From 435b3e43dd054a716b3fc67fc34b43267f8e9809 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Mon, 8 Feb 2021 11:02:25 +0200
Subject: Enter scope src directories into scope map

---
 build2/b.cxx                   | 16 +++++++-----
 libbuild2/cc/compile-rule.cxx  | 20 +++++---------
 libbuild2/config/operation.cxx |  2 +-
 libbuild2/context.cxx          |  4 +--
 libbuild2/dist/operation.cxx   |  2 +-
 libbuild2/dump.cxx             | 17 ++++++------
 libbuild2/file.cxx             | 48 ++++++++++++++++++++++------------
 libbuild2/file.hxx             |  2 +-
 libbuild2/parser.hxx           |  2 +-
 libbuild2/scope.cxx            | 59 ++++++++++++++++++++++++++++++++----------
 libbuild2/scope.hxx            | 57 +++++++++++++++++++++++++++++++++-------
 libbuild2/search.cxx           |  2 +-
 12 files changed, 157 insertions(+), 74 deletions(-)

diff --git a/build2/b.cxx b/build2/b.cxx
index 9a924d6..ecf8c7f 100644
--- a/build2/b.cxx
+++ b/build2/b.cxx
@@ -1151,7 +1151,7 @@ main (int argc, char* argv[])
           // use to the bootstrap files (other than src-root.build, which,
           // BTW, doesn't need to exist if src_root == out_root).
           //
-          scope& rs (create_root (*ctx, out_root, src_root)->second);
+          scope& rs (*create_root (*ctx, out_root, src_root)->second.scope);
 
           bool bstrapped (bootstrapped (rs));
 
@@ -1561,9 +1561,10 @@ main (int argc, char* argv[])
               // If we have a directory, enter the scope, similar to how we do
               // it in the context ctor.
               //
-              scope& s (o.dir
-                        ? sm.insert ((out_base / *o.dir).normalize ())->second
-                        : *rs.weak_scope ());
+              scope& s (
+                o.dir
+                ? *sm.insert ((out_base / *o.dir).normalize ())->second.scope
+                : *rs.weak_scope ());
 
               auto p (s.vars.insert (o.ovr));
 
@@ -1581,9 +1582,10 @@ main (int argc, char* argv[])
               if (o.ovr.visibility == variable_visibility::global)
                 continue;
 
-              scope& s (o.dir
-                        ? sm.insert ((out_base / *o.dir).normalize ())->second
-                        : rs);
+              scope& s (
+                o.dir
+                ? *sm.insert ((out_base / *o.dir).normalize ())->second.scope
+                : rs);
 
               auto p (s.vars.insert (o.ovr));
 
diff --git a/libbuild2/cc/compile-rule.cxx b/libbuild2/cc/compile-rule.cxx
index 8354bca..c9d2652 100644
--- a/libbuild2/cc/compile-rule.cxx
+++ b/libbuild2/cc/compile-rule.cxx
@@ -2151,8 +2151,7 @@ namespace build2
 
                   if (j != je)
                   {
-                    // The groups are ordered from the most to least
-                    // specific.
+                    // The groups are ordered from the most to least specific.
                     //
                     for (const string& g: j->second)
                       if ((i = ths.find (g)) != ie)
@@ -2812,18 +2811,11 @@ namespace build2
         if (!e.empty ())
           n.resize (n.size () - e.size () - 1); // One for the dot.
 
-        // See if this directory is part of any project out_root hierarchy and
-        // if so determine the target type.
+        // See if this directory is part of any project and if so determine
+        // the target type.
         //
-        // Note that this will miss all the headers that come from src_root
-        // (so they will be treated as generic C headers below). Generally, we
-        // don't have the ability to determine that some file belongs to
-        // src_root of some project. But that's not a problem for our
-        // purposes: it is only important for us to accurately determine
-        // target types for headers that could be auto-generated.
-        //
-        // While at it also try to determine if this target is from the src or
-        // out tree of said project.
+        // While at it also determine if this target is from the src or out
+        // tree of said project.
         //
         dir_path out;
 
@@ -2839,7 +2831,7 @@ namespace build2
         {
           tts = map_extension (bs, n, e);
 
