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Postings from June 2016
On Fri May 27 17:55:20 2016, sprout wrote: > It’s more complicated than that. vec does accept $_+1 if vec itself > is in rvalue context, so its actual behaviour cannot be represented > perfectly with a prototype. > > > Also, those ‘Can't modify’ messages cite the wrong op (list/scalar > > assignment instead of vec). > > That’s actually a clue to the problem. Scalar assignment dies at > compile time, but list assignment goes on to do the wrong thing (and > fail an assertion) at run time, because vec’s own type of lvalue > context is being propagated, whereas it probably should not be. > > $ perl -we 'vec(%a,0,1)=0' > Can't modify hash dereference in scalar assignment at -e line 1, at > EOF > Execution of -e aborted due to compilation errors. > $ perl -we '(vec%a,0,1)=0' > Name "main::a" used only once: possible typo at -e line 1. > Use of uninitialized value within %a in vec at -e line 1. > Can't coerce HASH to string in aassign at -e line 1. > > vec is not the only problematic operator. > > $ ./perl -we '(substr %a,0,1)=0' > Name "main::a" used only once: possible typo at -e line 1. > Can't coerce HASH to string in list assignment at -e line 1. > $ ./perl -we 'substr(%a,0,1)=0' > Can't modify hash dereference in scalar assignment at -e line 1, at > EOF > Execution of -e aborted due to compilation errors. > > The second one dies at compile time; the first one does the wrong > thing at run time. Same problem. Should assignment to substr(keys) be allowed? $ ./perl -le 'substr(keys %h,1) = 3; print "ok"' ok $ ./perl -e '(substr keys %h,1) = 3;' Can't modify keys in list assignment at -e line 1, near "3;" Execution of -e aborted due to compilation errors. (The logic in op.c:op_lvalue_flags is really broken.) Currently assignment to substr(keys) actually does something: $ ./perl -le 'substr(keys %h,1) = 3; use Devel::Peek; Dump %h' ok SV = PVHV(0x7fb14c00aea0) at 0x7fb14c02b7e0 REFCNT = 1 FLAGS = (OOK,SHAREKEYS) AUX_FLAGS = 0 ARRAY = 0x7fb14bc09970 KEYS = 0 FILL = 0 (cached = 0) MAX = 7 RITER = -1 EITER = 0x0 RAND = 0x34097f19 $ ./perl -le 'substr(keys %h,1) = 30; use Devel::Peek; Dump %h' ok SV = PVHV(0x7fa35880aea0) at 0x7fa35882b7e0 REFCNT = 1 FLAGS = (OOK,SHAREKEYS) AUX_FLAGS = 0 ARRAY = 0x7fa358412350 KEYS = 0 FILL = 0 (cached = 0) MAX = 31 RITER = -1 EITER = 0x0 RAND = 0x77bd0a5d (See the MAX line, indicating the highest bucket index.) I just want to know if I should go ahead and break that, which would be the easiest way to fix the other bugs in this ticket. -- Father Chrysostomos --- via perlbug: queue: perl5 status: open https://rt.perl.org/Ticket/Display.html?id=128260Thread Previous | Thread Next