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Diffstat (limited to 'doc/concepts/built-in-rules.org')
| -rw-r--r-- | doc/concepts/built-in-rules.org | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/doc/concepts/built-in-rules.org b/doc/concepts/built-in-rules.org index 28784193..14c48ec5 100644 --- a/doc/concepts/built-in-rules.org +++ b/doc/concepts/built-in-rules.org @@ -136,3 +136,19 @@ evaluating the given target, and thereby performs a configuration transition. It forwards all results (artifacts/runfiles/provides map) of the configured target to the upper context. The result of a target that uses this rule is the result of the target given in the ~"target"~ field (the configured target). + +As a full configuration transition is performed, the same care has +to be taken when using this rule as when writing a configuration +transition in a rule. Typically, this rule is used only at a +top-level target of a project and configures only variables internally +to the project. In any case, when using non-internal targets as +dependencies (i.e., targets that a caller of the ~"configure"~ +potentially might use as well), care should be taken that those +are only used in the initial configuration. Such preservation of +the configuraiton is necessary to avoid conflicts, if the targets +depended upon are visible in the ~"configure"~ target itself, e.g., +as link dependency (which almost always happens when depending on a +library). Even if a non-internal target depended upon is not visible +in the ~"configure"~ target itself, requesting it in a modified +configuration causes additional overhead by increasing the target +graph and potentially the action graph. |