We use this so you can run fish from the build directory and it picks
up its data files.
If this wasn't canonicalized, that would break if you're building with
a $PWD through a symlink.
NCurses headers contain this conditional "#define cur_term":
print "#elif @cf_cv_enable_reentrant@"
print "NCURSES_WRAPPED_VAR(TERMINAL *, cur_term);"
print "#define cur_term NCURSES_PUBLIC_VAR(cur_term())"
print "#else"
OpenSUSE Tumbleweed uses this configuration option; For reentrancy, cur_term
is a function. If the NCurses autoconf variable @NCURSES_WRAP_PREFIX@
is not changed from its default, the function is called _nc_cur_term.
I'm not sure if we have a need to support non-default @NCURSES_WRAP_PREFIX@
but if we do there are various ways;
- search for the symbol with the cur_term suffix
- figure out the prefix based on the local curses installation,
for example by looking at the header files.
Fixes#10243
Since none of the compiles(xxx) calls are to particularly complex code, we can
just use `rsconf` directly to test for the presence of the symbols or headers as
needed.
Note that it seems at least some of the previous detection was not working
correctly; in particular HAVE_PIPE2 was evaluating to false on my WSL install
where pipe2(2) was available (caught because it revealed some compilation errors
in that conditional compilation path after porting).
I kept the cfg names and the tests themselves mostly as-is, though we might want
to change that to conform with the rust convention of lowercase cfg names and
decide whether we want to prefix all these with have_, fish_, or nothing at all.
Also the posix_spawn() test should probably check for the symbol `posix_spawn()`
rather than the header `spawn.h` since we don't use it via the header but rather
via the symbol (but in reality they're almost certainly going to give the same
result).
