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perlman:perldiag

by gods
on Aug 25, 1999 at 07:15 UTC ( #421=perlman: print w/ replies, xml ) Need Help??

perldiag

Current Perl documentation can be found at perldoc.perl.org.

Here is our local, out-dated (pre-5.6) version:


NAME

perldiag - various Perl diagnostics


DESCRIPTION

These messages are classified as follows (listed in increasing order of desperation):

    (W) A warning (optional).
    (D) A deprecation (optional).
    (S) A severe warning (mandatory).
    (F) A fatal error (trappable).
    (P) An internal error you should never see (trappable).
    (X) A very fatal error (nontrappable).
    (A) An alien error message (not generated by Perl).

Optional warnings are enabled by using the -w switch. Warnings may be captured by setting $SIG{__WARN__} to a reference to a routine that will be called on each warning instead of printing it. See the perlvar manpage. Trappable errors may be trapped using the eval operator. See eval.

Some of these messages are generic. Spots that vary are denoted with a %s, just as in a printf format. Note that some messages start with a %s! The symbols "%(-?@ sort before the letters, while [ and \ sort after.

"my" variable %s can't be in a package

(F) Lexically scoped variables aren't in a package, so it doesn't make sense to try to declare one with a package qualifier on the front. Use local() if you want to localize a package variable.

"my" variable %s masks earlier declaration in same scope

(W) A lexical variable has been redeclared in the same scope, effectively eliminating all access to the previous instance. This is almost always a typographical error. Note that the earlier variable will still exist until the end of the scope or until all closure referents to it are destroyed.

"no" not allowed in expression

(F) The ``no'' keyword is recognized and executed at compile time, and returns no useful value. See the perlmod manpage.

"use" not allowed in expression

(F) The ``use'' keyword is recognized and executed at compile time, and returns no useful value. See the perlmod manpage.

% may only be used in unpack

(F) You can't pack a string by supplying a checksum, because the checksumming process loses information, and you can't go the other way. See unpack.

%s (...) interpreted as function

(W) You've run afoul of the rule that says that any list operator followed by parentheses turns into a function, with all the list operators arguments found inside the parentheses. See perlman:perlop.

%s argument is not a HASH element

(F) The argument to exists() must be a hash element, such as

    $foo{$bar}
    $ref->[12]->{"susie"}
%s argument is not a HASH element or slice

(F) The argument to delete() must be either a hash element, such as

    $foo{$bar}
    $ref->[12]->{"susie"}

or a hash slice, such as

    @foo{$bar, $baz, $xyzzy}
    @{$ref->[12]}{"susie", "queue"}
%s did not return a true value

(F) A required (or used) file must return a true value to indicate that it compiled correctly and ran its initialization code correctly. It's traditional to end such a file with a ``1;'', though any true value would do. See require.

%s found where operator expected

(S) The Perl lexer knows whether to expect a term or an operator. If it sees what it knows to be a term when it was expecting to see an operator, it gives you this warning. Usually it indicates that an operator or delimiter was omitted, such as a semicolon.

%s had compilation errors

(F) The final summary message when a perl -c fails.

%s has too many errors

(F) The parser has given up trying to parse the program after 10 errors. Further error messages would likely be uninformative.

%s matches null string many times

(W) The pattern you've specified would be an infinite loop if the regular expression engine didn't specifically check for that. See the perlre manpage.

%s never introduced

(S) The symbol in question was declared but somehow went out of scope before it could possibly have been used.

%s syntax OK

(F) The final summary message when a perl -c succeeds.

%s: Command not found

(A) You've accidentally run your script through csh instead of Perl. Check the #! line, or manually feed your script into Perl yourself.

%s: Expression syntax

(A) You've accidentally run your script through csh instead of Perl. Check the #! line, or manually feed your script into Perl yourself.

%s: Undefined variable

(A) You've accidentally run your script through csh instead of Perl. Check the #! line, or manually feed your script into Perl yourself.

%s: not found

(A) You've accidentally run your script through the Bourne shell instead of Perl. Check the #! line, or manually feed your script into Perl yourself.

(Missing semicolon on previous line?)

(S) This is an educated guess made in conjunction with the message ``%s found where operator expected''. Don't automatically put a semicolon on the previous line just because you saw this message.

-P not allowed for setuid/setgid script

(F) The script would have to be opened by the C preprocessor by name, which provides a race condition that breaks security.

-T and -B not implemented on filehandles

(F) Perl can't peek at the stdio buffer of filehandles when it doesn't know about your kind of stdio. You'll have to use a filename instead.

-p destination: %s

(F) An error occurred during the implicit output invoked by the -p command-line switch. (This output goes to STDOUT unless you've redirected it with select().)

  • Server error See Server error.

    ?+* follows nothing in regexp

    (F) You started a regular expression with a quantifier. Backslash it if you meant it literally. See the perlre manpage.

    @ outside of string

    (F) You had a pack template that specified an absolute position outside the string being unpacked. See pack.

    accept() on closed fd

    (W) You tried to do an accept on a closed socket. Did you forget to check the return value of your socket() call? See accept.