-          if (bs.out_path () != bs.src_path () && d.sub (bs.src_path ()))
+          if (!bs.out_eq_src () && d.sub (bs.src_path ()))
             out = out_src (d, *rs);
         }
 
diff --git a/libbuild2/config/operation.cxx b/libbuild2/config/operation.cxx
index f9d83da..7490bc3 100644
--- a/libbuild2/config/operation.cxx
+++ b/libbuild2/config/operation.cxx
@@ -720,7 +720,7 @@ namespace build2
         //
         create_bootstrap_inner (rs);
 
-        if (rs.out_path () == rs.src_path ())
+        if (rs.out_eq_src ())
           fail (l) << "forwarding to source directory " << rs.src_path ();
       }
       else
diff --git a/libbuild2/context.cxx b/libbuild2/context.cxx
index 3224dc1..df06aa8 100644
--- a/libbuild2/context.cxx
+++ b/libbuild2/context.cxx
@@ -35,7 +35,7 @@ namespace build2
   create_global_scope (scope_map& m)
   {
     auto i (m.insert (dir_path ()));
-    scope& r (i->second);
+    scope& r (*i->second.scope);
     r.out_path_ = &i->first;
     return r;
   };
@@ -488,7 +488,7 @@ namespace build2
       //
       if (c == '!' || (dir && dir->absolute ()))
       {
-        scope& s (c == '!' ? gs : sm.insert (*dir)->second);
+        scope& s (c == '!' ? gs : *sm.insert (*dir)->second.scope);
 
         auto p (s.vars.insert (*o));
         assert (p.second); // Variable name is unique.
diff --git a/libbuild2/dist/operation.cxx b/libbuild2/dist/operation.cxx
index 07f3b42..ac76a62 100644
--- a/libbuild2/dist/operation.cxx
+++ b/libbuild2/dist/operation.cxx
@@ -597,7 +597,7 @@ namespace build2
           (rs->out_path () != t.dir && rs->src_path () != t.dir))
         fail << "dist meta-operation target must be project root directory";
 
-      if (rs->out_path () == rs->src_path ())
+      if (rs->out_eq_src ())
         fail << "in-tree distribution of target " << t <<
           info << "distribution requires out-of-tree build";
 
diff --git a/libbuild2/dump.cxx b/libbuild2/dump.cxx
index 95c7cae..7cd95dd 100644
--- a/libbuild2/dump.cxx
+++ b/libbuild2/dump.cxx
@@ -438,7 +438,7 @@ namespace build2
               scope_map::const_iterator& i,
               bool rel)
   {
-    const scope& p (i->second);
+    const scope& p (*i->second.scope);
     const dir_path& d (i->first);
     ++i;
 
@@ -484,7 +484,8 @@ namespace build2
       vb = true;
     }
 
-    // Nested scopes of which we are an immediate parent.
+    // Nested scopes of which we are an immediate parent. Only consider the
+    // out hierarchy.
     //
     // Note that because we use the logical (rather than physical) parent, we
     // will be printing the logical scope hierarchy (i.e., a project with
@@ -492,7 +493,7 @@ namespace build2
     // scope).
     //
     for (auto e (p.ctx.scopes.end ());
-         i != e && i->second.parent_scope () == &p; )
+         i != e && i->second.out && i->second.scope->parent_scope () == &p; )
     {
       if (vb)
       {
@@ -541,8 +542,8 @@ namespace build2
   void
   dump (const context& c, optional<action> a)
   {
-    auto i (c.scopes.cbegin ());
-    assert (&i->second == &c.global_scope);
+    auto i (c.scopes.begin ());
+    assert (i->second.scope == &c.global_scope);
 
     // We don't lock diag_stream here as dump() is supposed to be called from
     // the main thread prior/after to any other threads being spawned.
@@ -556,9 +557,9 @@ namespace build2
   void
   dump (const scope& s, const char* cind)
   {
-    const scope_map_base& m (s.ctx.scopes); // Iterator interface.
-    auto i (m.find (s.out_path ()));
-    assert (i != m.end () && &i->second == &s);
+    const scope_map& m (s.ctx.scopes);
+    auto i (m.find_exact (s.out_path ()));
+    assert (i != m.end () && i->second.scope == &s);
 
     string ind (cind);
     ostream& os (*diag_stream);
diff --git a/libbuild2/file.cxx b/libbuild2/file.cxx
index 5d1487f..87e21a6 100644
--- a/libbuild2/file.cxx
+++ b/libbuild2/file.cxx
@@ -399,7 +399,7 @@ namespace build2
                const dir_path& src_root)
   {
     auto i (ctx.scopes.rw ().insert (out_root, true /* root */));
-    scope& rs (i->second);
+    scope& rs (*i->second.scope);
 
