With USE=doc, emerge ginac fails in "emake html" (see below).
Moreover, when emake html is omitted from the ebuild,
emerge runs without errors and TeXs some pdf but does not install any pdf.
The error message for "emake html" is (with some lines of content - I have not
checked whether the warning might be related):
/bin/bash /var/tmp/portage/sci-mathematics/ginac-1.4.3/work/ginac-1.4.3/missing
--run makeinfo --no-split --no-headers ./ginac-examples.texi >
ginac-examples.txt
./ginac-examples.texi:25: warning: `@contents' omitted since writing to stdout.
/bin/bash /var/tmp/portage/sci-mathematics/ginac-1.4.3/work/ginac-1.4.3/missing
--run makeinfo --no-split --html ./ginac-examples.texi
make[3]: Leaving directory
[...]
make: *** No rule to make target `html'. Stop.
