A strange cmake problem

Hello *,

I'm trying to bump wxmaxima to 26.06.2. Renaming 
wxmaxima-26.05.0-r1.ebuild -> wxmaxima-26.06.2.ebuild should work. But I 
get

CMake Error at data/CMakeLists.txt:47 (add_custom_command):
   add_custom_command called with wrong number of arguments.

The relevant part of data/CMakeLists.txt is

     # Compress man pages
     add_custom_command(
         OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/wxmaxima.1.gz"
         COMMAND gzip -cn9 "${CMAKE_CURRENT_BINARY_DIR}/wxmaxima.1" > "${CMAKE_CURRENT_BINARY_DIR}/wxmaxima.1.gz"
         DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/wxmaxima.1"
         COMMENT "Compressing man page"
     )
     add_custom_target(generate_man ALL DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/wxmaxima.1.gz")

The line 47 is add_custom_target, i.e., the line after the end of 
add_custom_command. I get this behaviour with cmake-4.3.4 and 
cmake-4.3.3-r1. I have asked the maxima mailing list:

1. They say that this piece of code has been added recently.

2. on an up-to-date Debian/Sid environment, version 26.06.2 of wxmaxima 
builds well.

3. Compiles without problems in ubuntu 24.04.

Is there something odd in cmake in Gentoo, or the way it is called, that 
leads to this difference to debian and ubuntu?

I don't see anything suspicious in this add_custom_command.

Hoping for your help,
Andrey