    Allocation too large: %lx

    (X) You can't allocate more than 64K on an MS-DOS machine.

    Applying %s to %s will act on scalar(%s)

    (W) The pattern match (//), substitution (s///), and transliteration (tr///) operators work on scalar values. If you apply one of them to an array or a hash, it will convert the array or hash to a scalar value -- the length of an array, or the population info of a hash -- and then work on that scalar value. This is probably not what you meant to do. See grep and map for alternatives.

    Arg too short for msgsnd

    (F) msgsnd() requires a string at least as long as sizeof(long).

    Ambiguous use of %s resolved as %s

    (W)(S) You said something that may not be interpreted the way you thought. Normally it's pretty easy to disambiguate it by supplying a missing quote, operator, parenthesis pair or declaration.

    Ambiguous call resolved as CORE::%s(), qualify as such or use &

    (W) A subroutine you have declared has the same name as a Perl keyword, and you have used the name without qualification for calling one or the other. Perl decided to call the builtin because the subroutine is not imported.

    To force interpretation as a subroutine call, either put an ampersand before the subroutine name, or qualify the name with its package. Alternatively, you can import the subroutine (or pretend that it's imported with the use subs pragma).

    To silently interpret it as the Perl operator, use the CORE:: prefix on the operator (e.g. CORE::log($x)) or by declaring the subroutine to be an object method (see the attrs manpage).

    Args must match #! line

    (F) The setuid emulator requires that the arguments Perl was invoked with match the arguments specified on the #! line. Since some systems impose a one-argument limit on the #! line, try combining switches; for example, turn -w -U into -wU.

    Argument "%s" isn't numeric%s

    (W) The indicated string was fed as an argument to an operator that expected a numeric value instead. If you're fortunate the message will identify which operator was so unfortunate.

    Array @%s missing the @ in argument %d of %s()

    (D) Really old Perl let you omit the @ on array names in some spots. This is now heavily deprecated.

    assertion botched: %s

    (P) The malloc package that comes with Perl had an internal failure.

    Assertion failed: file "%s"

    (P) A general assertion failed. The file in question must be examined.

    Assignment to both a list and a scalar

    (F) If you assign to a conditional operator, the 2nd and 3rd arguments must either both be scalars or both be lists. Otherwise Perl won't know which context to supply to the right side.

    Attempt to free non-arena SV: 0x%lx

    (P) All SV objects are supposed to be allocated from arenas that will be garbage collected on exit. An SV was discovered to be outside any of those arenas.

    Attempt to free nonexistent shared string

    (P) Perl maintains a reference counted internal table of strings to optimize the storage and access of hash keys and other strings. This indicates someone tried to decrement the reference count of a string that can no longer be found in the table.

    Attempt to free temp prematurely

    (W) Mortalized values are supposed to be freed by the free_tmps() routine. This indicates that something else is freeing the SV before the free_tmps() routine gets a chance, which means that the free_tmps() routine will be freeing an unreferenced scalar when it does try to free it.

    Attempt to free unreferenced glob pointers

    (P) The reference counts got screwed up on symbol aliases.

    Attempt to free unreferenced scalar

    (W) Perl went to decrement the reference count of a scalar to see if it would go to 0, and discovered that it had already gone to 0 earlier, and should have been freed, and in fact, probably was freed. This could indicate that SvREFCNT_dec() was called too many times, or that SvREFCNT_inc() was called too few times, or that the SV was mortalized when it shouldn't have been, or that memory has been corrupted.

    Attempt to pack pointer to temporary value

    (W) You tried to pass a temporary value (like the result of a function, or a computed expression) to the ``p'' pack() template. This means the result contains a pointer to a location that could become invalid anytime, even before the end of the current statement. Use literals or global values as arguments to the ``p'' pack() template to avoid this warning.

    Attempt to use reference as lvalue in substr

    (W) You supplied a reference as the first argument to substr() used as an lvalue, which is pretty strange. Perhaps you forgot to dereference it first. See substr.

    Bad arg length for %s, is %d, should be %d

    (F) You passed a buffer of the wrong size to one of msgctl(), semctl() or shmctl(). In C parlance, the correct sizes are, respectively, sizeof(struct msqid_ds *), sizeof(struct semid_ds *), and sizeof(struct shmid_ds *).

    Bad filehandle: %s

    (F) A symbol was passed to something wanting a filehandle, but the symbol has no filehandle associated with it. Perhaps you didn't do an open(), or did it in another package.

    Bad free() ignored

    (S) An internal routine called free() on something that had never been malloc()ed in the first place. Mandatory, but can be disabled by setting environment variable PERL_BADFREE to 1.

    This message can be quite often seen with DB_File on systems with ``hard'' dynamic linking, like AIX and OS/2. It is a bug of Berkeley DB which is left unnoticed if DB uses forgiving system malloc().

