bitbake/providers.py: Fix runtime providers problems

Take a real world testcase where you have two recipes, each of which
contains PACKAGES_DYNAMIC = "gdk-pixbuf-loaders-*" and recipes which
RDEPEND on some gdk-pixbuf-loaders-xxx package. To select between these
you need to set a PREFERRED_PROVIDER.

These are specified in the PN namespace so the locgical conclusion is
that setting PREFERRED_PROVIDER_gdk-pixbuf = "gtk+" should work. It
doesn't and instead checks crazy things.

The code was correctly finding the two possible providers, gtk+ and
gdk-pixbuf. It was however only accepting PREFERRED_PROVIDER_gtk+
= "gdk-pixbuf" to resolve this problem which reads as the exact
opposite to what was wanted.

This patch changes the code to do something that makes sense. I suspect
that before these changes it was pretty much a null operation rubber
stamping the single provider case. For Poky at least it exposes a few
cases where -nativesdk recipes were providing the same things as their
normal counterparts but these are genuine bugs in the metadata.

I've also attempted to make the multiple provider error message human
readable as I counldn't understand it and I doubt anyone else could
either.

Signed-off-by: Richard  Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 11 insertions, 7 deletions

diff --git a/bitbake/lib/bb/providers.py b/bitbake/lib/bb/providers.py
index d017d6006f..dcba9ae255 100644
--- a/bitbake/lib/bb/providers.py
+++ b/bitbake/lib/bb/providers.py
@@ -267,25 +267,29 @@ def filterProvidersRunTime(providers, item, cfgData, dataCache):
     # Should use dataCache.preferred here?
     preferred = []
     preferred_vars = []
+    pns = {}
+    for p in eligible:
+        pns[dataCache.pkg_fn[p]] = p
     for p in eligible:
         pn = dataCache.pkg_fn[p]
         provides = dataCache.pn_provides[pn]
         for provide in provides:
-            logger.verbose("checking PREFERRED_PROVIDER_%s", provide)
             prefervar = bb.data.getVar('PREFERRED_PROVIDER_%s' % provide, cfgData, 1)
-            if prefervar == pn:
+            logger.verbose("checking PREFERRED_PROVIDER_%s (value %s) against %s", provide, prefervar, pns.keys())
+            if prefervar in pns and pns[prefervar] not in preferred:
                 var = "PREFERRED_PROVIDER_%s = %s" % (provide, prefervar)
-                logger.verbose("selecting %s to satisfy runtime %s due to %s", pn, item, var)
+                logger.verbose("selecting %s to satisfy runtime %s due to %s", prefervar, item, var)
                 preferred_vars.append(var)
-                eligible.remove(p)
-                eligible = [p] + eligible
-                preferred.append(p)
+                pref = pns[prefervar]
+                eligible.remove(pref)
+                eligible = [pref] + eligible
+                preferred.append(pref)
                 break
 
     numberPreferred = len(preferred)
 
     if numberPreferred > 1:
-        logger.error("Conflicting PREFERRED_PROVIDER entries were found which resulted in an attempt to select multiple providers (%s) for runtime dependecy %s\nThe entries resulting in this conflict were: %s", preferred, item, preferred_vars)
+        logger.error("Trying to resolve runtime dependency %s resulted in conflicting PREFERRED_PROVIDER entries being found.\nThe providers found were: %s\nThe PREFERRED_PROVIDER entries resulting in this conflict were: %s", item, preferred, preferred_vars)
 
     logger.debug(1, "sorted providers for %s are: %s", item, eligible)