Bug#1150262: gtkmm: Compile error: conflicting declaration `using GdkCursorClass = struct _GdkCursorClass`

[Andre Offringa]

Package: libgtkmm-4.0-dev
Version: 4.22.0-1
Severity: important
File: gtkmm
X-Debbugs-Cc: offringa at gmail.com

Dear Maintainer,

When compiling software that includes a gtkmm header file, using g++, the
software fails to compile due to this error:

/usr/include/gtkmm-4.0/gdkmm/cursor.h:30:7: error: conflicting declaration
‘using GdkCursorClass = struct _GdkCursorClass’

In file included from /usr/include/glib-2.0/gobject/gobject.h:26,
                 from /usr/include/glib-2.0/gobject/gbinding.h:31,
                 from /usr/include/glib-2.0/glib-object.h:24,
                 from /usr/include/glibmm-2.68/glibmm/class.h:21,
                 from /usr/include/glibmm-2.68/glibmm/objectbase.h:21,
                 from /usr/include/glibmm-2.68/glibmm/object.h:29,
                 from /usr/include/gtkmm-4.0/gdkmm/clipboard.h:25,
                 from /usr/include/gtkmm-4.0/gtkmm/widget.h:32:
/usr/include/gtk-4.0/gdk/gdkcursor.h:38:1: note: previous declaration as
‘typedef struct GdkCursorClass GdkCursorClass’

This seems to hold for including most of the header files, in this case e.g.
the widget.h file:

[..]
In file included from /usr/include/gtkmm-4.0/gtkmm/widget.h:33,
                 from /usr/include/gtkmm-4.0/gtkmm/box.h:26,
[..]

This affects e.g. the build of the aoflagger package (and probably many
others), which no longer builds against the current version of
libgtkmm-4.0-dev.

Regards,
André


-- System Information:
Debian Release: forky/sid
  APT prefers testing
  APT policy: (900, 'testing'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 7.2.8+deb14-amd64 (SMP w/14 CPU threads; PREEMPT)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US:en
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages libgtkmm-4.0-dev:amd64 depends on:
ii  libgdk-pixbuf-2.0-dev  2.44.8+dfsg-1
ii  libglibmm-2.68-dev     2.90.0-1
ii  libgtk-4-dev           4.24.0+ds-2
ii  libgtkmm-4.0-0         4.22.0-1
ii  libpangomm-2.48-dev    2.56.2-1

libgtkmm-4.0-dev:amd64 recommends no packages.

Versions of packages libgtkmm-4.0-dev:amd64 suggests:
pn  libgtkmm-4.0-doc  <none>

-- no debconf information