    Bad hash

    (P) One of the internal hash routines was passed a null HV pointer.

    Bad index while coercing array into hash

    (F) The index looked up in the hash found as the 0'th element of a pseudo-hash is not legal. Index values must be at 1 or greater. See the perlref manpage.

    Bad name after %s::

    (F) You started to name a symbol by using a package prefix, and then didn't finish the symbol. In particular, you can't interpolate outside of quotes, so

        $var = 'myvar';
        $sym = mypack::$var;
    

    is not the same as

        $var = 'myvar';
        $sym = "mypack::$var";
    
    Bad symbol for array

    (P) An internal request asked to add an array entry to something that wasn't a symbol table entry.

    Bad symbol for filehandle

    (P) An internal request asked to add a filehandle entry to something that wasn't a symbol table entry.

    Bad symbol for hash

    (P) An internal request asked to add a hash entry to something that wasn't a symbol table entry.

    Badly placed ()'s

    (A) You've accidentally run your script through csh instead of Perl. Check the #! line, or manually feed your script into Perl yourself.

    Bareword "%s" not allowed while "strict subs" in use

    (F) With ``strict subs'' in use, a bareword is only allowed as a subroutine identifier, in curly braces or to the left of the ``=>'' symbol. Perhaps you need to predeclare a subroutine?

    Bareword "%s" refers to nonexistent package

    (W) You used a qualified bareword of the form Foo::, but the compiler saw no other uses of that namespace before that point. Perhaps you need to predeclare a package?

    BEGIN failed--compilation aborted

    (F) An untrapped exception was raised while executing a BEGIN subroutine. Compilation stops immediately and the interpreter is exited.

    BEGIN not safe after errors--compilation aborted

    (F) Perl found a BEGIN {} subroutine (or a use directive, which implies a BEGIN {}) after one or more compilation errors had already occurred. Since the intended environment for the BEGIN {} could not be guaranteed (due to the errors), and since subsequent code likely depends on its correct operation, Perl just gave up.

    bind() on closed fd

    (W) You tried to do a bind on a closed socket. Did you forget to check the return value of your socket() call? See bind.

    Bizarre copy of %s in %s

    (P) Perl detected an attempt to copy an internal value that is not copiable.

    Callback called exit

    (F) A subroutine invoked from an external package via perl_call_sv() exited by calling exit.

    Can't "goto" outside a block

    (F) A ``goto'' statement was executed to jump out of what might look like a block, except that it isn't a proper block. This usually occurs if you tried to jump out of a sort() block or subroutine, which is a no-no. See goto.

    Can't "goto" into the middle of a foreach loop

    (F) A ``goto'' statement was executed to jump into the middle of a foreach loop. You can't get there from here. See goto.

    Can't "last" outside a block

    (F) A ``last'' statement was executed to break out of the current block, except that there's this itty bitty problem called there isn't a current block. Note that an ``if'' or ``else'' block doesn't count as a ``loopish'' block, as doesn't a block given to sort(). You can usually double the curlies to get the same effect though, because the inner curlies will be considered a block that loops once. See last.

    Can't "next" outside a block

    (F) A ``next'' statement was executed to reiterate the current block, but there isn't a current block. Note that an ``if'' or ``else'' block doesn't count as a ``loopish'' block, as doesn't a block given to sort(). You can usually double the curlies to get the same effect though, because the inner curlies will be considered a block that loops once. See next.

    Can't "redo" outside a block

    (F) A ``redo'' statement was executed to restart the current block, but there isn't a current block. Note that an ``if'' or ``else'' block doesn't count as a ``loopish'' block, as doesn't a block given to sort(). You can usually double the curlies to get the same effect though, because the inner curlies will be considered a block that loops once. See redo.

    Can't bless non-reference value

    (F) Only hard references may be blessed. This is how Perl ``enforces'' encapsulation of objects. See the perlobj manpage.

    Can't break at that line

    (S) A warning intended to only be printed while running within the debugger, indicating the line number specified wasn't the location of a statement that could be stopped at.

    Can't call method "%s" in empty package "%s"

    (F) You called a method correctly, and it correctly indicated a package functioning as a class, but that package doesn't have ANYTHING defined in it, let alone methods. See the perlobj manpage.

    Can't call method "%s" on unblessed reference

    (F) A method call must know in what package it's supposed to run. It ordinarily finds this out from the object reference you supply, but you didn't supply an object reference in this case. A reference isn't an object reference until it has been blessed. See the perlobj manpage.

    Can't call method "%s" without a package or object reference

    (F) You used the syntax of a method call, but the slot filled by the object reference or package name contains an expression that returns a defined value which is neither an object reference nor a package name. Something like this will reproduce the error:

        $BADREF = 42;
        process $BADREF 1,2,3;
        $BADREF->process(1,2,3);
    
    Can't call method "%s" on an undefined value

    (F) You used the syntax of a method call, but the slot filled by the object reference or package name contains an undefined value. Something like this will reproduce the error:

        $BADREF = undef;
        process $BADREF 1,2,3;
        $BADREF->process(1,2,3);
    
    Can't chdir to %s

    (F) You called perl -x/foo/bar, but /foo/bar is not a directory that you can chdir to, possibly because it doesn't exist.

