Re: [fpc-devel] Different handling of try..except depending on OS?
Op 2020-12-10 om 21:57 schreef Sven Barth via fpc-devel: Am 10.12.2020 um 20:54 schrieb Bart via fpc-devel: No fpc in your linux vm ? I'm shocked... ;-) Well, no trunk ;-) On Windows I know how to easily switch between using compilers. 3.2.0 is in path and I have some batch files to change that for 3.0.4 and trunk respectively (only in the current console session). I never had the courage to figure out how to do that on linux (in such a way it does not interfere with my normal setup). I use a script to change symlinks that are inside a directory that's in PATH. In the past I used the -V parameter a lot. -V Append '-' to the used compiler binary name (e.g. for version) This allows to make symlinks like e.g. ppcx64-3.0 to /usr/local/lib/fpc/3.0.4/ppcx64 and then compile with fpc -V3.0 etc. Of course this meant that the fpc.cfg had to be carefully crafted with $FPCVERSION The biggest drawback is that it only goes for the compiler not for the other binaries. AND it requires a parameter, but for a quick check with an old/release compiler that is enough. ___ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
Re: [fpc-devel] Different handling of try..except depending on OS?
Am 10.12.2020 um 20:54 schrieb Bart via fpc-devel: No fpc in your linux vm ? I'm shocked... ;-) Well, no trunk ;-) On Windows I know how to easily switch between using compilers. 3.2.0 is in path and I have some batch files to change that for 3.0.4 and trunk respectively (only in the current console session). I never had the courage to figure out how to do that on linux (in such a way it does not interfere with my normal setup). I use a script to change symlinks that are inside a directory that's in PATH. Regards, Sven ___ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
Re: [fpc-devel] Different handling of try..except depending on OS?
> No fpc in your linux vm ? I'm shocked... ;-) Well, no trunk ;-) On Windows I know how to easily switch between using compilers. 3.2.0 is in path and I have some batch files to change that for 3.0.4 and trunk respectively (only in the current console session). I never had the courage to figure out how to do that on linux (in such a way it does not interfere with my normal setup). -- Bart ___ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
Re: [fpc-devel] Different handling of try..except depending on OS?
On Thu, Dec 10, 2020 at 11:53 AM Michael Van Canneyt via fpc-devel wrote: > > Yes, it should. it's definitely a bug. Done: https://bugs.freepascal.org/view.php?id=38201 -- Bart ___ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
Re: [fpc-devel] Different handling of try..except depending on OS?
Bart via fpc-devel schrieb am Do., 10. Dez. 2020, 11:56: > On Thu, Dec 10, 2020 at 7:34 AM Sven Barth via fpc-devel > wrote: > > > That is correct, because without the SysUtils unit (which declared the > > Exception type) the RTL can't convert the triggered runtime error to an > > exception type that can be caught inside the try ... except ... end > block. > > I would have expected that in that scenario (no sysutils) try..except > or try..finally should raise a compilation error then. > Since you teel the compiler to do things it cannot do? > It would be Delphi incompatible of course ... > The *compiler* handles it correctly. It's the *RTL* that's not setup in a way that it would work correctly in that case. And since in theory the user is completely free to provide their own RTL the compiler can't do any checks here. > B.t.w. (cannot test now, am at work): does it catc exceptions if any > other used unit in the main program uses sysutils? > I.o.w.: is it enough if sysutils gets linked in, or must it be in the > unit/prgram that actually has the try..except/try..finally code in it? > The initialization section of the SysUtils unit needs to be executed, so as long as any other unit includes the SysUtils unit it will work. Regards, Sven ___ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
Re: [fpc-devel] Different handling of try..except depending on OS?
On Thu, 10 Dec 2020, Tomas Hajny via fpc-devel wrote: On 2020-12-10 07:34, Sven Barth via fpc-devel wrote: Am 09.12.2020 um 23:45 schrieb Bart via fpc-devel: Compiled with fpc 3.2.0 on Windows it will output (both 32 and 64 bit): Runtime error 201 at $004015F1 $004015F1 $00407307 Compiled with fpc 3.2.0 on linux X86_64 it will output Except block Finally block On Windows you need to include the sysutils unit to execute the except and finally block. That is correct, because without the SysUtils unit (which declared the Exception type) the RTL can't convert the triggered runtime error to an exception type that can be caught inside the try ... except ... end block. . . Is the current behaviour on "other" (non-MS Windows) targets really correct (I checked under OS/2 for both 3.2.0 and trunk and it behaves the same way as Linux)? Including SysUtils should result in converting a run-time error to an exception. If SysUtils is not included, run-time error should be raised regardless from the try..except block (as it does under MS Windows, but not on other platforms at the moment), shouldn't it? Shouldn't the try..except construct by default (i.e. without using SysUtils) catch only explicitly raised exceptions? Yes, it should. it's definitely a bug. Michael. ___ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
Re: [fpc-devel] Different handling of try..except depending on OS?
On 2020-12-10 07:34, Sven Barth via fpc-devel wrote: Am 09.12.2020 um 23:45 schrieb Bart via fpc-devel: Compiled with fpc 3.2.0 on Windows it will output (both 32 and 64 bit): Runtime error 201 at $004015F1 $004015F1 $00407307 Compiled with fpc 3.2.0 on linux X86_64 it will output Except block Finally block On Windows you need to include the sysutils unit to execute the except and finally block. That is correct, because without the SysUtils unit (which declared the Exception type) the RTL can't convert the triggered runtime error to an exception type that can be caught inside the try ... except ... end block. . . Is the current behaviour on "other" (non-MS Windows) targets really correct (I checked under OS/2 for both 3.2.0 and trunk and it behaves the same way as Linux)? Including SysUtils should result in converting a run-time error to an exception. If SysUtils is not included, run-time error should be raised regardless from the try..except block (as it does under MS Windows, but not on other platforms at the moment), shouldn't it? Shouldn't the try..except construct by default (i.e. without using SysUtils) catch only explicitly raised exceptions? Tomas ___ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
Re: [fpc-devel] Different handling of try..except depending on OS?
