GLOBAL_VAR being inlined?

I noticed that :def wasn't working in my HEAD (as of today) build of ghc. It would accept my command definitions silently, but they were ignored.

In InteractiveUI:

GLOBAL_VAR(commands, builtin_commands, [Command])

builtin_commands :: [Command]
builtin_commands = [ ...

After a random change :

builtin_commands = commands `seq` [ 
....
]

it seems to me that, under certain conditions (which?), GLOBAL_VARs can end up being inlined.

To see if you can reproduce this issue, simply try defining a new command in a -O2 HEAD build of ghci using :def, and then calling it.

Output of ghci005 here in my build of HEAD:

unknown command ':echo'
use :? for help.
unknown command ':echo'
use :? for help.
command 'echo' not defined
unknown command ':echo'
use :? for help.

With the seq'ing of commands above the test passes finely.

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