From 8aee78c8d0eb06334571e596f6fbdf7ed5756f0c Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Wed, 8 Feb 2017 09:24:07 +0200
Subject: Tighten target constness further

---
 build2/cli/rule.cxx   |  2 +-
 build2/cli/target     | 39 ++++++++++++---------------------------
 build2/cli/target.cxx |  9 +++++++--
 3 files changed, 20 insertions(+), 30 deletions(-)

(limited to 'build2/cli')

diff --git a/build2/cli/rule.cxx b/build2/cli/rule.cxx
index 7928c5c..ba4963e 100644
--- a/build2/cli/rule.cxx
+++ b/build2/cli/rule.cxx
@@ -207,7 +207,7 @@ namespace build2
 
     static void
     append_extension (cstrings& args,
-                      path_target& t,
+                      const path_target& t,
                       const char* option,
                       const char* default_extension)
     {
diff --git a/build2/cli/target b/build2/cli/target
index f4ab7e7..c10e4b8 100644
--- a/build2/cli/target
+++ b/build2/cli/target
@@ -26,37 +26,22 @@ namespace build2
       virtual const target_type& dynamic_type () const {return static_type;}
     };
 
-    class cli_cxx: public mtime_target
+    // Standard layout type compatible with target*[3].
+    //
+    struct cli_cxx_members
     {
-    public:
-      union
-      {
-        // It is theoretically possible that the compiler will add
-        // padding between the members of this struct. This would
-        // mean that the optimal alignment for a pointer is greater
-        // than its size (and that an array of pointers is sub-
-        // optimally aligned). We will deal with such a beast of
-        // an architecture when we see it.
-        //
-        struct
-        {
-          cxx::hxx* h;
-          cxx::cxx* c;
-          cxx::ixx* i;
-        };
-        target* m[3] /*= {nullptr, nullptr, nullptr}*/; // @@ GCC 4.8
-      };
-
-      //using mtime_target::mtime_target; // @@ GCC 4.8
+      const_ptr<cxx::hxx> h = nullptr;
+      const_ptr<cxx::cxx> c = nullptr;
+      const_ptr<cxx::ixx> i = nullptr;
+    };
 
-      cli_cxx (dir_path d, dir_path o, string n)
-          : mtime_target (move (d), move (o), move (n))
-      {
-        m[0] = m[1] = m[2] = nullptr;
-      }
+    class cli_cxx: public mtime_target, public cli_cxx_members
+    {
+    public:
+      using mtime_target::mtime_target;
 
       virtual group_view
-      group_members (action_type) const;
+      group_members (action_type);
 
       virtual timestamp
       load_mtime () const;
diff --git a/build2/cli/target.cxx b/build2/cli/target.cxx
index 48dc95b..200f6f0 100644
--- a/build2/cli/target.cxx
+++ b/build2/cli/target.cxx
@@ -32,10 +32,15 @@ namespace build2
     // cli.cxx
     //
     group_view cli_cxx::
-    group_members (action_type) const
+    group_members (action_type)
     {
+      static_assert (offsetof (cli_cxx_members, i) -
+                     offsetof (cli_cxx_members, h) == sizeof (target*) * 2,
+                     "member layout incompatible with array");
+
       return h != nullptr
-        ? group_view {m, (i != nullptr ? 3U : 2U)}
+        ? group_view {reinterpret_cast<target* const*> (&h),
+                      (i != nullptr ? 3U : 2U)}
         : group_view {nullptr, 0};
     }
 
-- 
cgit v1.1