From 18394bc05dc4cadb2dc193cfeb78598c70447869 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Wed, 19 Oct 2022 10:26:22 +0200
Subject: Add support for post hoc prerequisites

Unlike normal and ad hoc prerequisites, a post hoc prerequisite is built
after the target, not before. It may also form a dependency cycle together
with normal/ad hoc prerequisites. In other words, all this form of dependency
guarantees is that a post hoc prerequisite will be built if its dependent
target is built.

See the NEWS file for details and an example.
---
 libbuild2/algorithm.hxx | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

(limited to 'libbuild2/algorithm.hxx')

diff --git a/libbuild2/algorithm.hxx b/libbuild2/algorithm.hxx
index e558d3a..756c3fe 100644
--- a/libbuild2/algorithm.hxx
+++ b/libbuild2/algorithm.hxx
@@ -195,6 +195,8 @@ namespace build2
 
     explicit operator bool () const {return target != nullptr;}
 
+    // Note: achieved offset is preserved.
+    //
     void
     unlock ();
 
@@ -374,6 +376,12 @@ namespace build2
   pair<bool, target_state>
   match_sync (action, const target&, unmatch);
 
+  // As above but without incrementing the target's dependents count. Should
+  // be executed with execute_direct_*().
+  //
+  target_state
+  match_direct_sync (action, const target&, bool fail = true);
+
   // Start asynchronous match. Return target_state::postponed if the
   // asynchronous operation has been started and target_state::busy if the
   // target has already been busy. Regardless of the result, match_complete()
@@ -486,11 +494,11 @@ namespace build2
   // target pointers are skipped.
   //
   LIBBUILD2_SYMEXPORT void
-  match_members (action, target&, const target* const*, size_t);
+  match_members (action, const target&, const target* const*, size_t);
 
   template <size_t N>
   inline void
-  match_members (action a, target& t, const target* (&ts)[N])
+  match_members (action a, const target& t, const target* (&ts)[N])
   {
     match_members (a, t, ts, N);
   }
@@ -501,7 +509,7 @@ namespace build2
   //
   LIBBUILD2_SYMEXPORT void
   match_members (action a,
-                 target& t,
+                 const target& t,
                  prerequisite_targets& ts,
                  size_t start = 0,
                  pair<uintptr_t, uintptr_t> include = {0, 0});
@@ -613,7 +621,7 @@ namespace build2
   // translates target_state::failed to the failed exception.
   //
   target_state
-  execute_direct_sync (action, const target&);
+  execute_direct_sync (action, const target&, bool fail = true);
 
   target_state
   execute_direct_async (action, const target&,
@@ -795,8 +803,9 @@ namespace build2
 
   // Call straight or reverse depending on the current mode.
   //
+  template <typename T>
   target_state
-  execute_members (action, const target&, const target*[], size_t);
+  execute_members (action, const target&, T[], size_t);
 
   template <size_t N>
   inline target_state
-- 
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