bsc: uses_from_macos "tcl-tk", backport TCL 9 support

[cho-m]

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Looks like this uses system TCL on macOS - https://github.com/B-Lang-org/bsc/blob/main/platform.sh#L81-L86

[carlocab]

macOS tcl-tk is old and deprecated; we probably shouldn't be using it anymore.

[cho-m]

Would need upstream changes as they specifically set to system copy - https://github.com/B-Lang-org/bsc/blob/main/platform.sh#L81-L86

if [ ${OSTYPE} = "Darwin" ] ; then
    # Have Makefile avoid Homebrew's install of tcl on Mac
    TCLSH=/usr/bin/tclsh
else
    TCLSH=`which tclsh`
fi

[gromgit]

Probably worth clarifying with upstream if this change, introduced over 4 years ago, still makes sense, especially since:-

sonoma$ /usr/bin/tclsh

WARNING: This version of tcl is included in macOS for compatibility with legacy software.
In future versions of macOS the tcl runtime will not be available by
default, and may require you to install an additional package.

% 

[cho-m]

Maybe I'll try make TCLSH=... to see if it overrides lookup.

EDIT: insufficient as still used to find tclversion and tclinc:

Using tclsh: /opt/homebrew/opt/tcl-tk/bin/tclsh
Tcl version: 8.5
Using Tcl defines: TCL85
Using tcl include flags: 
Using tcl library flags: -ltcl8.5

[cho-m]

Upstream should be aware that system Tcl is outdated and has mentioned interest in moving away from it back in 2022:

• Tcl-X11 on MacOS B-Lang-org/bsc#504 (comment)

Someone in issue discussion patched out the system Tcl logic like: kammoh/bsc@ded6d77