A number of C compiler suites have a math.h library that includes a yn()
function name that conflicts with NetHack's yn() macro:
"The y0(), y1(), and yn() functions are Bessel functions of the second kind,
for orders 0, 1, and n, respectively. The argument x must be positive. The
argument n should be greater than or equal to zero. If n is less than zero,
there will be a negative exponent in the result."
At one point, isaac64.h included math.h, although that has since been removed.
Some libraries used in NetHack (Qt for one) do include math.h and that required
build work-arounds to avoid the conflict.
Rename the NetHack macro from yn() to y_n() and avoid the math.h conflict
altogether, eliminating the need for that particular work-around.
I forced a test compile to -std=c++20 mostly to see what we would
be up against. There was only a small number of things and they
are corrected in this commit.
c++20 has some issues with comparisons and bit twiddling between
different enums.
The vendor-supplied Qt5 header files triggered some of those issues as
well, so the qt_pre.h and qt_post.h NetHack header files were adjusted
to make those new warnings go away. I have not tested Qt6 under the
new compiler and c++ version yet.
Because there are multiple pragmas in qt_pre.h now, the conditional
ifdef structure in there was modified a little to make maintenance
simpler and have a single pragma push at the top. The pragma pop
comes after the Qt vendor-supplied header files, and is done
in qt_post.h.
The display.h macro cmap_to_glyph() was used in
a Qt c++ file and triggered a series of warnings because of that.
Rather than write c++20-friendly versions of those macros, the
simple fix is to provide a function on the C side of things
to front the cmap_to_glyph() macro, so fn_cmap_to_glyph()
was added.
Also thrown into this commit, PatR picked up on the fact that for
yesterday's new warning in qt_menu.cpp, the compiler had correctly
picked up on the fact that the format range of the variable 'cash'
had been correctly upper-capped at 999999999L in the warning message
because of an assignment prior. He suggested that perhaps by also adding
if (cash < 0)
cash = 0;
the warning might be eliminated altogether.
After a test, that was proven to be correct, so yesterday's
more-kludgy change is reverted and replaced with that variable
variable restriction ahead of the snprintf().
Our C() macro conflicts with Qt6 usage, so #undef C has added. Move
that from nearly every qt_*.cpp into qt_pre.h where other similar
fixups are handled.
Move the nine #undef's common to all qt_*.cpp sources into qt_pre.h.
Make "hack.h" usage consistent; always enclose withing 'extern "C {'
and '}' even though only some of the sources care.
