configure: Don't depend upon alex in source dist build

Authored by bgamari on Sep 18 2019, 10:50 PM.

Description

configure: Don't depend upon alex in source dist build

This fixes Trac #16860 by verifying that the generated sources don't already
exist before asserting that the alex executable was found. This
replicates the logic already used for happy in the case of alex.

Details

Committed
Marge Bot <ben+marge-bot@smart-cactus.org>Fri, Sep 27, 9:11 PM
Parents
rGHC9c02a793be61: Allow users to disable Unicode with an env var
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Marge Bot <ben+marge-bot@smart-cactus.org> committed rGHC144abba394c6: configure: Don't depend upon alex in source dist build (authored by bgamari).Fri, Sep 27, 9:11 PM