diff options
Diffstat (limited to 'libbuild2/target.hxx')
| -rw-r--r-- | libbuild2/target.hxx | 31 |
1 files changed, 21 insertions, 10 deletions
diff --git a/libbuild2/target.hxx b/libbuild2/target.hxx index ed8c0bf..32f717f 100644 --- a/libbuild2/target.hxx +++ b/libbuild2/target.hxx @@ -184,15 +184,22 @@ namespace build2 // // On initial match()/apply(), cur_options is initialized to ~0 (all // options enabled) and the matching rule is expected to override it with - // new_options in match() (if it matches). This way a rule that does not - // support any match options does not need to do anything. On rematch in - // the reapply() call, cur_options are the currently enabled options and - // new_options are the newly requested options. Here the rule is expected - // to factor new_options to cur_options as appropriate. Note also that on - // rematch, if current options already include new options, then no call - // to reapply() is made. This, in particular, means that a rule that does - // not adjust cur_options in match() will never get a reapply() call - // (because all the options are enabled from the start). + // new_options in apply() (note that match() should no base any decisions + // on new_options since they may change between match() and apply()). This + // way a rule that does not support any match options does not need to do + // anything. On rematch in the reapply() call, cur_options are the + // currently enabled options and new_options are the newly requested + // options. Here the rule is expected to factor new_options to cur_options + // as appropriate. Note also that on rematch, if current options already + // include new options, then no call to reapply() is made. This, in + // particular, means that a rule that does not adjust cur_options in + // match() will never get a reapply() call (because all the options are + // enabled from the start). + // + // Note: options are currently not supported in ad hoc recipes/rules. + // + // @@ We could use 0 new_options (which otherwise don't make sense) for + // match for the purpose of resolving members? // // @@ TODO: clear already enabled options from new_options on rematch. // @@ -789,7 +796,11 @@ namespace build2 // mutable atomic_count dependents {0}; - // Match state storage between the match() and apply() calls. + // Match state storage between the match() and apply() calls with only + // the *_options members extended to reapply(). + // + // Note: in reality, cur_options are used beyong (re)apply() as an + // implementation detail. // build2::match_extra match_extra; |