[Gretl-devel] Re: CRASH: passed integer value out-of bounds
On Wed, 3 Mar 2021, atecon wrote: Am 03.03.2021 15:38 schrieb Allin Cottrell: That's right. "const" doesn't have any effect when placed in front of (non-pointerized) scalar arguments of any sort. Illustration: function void simple (const int N[2::]) printf "very simple (%d)\n", N # no error flagged here N = 24 end function Ah, I never checked that but simply assumed that the const qualifier would flag an error inside a function. function void dimple (const matrix m) printf "very dimple\n" # this does give an error m = m + 5 end function k = 7 simple(k) print k # note: k is still 7 dimple(I(3)) I guess this is a buglet: either "const" should be disallowed for plain scalar arguments, or else it should prevent changing the argument inside the function (although the caller will not inherit a change in any case). Yes, either case I guess. Personally I would favor that const is allowed for all data types (but there may be good reason why not to do so). It's not so much that there's good reason NOT to do so -- rather that there's little or no good reason to do so. Scalars are always passed by value unless they're explicitly pointerized. So if you mark a plain scalar argument as const, you're just tying your hands as a function writer. But... I guess in some contexts it could make sense as a guard against forgetfulness: e.g. you get a scalar n as argument, then forget that fact and assign a different value to n for some local purpose, thereby losing track of the input value. (This should be pretty much impossible in tightly modular code, but could be an issue with a function of many lines.) Allin ___ Gretl-devel mailing list -- gretl-devel@gretlml.univpm.it To unsubscribe send an email to gretl-devel-le...@gretlml.univpm.it Website: https://gretlml.univpm.it/postorius/lists/gretl-devel.gretlml.univpm.it/
[Gretl-devel] Re: CRASH: passed integer value out-of bounds
Am 03.03.2021 15:38 schrieb Allin Cottrell: On Wed, 3 Mar 2021, Sven Schreiber wrote: Am 03.03.2021 um 13:31 schrieb atecon: with latest git version under Ubuntu 18.04 I obtain a crash when running the following script: Confirmed with a recent snapshot on Windows. That one looks pretty bad, but... function void simple (const int N[2::]) ...it doesn't crash anymore for me when removing "const". And only Artur would put a const in front of an int ;-) Actually, I believe it is not supported by hansl to do "const int": The guide says "the const modifier may be used... for all the types that support the pointer apparatus". That's right. "const" doesn't have any effect when placed in front of (non-pointerized) scalar arguments of any sort. Illustration: function void simple (const int N[2::]) printf "very simple (%d)\n", N # no error flagged here N = 24 end function Ah, I never checked that but simply assumed that the const qualifier would flag an error inside a function. function void dimple (const matrix m) printf "very dimple\n" # this does give an error m = m + 5 end function k = 7 simple(k) print k # note: k is still 7 dimple(I(3)) I guess this is a buglet: either "const" should be disallowed for plain scalar arguments, or else it should prevent changing the argument inside the function (although the caller will not inherit a change in any case). Yes, either case I guess. Personally I would favor that const is allowed for all data types (but there may be good reason why not to do so). Artur ___ Gretl-devel mailing list -- gretl-devel@gretlml.univpm.it To unsubscribe send an email to gretl-devel-le...@gretlml.univpm.it Website: https://gretlml.univpm.it/postorius/lists/gretl-devel.gretlml.univpm.it/
[Gretl-devel] Re: CRASH: passed integer value out-of bounds
Am 03.03.2021 14:23 schrieb Allin Cottrell: On Wed, 3 Mar 2021, atecon wrote: with latest git version under Ubuntu 18.04 I obtain a crash when running the following script: clear set verbose off function void simple (const int N[2::]) print "very simple" end function simple(1) Ah, I think this was a newly introduced bug, specific to tearing down an invalid function call (in this case an out-of-bounds argument). That's now fixed in git. Thank you, Allin. Works as intended now. Artur ___ Gretl-devel mailing list -- gretl-devel@gretlml.univpm.it To unsubscribe send an email to gretl-devel-le...@gretlml.univpm.it Website: https://gretlml.univpm.it/postorius/lists/gretl-devel.gretlml.univpm.it/
[Gretl-devel] Re: CRASH: passed integer value out-of bounds
