__fish_apropos: assume only /usr/bin/apropos is broken

Also, remove a macOS version check that's doom to obsolescence,
and extract a function (WIP).

share/completions/man.fish

@@ -38,7 +38,7 @@ complete -c man -n 'string match -q -- "*/*" (commandline -t | string collect)'
 if command -q man
     # We have a conditionally-defined man function,
     # so we need to check for existence here.
-    if echo | MANPAGER=cat command man -l - &>/dev/null
+    if echo | __fish_without_manpager command man -l - &>/dev/null
         complete -c man -s l -l local-file -d "Local file" -r
     end
 end

share/functions/__fish_apropos.fish

@@ -5,9 +5,7 @@ if not type -q apropos
     exit
 end
 
-# Check for macOS Catalina or above.
 if test (__fish_uname) = Darwin
-    and test (string match -r "^\d+" "$(uname -r)") -ge 19
     and test -x /usr/libexec/makewhatis
 
     set -l dir
@@ -18,6 +16,11 @@ if test (__fish_uname) = Darwin
     end
 
     function __fish_apropos -V dir
+        if test "$(command -v apropos)" != /usr/bin/apropos
+            __fish_without_manpager apropos "$argv"
+            return
+        end
+
         # macOS 10.15 "Catalina" has a read only filesystem where the whatis database should be.
         # The whatis database is non-existent, so apropos tries (and fails) to create it every time,
         # which can take seconds.
@@ -34,17 +37,19 @@ if test (__fish_uname) = Darwin
             set age (path mtime -R -- $whatis)
         end
 
-        MANPATH="$dir" MANPAGER=cat WHATISPAGER=cat apropos "$argv"
+        MANPATH="$dir" __fish_without_manpager apropos "$argv"
 
         if test $age -ge $max_age
             test -d "$dir" || mkdir -m 700 -p $dir
-            /bin/sh -c '( "$@" ) >/dev/null 2>&1 </dev/null &' -- /usr/libexec/makewhatis -o "$whatis" (/usr/bin/manpath | string split : | xargs realpath)
+            /bin/sh -c '( "$@" ) >/dev/null 2>&1 </dev/null &' -- \
+                /usr/libexec/makewhatis -o "$whatis" \
+                (/usr/bin/manpath | string split : | xargs realpath)
         end
     end
 else
     function __fish_apropos
         # we only ever prefix match for completions. This also ensures results for bare apropos <TAB>
         # (apropos '' gives no results, but apropos '^' lists all manpages)
-        MANPAGER=cat WHATISPAGER=cat apropos "$argv"
+        __fish_without_manpager apropos "$argv"
     end
 end

share/functions/__fish_print_help.fish

@@ -10,7 +10,7 @@ function __fish_print_help --description "Print help for the specified fish func
         end
         set -l args -l (path filter -- $man1/$item.1 $man1/$item.1.gz)[1]
         # Work around macOS/FreeBSD man not supporting -l yet (only mandoc really needs it).
-        if not MANPAGER=cat WHATISPAGER=cat command man -l $args[2] &>/dev/null
+        if not __fish_without_manpager command man -l $args[2] &>/dev/null
             set -e args[1]
         end
         command man $args

share/functions/__fish_without_manpager.fish

@@ -0,0 +1,7 @@
+function __fish_without_manpager
+    MANPAGER=cat WHATISPAGER=cat if test "$argv[1]" = command
+        command $argv[2..]
+    else
+        $argv
+    end
+end