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authorBoris Kolpackov <boris@codesynthesis.com>2020-03-16 08:06:15 +0200
committerBoris Kolpackov <boris@codesynthesis.com>2020-03-17 07:47:17 +0200
commit9f71deeeb0f8e6fe2c29f209fc96f466fc2831b6 (patch)
tree81e07870c7a16f12c7aca69bf70a71d69251d1fc /libbuild2/config/utility.txx
parent1adbf7b710d52958f6c0168ccb492252c1f19d4a (diff)
Rework config::{omitted,required,optional}() into unified config_lookup()
Diffstat (limited to 'libbuild2/config/utility.txx')
-rw-r--r--libbuild2/config/utility.txx39
1 files changed, 33 insertions, 6 deletions
diff --git a/libbuild2/config/utility.txx b/libbuild2/config/utility.txx
index f52df8d..ae40ba7 100644
--- a/libbuild2/config/utility.txx
+++ b/libbuild2/config/utility.txx
@@ -7,13 +7,14 @@ namespace build2
{
template <typename T>
pair<lookup, bool>
- required (scope& rs,
- const variable& var,
- T&& def_val,
- bool def_ovr,
- uint64_t sflags)
+ lookup_config_impl (scope& rs,
+ const variable& var,
+ T&& def_val,
+ uint64_t sflags,
+ bool def_ovr)
{
- // Note: see also omitted() if changing anything here.
+ // Note: see also the other lookup_config() implementation if changing
+ // anything here.
save_variable (rs, var, sflags);
@@ -28,6 +29,32 @@ namespace build2
// are going to do is first ignore overrides and perform the normal
// logic on the original. Then we apply the overrides on the result.
//
+ // Note that this is not exactly the "lookup and set to default if
+ // undefined" semantics in case there is no original but there is an
+ // override. In this case we will set original to default and then apply
+ // the override, which could be append or non-recursive (as mentioned
+ // above). It does, however, feel like taking into account the default
+ // in such cases is the correct semantics since append is meant as an
+ // addition to something existing and non-recursive override is only
+ // meant to override at the level it was specified. Though it won't be
+ // surprising at all if we end up with some counter-intuitive behavior
+ // here.
+ //
+ // Actually, the above analysis is not the full picture: if we have one
+ // of those overrides (append, non-recursive) in the outer project, then
+ // the lookup_config() call at that level will set the corresponding
+ // variable on that scope and we will see it as "original-defined" from
+ // our scope. Of course if there is no call to lookup_config() for this
+ // variable in the outer scope, then we won't see anything but then our
+ // behavior in this case seems correct: since that value is not part of
+ // the configuration (and won't be saved), then we should stick to our
+ // default. In other words, we should only inherit the value if it is
+ // actually recognized as a configuration value by the outer project.
+ //
+ // So, to summarize the current understanding, while our semantics is
+ // not exactly "lookup and set to default if undefined" in some obscure
+ // corner cases, it seem to be the correct/preferred one.
+ //
if (!l.defined () || (def_ovr && !l.belongs (rs)))
{
value& v (rs.assign (var) = std::forward<T> (def_val)); // VC14