    Can't coerce %s to integer in %s

    (F) Certain types of SVs, in particular real symbol table entries (typeglobs), can't be forced to stop being what they are. So you can't say things like:

        *foo += 1;
    

    You CAN say

        $foo = *foo;
        $foo += 1;
    

    but then $foo no longer contains a glob.

    Can't coerce %s to number in %s

    (F) Certain types of SVs, in particular real symbol table entries (typeglobs), can't be forced to stop being what they are.

    Can't coerce %s to string in %s

    (F) Certain types of SVs, in particular real symbol table entries (typeglobs), can't be forced to stop being what they are.

    Can't coerce array into hash

    (F) You used an array where a hash was expected, but the array has no information on how to map from keys to array indices. You can do that only with arrays that have a hash reference at index 0.

    Can't create pipe mailbox

    (P) An error peculiar to VMS. The process is suffering from exhausted quotas or other plumbing problems.

    Can't declare %s in my

    (F) Only scalar, array, and hash variables may be declared as lexical variables. They must have ordinary identifiers as names.

    Can't do inplace edit on %s: %s

    (S) The creation of the new file failed for the indicated reason.

    Can't do inplace edit without backup

    (F) You're on a system such as MS-DOS that gets confused if you try reading from a deleted (but still opened) file. You have to say -i.bak, or some such.

    Can't do inplace edit: %s gt 14 characters

    (S) There isn't enough room in the filename to make a backup name for the file.

    Can't do inplace edit: %s is not a regular file

    (S) You tried to use the -i switch on a special file, such as a file in /dev, or a FIFO. The file was ignored.

    Can't do setegid!

    (P) The setegid() call failed for some reason in the setuid emulator of suidperl.

    Can't do seteuid!

    (P) The setuid emulator of suidperl failed for some reason.

    Can't do setuid

    (F) This typically means that ordinary perl tried to exec suidperl to do setuid emulation, but couldn't exec it. It looks for a name of the form sperl5.000 in the same directory that the perl executable resides under the name perl5.000, typically /usr/local/bin on Unix machines. If the file is there, check the execute permissions. If it isn't, ask your sysadmin why he and/or she removed it.

    Can't do waitpid with flags

    (F) This machine doesn't have either waitpid() or wait4(), so only waitpid() without flags is emulated.

    Can't do {n,m} with n gt m

    (F) Minima must be less than or equal to maxima. If you really want your regexp to match something 0 times, just put {0}. See the perlre manpage.

    Can't emulate -%s on #! line

    (F) The #! line specifies a switch that doesn't make sense at this point. For example, it'd be kind of silly to put a -x on the #! line.

    Can't exec "%s": %s

    (W) An system(), exec(), or piped open call could not execute the named program for the indicated reason. Typical reasons include: the permissions were wrong on the file, the file wasn't found in $ENV{PATH}, the executable in question was compiled for another architecture, or the #! line in a script points to an interpreter that can't be run for similar reasons. (Or maybe your system doesn't support #! at all.)

    Can't exec %s

    (F) Perl was trying to execute the indicated program for you because that's what the #! line said. If that's not what you wanted, you may need to mention ``perl'' on the #! line somewhere.

    Can't execute %s

    (F) You used the -S switch, but the copies of the script to execute found in the PATH did not have correct permissions.

    Can't find %s on PATH, '.' not in PATH

    (F) You used the -S switch, but the script to execute could not be found in the PATH, or at least not with the correct permissions. The script exists in the current directory, but PATH prohibits running it.

    Can't find %s on PATH

    (F) You used the -S switch, but the script to execute could not be found in the PATH.

    Can't find label %s

    (F) You said to goto a label that isn't mentioned anywhere that it's possible for us to go to. See goto.

    Can't find string terminator %s anywhere before EOF

    (F) Perl strings can stretch over multiple lines. This message means that the closing delimiter was omitted. Because bracketed quotes count nesting levels, the following is missing its final parenthesis:

        print q(The character '(' starts a side comment.);
    

    If you're getting this error from a here-document, you may have included unseen whitespace before or after your closing tag. A good programmer's editor will have a way to help you find these characters.

    Can't fork

    (F) A fatal error occurred while trying to fork while opening a pipeline.

    Can't get filespec - stale stat buffer?

    (S) A warning peculiar to VMS. This arises because of the difference between access checks under VMS and under the Unix model Perl assumes. Under VMS, access checks are done by filename, rather than by bits in the stat buffer, so that ACLs and other protections can be taken into account. Unfortunately, Perl assumes that the stat buffer contains all the necessary information, and passes it, instead of the filespec, to the access checking routine. It will try to retrieve the filespec using the device name and FID present in the stat buffer, but this works only if you haven't made a subsequent call to the CRTL stat() routine, because the device name is overwritten with each call. If this warning appears, the name lookup failed, and the access checking routine gave up and returned FALSE, just to be conservative. (Note: The access checking routine knows about the Perl stat operator and file tests, so you shouldn't ever see this warning in response to a Perl command; it arises only if some internal code takes stat buffers lightly.)

