From 01a4fbf163f6cf1aa1d36473d7f87cd26b833281 Mon Sep 17 00:00:00 2001 From: Richard Leach Date: Sat, 14 Dec 2024 22:32:43 +0000 Subject: [PATCH] Undefined subroutine &%s called, close to label '%s' https://github.com/Perl/perl5/issues/17839 requested a compile-time warning for the situation whereby a single colon is accdentally typed as a package separator when calling a function. For example: ``` package BOOP; sub beep; package main; BOOP:beep(); # Meant to be BOOP::beep(); ``` However, because of both Perl's syntax and the potential to populate the stash at runtime, this falls somewhere between very difficult and impossible. As an alternative, some enhanced fatal error wording was requested and these commits attempt to provide that. The above example would previously die with the message: ``` Undefined subroutine &main::beep called at ... line 4. ``` Now it dies with the message: ``` Undefined subroutine &main::beep called, close to label 'BOOP' at ... line 4. ``` For some of the same reasons mentioned, distinguishing this typo from other errors at runtime - such as the target subroutine not being present at all - is also nigh on impossible. The hope is that the error message will give some additional clue when the error is the result of a typo, without distracting the user in all other cases. As part of these commits, some common `DIE()` calls in `pp_entersub` were extracted into a new helper function, `S_croak_undefined_subroutine`, to avoid adding (and slightly reduce) cold code bloating in `pp_entersub`. --- pod/perldelta.pod | 8 ++++++++ pod/perldiag.pod | 6 ++++++ pp_hot.c | 40 +++++++++++++++++++++++++++++++--------- t/lib/croak/pp_hot | 8 ++++++++ 4 files changed, 53 insertions(+), 9 deletions(-) diff --git a/pod/perldelta.pod b/pod/perldelta.pod index d53738408312..ed1fe8a71f2c 100644 --- a/pod/perldelta.pod +++ b/pod/perldelta.pod @@ -260,6 +260,14 @@ and L =item * +L + +(F) The subroutine indicated hasn't been defined, or if it was, it has +since been undefined. This could also indicate a mistyped package +separator, when a single colon was typed instead of two colons. + +=item * + XXX L =back diff --git a/pod/perldiag.pod b/pod/perldiag.pod index 7f981e8008ff..14b3021e1ccf 100644 --- a/pod/perldiag.pod +++ b/pod/perldiag.pod @@ -6820,6 +6820,12 @@ Perhaps it's in a different package? See L. (F) The subroutine indicated hasn't been defined, or if it was, it has since been undefined. +=item Undefined subroutine &%s called, close to label '%s' + +(F) The subroutine indicated hasn't been defined, or if it was, it has +since been undefined. This could also indicate a mistyped package +separator, when a single colon was typed instead of two colons. + =item Undefined subroutine called (F) The anonymous subroutine you're trying to call hasn't been defined, diff --git a/pp_hot.c b/pp_hot.c index 641bedc42569..d8ec7858c816 100644 --- a/pp_hot.c +++ b/pp_hot.c @@ -6212,6 +6212,33 @@ Perl_clear_defarray(pTHX_ AV* av, bool abandon) } } +/* S_croak_undefined_subroutine is a helper function for pp_entersub. + * It takes assorted DIE() logic out of that hot function. + */ +static void +S_croak_undefined_subroutine(pTHX_ CV const *cv, GV const *gv) +{ + if (cv) { + if (CvLEXICAL(cv) && CvHASGV(cv)) + croak(aTHX_ "Undefined subroutine &%" SVf " called", + SVfARG(cv_name((CV*)cv, NULL, 0))); + else /* pp_entersub triggers when (CvANON(cv) || !CvHASGV(cv)) */ + croak(aTHX_ "Undefined subroutine called"); + } else { /* pp_entersub triggers when (!cv) after `try_autoload` */ + SV *sub_name = newSV_type_mortal(SVt_PV); + gv_efullname3(sub_name, gv, NULL); + + /* Heuristic to spot BOOP:boop() typo, when the intention was + * to call BOOP::boop(). */ + const char * label = CopLABEL(PL_curcop); + if (label) { + croak(aTHX_ "Undefined subroutine &%" SVf " called, close to label '%s'", + SVfARG(sub_name), label); + } + croak(aTHX_ "Undefined subroutine &%" SVf " called", SVfARG(sub_name)); + } + NOT_REACHED; /* NOTREACHED */ +} PP(pp_entersub) { @@ -6306,14 +6333,12 @@ PP(pp_entersub) assert((void*)&CvROOT(cv) == (void*)&CvXSUB(cv)); while (UNLIKELY(!CvROOT(cv))) { GV* autogv; - SV* sub_name; /* anonymous or undef'd function leaves us no recourse */ if (CvLEXICAL(cv) && CvHASGV(cv)) - DIE(aTHX_ "Undefined subroutine &%" SVf " called", - SVfARG(cv_name(cv, NULL, 0))); + S_croak_undefined_subroutine(cv, NULL); if (CvANON(cv) || !CvHASGV(cv)) { - DIE(aTHX_ "Undefined subroutine called"); + S_croak_undefined_subroutine(cv, NULL); } /* autoloaded stub? */ @@ -6330,11 +6355,8 @@ PP(pp_entersub) : 0)); cv = autogv ? GvCV(autogv) : NULL; } - if (!cv) { - sub_name = sv_newmortal(); - gv_efullname3(sub_name, gv, NULL); - DIE(aTHX_ "Undefined subroutine &%" SVf " called", SVfARG(sub_name)); - } + if (!cv) + S_croak_undefined_subroutine(NULL, gv); } /* unrolled "CvCLONE(cv) && ! CvCLONED(cv)" */ diff --git a/t/lib/croak/pp_hot b/t/lib/croak/pp_hot index bc00a484c6df..325091c28e1c 100644 --- a/t/lib/croak/pp_hot +++ b/t/lib/croak/pp_hot @@ -46,6 +46,14 @@ Undefined subroutine &main::foo called at - line 3. EXPECT Undefined subroutine &main::foo called at - line 2. ######## +# NAME package separator typo, creating a label by accident + package BEEP; + sub boop; + package main; + BEEP:boop(); +EXPECT +Undefined subroutine &main::boop called, close to label 'BEEP' at - line 4. +######## # NAME calling undef scalar &{+undef}; EXPECT