Possible bug in FpDebug

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440bx:
Hello,

FPC v3.2.2 & Lazarus v3.99 (2024-10-23)

Consider the following code:
--- Code: Pascal [+][-]window.onload = function(){var x1 = document.getElementById("main_content_section"); if (x1) { var x = document.getElementsByClassName("geshi");for (var i = 0; i < x.length; i++) { x[i].style.maxHeight='none'; x[i].style.height = Math.min(x[i].clientHeight+15,306)+'px'; x[i].style.resize = "vertical";}};} ---{$APPTYPE CONSOLE} program _WatchEnums; uses Windows ; type {$PACKENUM 1} TDATA_TYPE = { prefix: dt_ } ( dt_not_examined = 0, dt_unknown, dt_code_first, dt_code_last, dt_data_first, dt_data_last, { make the filler and markers easy to recognize by setting their numeric } { values to easily identifiable numbers } dt_pe_filler_first = 240, { filler is supposed to be } dt_pe_filler_code, { inaccessible } dt_pe_filler_data, dt_pe_filler_last, dt_markers_first = 250, dt_marker_bottom, { bottom message map sentinel } dt_marker_top, { top " " " } dt_markers_last ); {$PACKENUM 4} type TRECORD = record field_value : DWORD; field_type : TDATA_TYPE; field_info : array[0..5] of DWORD; end; function AFunction : boolean;var Table : array[0..9] of TRECORD; ti : DWORD = 0; begin result := FALSE; ZeroMemory(@Table, sizeof(Table)); for ti := 0 to 3 do begin with Table[ti] do begin field_value := ti; Field_info[0] := ti; case ti of 0 : field_type := dt_marker_bottom; 1, 2 : field_type := dt_pe_filler_code; 3 : field_type := dt_marker_top; end; end; end; result := TRUE;end; begin AFunction(); readln;end. When watching the values of the "Table" array, the values of "field_type" are not as expected.

field_type is defined to be of type TDATA_TYPE which consists of all positive constants yet the watch window shows the values assigned to "field_type" to be negative. (please see attachment.)

Is the compiler posting incorrect symbols for TDATA_TYPE or is the debugger (FpDebug) misinterpreting them ?

it would be nice if the values in the watch window were as they are defined in the data type, i.e, 240 241 instead of -15, 250 251 instead of -5 and 251 252 instead of -4.

comments welcome.

ETA:

Added forgotten attachment.

Corrected the expected values which were originally off by one in the text.

Martin_fr:
Please report.

Please copy the below to the report.

The issue is that fpc treats the enum as signed

--- Code: Pascal [+][-]window.onload = function(){var x1 = document.getElementById("main_content_section"); if (x1) { var x = document.getElementsByClassName("geshi");for (var i = 0; i < x.length; i++) { x[i].style.maxHeight='none'; x[i].style.height = Math.min(x[i].clientHeight+15,306)+'px'; x[i].style.resize = "vertical";}};} ---type TFoo= (f1=1, f2=$FFFFFFFF); gives

--- Code: Text [+][-]window.onload = function(){var x1 = document.getElementById("main_content_section"); if (x1) { var x = document.getElementsByClassName("geshi");for (var i = 0; i < x.length; i++) { x[i].style.maxHeight='none'; x[i].style.height = Math.min(x[i].clientHeight+15,306)+'px'; x[i].style.resize = "vertical";}};} ---project1.lpr(7,28) Error: Enumeration symbols can only have values in the range of -2^31 to 2^31-1
Your enum has a value of $FF

FPC marks it as being a 1 byte sized value. => so the debugger sees it has -1.

But fpc does write the value as a 4 byte constant 000000FF.
And for a 1 byte enum with actually -1 it writes the constant FFFFFFFF.

That may also differ between fpc versions.

Martin_fr:
This may be really tricky to fix.... Maybe not at all.

--- Code: Pascal [+][-]window.onload = function(){var x1 = document.getElementById("main_content_section"); if (x1) { var x = document.getElementsByClassName("geshi");for (var i = 0; i < x.length; i++) { x[i].style.maxHeight='none'; x[i].style.height = Math.min(x[i].clientHeight+15,306)+'px'; x[i].style.resize = "vertical";}};} ---program Project1;{$PackEnum 1}type Tfoo = (f1=-1, f2=255);var a,b: TFoo;begin a:= f1; b:= f2; b:= f2;end.
Both variables have the value $FF

There is no way the debugger can tell if $FF is -1 or 255

So if we have a 1 byte value. And if enums are generally signed...
Then if the debugger finds $FF that is -1

Martin_fr:
There is another issue ... https://gitlab.com/freepascal.org/lazarus/lazarus/-/issues/41240

But that does not affect the display you have

Martin_fr:
https://lists.freepascal.org/pipermail/fpc-devel/2024-November/045825.html

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