From 49ecdc7c1e93a52147ce37d0cd7c8ef836fa5e75 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jurko=20Gospodneti=C4=87?= <jurko.gospodnetic@pke.hr>
Date: Wed, 8 Aug 2012 17:31:08 +0000
Subject: [PATCH] Added a better Boost Build diagnostic error message when
 attempting to reference a target using an explicitly specified project id but
 without a leading slash ('/') character, e.g. as in:

  use-project xxx : ../external/some-project ;
  exe a : xxx//some-obj ;

as opposed to:

  use-project xxx : ../external/some-project ;
  exe a : /xxx//some-obj ;

[SVN r79931]
---
 src/build/project.jam | 8 ++++++++
 src/build/targets.jam | 9 +++++++++
 2 files changed, 17 insertions(+)

diff --git a/src/build/project.jam b/src/build/project.jam
index 8bf116ca5..d99f0aaa2 100644
--- a/src/build/project.jam
+++ b/src/build/project.jam
@@ -575,6 +575,14 @@ rule inherit-attributes ( project-module : parent-module )
 }
 
 
+# Returns whether the given string is a valid registered project id.
+#
+rule is-registered-id ( id )
+{
+    return $($(id).jamfile-module) ;
+}
+
+
 # Associate the given id with the given project module. Returns the possibly
 # corrected project id.
 #
diff --git a/src/build/targets.jam b/src/build/targets.jam
index 7a409ce88..9813e1cc2 100644
--- a/src/build/targets.jam
+++ b/src/build/targets.jam
@@ -374,6 +374,15 @@ class project-target : abstract-target
             {
                 extra-error-message = could not resolve project reference
                     '$(project-part)' ;
+                if ! [ path.is-rooted $(project-part) ]
+                {
+                    local rooted = [ path.root $(project-part) / ] ;
+                    if [ project.is-registered-id $(rooted) ]
+                    {
+                        extra-error-message += - possibly missing a leading
+                            slash ('/') character. ;
+                    }
+                }
             }
         }
         else