Diagnostic messages

When a program goes wrong, Perl tells you about it. Some diagnostics stop the program (die-style fatal errors); others print a line to STDERR and let it run on (warnings). This reference lists the diagnostics PetaPerl emits, grouped by where they come from, with the cause and the fix for each.

Every entry shows the message verbatim in a code span - the exact text the interpreter prints, with the placeholders (%s, %d, a named variable) shown the way they appear in the output. Search this page for the literal words you saw on STDERR and you will land on the entry.

Reading an entry

Each entry opens with the message text, then a short classification badge in parentheses, then the cause and the fix:

`Illegal division by zero`   (F) You divided by zero. Guard the divisor.

The badge follows the same letter code Perl has always used:

Code	Meaning
W	A warning - printed only when warnings are enabled. Optionally restricted to a category (shown as (W category)).
D	A deprecation - a warning that a feature is on the way out.
S	A severe warning - on by default, but still only a warning.
F	A fatal error - the program dies unless the error is trapped (eval, try).
P	An internal error (a panic) - should never reach a user. If you see one, it is a bug in pperl.
X	A very fatal error - the program exits immediately.
A	An alien error - produced by something other than Perl itself.

Enabling and silencing warnings

Warnings (the W, D, and S classes) are controlled by the warnings pragma. Without it, only the severe (S) warnings print:

use warnings;                    # turn on every warning
no warnings;                     # turn them all off (lexically)
no warnings 'uninitialized';     # turn off one category
use warnings FATAL => 'all';     # promote warnings to fatal errors

The category named in a (W category) badge is the string you pass to no warnings to silence just that diagnostic. A single $SIG{__WARN__} handler can intercept every warning at runtime; $SIG{__DIE__} does the same for fatal errors. See %SIG.

A note on portability

PetaPerl runs only on Linux and ships no XS layer. The platform diagnostic families a portable perl carries - VMS status codes, Win32 GetLastError text, “unimplemented on this architecture” notices, XS-loader failures - therefore do not arise here. Where upstream Perl documents a diagnostic that only fires on another operating system or through XS, PetaPerl simply never emits it.

The diagnostics

• General fatal errors
• Regex compilation errors
• Compile-time syntax errors
• Warnings
• Value and type errors
• Internal errors
• pperl-specific diagnostics

• General fatal errors - method resolution, references, arithmetic, restricted hashes, filehandles, and the rest of the runtime dies that are not regex- or parser-specific.

• Regex compilation errors - everything the pattern compiler rejects, from Unmatched ) to malformed \g, \N, \o, and (?...) constructs.

• Compile-time syntax errors - errors the parser and codegen raise before the program runs.

• Warnings - the non-fatal diagnostics: deep recursion, wide characters, useless constructs.

• Value and type errors - diagnostics about what a value is and is not: not a reference, not a code reference, division by zero, restricted-hash access.

• Internal errors - the panics that signal a bug in pperl itself.

• pperl-specific diagnostics - messages PetaPerl emits that have no upstream Perl counterpart.