     // Set out_path. Note that src_path is set in setup_root() below.
     //
@@ -457,9 +457,17 @@ namespace build2
     const dir_path& d (cast<dir_path> (v));
 
     if (s.src_path_ == nullptr)
-      s.src_path_ = &d;
+    {
+      if (*s.out_path_ != d)
+      {
+        auto i (ctx.scopes.rw (s).insert (s, d));
+        s.src_path_ = &i->first;
+      }
+      else
+        s.src_path_ = s.out_path_;
+    }
     else
-      assert (s.src_path_ == &d);
+      assert (*s.src_path_ == d);
 
     s.assign (ctx.var_forwarded) = forwarded;
   }
@@ -469,7 +477,7 @@ namespace build2
               const dir_path& out_base,
               const dir_path& src_base)
   {
-    scope& s (i->second);
+    scope& s (*i->second.scope);
     context& ctx (s.ctx);
 
     // Set src/out_base variables.
@@ -496,7 +504,15 @@ namespace build2
       assert (*s.out_path_ == out_base);
 
     if (s.src_path_ == nullptr)
-      s.src_path_ = &cast<dir_path> (sv);
+    {
+      if (out_base != src_base)
+      {
+        auto i (ctx.scopes.rw (s).insert (s, src_base));
+        s.src_path_ = &i->first;
+      }
+      else
+        s.src_path_ = s.out_path_;
+    }
     else
       assert (*s.src_path_ == src_base);
 
@@ -504,21 +520,22 @@ namespace build2
   }
 
   pair<scope&, scope*>
-  switch_scope (scope& root, const dir_path& p, bool proj)
+  switch_scope (scope& root, const dir_path& out_base, bool proj)
   {
     // First, enter the scope into the map and see if it is in any project. If
     // it is not, then there is nothing else to do.
     //
-    auto i (root.ctx.scopes.rw (root).insert (p));
-    scope& base (i->second);
+    auto i (root.ctx.scopes.rw (root).insert (out_base));
+    scope& base (*i->second.scope);
 
     scope* rs (nullptr);
 
     if (proj && (rs = base.root_scope ()) != nullptr)
     {
-      // Path p can be src_base or out_base. Figure out which one it is.
+      // The path must be in the out (since we've inserted it as out into the
+      // scope map).
       //
-      dir_path out_base (p.sub (rs->out_path ()) ? p : out_src (p, *rs));
+      assert (out_base.sub (rs->out_path ()));
 
       // Create and bootstrap root scope(s) of subproject(s) that this scope
       // may belong to. If any were created, load them. Note that we need to
@@ -534,8 +551,7 @@ namespace build2
 
       // Now we can figure out src_base and finish setting the scope.
       //
-      dir_path src_base (src_out (out_base, *rs));
-      setup_base (i, move (out_base), move (src_base));
+      setup_base (i, out_base, src_out (out_base, *rs));
     }
 
     return pair<scope&, scope*> (base, rs);
@@ -1316,7 +1332,7 @@ namespace build2
     // probably be tried first since that src_root was explicitly configured
     // by the user. After that, #2 followed by #1 seems reasonable.
     //
-    scope& rs (create_root (ctx, out_root, dir_path ())->second);
+    scope& rs (*create_root (ctx, out_root, dir_path ())->second.scope);
 
     bool bstrapped (bootstrapped (rs));
 
