Allow mro_isa_changed_in to be called on nonexistent packages

This is necessary for an upcoming bug fix.

(For this bug:

 @left::ISA = 'outer::inner';
 @right::ISA = 'clone::inner';
 *clone:: = \%outer::;
 print left->isa('clone::inner'),"\n";
 print right->isa('outer::inner'),"\n";

)

This commit actually replaces mro_isa_changed_in with
mro_isa_changed_in3. See the docs for it in the diff for mro.c.

1 files changed, 36 insertions, 17 deletions

diff --git a/mro.c b/mro.c
index bd59465eb3..d8ef79c749 100644
--- a/mro.c
+++ b/mro.c
@@ -411,10 +411,22 @@ Takes the necessary steps (cache invalidations, mostly)
 when the @ISA of the given package has changed.  Invoked
 by the C<setisa> magic, should not need to invoke directly.
 
+=for apidoc mro_isa_changed_in3
+
+Takes the necessary steps (cache invalidations, mostly)
+when the @ISA of the given package has changed.  Invoked
+by the C<setisa> magic, should not need to invoke directly.
+
+The stash can be passed as the first argument, or its name and length as
+the second and third (or both). If just the name is passed and the stash
+does not exist, then only the subclasses' method and isa caches will be
+invalidated.
+
 =cut
 */
 void
-Perl_mro_isa_changed_in(pTHX_ HV* stash)
+Perl_mro_isa_changed_in3(pTHX_ HV* stash, const char *stashname,
+                         STRLEN stashname_len)
 {
     dVAR;
     HV* isarev;
@@ -423,35 +435,39 @@ Perl_mro_isa_changed_in(pTHX_ HV* stash)
     SV** svp;
     I32 items;
     bool is_universal;
-    struct mro_meta * meta;
-
-    const char * const stashname = HvNAME_get(stash);
-    const STRLEN stashname_len = HvNAMELEN_get(stash);
+    struct mro_meta * meta = NULL;
 
-    PERL_ARGS_ASSERT_MRO_ISA_CHANGED_IN;
+    if(!stashname && stash) {
+        stashname = HvNAME_get(stash);
+        stashname_len = HvNAMELEN_get(stash);
+    }
+    else if(!stash)
+        stash = gv_stashpvn(stashname, stashname_len, 0 /* don't add */);
 
     if(!stashname)
         Perl_croak(aTHX_ "Can't call mro_isa_changed_in() on anonymous symbol table");
 
-    /* wipe out the cached linearizations for this stash */
-    meta = HvMROMETA(stash);
-    if (meta->mro_linear_all) {
+    if(stash) {
+      /* wipe out the cached linearizations for this stash */
+      meta = HvMROMETA(stash);
+      if (meta->mro_linear_all) {
 	SvREFCNT_dec(MUTABLE_SV(meta->mro_linear_all));
 	meta->mro_linear_all = NULL;
 	/* This is just acting as a shortcut pointer.  */
 	meta->mro_linear_current = NULL;
-    } else if (meta->mro_linear_current) {
+      } else if (meta->mro_linear_current) {
 	/* Only the current MRO is stored, so this owns the data.  */
 	SvREFCNT_dec(meta->mro_linear_current);
 	meta->mro_linear_current = NULL;
-    }
-    if (meta->isa) {
+      }
+      if (meta->isa) {
 	SvREFCNT_dec(meta->isa);
 	meta->isa = NULL;
-    }
+      }
 
-    /* Inc the package generation, since our @ISA changed */
-    meta->pkg_gen++;
+      /* Inc the package generation, since our @ISA changed */
+      meta->pkg_gen++;
+    }
 
     /* Wipe the global method cache if this package
        is UNIVERSAL or one of its parents */
@@ -465,12 +481,12 @@ Perl_mro_isa_changed_in(pTHX_ HV* stash)
         is_universal = TRUE;
     }
     else { /* Wipe the local method cache otherwise */
-        meta->cache_gen++;
+        if(meta) meta->cache_gen++;
 	is_universal = FALSE;
     }
 
     /* wipe next::method cache too */
-    if(meta->mro_nextmethod) hv_clear(meta->mro_nextmethod);
+    if(meta && meta->mro_nextmethod) hv_clear(meta->mro_nextmethod);
 
     /* Iterate the isarev (classes that are our children),
        wiping out their linearization, method and isa caches */
@@ -511,6 +527,9 @@ Perl_mro_isa_changed_in(pTHX_ HV* stash)
          3) Add everything from our isarev to their isarev
     */
 
+    /* This only applies if the stash exists. */
+    if(!stash) return;
+
     /* We're starting at the 2nd element, skipping ourselves here */
     linear_mro = mro_get_linear_isa(stash);
     svp = AvARRAY(linear_mro) + 1;