    Can't get pipe mailbox device name

    (P) An error peculiar to VMS. After creating a mailbox to act as a pipe, Perl can't retrieve its name for later use.

    Can't get SYSGEN parameter value for MAXBUF

    (P) An error peculiar to VMS. Perl asked $GETSYI how big you want your mailbox buffers to be, and didn't get an answer.

    Can't goto subroutine outside a subroutine

    (F) The deeply magical ``goto subroutine'' call can only replace one subroutine call for another. It can't manufacture one out of whole cloth. In general you should be calling it out of only an AUTOLOAD routine anyway. See goto.

    Can't goto subroutine from an eval-string

    (F) The ``goto subroutine'' call can't be used to jump out of an eval ``string''. (You can use it to jump out of an eval {BLOCK}, but you probably don't want to.)

    Can't localize through a reference

    (F) You said something like local $$ref, which Perl can't currently handle, because when it goes to restore the old value of whatever perlfunc:ref pointed to after the scope of the local() is finished, it can't be sure that perlfunc:ref will still be a reference.

    Can't localize lexical variable %s

    (F) You used local on a variable name that was previously declared as a lexical variable using ``my''. This is not allowed. If you want to localize a package variable of the same name, qualify it with the package name.

    Can't localize pseudo-hash element

    (F) You said something like local $ar->{'key'}, where $ar is a reference to a pseudo-hash. That hasn't been implemented yet, but you can get a similar effect by localizing the corresponding array element directly -- local $ar->[$ar->[0]{'key'}].

    Can't locate auto/%s.al in @INC

    (F) A function (or method) was called in a package which allows autoload, but there is no function to autoload. Most probable causes are a misprint in a function/method name or a failure to AutoSplit the file, say, by doing make install.

    Can't locate %s in @INC

    (F) You said to do (or require, or use) a file that couldn't be found in any of the libraries mentioned in @INC. Perhaps you need to set the PERL5LIB or PERL5OPT environment variable to say where the extra library is, or maybe the script needs to add the library name to @INC. Or maybe you just misspelled the name of the file. See require.

    Can't locate object method "%s" via package "%s"

    (F) You called a method correctly, and it correctly indicated a package functioning as a class, but that package doesn't define that particular method, nor does any of its base classes. See the perlobj manpage.

    Can't locate package %s for @%s::ISA

    (W) The @ISA array contained the name of another package that doesn't seem to exist.

    Can't make list assignment to \%ENV on this system

    (F) List assignment to %ENV is not supported on some systems, notably VMS.

    Can't modify %s in %s

    (F) You aren't allowed to assign to the item indicated, or otherwise try to change it, such as with an auto-increment.

    Can't modify nonexistent substring

    (P) The internal routine that does assignment to a substr() was handed a NULL.

    Can't msgrcv to read-only var

    (F) The target of a msgrcv must be modifiable to be used as a receive buffer.

    Can't open %s: %s

    (S) The implicit opening of a file through use of the <> filehandle, either implicitly under the -n or -p command-line switches, or explicitly, failed for the indicated reason. Usually this is because you don't have read permission for a file which you named on the command line.

    Can't open bidirectional pipe

    (W) You tried to say open(CMD, "|cmd|"), which is not supported. You can try any of several modules in the Perl library to do this, such as IPC::Open2. Alternately, direct the pipe's output to a file using ``>'', and then read it in under a different file handle.

    Can't open error file %s as stderr

    (F) An error peculiar to VMS. Perl does its own command line redirection, and couldn't open the file specified after '2>' or '2>>' on the command line for writing.

    Can't open input file %s as stdin

    (F) An error peculiar to VMS. Perl does its own command line redirection, and couldn't open the file specified after '<' on the command line for reading.

    Can't open output file %s as stdout

    (F) An error peculiar to VMS. Perl does its own command line redirection, and couldn't open the file specified after '>' or '>>' on the command line for writing.

    Can't open output pipe (name: %s)

    (P) An error peculiar to VMS. Perl does its own command line redirection, and couldn't open the pipe into which to send data destined for stdout.

    Can't open perl script "%s": %s

    (F) The script you specified can't be opened for the indicated reason.

    Can't redefine active sort subroutine %s

    (F) Perl optimizes the internal handling of sort subroutines and keeps pointers into them. You tried to redefine one such sort subroutine when it was currently active, which is not allowed. If you really want to do this, you should write sort { &func } @x instead of sort func @x.

    Can't rename %s to %s: %s, skipping file

    (S) The rename done by the -i switch failed for some reason, probably because you don't have write permission to the directory.

    Can't reopen input pipe (name: %s) in binary mode

    (P) An error peculiar to VMS. Perl thought stdin was a pipe, and tried to reopen it to accept binary data. Alas, it failed.

