From 78724c86b63d08b08ebe8be2a98856a7c9dc6d75 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Wed, 24 Aug 2016 16:50:03 +0200
Subject: Pick *.libs variable depending on library type during static linking

---
 build2/c/init.cxx   |  2 ++
 build2/cc/common    |  2 ++
 build2/cc/init.cxx  |  7 +++++++
 build2/cc/link.cxx  | 42 +++++++++++++++++++++++++++++++++---------
 build2/cxx/init.cxx |  2 ++
 5 files changed, 46 insertions(+), 9 deletions(-)

diff --git a/build2/c/init.cxx b/build2/c/init.cxx
index 4eab8a6..be72655 100644
--- a/build2/c/init.cxx
+++ b/build2/c/init.cxx
@@ -148,6 +148,8 @@ namespace build2
           v["cc.export.loptions"],
           v["cc.export.libs"],
 
+          v["cc.type"],
+
           v.insert<string>   ("c.std", true),
 
           v.insert<string>   ("c.id"),
diff --git a/build2/cc/common b/build2/cc/common
index 987fe7b..ff6841f 100644
--- a/build2/cc/common
+++ b/build2/cc/common
@@ -57,6 +57,8 @@ namespace build2
       const variable& c_export_loptions;
       const variable& c_export_libs;
 
+      const variable& c_type; // cc.type
+
       const variable& x_std;
 
       const variable& x_id;
diff --git a/build2/cc/init.cxx b/build2/cc/init.cxx
index 0c82169..0f1fda7 100644
--- a/build2/cc/init.cxx
+++ b/build2/cc/init.cxx
@@ -60,6 +60,13 @@ namespace build2
       v.insert<string> ("config.cc.target");
       v.insert<string> ("config.cc.pattern");
 
+      // Target type, for example, "C library" or "C++ library". Should be set
+      // on the target by the matching rule to the name of the module (e.g.,
+      // "c", "cxx"). Currenly only set for libraries and is used to decide
+      // which *.libs to use during static linking.
+      //
+      v.insert<string> ("cc.type");
+
       return true;
     }
 
diff --git a/build2/cc/link.cxx b/build2/cc/link.cxx
index ffa088f..b608817 100644
--- a/build2/cc/link.cxx
+++ b/build2/cc/link.cxx
@@ -575,6 +575,9 @@ namespace build2
         }
       }
 
+      if (!(seen_x || seen_c || seen_obj || seen_lib))
+        return nullptr;
+
       // We will only chain a C source if there is also an X source or we were
       // explicitly told to.
       //
@@ -584,10 +587,14 @@ namespace build2
         return nullptr;
       }
 
-      // If we have any prerequisite libraries (which also means that
-      // we match), search/import and pre-match them to implement the
-      // "library meta-information protocol". Don't do this if we are
-      // called from the install rule just to check if we would match.
+      // Set the library type.
+      //
+      t.vars.assign (c_type) = string (x);
+
+      // If we have any prerequisite libraries, search/import and pre-match
+      // them to implement the "library meta-information protocol". Don't do
+      // this if we are called from the install rule just to check if we would
+      // match.
       //
       auto op (a.operation ());
       auto oop (a.outer_operation ());
@@ -629,7 +636,7 @@ namespace build2
         }
       }
 
-      return seen_x || seen_c || seen_obj || seen_lib ? &t : nullptr;
+      return &t;
     }
 
     recipe link::
@@ -1046,8 +1053,15 @@ namespace build2
 
       if (la)
       {
-        append_options (args, l, c_libs);
-        append_options (args, l, x_libs);
+        // See what type of library this is (C, C++, etc). Use it do decide
+        // which x.libs variable name. If it is not a C-common library, then
+        // it probably doesn't have cc.libs either.
+        //
+        if (const string* t = cast_null<string> (l.vars[c_type]))
+        {
+          append_options (args, l, c_libs);
+          append_options (args, l, *t == x ? x_libs : var_pool[*t + ".libs"]);
+        }
       }
       else
       {
@@ -1092,6 +1106,9 @@ namespace build2
           }
         };
 
+        // @@ Should we also pick one based on cc.type? And also *.poptions in
+        //    compile? Feels right.
+        //
         append (c_export_libs);
         append (x_export_libs);
       }
@@ -1117,8 +1134,15 @@ namespace build2
 
       if (la)
       {
-        hash_options (cs, l, c_libs);
-        hash_options (cs, l, x_libs);
+        // See what type of library this is (C, C++, etc). Use it do decide
+        // which x.libs variable name. If it is not a C-common library, then
+        // it probably doesn't have cc.libs either.
+        //
+        if (const string* t = cast_null<string> (l.vars[c_type]))
+        {
+          hash_options (cs, l, c_libs);
+          hash_options (cs, l, *t == x ? x_libs : var_pool[*t + ".libs"]);
+        }
       }
       else
       {
diff --git a/build2/cxx/init.cxx b/build2/cxx/init.cxx
index 3dd6b1f..8202139 100644
--- a/build2/cxx/init.cxx
+++ b/build2/cxx/init.cxx
@@ -148,6 +148,8 @@ namespace build2
           v["cc.export.loptions"],
           v["cc.export.libs"],
 
+          v["cc.type"],
+
           v.insert<string>   ("cxx.std", true),
 
           v.insert<string>   ("cxx.id"),
-- 
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