From:
http://mail.openjdk.java.net/pipermail/build-dev/2020-April/027207.html

----
A patch from last year [1] discussed on this list adds an autoconf
fallback test for a shell builtin command using the bash command 'help
<command>' and invokes it for ulimit. It's probably not very portable
to start with but bash can be compiled specifically without the help
command by passing --disable-help-builtin to configure. guix uses this
option for it's build environment shell [4], hence openjdk fails to
configure there without a patch such as the one below.

For openjdk 14[3], is it possible to use a more portable sequence in the
BASIC_REQUIRE_BUILTIN_PROGS macro? The internet [2] suggests using
"command -v <command>" or "type <command>" for this purpose.

Although I have not tried, the same appears to apply to openjdk-15
although the macro has been moved to UTIL_REQUIRE_BUILTIN_PROGS in
make/autoconf/util.m4

Thanks,
  Z

[1]
https://mail.openjdk.java.net/pipermail/build-dev/2019-November/026307.html
[2]
https://stackoverflow.com/questions/592620/how-can-i-check-if-a-program-exists-from-a-bash-script
[3] http://hg.openjdk.java.net/jdk/jdk14/rev/bc54620a3848
[4]
https://git.savannah.gnu.org/cgit/guix.git/tree/gnu/packages/bash.scm#n202

$ help command
command: command [-pVv] command [arg ...]
     Execute a simple command or display information about commands.

     Runs COMMAND with ARGS suppressing shell function lookup, or display
     information about the specified COMMANDs. Can be used to invoke
commands
     on disk when a function with the same name exists.

     Options:
       -p use a default value for PATH that is guaranteed to find all of
             the standard utilities
       -v print a description of COMMAND similar to the `type' builtin
       -V print a more verbose description of each COMMAND

     Exit Status:
     Returns exit status of COMMAND, or failure if COMMAND is not found.


--- jdk14-bc54620a3848/make/autoconf/basics.m4 2020-02-07
04:40:54.000000000 +1030
+++ jdk14-bc54620a3848-new/make/autoconf/basics.m4 2020-04-24
10:59:33.056098506 +0930
@@ -583,7 +583,7 @@
    BASIC_SETUP_TOOL($1, [AC_PATH_PROGS($1, $2, , $3)])
    if test "x[$]$1" = x; then
      AC_MSG_NOTICE([Required tool $2 not found in PATH, checking built-in])
- if help $2 > /dev/null 2>&1; then
+ if command -v $2 > /dev/null 2>&1; then
        AC_MSG_NOTICE([Found $2 as shell built-in. Using it])
        $1="$2"
      else