In the emacs dir I see config.log:

configure:14159: checking for libwebpdemux >= 0.6.0
configure:14323: gcc -o conftest  -g3 -O2 -pthread -isystem
/usr/include/librsvg-2.0 -isystem /usr/include/gdk-pixbuf-2.0 -isystem
/usr/include/x86_64-linux-gnu -isystem /usr/include/libmount -isystem
/usr/include/blkid -isystem /usr/include/cairo -isystem
/usr/include/glib-2.0 -isystem /usr/lib/x86_64-linux-gnu/glib-2.0/include
-isystem /usr/include/pixman-1 -isystem /usr/include/uuid -isystem
/usr/include/freetype2 -isystem /usr/include/libpng16 -isystem
/usr/include/webp       conftest.c -lsqlite3  -lsqlite3 -lX11   >&5
| #define HAVE_WEBP 1
pkg_cv_WEBP_CFLAGS=-I/usr/include/webp
WEBP_CFLAGS='-isystem /usr/include/webp'
WEBP_LIBS='-lwebpdemux'

I attached the log.

Best regards

-----Messaggio originale-----
Da: Eli Zaretskii <eliz@gnu.org> 
Inviato: marted́ 7 marzo 2023 15:11
A: Ugo Tomei <utomei@tiscali.it>
Cc: luangruo@yahoo.com; 61988@debbugs.gnu.org
Oggetto: Re: bug#61988: error compiling emacs

> From: "Ugo Tomei" <utomei@tiscali.it>
> Date: Tue, 7 Mar 2023 14:36:19 +0100
> 
> If i remove libwebpdecoder3 on my ubuntu 22.04 emacs compile well.

Compiles and supports display of WebP images?  Or compiles without WebP
support?  What does the "configure" script say when it ends? does it say

  Does Emacs use -lwebp?                                  yes

or does not say

  Does Emacs use -lwebp?                                  no

> If I install libwebpdecoder3 not compile (/usr/bin/ld:
> /lib/x86_64-linux-gnu/libwebp.so.7: error adding symbols: DSO missing 
> from command line):
> 
>   CC       textconv.o
>   CC       xgselect.o
>   CC       json.o
>   CC       terminfo.o
>   CC       lastfile.o
>   CCLD     temacs
>   GEN      ../etc/DOC
> /usr/bin/ld: image.o: undefined reference to symbol 'WebPGetInfo'
> /usr/bin/ld: /lib/x86_64-linux-gnu/libwebp.so.7: error adding symbols: 
> DSO missing from command line

Please show the parts of config.log where the configure script makes the
WebP related tests.  Here's what I see on my system:

  configure:14271: checking for libwebpdemux >= 0.6.0
  configure:14278: $PKG_CONFIG --exists --print-errors "$WEBP_MODULE"
  configure:14281: $? = 0
  configure:14295: $PKG_CONFIG --exists --print-errors "$WEBP_MODULE"
  configure:14298: $? = 0
  configure:14336: result: yes
  configure:14350: checking for WebPGetInfo
  configure:14350: gcc -I ./nt/inc -o conftest.exe -O0 -gdwarf-4 -g3
-mms-bitfields -isystem d:/usr/include/librsvg-2.0 -isystem
d:/usr/include/gdk-pixbuf-2.0 -isystem d:/usr/include/libpng16 -isystem
d:/usr/include/cairo -isystem d:/usr/include/glib-2.0 -isystem
d:/usr/lib/glib-2.0/include -isystem d:/usr/include/pixman-1 -isystem
d:/usr/include/libpng16   -mtune=pentium4    conftest.c   -lwebpdemux -lwebp
>&5 
  configure:14350: $? = 0
  configure:14350: result: yes