*warn-on-nested-reader-conditionals*

The handling of nested #+/#- conditionals in Allegro CL changed in release 8.0 in a non-backward-compatible way. When this variable is true (its initial value is t), a warning is signaled when a nested conditional is encountered, noting that the behavior has changed and that the conditionalized code may therefore work differently. the warning is suppressed when this variable is nil.

The following two forms are examples of nested conditionals whose behavior has changed (the old and new behavior are shown in the section of implementation.htm linked to below):

(list #+allegro :allegro #-allegro #+foo :foo #-foo :default)
(list #+allegro :allegro #-allegro #+foo :foo)

The section The issue of nested conditionals in Allegro CL in implementation.htm discusses the issue assocated with this variable in detail, with examples. See also *sharp-plus-de-facto-standard-compatible*.

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This page was not revised from the 10.0 page.
Created 2019.8.20.