signatures: fix cx_dup #163

duplicate the cx->safearray with signatures correctly.
with sigs the safearray is just a MARK ptr onto the SV** stack, not a AV*.
duplicate both safearray and argarray with sigs to the new stack locations.

We don't need to dup more cv fields, CvSIGOP stays as is.

Closes #163

Author: Reini Urban

cop.h

@@ -555,8 +555,8 @@ struct block_sub {
     CV *	cv;
     /* Above here is the same for sub and format.  */
     I32		olddepth;
-    AV  	*savearray;
-    SV **	argarray; /* for signatures only */
+    AV * 	savearray; /* with signatures just a SV** on the stack */
+    SV **	argarray;  /* for signatures only, the MARK */
 };
 
 

cpan/Test-Simple/t/subtest/fork.t

@@ -20,11 +20,7 @@ else {
 }
 
 subtest 'fork within subtest' => sub {
-  plan tests => 2;
-
-  TODO: {
-    local $TODO = "random fork problem with MSVC"
-      if ($^O eq 'MSWin32' and $Config{cc} eq 'cl');
+    plan tests => 2;
 
     my $pipe = IO::Pipe->new;
     my $pid = fork;
@@ -51,6 +47,5 @@ subtest 'fork within subtest' => sub {
       diag 'Child Done';
       exit 0;
     }
-  }
 };
 

sv.c

@@ -14075,14 +14075,22 @@ Perl_cx_dup(pTHX_ PERL_CONTEXT *cxs, I32 ix, I32 max, CLONE_PARAMS* param)
 	    ncx->blk_oldcop = (COP*)any_dup(ncx->blk_oldcop, param->proto_perl);
 	    switch (CxTYPE(ncx)) {
 	    case CXt_SUB:
-		ncx->blk_sub.cv		= cv_dup_inc(ncx->blk_sub.cv, param);
-		if(CxHASARGS(ncx)){
-		    ncx->blk_sub.savearray = av_dup_inc(ncx->blk_sub.savearray,param);
-		} else {
-		    ncx->blk_sub.savearray = NULL;
-		}
+		ncx->blk_sub.cv	= cv_dup_inc(ncx->blk_sub.cv, param);
+                if (CvHASSIG(ncx->blk_sub.cv)) { /* SP ptrs */
+                    PerlInterpreter *proto_perl = param->proto_perl;
+                    int oldsave = (SV**)ncx->blk_sub.savearray - proto_perl->Istack_base;
+                    int oldarg  = ncx->blk_sub.argarray - proto_perl->Istack_base;
+                    ncx->blk_sub.savearray = (AV*)(PL_stack_base + oldsave);
+                    ncx->blk_sub.argarray  = PL_stack_base + oldarg;
+                } else {
+                    if (CxHASARGS(ncx)) {
+                        ncx->blk_sub.savearray = av_dup_inc(ncx->blk_sub.savearray, param);
+                    } else {
+                        ncx->blk_sub.savearray = NULL;
+                    }
+                }
 		ncx->blk_sub.prevcomppad = (PAD*)ptr_table_fetch(PL_ptr_table,
-					   ncx->blk_sub.prevcomppad);
+					       ncx->blk_sub.prevcomppad);
 		break;
 	    case CXt_EVAL:
 		ncx->blk_eval.old_namesv = sv_dup_inc(ncx->blk_eval.old_namesv,