TOOLS_PLATFORM.bash required version

Earlier I wrote that builds on macOS were failing because system bash
was bash 3, and [some package] was written expecting newer bash, because
bash 4.0 was released in 2009.

bash 5.0 was released in 2019.

Observation:

  The TOOLS_PLATFORM.foo definitions in platform/bar.mk are sort of like
  builtin.mk, except that they are static configured rather than search.

Two questions phrased as assertions:

  We do not seem to have a way of encoding a minimum version of a tool,
  unlike builtin.mk and buildlink3.mk.

  We do not seem to document what USE_TOOLS+=bash means in terms of
  whether the package can then expect bash 4, bash 5, or some particular
  5.x.


I propose to document, perhaps in a comment in tools/defaults.mk, that
bash as a tool will be >= 5.0.  Then:

  It will be a bug if TOOLS_PLATFORM.bash is set and the pointed-to bash
  is < 5.0.

  It will be a buglet to be cleaned up if a Makefile hacks around
  TOOLS_PLATFORM.bash ending up with old bash, when bash 5 is ok.


The only bash tool workarounds are devel/aceunit and
net/wireguard-tools.  I just gc'd the wireguard-tools one, explicitly as
about mac/bash3, and will follow up with aceunit $MAINTAINER.


Does anybody think we should say

  TOOLS_PLATFORM.bash must be >= 4.0

  packages that use bash but aren't ok with 4 must patch or work around
  TOOLS_PLATFORM.bash being set

instead?  If so, rationale for why that's better than assuming 5?



--- defaults.mk.~1.66.~ 2024-07-05 11:13:01.465622493 -0400
+++ defaults.mk 2026-06-30 06:44:15.606304239 -0400
@@ -53,6 +53,7 @@ TOOLS_DEFAULTS_MK=    defined

 _TOOLS_VARNAME.awk=            AWK
 _TOOLS_VARNAME.basename=       BASENAME
+# TOOLS_PLATFORM.bash must be >= 5.0.
 _TOOLS_VARNAME.bash=           BASH
 _TOOLS_VARNAME.bison-yacc=     YACC
 _TOOLS_VARNAME.byacc=          YACC