@@ -1383,7 +1399,7 @@ namespace build2
 
         // The same logic to src_root as in create_bootstrap_outer().
         //
-        scope& rs (create_root (ctx, out_root, dir_path ())->second);
+        scope& rs (*create_root (ctx, out_root, dir_path ())->second.scope);
 
         optional<bool> altn;
         if (!bootstrapped (rs))
@@ -1618,7 +1634,7 @@ namespace build2
     assert (!forwarded || out_root != src_root);
 
     auto i (create_root (ctx, out_root, src_root));
-    scope& rs (i->second);
+    scope& rs (*i->second.scope);
 
     if (!bootstrapped (rs))
     {
@@ -2327,7 +2343,7 @@ namespace build2
     {
       bool top (proot == nullptr);
 
-      root = &create_root (ctx, out_root, src_root)->second;
+      root = create_root (ctx, out_root, src_root)->second.scope;
 
       bool bstrapped (bootstrapped (*root));
 
diff --git a/libbuild2/file.hxx b/libbuild2/file.hxx
index e0291fe..0c4ad62 100644
--- a/libbuild2/file.hxx
+++ b/libbuild2/file.hxx
@@ -146,7 +146,7 @@ namespace build2
   // second.
   //
   LIBBUILD2_SYMEXPORT pair<scope&, scope*>
-  switch_scope (scope& root, const dir_path&, bool project = true);
+  switch_scope (scope& root, const dir_path& out_base, bool project = true);
 
   // Bootstrap and optionally load an ad hoc (sub)project (i.e., the kind that
   // is not discovered and loaded automatically by bootstrap/load functions
diff --git a/libbuild2/parser.hxx b/libbuild2/parser.hxx
index 1e924f0..3efb94a 100644
--- a/libbuild2/parser.hxx
+++ b/libbuild2/parser.hxx
@@ -531,7 +531,7 @@ namespace build2
     // project. So both must be saved and restored.
     //
     void
-    switch_scope (const dir_path&);
+    switch_scope (const dir_path& out_base);
 
     void
     process_default_target (token&);
diff --git a/libbuild2/scope.cxx b/libbuild2/scope.cxx
index 53c859f..29e0c55 100644
--- a/libbuild2/scope.cxx
+++ b/libbuild2/scope.cxx
@@ -944,10 +944,21 @@ namespace build2
   auto scope_map::
   insert (const dir_path& k, bool root) -> iterator
   {
-    scope_map_base& m (*this);
+    auto er (map_.emplace (k, true /* out */));
 
-    auto er (m.emplace (k, scope (ctx, true /* global */)));
-    scope& s (er.first->second);
+    if (er.second)
+    {
+      er.first->second.scope = new scope (ctx, true /* global */);
+    }
+    else if (!er.first->second.out)
+    {
+      // This can potentially be triggered if we use the same directory as one
+      // project's out and another's src.
+      //
+      fail << "directory " << k << " is used as both src and out scope";
+    }
+
+    scope& s (*er.first->second.scope);
 
     // If this is a new scope, update the parent chain.
     //
@@ -958,14 +969,14 @@ namespace build2
       // Update scopes of which we are a new parent/root (unless this is the
       // global scope). Also find our parent while at it.
       //
-      if (m.size () > 1)
+      if (map_.size () > 1)
       {
         // The first entry is ourselves.
         //
-        auto r (m.find_sub (k));
+        auto r (map_.find_sub (k));
         for (++r.first; r.first != r.second; ++r.first)
         {
-          scope& c (r.first->second);
+          scope& c (*r.first->second.scope);
 
           // The first scope of which we are a parent is the least (shortest)
           // one which means there is no other scope between it and our
@@ -995,10 +1006,10 @@ namespace build2
     {
       // Upgrade to root scope.
       //
-      auto r (m.find_sub (k));
+      auto r (map_.find_sub (k));
       for (++r.first; r.first != r.second; ++r.first)
       {
-        scope& c (r.first->second);
+        scope& c (*r.first->second.scope);
 
         if (c.root_ == s.root_) // No intermediate root.
           c.root_ = &s;
@@ -1010,14 +1021,36 @@ namespace build2
     return er.first;
   }
 
