tags fail with dummy source for libtool

[Robert Sachunsky]

Hi all,

I am using software that specifies a nodist_EXTRA_*_SOURCES dummy source
file in its top-level Makefile.am, as recommended by the Automake manual
to get the C++ linker to combine several libtool convenience libraries
for subdirectories:

https://www.gnu.org/software/automake/manual/html_node/Libtool-Convenience-Libraries.html

https://github.com/tesseract-ocr/tesseract/blob/14c6e387239a679ac5b58f126ab96e851a5e6624/Makefile.am#L137


However, this also causes the `tags`, `ctags` and `cscope` targets to fail:

--->8---
Making tags in .
make[1]: Entering directory 'tesseract/build'
make[1]: *** No rule to make target 'dummy.cxx', needed by 'tags-am'.  Stop.
make[1]: Leaving directory 'tesseract/build'
Makefile:4392: recipe for target 'tags-recursive' failed
---8<---


Does anyone know how to repair this (i.e. get both the desired linking
_and_ recursive tag generation rules)?


Regards,
Robert