Update: Building the FLTK PDF docs with
doxygen version 1.8.14
(the same version the OP used) does indeed fail on my system as
well:
$ cmake --build . --target pdf
Converting Doxybook to doxygen version 1.8.14
Generating PDF documentation
/home/albrecht/temp/fltk/fltk-1.4.3/documentation/src/preface.dox:82: warning: expected whitespace after { command
/home/albrecht/temp/fltk/fltk-1.4.3/documentation/src/osissues.dox:1016: warning: Unsupported xml/html tag <u> found
/home/albrecht/temp/fltk/fltk-1.4.3/documentation/src/osissues.dox:1016: warning: Unsupported xml/html tag </u> found
/home/albrecht/temp/fltk/fltk-1.4.3/documentation/src/osissues.dox:1032: warning: Unsupported xml/html tag <u> found
/home/albrecht/temp/fltk/fltk-1.4.3/documentation/src/osissues.dox:1032: warning: Unsupported xml/html tag </u> found
/home/albrecht/temp/fltk/fltk-1.4.3/documentation/src/wayland.dox:168: warning: Unsupported xml/html tag <u> found
/home/albrecht/temp/fltk/fltk-1.4.3/documentation/src/wayland.dox:168: warning: Unsupported xml/html tag </u> found
/home/albrecht/temp/fltk/fltk-1.4.3/documentation/src/wayland.dox:876: warning: Unsupported xml/html tag <u> found
/home/albrecht/temp/fltk/fltk-1.4.3/documentation/src/wayland.dox:876: warning: Unsupported xml/html tag </u> found
/home/albrecht/temp/fltk/fltk-1.4.3/documentation/src/wayland.dox:883: warning: Unsupported xml/html tag <u> found
/home/albrecht/temp/fltk/fltk-1.4.3/documentation/src/wayland.dox:883: warning: Unsupported xml/html tag </u> found
/home/albrecht/temp/fltk/fltk-1.4.3/documentation/src/wayland.dox:1007: warning: Unsupported xml/html tag <u> found
/home/albrecht/temp/fltk/fltk-1.4.3/documentation/src/wayland.dox:1007: warning: Unsupported xml/html tag </u> found
/home/albrecht/temp/fltk/fltk-1.4.3/src/Fl_compose.cxx:69: warning: Unsupported xml/html tag <u> found
/home/albrecht/temp/fltk/fltk-1.4.3/src/Fl_compose.cxx:69: warning: Unsupported xml/html tag </u> found
/home/albrecht/temp/fltk/fltk-1.4.3/FL/Fl_Terminal.H:833: warning: unable to resolve reference to `Fl_Scrollbar::value(void)' for \ref command
/home/albrecht/temp/fltk/fltk-1.4.3/documentation/src/index.dox:14: warning: expected whitespace after { command
/home/albrecht/temp/fltk/fltk-1.4.3/documentation/src/index.dox:99: warning: expected whitespace after { command
cp: cannot stat 'latex/refman.pdf': No such file or directory
gmake[3]: *** [documentation/CMakeFiles/pdf.dir/build.make:77: documentation/fltk.pdf] Error 1
gmake[2]: *** [CMakeFiles/Makefile2:436: documentation/CMakeFiles/pdf.dir/all] Error 2
gmake[1]: *** [CMakeFiles/Makefile2:443: documentation/CMakeFiles/pdf.dir/rule] Error 2
gmake: *** [Makefile:195: pdf] Error 2
The warnings (blue color, normal text) are the same as when
generating the HTML docs, which works w/o errors. The error messages
(red color, bold italics) appear only when building the PDF docs
with doxygen 1.8.14.
@Eric: can you try to use a newer doxygen version? Doxygen 1.8.14 is
now about 6 1/2 years old (release date 25-12-2017 according to the
website). I'm not sure if we can "fix" this in our code, it can
either be a bug in doxygen or we are using a feature that has been
introduced in a later version. I'll check this, but please don't
hold your breath and don't
*expect* a (quick) fix on our
side.
I'm regularly building my own doxygen versions for testing, and IIRC
the build is not very complicated, but it takes its time. Anyway, I
found a short recipe for doing this in a stackoverflow answer, and I
hope this helps:
https://stackoverflow.com/questions/45431868/doxygen-usage-of-includedoc
This post is related to the issue that's most likely causing the
fail: we are using `include{doc}` in doxygen at several places.
BTW: the other warnings about
Unsupported
xml/html tag <u> seem to be benign. I don't know
if/when recognition of this tag has been introduced in doxygen, or
if it is another doxygen bug in version 1.8.14.
I hope this helps.
Albrecht