Integrate:

[ 34132]
Test that formats can be dumped.

[ 34133]
PVFMs don't need to access the IVX any more. (as of change 32836, which
re-implemented SvOOK() to avoid using it)

[ 34167]
You can't (and shouldn't) use CvDEPTH on a PVFM.

[ 35022]
in Dump output, PV field of format may or not be displayed in 5.10.0

[ 35023]
whether DEPTH gets dumped in formats varies within 5.10.0
p4raw-link: @35023 on //depot/perl: c12100a
p4raw-link: @35022 on //depot/perl: 251a4af
p4raw-link: @34167 on //depot/perl: 5129b2c
p4raw-link: @34133 on //depot/perl: 30ec677
p4raw-link: @34132 on //depot/perl: bfe27a5

p4raw-id: //depot/maint-5.10/perl@35024
p4raw-integrated: from //depot/perl@35022 'ignore'
	ext/Devel/Peek/t/Peek.t (@34167..)
p4raw-integrated: from //depot/perl@34167 'edit in' dump.c (@34133..)
	'merge in' cv.h (@34030..)
p4raw-integrated: from //depot/perl@34133 'merge in' sv.h (@34038..)

cv.h

@@ -124,8 +124,7 @@ Returns the stash of the CV.
 #define CvFILEGV(sv)	(gv_fetchfile(CvFILE(sv)))
 #if defined(__GNUC__) && !defined(PERL_GCC_BRACE_GROUPS_FORBIDDEN)
 #  define CvDEPTH(sv) (*({const CV *_cvdepth = (CV *)sv;         \
-			  assert(SvTYPE(_cvdepth) == SVt_PVCV || \
-				 SvTYPE(_cvdepth) == SVt_PVFM);	 \
+			  assert(SvTYPE(_cvdepth) == SVt_PVCV);	 \
 			  &((XPVCV*)SvANY(_cvdepth))->xiv_u.xivu_i32; \
 			}))
 #else

dump.c

@@ -1521,7 +1521,7 @@ Perl_do_sv_dump(pTHX_ I32 level, PerlIO *file, SV *sv, I32 nest, I32 maxnest, bo
 	return;
     }
     if ((type >= SVt_PVIV && type != SVt_PVAV && type != SVt_PVHV
-	 && type != SVt_PVCV && !isGV_with_GP(sv))
+	 && type != SVt_PVCV && !isGV_with_GP(sv) && type != SVt_PVFM)
 	|| type == SVt_IV) {
 	if (SvIsUV(sv)
 #ifdef PERL_OLD_COPY_ON_WRITE
@@ -1769,7 +1769,8 @@ Perl_do_sv_dump(pTHX_ I32 level, PerlIO *file, SV *sv, I32 nest, I32 maxnest, bo
 	}
  	do_gvgv_dump(level, file, "  GVGV::GV", CvGV(sv));
 	Perl_dump_indent(aTHX_ level, file, "  FILE = \"%s\"\n", CvFILE(sv));
-	Perl_dump_indent(aTHX_ level, file, "  DEPTH = %"IVdf"\n", (IV)CvDEPTH(sv));
+	if (type == SVt_PVCV)
+	    Perl_dump_indent(aTHX_ level, file, "  DEPTH = %"IVdf"\n", (IV)CvDEPTH(sv));
 	Perl_dump_indent(aTHX_ level, file, "  FLAGS = 0x%"UVxf"\n", (UV)CvFLAGS(sv));
 	Perl_dump_indent(aTHX_ level, file, "  OUTSIDE_SEQ = %"UVuf"\n", (UV)CvOUTSIDE_SEQ(sv));
 	if (type == SVt_PVFM)

ext/Devel/Peek/t/Peek.t

@@ -14,11 +14,21 @@ BEGIN { require "./test.pl"; }
 
 use Devel::Peek;
 
-plan(50);
+plan(52);
 
 our $DEBUG = 0;
 open(SAVERR, ">&STDERR") or die "Can't dup STDERR: $!";
 
+# If I reference any lexicals in this, I get the entire outer subroutine (or
+# MAIN) dumped too, which isn't really what I want, as it's a lot of faff to
+# maintain that.
+format PIE =
+Pie     @<<<<<
+$::type
+Good    @>>>>>
+$::mmmm
+.
+
 sub do_test {
     my $todo = $_[3];
     my $repeat_todo = $_[4];
@@ -624,3 +634,32 @@ do_test(25,
     SUBPROCESS = 0				# $] < 5.009
     TYPE = \'>\'
     FLAGS = 0x0');
+
+do_test(26,
+	*PIE{FORMAT},
+'SV = $RV\\($ADDR\\) at $ADDR
+  REFCNT = 1
+  FLAGS = \\(ROK\\)
+  RV = $ADDR
+  SV = PVFM\\($ADDR\\) at $ADDR
+    REFCNT = 2
+    FLAGS = \\(\\)
+    IV = 0					# $] < 5.009
+    NV = 0					# $] < 5.009
+(?:    PV = 0
+)?    COMP_STASH = 0x0
+    START = $ADDR ===> \\d+
+    ROOT = $ADDR
+    XSUB = 0x0					# $] < 5.009
+    XSUBANY = 0					# $] < 5.009
+    GVGV::GV = $ADDR\\t"main" :: "PIE"
+    FILE = ".*\\b(?i:peek\\.t)"
+(?:    DEPTH = 0
+    MUTEXP = $ADDR
+    OWNER = $ADDR
+)?    FLAGS = 0x0
+    OUTSIDE_SEQ = \\d+
+    LINES = 0
+    PADLIST = $ADDR
+    PADNAME = $ADDR\\($ADDR\\) PAD = $ADDR\\($ADDR\\)
+    OUTSIDE = $ADDR \\(MAIN\\)');

sv.h

@@ -1276,6 +1276,7 @@ the scalar's value cannot change unless written to.
 	    assert(SvTYPE(_svivx) != SVt_PVAV);				\
 	    assert(SvTYPE(_svivx) != SVt_PVHV);				\
 	    assert(SvTYPE(_svivx) != SVt_PVCV);				\
+	    assert(SvTYPE(_svivx) != SVt_PVFM);				\
 	    assert(!isGV_with_GP(_svivx));				\
 	    &(((XPVIV*) SvANY(_svivx))->xiv_iv);			\
 	 }))
@@ -1285,6 +1286,7 @@ the scalar's value cannot change unless written to.
 	    assert(SvTYPE(_svuvx) != SVt_PVAV);				\
 	    assert(SvTYPE(_svuvx) != SVt_PVHV);				\
 	    assert(SvTYPE(_svuvx) != SVt_PVCV);				\
+	    assert(SvTYPE(_svuvx) != SVt_PVFM);				\
 	    assert(!isGV_with_GP(_svuvx));				\
 	    &(((XPVUV*) SvANY(_svuvx))->xuv_uv);			\
 	 }))