Works for me. What your build output and your .c?

But I've found that it creates a second scalar that points to root, so DESTROY is now being called twice for the same pointer.

Okay. Forget it. Mismatch (case) between package name and struct typedef!

C:\test>ICobject.pl
Starting Build Preprocess Stage
Finished Build Preprocess Stage

Starting Build Parse Stage
Finished Build Parse Stage

Starting Build Glue 1 Stage
Finished Build Glue 1 Stage

Starting Build Glue 2 Stage
Finished Build Glue 2 Stage

Starting Build Glue 3 Stage
Finished Build Glue 3 Stage

Starting Build Compile Stage
  Starting "perl Makefile.PL" Stage
Writing Makefile for ICobject
  Finished "perl Makefile.PL" Stage

  Starting "make" Stage

Microsoft (R) Program Maintenance Utility Version 9.00.21022.08
Copyright (C) Microsoft Corporation.  All rights reserved.

        C:\Perl64\bin\perl.exe C:\Perl64\lib\ExtUtils\xsubpp  -typemap
+ C:\Perl
        cl -c  -IC:/test  -nologo -GF -W3 -MD -Zi -DNDEBUG -Ox -GL -fp
+:precise
ICobject.c
Running Mkbootstrap for ICobject ()
        C:\Perl64\bin\perl.exe -MExtUtils::Command -e "chmod" -- 644 I
+Cobject.
        C:\Perl64\bin\perl.exe -MExtUtils::Mksymlists  -e "Mksymlists(
+'NAME'=>
        link -out:blib\arch\auto\ICobject\ICobject.dll -dll -nologo -n
+odefault
   Creating library blib\arch\auto\ICobject\ICobject.lib and object bl
+ib\arch\
Generating code
Finished generating code
        if exist blib\arch\auto\ICobject\ICobject.dll.manifest mt -nol
+ogo -man
        if exist blib\arch\auto\ICobject\ICobject.dll.manifest del bli
+b\arch\a
        C:\Perl64\bin\perl.exe -MExtUtils::Command -e "chmod" -- 755 b
+lib\arch
        C:\Perl64\bin\perl.exe -MExtUtils::Command -e "cp" -- ICobject
+.bs blib
        C:\Perl64\bin\perl.exe -MExtUtils::Command -e "chmod" -- 644 b
+lib\arch
  Finished "make" Stage

  Starting "make install" Stage

Microsoft (R) Program Maintenance Utility Version 9.00.21022.08
Copyright (C) Microsoft Corporation.  All rights reserved.

Files found in blib\arch: installing files in blib\lib into architectu
+re depen
Installing C:\test\_Inline\lib\auto\ICobject\ICobject.dll
Installing C:\test\_Inline\lib\auto\ICobject\ICobject.exp
Installing C:\test\_Inline\lib\auto\ICobject\ICobject.lib
Installing C:\test\_Inline\lib\auto\ICobject\ICobject.pdb
  Finished "make install" Stage

  Starting Cleaning Up Stage
  Finished Cleaning Up Stage

Finished Build Compile Stage

new
SV = RV(0xe7bd8) at 0xe7bc8
  REFCNT = 1
  FLAGS = (PADMY,ROK)
  RV = 0x3a89d70
  SV = PVMG(0x3a2ff78) at 0x3a89d70
    REFCNT = 1
    FLAGS = (OBJECT,IOK,pIOK)
    IV = 867784
    NV = 0
    PV = 0
    STASH = 0x1cde08    "Node"

Node=SCALAR(0x3a89d70)
Can't locate object method "insert" via package "Node" at C:\test\ICob
+ject.pl
[download]

#! perl -slw
package NODE;
use Inline C => Config => BUILD_NOISY => 1; #, TYPEMAPS => './ICobject
+.tmap';
use Inline C => <<'END_C',  NAME => 'ICobject', CLEAN_AFTER_BUILD => 0
+;


struct _node {
      struct _node  *left;
      struct _node  *right;
};

typedef struct _node Node;

Node* new( char *class ) {
    Node* node;
    warn("new\n"); // DEBUG
    Newx(node, 1, Node);
    // node->... = ...;
    return node;
}

Node* insert( Node* root ) {
    warn("insert\n"); // DEBUG
    return root;
}

void DESTROY(Node* node) {
    warn("DESTROY\n"); // DEBUG
    Safefree(node);
}

END_C

package main;
use strict;
use Devel::Peek;

my $tree = NODE->new();

print Dump $tree;

print $tree;

$tree->insert( 'fred', 3 );
[download]

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