On Wed, 3 Mar 2021, Sven Schreiber wrote: Am 03.03.2021 um 13:31 schrieb atecon: with latest git version under Ubuntu 18.04 I obtain a crash when running the following script: Confirmed with a recent snapshot on Windows. That one looks pretty bad, but... function void simple (const int N[2::]) ...it doesn't crash anymore for me when removing "const". And only Artur would put a const in front of an int ;-) Actually, I believe it is not supported by hansl to do "const int": The guide says "the const modifier may be used... for all the types that support the pointer apparatus". That's right. "const" doesn't have any effect when placed in front of (non-pointerized) scalar arguments of any sort. Illustration: function void simple (const int N[2::]) printf "very simple (%d)\n", N # no error flagged here N = 24 end function function void dimple (const matrix m) printf "very dimple\n" # this does give an error m = m + 5 end function k = 7 simple(k) print k # note: k is still 7 dimple(I(3)) I guess this is a buglet: either "const" should be disallowed for plain scalar arguments, or else it should prevent changing the argument inside the function (although the caller will not inherit a change in any case). Allin ___ Gretl-devel mailing list -- gretl-devel@gretlml.univpm.it To unsubscribe send an email to gretl-devel-le...@gretlml.univpm.it Website: https://gretlml.univpm.it/postorius/lists/gretl-devel.gretlml.univpm.it/
[Gretl-devel] Re: CRASH: passed integer value out-of bounds
Am 03.03.2021 14:06 schrieb Sven Schreiber: Am 03.03.2021 um 13:31 schrieb atecon: with latest git version under Ubuntu 18.04 I obtain a crash when running the following script: Confirmed with a recent snapshot on Windows. That one looks pretty bad, but... Thanks for confirming this, Sven. function void simple (const int N[2::]) ...it doesn't crash anymore for me when removing "const". And only Artur would put a const in front of an int ;-) It also does not crash in case the lower bound is _not_ hit void simple (const int N[1::])> ;-) That is true. Writing const is such an automatism for me ;-) Even though the pointer speed effect is negligible in this case, I still have the "security effect" that the supposed to be constant parameter cannot be overwritten ;-) Actually, I believe it is not supported by hansl to do "const int": The guide says "the const modifier may be used... for all the types that support the pointer apparatus". And if you try the following function: function void simplestar ( int *N) print "very simple" end function you get the error message "unknown data type 'int *'". You have to use "scalar *N" instead. And indeed, the variant "const scalar N[2::])" works and doesn't crash. Yes, that sounds familiar to me. But of course the above is a bad bug anyway, and "const int" should be intercepted by gretl in the first place. Or may be not so given the other side effect I mentioned: the "security effect" ;-) Artur ___ Gretl-devel mailing list -- gretl-devel@gretlml.univpm.it To unsubscribe send an email to gretl-devel-le...@gretlml.univpm.it Website: https://gretlml.univpm.it/postorius/lists/gretl-devel.gretlml.univpm.it/
[Gretl-devel] Re: CRASH: passed integer value out-of bounds
On Wed, 3 Mar 2021, atecon wrote: with latest git version under Ubuntu 18.04 I obtain a crash when running the following script: clear set verbose off function void simple (const int N[2::]) print "very simple" end function simple(1) Ah, I think this was a newly introduced bug, specific to tearing down an invalid function call (in this case an out-of-bounds argument). That's now fixed in git. Allin ___ Gretl-devel mailing list -- gretl-devel@gretlml.univpm.it To unsubscribe send an email to gretl-devel-le...@gretlml.univpm.it Website: https://gretlml.univpm.it/postorius/lists/gretl-devel.gretlml.univpm.it/
[Gretl-devel] Re: CRASH: passed integer value out-of bounds
Am 03.03.2021 um 13:31 schrieb atecon: with latest git version under Ubuntu 18.04 I obtain a crash when running the following script: Confirmed with a recent snapshot on Windows. That one looks pretty bad, but... function void simple (const int N[2::]) ...it doesn't crash anymore for me when removing "const". And only Artur would put a const in front of an int ;-) Actually, I believe it is not supported by hansl to do "const int": The guide says "the const modifier may be used... for all the types that support the pointer apparatus". And if you try the following function: function void simplestar ( int *N) print "very simple" end function you get the error message "unknown data type 'int *'". You have to use "scalar *N" instead. And indeed, the variant "const scalar N[2::])" works and doesn't crash. But of course the above is a bad bug anyway, and "const int" should be intercepted by gretl in the first place. thanks sven ___ Gretl-devel mailing list -- gretl-devel@gretlml.univpm.it To unsubscribe send an email to gretl-devel-le...@gretlml.univpm.it Website: https://gretlml.univpm.it/postorius/lists/gretl-devel.gretlml.univpm.it/