    Can't reswap uid and euid

    (P) The setreuid() call failed for some reason in the setuid emulator of suidperl.

    Can't return outside a subroutine

    (F) The return statement was executed in mainline code, that is, where there was no subroutine call to return out of. See the perlsub manpage.

    Can't stat script "%s"

    (P) For some reason you can't fstat() the script even though you have it open already. Bizarre.

    Can't swap uid and euid

    (P) The setreuid() call failed for some reason in the setuid emulator of suidperl.

    Can't take log of %g

    (F) For ordinary real numbers, you can't take the logarithm of a negative number or zero. There's a Math::Complex package that comes standard with Perl, though, if you really want to do that for the negative numbers.

    Can't take sqrt of %g

    (F) For ordinary real numbers, you can't take the square root of a negative number. There's a Math::Complex package that comes standard with Perl, though, if you really want to do that.

    Can't undef active subroutine

    (F) You can't undefine a routine that's currently running. You can, however, redefine it while it's running, and you can even undef the redefined subroutine while the old routine is running. Go figure.

    Can't unshift

    (F) You tried to unshift an ``unreal'' array that can't be unshifted, such as the main Perl stack.

    Can't upgrade that kind of scalar

    (P) The internal sv_upgrade routine adds ``members'' to an SV, making it into a more specialized kind of SV. The top several SV types are so specialized, however, that they cannot be interconverted. This message indicates that such a conversion was attempted.

    Can't upgrade to undef

    (P) The undefined SV is the bottom of the totem pole, in the scheme of upgradability. Upgrading to undef indicates an error in the code calling sv_upgrade.

    Can't use %%! because Errno.pm is not available

    (F) The first time the %! hash is used, perl automatically loads the Errno.pm module. The Errno module is expected to tie the %! hash to provide symbolic names for $! errno values.

    Can't use "my %s" in sort comparison

    (F) The global variables $a and $b are reserved for sort comparisons. You mentioned $a or $b in the same line as the <=> or cmp operator, and the variable had earlier been declared as a lexical variable. Either qualify the sort variable with the package name, or rename the lexical variable.

    Can't use %s for loop variable

    (F) Only a simple scalar variable may be used as a loop variable on a foreach.

    Can't use %s ref as %s ref

    (F) You've mixed up your reference types. You have to dereference a reference of the type needed. You can use the ref() function to test the type of the reference, if need be.

    Can't use \1 to mean $1 in expression

    (W) In an ordinary expression, backslash is a unary operator that creates a reference to its argument. The use of backslash to indicate a backreference to a matched substring is valid only as part of a regular expression pattern. Trying to do this in ordinary Perl code produces a value that prints out looking like SCALAR(0xdecaf). Use the $1 form instead.

    Can't use bareword ("%s") as %s ref while \"strict refs\" in use

    (F) Only hard references are allowed by ``strict refs''. Symbolic references are disallowed. See the perlref manpage.

    Can't use string ("%s") as %s ref while "strict refs" in use

    (F) Only hard references are allowed by ``strict refs''. Symbolic references are disallowed. See the perlref manpage.

    Can't use an undefined value as %s reference

    (F) A value used as either a hard reference or a symbolic reference must be a defined value. This helps to delurk some insidious errors.

    Can't use global %s in "my"

    (F) You tried to declare a magical variable as a lexical variable. This is not allowed, because the magic can be tied to only one location (namely the global variable) and it would be incredibly confusing to have variables in your program that looked like magical variables but weren't.

    Can't use subscript on %s

    (F) The compiler tried to interpret a bracketed expression as a subscript. But to the left of the brackets was an expression that didn't look like an array reference, or anything else subscriptable.

    Can't x= to read-only value

    (F) You tried to repeat a constant value (often the undefined value) with an assignment operator, which implies modifying the value itself. Perhaps you need to copy the value to a temporary, and repeat that.

    Cannot find an opnumber for "%s"

    (F) A string of a form CORE::word was given to prototype(), but there is no builtin with the name word.

    Cannot resolve method `%s' overloading `%s' in package `%s'

    (F|P) Error resolving overloading specified by a method name (as opposed to a subroutine reference): no such method callable via the package. If method name is ???, this is an internal error.

    Character class syntax [. .] is reserved for future extensions

    (W) Within regular expression character classes ([]) the syntax beginning with ``[.'' and ending with ``.]'' is reserved for future extensions. If you need to represent those character sequences inside a regular expression character class, just quote the square brackets with the backslash: ``\[.'' and ``.\]''.

    Character class syntax [: :] is reserved for future extensions

    (W) Within regular expression character classes ([]) the syntax beginning with ``[:'' and ending with ``:]'' is reserved for future extensions. If you need to represent those character sequences inside a regular expression character class, just quote the square brackets with the backslash: ``\[:'' and ``:\]''.

