From efedf5c4700bcdd22841cf6885485677a93cc31c Mon Sep 17 00:00:00 2001
From: Julian Andres Klode <julian.klode@canonical.com>
Date: Wed, 5 Feb 2025 16:29:37 +0100
Subject: solver3: Replace PropagateInstall() with Discover()

Just propagate the stored clauses after we have discovered them;
this is quite straightforward. We now more reliably discover common
dependencies at the package level, adjust the test case accordingly.

The next step is to make discovery recursive, or iterative, to build
an entire recursive tree from all roots, and then we can reject reverse
dependencies based on it.

A bunch of refactorings are needed in the process. We remove the
useless Hint enumeration and insert a flags struct into the State,
such that we can record whether a package/version has been
discovered, to avoid spending double time on discovery.
---
 apt-pkg/solver3.h | 36 ++++++++++++++++++------------------
 1 file changed, 18 insertions(+), 18 deletions(-)

(limited to 'apt-pkg/solver3.h')

diff --git a/apt-pkg/solver3.h b/apt-pkg/solver3.h
index 42cde96f5..118ea5e28 100644
--- a/apt-pkg/solver3.h
+++ b/apt-pkg/solver3.h
@@ -174,18 +174,19 @@ class Solver
    // \brief If set, we install missing recommends and pick new best packages.
    bool FixPolicyBroken{_config->FindB("APT::Get::Fix-Policy-Broken")};
 
+   // \brief Discover a variable, translating the underlying dependencies to the SAT presentation
+   void Discover(Var var);
+   // \brief Link a clause into the watchers
+   void RegisterClause(Clause &&clause);
    // \brief Enqueue dependencies shared by all versions of the package.
-   [[nodiscard]] bool EnqueueCommonDependencies(pkgCache::PkgIterator Pkg);
+   void RegisterCommonDependencies(pkgCache::PkgIterator Pkg);
+
    // \brief Reject reverse dependencies. Must call std::make_heap() after.
    [[nodiscard]] bool RejectReverseDependencies(pkgCache::VerIterator Ver);
    // \brief Translate an or group into a clause object
    [[nodiscard]] Clause TranslateOrGroup(pkgCache::DepIterator start, pkgCache::DepIterator end, Var reason);
-   // \brief Enqueue a single or group
-   [[nodiscard]] bool EnqueueOrGroup(pkgCache::DepIterator start, pkgCache::DepIterator end, Var reason);
    // \brief Propagate all pending propagations
    [[nodiscard]] bool Propagate();
-   // \brief Propagate a "true" value of a variable
-   [[nodiscard]] bool PropagateInstall(Var var);
    // \brief Propagate a rejection of a variable
    [[nodiscard]] bool PropagateReject(Var var);
 
@@ -300,6 +301,8 @@ struct APT::Solver::Var
  */
 struct APT::Solver::Clause
 {
+   // \brief Underyling dependency
+   pkgCache::Dependency *dep = nullptr;
    // \brief Var for the work
    Var reason;
    // \brief The group we are in
@@ -365,17 +368,6 @@ enum class APT::Solver::Decision : uint16_t
    MUSTNOT,
 };
 
-// \brief Hints for the solver about the item.
-enum class APT::Solver::Hint : uint16_t
-{
-   // \brief We have not made a choice about the package yet
-   NONE,
-   // \brief This package was listed as a Recommends of a must package,
-   SHOULD,
-   // \brief This package was listed as a Suggests of a must-not package
-   MAY,
-};
-
 /**
  * \brief The solver state
  *
@@ -403,8 +395,16 @@ struct APT::Solver::State
    // \brief This essentially describes the install state in RFC2119 terms.
    Decision decision{Decision::NONE};
 
-   // \brief Any hint.
-   Hint hint{Hint::NONE};
+   // \brief Flags.
+   struct
+   {
+      bool discovered{};
+   } flags;
+
+   static_assert(sizeof(flags) <= sizeof(int));
+
+   // \brief Clauses owned by this package/version
+   std::vector<std::unique_ptr<Clause>> clauses;
 };
 
 /**
-- 
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