From 41b9672a828dbe3aa6a6dbdcd786a6d6402eda7b Mon Sep 17 00:00:00 2001
From: Vladimir Prus <ghost@cs.msu.su>
Date: Thu, 2 Jun 2005 07:19:11 +0000
Subject: [PATCH] Improve "linking" of libraries into static libraries.

When a library is present in sources of a static library, return it
to dependents via usage requirements, not by adding it to the list
of created targets.


[SVN r29362]
---
 src/tools/builtin.jam | 25 +++++++++++++++++++++----
 src/tools/unix.jam    |  2 +-
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/src/tools/builtin.jam b/src/tools/builtin.jam
index b81c08b41..593f50ae1 100644
--- a/src/tools/builtin.jam
+++ b/src/tools/builtin.jam
@@ -695,21 +695,38 @@ class archive-generator : generator
         local result = [ generator.run $(project) $(name) : $(property-set)
           : $(sources) ] ;
         
-        # For static linking, we can't directly link to libraries.
+        # For static linking, if we get a library in source, we can't
+        # directly link to it. So, we need to cause our dependencies 
+        # to link to that library. There are two approaches:
+        # - adding the library to the list of returned targets.
+        # - using the <library> usage requirements.
+        # The problem with the first is:
+        # 
+        #     lib a1 : : <file>liba1.a ;
+        #     lib a2 : a2.cpp a1 : <link>static ;
+        #     install dist : a2 ;
+        #
+        # here we'll try to install 'a1', even though it's not necessary in
+        # the general case.
+        # With the second approaches, even indirect dependents will link to
+        # the library, but it should not cause any harm.
         # So, return all LIB sources together with created targets,
         # so that dependents link to them.
+        local usage-requirements ;
         if [ $(property-set).get <link> ] = static
         {
             for local t in $(sources)
             {
                 if [ type.is-derived [ $(t).type ] LIB ]
                 {
-                    result += $(t) ;
+                    usage-requirements += <library>$(t) ;
                 }                
             }            
         }
-             
-        return $(result) ;
+                
+        usage-requirements = [ property-set.create $(usage-requirements) ] ;
+                                
+        return $(usage-requirements) $(result) ;
     }    
 }
 
diff --git a/src/tools/unix.jam b/src/tools/unix.jam
index b85ef5809..4e5d7697f 100644
--- a/src/tools/unix.jam
+++ b/src/tools/unix.jam
@@ -86,7 +86,7 @@ class unix-archive-generator : archive-generator
         local result = [ archive-generator.run $(project) $(name) : $(property-set)
           : $(sources) ] ;
         
-        unix.set-library-order $(sources) : $(property-set) : $(result) ;
+        unix.set-library-order $(sources) : $(property-set) : $(result[2-]) ;
         
         return $(result) ;