    Character class syntax [= =] is reserved for future extensions

    (W) Within regular expression character classes ([]) the syntax beginning with ``[='' and ending with ``=]'' is reserved for future extensions. If you need to represent those character sequences inside a regular expression character class, just quote the square brackets with the backslash: ``\[='' and ``=\]''.

    chmod: mode argument is missing initial 0

    (W) A novice will sometimes say

        chmod 777, $filename
    

    not realizing that 777 will be interpreted as a decimal number, equivalent to 01411. Octal constants are introduced with a leading 0 in Perl, as in C.

    Close on unopened file lt%sgt

    (W) You tried to close a filehandle that was never opened.

    Compilation failed in require

    (F) Perl could not compile a file specified in a require statement. Perl uses this generic message when none of the errors that it encountered were severe enough to halt compilation immediately.

    Complex regular subexpression recursion limit (%d) exceeded

    (W) The regular expression engine uses recursion in complex situations where back-tracking is required. Recursion depth is limited to 32766, or perhaps less in architectures where the stack cannot grow arbitrarily. (``Simple'' and ``medium'' situations are handled without recursion and are not subject to a limit.) Try shortening the string under examination; looping in Perl code (e.g. with while) rather than in the regular expression engine; or rewriting the regular expression so that it is simpler or backtracks less. (See the perlbook manpage for information on Mastering Regular Expressions.)

    connect() on closed fd

    (W) You tried to do a connect on a closed socket. Did you forget to check the return value of your socket() call? See connect.

    Constant subroutine %s redefined

    (S) You redefined a subroutine which had previously been eligible for inlining. See perlman:perlsub for commentary and workarounds.

    Constant subroutine %s undefined

    (S) You undefined a subroutine which had previously been eligible for inlining. See perlman:perlsub for commentary and workarounds.

    Copy method did not return a reference

    (F) The method which overloads ``='' is buggy. See Copy Constructor.

    Corrupt malloc ptr 0x%lx at 0x%lx

    (P) The malloc package that comes with Perl had an internal failure.

    corrupted regexp pointers

    (P) The regular expression engine got confused by what the regular expression compiler gave it.

    corrupted regexp program

    (P) The regular expression engine got passed a regexp program without a valid magic number.

    Deep recursion on subroutine "%s"

    (W) This subroutine has called itself (directly or indirectly) 100 times more than it has returned. This probably indicates an infinite recursion, unless you're writing strange benchmark programs, in which case it indicates something else.

    Delimiter for here document is too long

    (F) In a here document construct like <<FOO, the label FOO is too long for Perl to handle. You have to be seriously twisted to write code that triggers this error.

    Did you mean &%s instead?

    (W) You probably referred to an imported subroutine &FOO as $FOO or some such.

    Did you mean $ or @ instead of %?

    (W) You probably said %hash{$key} when you meant $hash{$key} or @hash{@keys}. On the other hand, maybe you just meant %hash and got carried away.

    Died

    (F) You passed die() an empty string (the equivalent of perlfunc:die) or you called it with no args and both $@ and $_ were empty.

    Do you need to predeclare %s?

    (S) This is an educated guess made in conjunction with the message ``%s found where operator expected''. It often means a subroutine or module name is being referenced that hasn't been declared yet. This may be because of ordering problems in your file, or because of a missing ``sub'', ``package'', ``require'', or ``use'' statement. If you're referencing something that isn't defined yet, you don't actually have to define the subroutine or package before the current location. You can use an empty ``sub foo;'' or ``package FOO;'' to enter a ``forward'' declaration.

    Don't know how to handle magic of type '%s'

    (P) The internal handling of magical variables has been cursed.

    do_study: out of memory

    (P) This should have been caught by safemalloc() instead.

    Duplicate free() ignored

    (S) An internal routine called free() on something that had already been freed.

    elseif should be elsif

    (S) There is no keyword ``elseif'' in Perl because Larry thinks it's ugly. Your code will be interpreted as an attempt to call a method named ``elseif'' for the class returned by the following block. This is unlikely to be what you want.

    END failed--cleanup aborted

    (F) An untrapped exception was raised while executing an END subroutine. The interpreter is immediately exited.

    Error converting file specification %s

    (F) An error peculiar to VMS. Because Perl may have to deal with file specifications in either VMS or Unix syntax, it converts them to a single form when it must operate on them directly. Either you've passed an invalid file specification to Perl, or you've found a case the conversion routines don't handle. Drat.

    %s: Eval-group in insecure regular expression

    (F) Perl detected tainted data when trying to compile a regular expression that contains the (?{ ... }) zero-width assertion, which is unsafe. See perlman:perlre, and the perlsec manpage.

    %s: Eval-group not allowed, use re 'eval'

    (F) A regular expression contained the (?{ ... }) zero-width assertion, but that construct is only allowed when the use re 'eval' pragma is in effect. See perlman:perlre.

    %s: Eval-group not allowed at run time

    (F) Perl tried to compile a regular expression containing the (?{ ... }) zero-width assertion at run time, as it would when the pattern contains interpolated values. Since that is a security risk, it is not allowed. If you insist, you may still do this by explicitly building the pattern from an interpolated string at run time and using that in an eval(). See perlman:perlre.

