tree so it can more easily be collapsed into simple assignments > (what pure functions should simplify to). Negative testing is still > limited, but I have stumbled across one potential problem. Using the > following code example: > > program pure1a; > {$MODE OBJFPC} > {$COPERATORS ON} > > function Factorial(N: Cardinal): Cardinal; pure; > var > X: Integer; > begin > Result := 1; > for X := N downto 2 do > Result *= X; > end; > > begin > WriteLn(Factorial(32)); > end. > > For those not familiar with the factorial function, the result > increases in value very quickly to the point that 13! > 2^32 > (LongWord), 21! > 2^64 (QWord) and 70! > 10^100 (a googol), so 32! is > guaranteed to overflow. > > Having not really handled this eventuality just yet, I decided to see > what happens when the compiler runs it as is: > > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (6227020800 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (27048749056 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (19184179200 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (32068960256 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (34071216128 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-288522240 must be between 0 and 4294967295) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (4006445056 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-5193400320 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-898433024 must be between 0 and 4294967295) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (3396534272 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-17070227456 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-2102132736 must be between 0 and 4294967295) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (2192834560 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-44144787456 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-1195114496 must be between 0 and 4294967295) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (3099852800 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-26292518912 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-522715136 must be between 0 and 4294967295) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (3772252160 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-12022448128 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (20698890240 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-775946240 must be between 0 and 4294967295) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (3519021056 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-19398656000 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (53980692480 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-1853882368 must be between 0 and 4294967295) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (2441084928 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-50054823936 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (41573941248 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-1375731712 must be between 0 and 4294967295) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (2919235584 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-39896219648 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-1241513984 must be between 0 and 4294967295) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (3053453312 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-37245419520 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (43687870464 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (23622320128 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Warning: Range check error while evaluating > constants (-2147483648 must be between 0 and 4294967295) > > Not an ideal cascade of warnings. I figured it might be better to > throw an error instead, so during the processing of pure functions, I > enforced range and overflow checking: > > pure1a.pp(15,24) Error: Range check error while evaluating constants > (6227020800 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (27048749056 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (19184179200 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (32068960256 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (34071216128 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-288522240 must be between 0 and 4294967295) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (4006445056 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-5193400320 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-898433024 must be between 0 and 4294967295) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (3396534272 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-17070227456 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (2192834560 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-2102132736 must be between 0 and 4294967295) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (2192834560 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-44144787456 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-1195114496 must be between 0 and 4294967295) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (3099852800 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-26292518912 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-522715136 must be between 0 and 4294967295) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (3772252160 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-12022448128 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (20698890240 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-775946240 must be between 0 and 4294967295) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (3519021056 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-19398656000 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (53980692480 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-1853882368 must be between 0 and 4294967295) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (2441084928 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-50054823936 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (41573941248 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-1375731712 must be between 0 and 4294967295) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (2919235584 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-39896219648 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-1241513984 must be between 0 and 4294967295) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (3053453312 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-37245419520 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (43687870464 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (23622320128 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: Range check error while evaluating constants > (-2147483648 must be between 0 and 4294967295) > pure1a.pp(17) Fatal: There were 39 errors compiling module, stopping > Fatal: Compilation aborted > > This is not much better and is very unhelpful and untidy in an error > log. Since the node tree is expanded during pure function analysis > (in this case, the for-loop is unrolled) and each node points to the > function call, each compiler message thus points here. Ideally there > should only be one warning/error message, but since these messages > are generated elsewhere in the node compilation process, it's not > that easy to catch it and drop out the instant an error is thrown. > > So to ask. If during analysis an overflow/range check error occurs, > how do you think it should be handled? And does anyone have tips on > how to program the compiler to immediately stop processing if a > single error is found or to otherwise suppress subsequent messages > that point to the same file location? > > Kit > > _______________________________________________ > fpc-devel maillist - > https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel > _______________________________________________ fpc-devel maillist - https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel

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J. Gareth Moreton8-17-2023 09:46 UTC

to J. Gareth Moreton

Getting there! I'm having one sticking point, and that's with pure functions of the following design:

procedure Factorial(N: Cardinal; out R: Cardinal); pure;
   begin
     if N < 2 then
       R := 1
     else
       begin
         Factorial(N - 1, R);
         R *= N;
       end;
   end;

Because of the recursive nature with the "out" parameter, it gets flagged as "address taken" and, as a result, constant propagation will not function. The deepest level of recursion works because it essentially collapses into just "R := 1" and this can be inserted in place of "Factorial(N - 1, R);" when N = 2, but constant propagation refuses to go any further.

I can't modify the symtable because pure functions may have to be called as regular functions (in the above example, if Factorial is called where the actual parameter for N is a variable, it won't be analysed) so I'm trying to work out if I can create a temporary procdef and symtable. So far I haven't had much luck, but I'll keep up the work.