+  auto scope_map::
+  insert (scope& s, const dir_path& k) -> iterator
+  {
+    auto er (map_.emplace (k, false /* out */));
+
+    if (er.second)
+    {
+      er.first->second.scope = &s;
+    }
+    else if (!er.first->second.out)
+    {
+      assert (er.first->second.scope == &s);
+    }
+    else
+    {
+      // This can be triggered, for example, by specifying a variable override
+      // with src instead of out directory.
+      //
+      fail << "directory " << k << " is used as both src and out scope";
+    }
+
+    return er.first;
+  }
+
   scope& scope_map::
   find (const dir_path& k)
   {
     assert (k.normalized (false)); // Allow non-canonical dir separators.
-
-    scope_map_base& m (*this);
-    auto i (m.find_sup (k));
-    assert (i != m.end ()); // Should have global scope.
-    return i->second;
+    auto i (map_.find_sup (k));
+    assert (i != map_.end ()); // Should have global scope.
+    return *i->second.scope;
   }
 }
diff --git a/libbuild2/scope.hxx b/libbuild2/scope.hxx
index bc04bae..11fdfe4 100644
--- a/libbuild2/scope.hxx
+++ b/libbuild2/scope.hxx
@@ -43,8 +43,10 @@ namespace build2
     const dir_path& out_path () const {return *out_path_;}
     const dir_path& src_path () const {return *src_path_;}
 
-    // The first is a pointer to the key in scope_map. The second is a pointer
-    // to the src_root/base variable value, if any (i.e., it can be NULL).
+    bool out_eq_src () const {return out_path_ == src_path_;}
+
+    // These are pointers to the keys in scope_map. The second can be NULL
+    // during bootstrap until initialized.
     //
     const dir_path* out_path_ = nullptr;
     const dir_path* src_path_ = nullptr;
@@ -627,21 +629,53 @@ namespace build2
     }
   };
 
-  // Scope map.
+  // Scope map. Protected by the phase mutex.
   //
-  // Protected by the phase mutex. Note that the scope map is only for paths
-  // from the out tree.
+  // While it contains both out and src paths, the latter is not available
+  // during bootstrap (see setup_root() and setup_base() for details).
   //
-  using scope_map_base = dir_path_map<scope>;
-
-  class scope_map: public scope_map_base
+  class scope_map
   {
   public:
+    struct scope_ptr
+    {
+      using scope_type = build2::scope;
+
+      scope_type* scope;
+      bool        out;
+
+      scope_ptr (bool o): scope (nullptr), out (o) {}
+      ~scope_ptr () {if (out) delete scope;}
+
+      scope_ptr (scope_ptr&& x) // For GCC 4.9
+          : scope (x.scope), out (x.out)
+      {
+        x.scope = nullptr;
+      }
+
+      scope_ptr& operator= (scope_ptr&&) = delete;
+
+      scope_ptr (const scope_ptr&) = delete;
+      scope_ptr& operator= (const scope_ptr&) = delete;
+    };
+
+    using map_type = dir_path_map<scope_ptr>;
+
+    using iterator = map_type::iterator;
+    using const_iterator = map_type::const_iterator;
+
+    // Insert a scope given its out path.
+    //
     // Note that we assume the first insertion into the map is always the
     // global scope with empty key.
     //
     LIBBUILD2_SYMEXPORT iterator
-    insert (const dir_path&, bool root = false);
+    insert (const dir_path& our_path, bool root = false);
+
+    // Insert a shallow reference to the scope for its src path.
+    //
+    LIBBUILD2_SYMEXPORT iterator
+    insert (scope&, const dir_path& src_path);
 
     // Find the most qualified scope that encompasses this path.
     //
@@ -667,6 +701,10 @@ namespace build2
       return find (path_cast<dir_path> (p));
     }
 
+    const_iterator begin () const {return map_.begin ();}
+    const_iterator end () const {return map_.end ();}
+    const_iterator find_exact (const dir_path& d) const {return map_.find (d);}
+
     // RW access.
     //
   public:
@@ -691,6 +729,7 @@ namespace build2
 
   private:
     context& ctx;
+    map_type map_;
   };
 }
 
diff --git a/libbuild2/search.cxx b/libbuild2/search.cxx
index 25a4199..fca19ea 100644
--- a/libbuild2/search.cxx
+++ b/libbuild2/search.cxx
@@ -175,7 +175,7 @@ namespace build2
 
     if (tk.out->empty ())
     {
-      if (s->out_path () != s->src_path ())
+      if (!s->out_eq_src ())
         out = out_src (d, *s->root_scope ());
     }
     else
-- 
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