Bug 264, which this workaround was for, has been fixed in other changes.
compiler/mode_errors.m:
Remove the temporary error.
compiler/modecheck_unify.m:
Don't check this error condition.
doc/reference_manual.texi:
Document the constraint that actually applies, namely that functions
that do not match the default mode do not match Mercury's 'ground'
inst.
Clarify that "no higher-order inst information" means no *explicit*
information. Given that there is a default, this is not the same as
saying there are no logical consequences.
tests/invalid/default_ho_inst.err_exp:
tests/invalid/default_ho_inst_2.err_exp:
Update expected output.
tests/valid/Mmakefile:
tests/valid/ho_func_call_2.m:
New test case. Function modes that are not the same as the default,
but that match it, can still safely be treated as ground.
