From b63d44e7812ee7f882103ff15bd7098618cfdc8d Mon Sep 17 00:00:00 2001
From: Steven Watanabe <steven@providere-consulting.com>
Date: Sun, 13 Jun 2010 04:00:10 +0000
Subject: [PATCH] Delay the warning that the Boost.Python Jamfile emits, until
 someone actually tries to use the library.  Fixes #2417.

[SVN r62895]
---
 build/Jamfile.v2 | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/build/Jamfile.v2 b/build/Jamfile.v2
index cc8a8be2..32bffb0f 100644
--- a/build/Jamfile.v2
+++ b/build/Jamfile.v2
@@ -14,14 +14,20 @@ if ! [ python.configured ] && ! ( --without-python in  [ modules.peek : ARGV ] )
     # Attempt default configuration of python
     import toolset : using ;
     using python ;
-    
-    if ! [ python.configured ]
-    {
-        ECHO "WARNING: No python installation configured and autoconfiguration" ; 
-        ECHO "         failed.  See http://www.boost.org/libs/python/doc/building.html" ;
-        ECHO "         for configuration instructions or pass --without-python to" ;
-        ECHO "         suppress this message and silently skip all Boost.Python targets" ;
-    }
+}
+
+if [ python.configured ] || ( --without-python in  [ modules.peek : ARGV ] )
+{
+    alias config-warning ;
+}
+else
+{
+    message config-warning
+        : "warning: No python installation configured and autoconfiguration"
+        : "note: failed.  See http://www.boost.org/libs/python/doc/building.html"
+        : "note: for configuration instructions or pass --without-python to"
+        : "note: suppress this message and silently skip all Boost.Python targets"
+        ;
 }
 
 rule find-py3-version
@@ -122,6 +128,7 @@ rule lib_boost_python ( is-py3 ? )
             # as it's not possible anyway, and to cause dependents to
             # fail to build
             [ unless [ python.configured ] : <build>no ]
+            <dependency>config-warning
 
             <python-debugging>on:<define>BOOST_DEBUG_PYTHON
             [ cond $(is-py3) : <python>$(py3-version) ]