On Thu, 10 Dec 2020, Bart via fpc-devel wrote: On Thu, Dec 10, 2020 at 7:34 AM Sven Barth via fpc-devel wrote: It's possibly related to FPC using SEH on Win32 and Win64 instead of the SetJump/LongJump based exception handling on other platforms. Slight differences are possible and we'd have to investigate why the later does not correctly trigger a runtime error. Should I file a bugreport for that? If so, someone should first confirm it with trunk (I don't have fpc trunk on my Linux VM). No fpc in your linux vm ? I'm shocked... ;-) I confirmed it with trunk. Michael. ___ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
Re: [fpc-devel] Different handling of try..except depending on OS?
On Thu, 10 Dec 2020, Bart via fpc-devel wrote:
On Thu, Dec 10, 2020 at 7:34 AM Sven Barth via fpc-devel
wrote:
That is correct, because without the SysUtils unit (which declared the
Exception type) the RTL can't convert the triggered runtime error to an
exception type that can be caught inside the try ... except ... end block.
I would have expected that in that scenario (no sysutils) try..except
or try..finally should raise a compilation error then.
Since you teel the compiler to do things it cannot do?
No.
Sysutils is only needed to convert run-time errors to exceptions.
You can perfectly use exceptions without sysutils, but they can not descend
from Exception, but from TObject. That exception classes descend from Exception
is a convention, not a compiler-enforced rule.
If you change your code to this
Except
On O : TObject do
Writeln('except block : ',O.ClassName)
You'll see there is no output, because there is no exception object.
The reason is as Sven surmised: the setjmp mechanism used on non-windows
platforms.
It would be Delphi incompatible of course ...
B.t.w. (cannot test now, am at work): does it catc exceptions if any
other used unit in the main program uses sysutils?
I.o.w.: is it enough if sysutils gets linked in, or must it be in the
unit/prgram that actually has the try..except/try..finally code in it?
It is enough that sysutils gets linked in.
I checked that, the program you sent does not have sysutils linked in.
Michael.
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Re: [fpc-devel] Different handling of try..except depending on OS?
On Thu, Dec 10, 2020 at 7:34 AM Sven Barth via fpc-devel wrote: > It's possibly related to FPC using SEH on Win32 and Win64 instead of the > SetJump/LongJump based exception handling on other platforms. Slight > differences are possible and we'd have to investigate why the later does > not correctly trigger a runtime error. Should I file a bugreport for that? If so, someone should first confirm it with trunk (I don't have fpc trunk on my Linux VM). -- Bart ___ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
Re: [fpc-devel] Different handling of try..except depending on OS?
On Thu, Dec 10, 2020 at 7:34 AM Sven Barth via fpc-devel wrote: > That is correct, because without the SysUtils unit (which declared the > Exception type) the RTL can't convert the triggered runtime error to an > exception type that can be caught inside the try ... except ... end block. I would have expected that in that scenario (no sysutils) try..except or try..finally should raise a compilation error then. Since you teel the compiler to do things it cannot do? It would be Delphi incompatible of course ... B.t.w. (cannot test now, am at work): does it catc exceptions if any other used unit in the main program uses sysutils? I.o.w.: is it enough if sysutils gets linked in, or must it be in the unit/prgram that actually has the try..except/try..finally code in it? > Behaves like 3.2.0 on what platform? I assume Windows, cause Delphi 10.2 Yes, on Windows. > It's possibly related to FPC using SEH on Win32 and Win64 instead of the > SetJump/LongJump based exception handling on other platforms. Slight > differences are possible and we'd have to investigate why the later does > not correctly trigger a runtime error. Ok. Not a big problem for me (I don't think I have any usefull program that doesn't include the sysutils unit), it just made me curious. -- Bart ___ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
Re: [fpc-devel] Different handling of try..except depending on OS?
Am 09.12.2020 um 23:45 schrieb Bart via fpc-devel: Compiled with fpc 3.2.0 on Windows it will output (both 32 and 64 bit): Runtime error 201 at $004015F1 $004015F1 $00407307 Compiled with fpc 3.2.0 on linux X86_64 it will output Except block Finally block On Windows you need to include the sysutils unit to execute the except and finally block. That is correct, because without the SysUtils unit (which declared the Exception type) the RTL can't convert the triggered runtime error to an exception type that can be caught inside the try ... except ... end block. Note 1: fpc 3.0.4 on Windows generates the same outpus as 3.2.0 on Linux... Note 2: Delphi 7 behaves like 3.2.0 Behaves like 3.2.0 on what platform? I assume Windows, cause Delphi 10.2 behaves the same as FPC 3.2.0 on Windows. Is there any explanation for that? Related forum discussion: https://forum.lazarus.freepascal.org/index.php/topic,52469.0/topicseen.html It's possibly related to FPC using SEH on Win32 and Win64 instead of the SetJump/LongJump based exception handling on other platforms. Slight differences are possible and we'd have to investigate why the later does not correctly trigger a runtime error. Regards, Sven ___ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