Kit

J. Gareth Moreton wrote 266 lines

Fixed my problem with the recursive function (enabling range check and overflow errors blocked dead-store elimination, so I worked around that) and the warning no longer cascades. Progress is being made! Kit On 16/08/2023 04:02, J. Gareth Moreton via fpc-devel wrote: > So managed to stop the cascade in a fairly clean way (it detects the > difference in ErrorCount, marks the call node as erroneous and flags > "codegenerror"), and it seems to work. > > pure1a.pp(15,24) Error: Range check error while evaluating constants > (6227020800 must be between -2147483648 and 2147483647) > pure1a.pp(15,24) Error: At least 1 error(s) occurred during the > purity analysis of subroutine "Factorial". > pure1a.pp(17) Fatal: There were 2 errors compiling module, stopping > Fatal: Compilation aborted > > The message says "at least X error(s)" because other errors may get > masked. > > My recursive version of the factorial function doesn't quite simplify > properly yet (it compiles successfully, but the call is a regular > call and a warning is generated): > > pure1b.pp(15,23) Warning: Subroutine "Factorial" is not eligible to > be a pure function due to the following reason: analysis did not > produce simple assignment. > > Being a warning, this cascades and is generated multiple times (the > number of times depends on how deep the recursion goes). I'll work on > suppressing the cascade too since when this warning is triggered, the > "pure" flag is removed from the subroutine. > > Currently the "analysis did not produce simple assignment" part is a > hard-coded string and not a part of errore.msg, for exmaple, so there > may need to be a way to adapt this to be multi-lingual. > > Kit > > On 12/08/2023 18:14, J. Gareth Moreton via fpc-devel wrote: >> Hi everyone, >> >> So I'm still working on pure functions and have pushed some merge >> requests that are indirectly related to it, mostly simplifying the >> node tree so it can more easily be collapsed into simple assignments >> (what pure functions should simplify to). Negative testing is still >> limited, but I have stumbled across one potential problem. Using >> the following code example: >> >> program pure1a; >> {$MODE OBJFPC} >> {$COPERATORS ON} >> >> function Factorial(N: Cardinal): Cardinal; pure; >> var >> X: Integer; >> begin >> Result := 1; >> for X := N downto 2 do >> Result *= X; >> end; >> >> begin >> WriteLn(Factorial(32)); >> end. >> >> For those not familiar with the factorial function, the result >> increases in value very quickly to the point that 13! > 2^32 >> (LongWord), 21! > 2^64 (QWord) and 70! > 10^100 (a googol), so 32! >> is guaranteed to overflow. >> >> Having not really handled this eventuality just yet, I decided to >> see what happens when the compiler runs it as is: >> >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (6227020800 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (27048749056 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (19184179200 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (32068960256 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (34071216128 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-288522240 must be between 0 and 4294967295) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (4006445056 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-5193400320 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-898433024 must be between 0 and 4294967295) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (3396534272 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-17070227456 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-2102132736 must be between 0 and 4294967295) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (2192834560 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-44144787456 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-1195114496 must be between 0 and 4294967295) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (3099852800 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-26292518912 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-522715136 must be between 0 and 4294967295) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (3772252160 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-12022448128 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (20698890240 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-775946240 must be between 0 and 4294967295) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (3519021056 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-19398656000 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (53980692480 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-1853882368 must be between 0 and 4294967295) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (2441084928 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-50054823936 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (41573941248 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-1375731712 must be between 0 and 4294967295) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (2919235584 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-39896219648 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-1241513984 must be between 0 and 4294967295) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (3053453312 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-37245419520 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (43687870464 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (23622320128 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Warning: Range check error while evaluating >> constants (-2147483648 must be between 0 and 4294967295) >> >> Not an ideal cascade of warnings. I figured it might be better to >> throw an error instead, so during the processing of pure functions, >> I enforced range and overflow checking: >> >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (6227020800 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (27048749056 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (19184179200 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (32068960256 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (34071216128 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-288522240 must be between 0 and 4294967295) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (4006445056 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-5193400320 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-898433024 must be between 0 and 4294967295) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (3396534272 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-17070227456 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (2192834560 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-2102132736 must be between 0 and 4294967295) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (2192834560 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-44144787456 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-1195114496 must be between 0 and 4294967295) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (3099852800 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-26292518912 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-522715136 must be between 0 and 4294967295) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (3772252160 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-12022448128 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (20698890240 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-775946240 must be between 0 and 4294967295) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (3519021056 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-19398656000 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (53980692480 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-1853882368 must be between 0 and 4294967295) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (2441084928 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-50054823936 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (41573941248 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-1375731712 must be between 0 and 4294967295) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (2919235584 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-39896219648 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-1241513984 must be between 0 and 4294967295) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (3053453312 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-37245419520 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (43687870464 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (23622320128 must be between -2147483648 and 2147483647) >> pure1a.pp(15,24) Error: Range check error while evaluating constants >> (-2147483648 must be between 0 and 4294967295) >> pure1a.pp(17) Fatal: There were 39 errors compiling module, stopping >> Fatal: Compilation aborted >> >> This is not much better and is very unhelpful and untidy in an error >> log. Since the node tree is expanded during pure function analysis >> (in this case, the for-loop is unrolled) and each node points to the >> function call, each compiler message thus points here. Ideally >> there should only be one warning/error message, but since these >> messages are generated elsewhere in the node compilation process, >> it's not that easy to catch it and drop out the instant an error is >> thrown. >> >> So to ask. If during analysis an overflow/range check error occurs, >> how do you think it should be handled? And does anyone have tips on >> how to program the compiler to immediately stop processing if a >> single error is found or to otherwise suppress subsequent messages >> that point to the same file location? >> >> Kit >> >> _______________________________________________ >> fpc-devel maillist - >> https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel >> > _______________________________________________ > fpc-devel maillist - > https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel > _______________________________________________ fpc-devel maillist - https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel

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