    Excessively long <> operator

    (F) The contents of a <> operator may not exceed the maximum size of a Perl identifier. If you're just trying to glob a long list of filenames, try using the glob() operator, or put the filenames into a variable and glob that.

    Execution of %s aborted due to compilation errors

    (F) The final summary message when a Perl compilation fails.

    Exiting eval via %s

    (W) You are exiting an eval by unconventional means, such as a goto, or a loop control statement.

    Exiting pseudo-block via %s

    (W) You are exiting a rather special block construct (like a sort block or subroutine) by unconventional means, such as a goto, or a loop control statement. See sort.

    Exiting subroutine via %s

    (W) You are exiting a subroutine by unconventional means, such as a goto, or a loop control statement.

    Exiting substitution via %s

    (W) You are exiting a substitution by unconventional means, such as a return, a goto, or a loop control statement.

    Explicit blessing to '' (assuming package main)

    (W) You are blessing a reference to a zero length string. This has the effect of blessing the reference into the package main. This is usually not what you want. Consider providing a default target package, e.g. bless($ref, $p or 'MyPackage');

    Fatal VMS error at %s, line %d

    (P) An error peculiar to VMS. Something untoward happened in a VMS system service or RTL routine; Perl's exit status should provide more details. The filename in ``at %s'' and the line number in ``line %d'' tell you which section of the Perl source code is distressed.

    fcntl is not implemented

    (F) Your machine apparently doesn't implement fcntl(). What is this, a PDP-11 or something?

    Filehandle %s never opened

    (W) An I/O operation was attempted on a filehandle that was never initialized. You need to do an open() or a socket() call, or call a constructor from the FileHandle package.

    Filehandle %s opened for only input

    (W) You tried to write on a read-only filehandle. If you intended it to be a read-write filehandle, you needed to open it with ``+<'' or ``+>'' or ``+>>'' instead of with ``<'' or nothing. If you intended only to write the file, use ``>'' or ``>>''. See open.

    Filehandle opened for only input

    (W) You tried to write on a read-only filehandle. If you intended it to be a read-write filehandle, you needed to open it with ``+<'' or ``+>'' or ``+>>'' instead of with ``<'' or nothing. If you intended only to write the file, use ``>'' or ``>>''. See open.

    Final $ should be \$ or $name

    (F) You must now decide whether the final $ in a string was meant to be a literal dollar sign, or was meant to introduce a variable name that happens to be missing. So you have to put either the backslash or the name.

    Final @ should be \@ or @name

    (F) You must now decide whether the final @ in a string was meant to be a literal ``at'' sign, or was meant to introduce a variable name that happens to be missing. So you have to put either the backslash or the name.

    Format %s redefined

    (W) You redefined a format. To suppress this warning, say

        {
            local $^W = 0;
            eval "format NAME =...";
        }
    
    Format not terminated

    (F) A format must be terminated by a line with a solitary dot. Perl got to the end of your file without finding such a line.

    Found = in conditional, should be ==

    (W) You said

        if ($foo = 123)
    

    when you meant

        if ($foo == 123)
    

    (or something like that).

    gdbm store returned %d, errno %d, key "%s"

    (S) A warning from the GDBM_File extension that a store failed.

    gethostent not implemented

    (F) Your C library apparently doesn't implement gethostent(), probably because if it did, it'd feel morally obligated to return every hostname on the Internet.

    get{sock,peer}name() on closed fd

    (W) You tried to get a socket or peer socket name on a closed socket. Did you forget to check the return value of your socket() call?

    getpwnam returned invalid UIC %#o for user "%s"

    (S) A warning peculiar to VMS. The call to sys$getuai underlying the getpwnam operator returned an invalid UIC.

    Glob not terminated

    (F) The lexer saw a left angle bracket in a place where it was expecting a term, so it's looking for the corresponding right angle bracket, and not finding it. Chances are you left some needed parentheses out earlier in the line, and you really meant a ``less than''.

    Global symbol "%s" requires explicit package name

    (F) You've said ``use strict vars'', which indicates that all variables must either be lexically scoped (using ``my''), or explicitly qualified to say which package the global variable is in (using ``::'').

    goto must have label

    (F) Unlike with ``next'' or ``last'', you're not allowed to goto an unspecified destination. See goto.

    Had to create %s unexpectedly

    (S) A routine asked for a symbol from a symbol table that ought to have existed already, but for some reason it didn't, and had to be created on an emergency basis to prevent a core dump.

    Hash %%s missing the % in argument %d of %s()

    (D) Really old Perl let you omit the % on hash names in some spots. This is now heavily deprecated.

    Identifier too long

    (F) Perl limits identifiers (names for variables, functions, etc.) to about 250 characters for simple names, and somewhat more for compound names (like $A::B). You've exceeded Perl's limits. Future versions of Perl are likely to eliminate these arbitrary limitations.

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