4 files changed, 34 insertions, 13 deletions

diff --git a/bitbake/lib/bb/__init__.py b/bitbake/lib/bb/__init__.py
index c95c91a4cb..62ceaaef6e 100644
--- a/bitbake/lib/bb/__init__.py
+++ b/bitbake/lib/bb/__init__.py
@@ -9,7 +9,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 #
 
-__version__ = "2.12.0"
+__version__ = "2.15.0"
 
 import sys
 if sys.version_info < (3, 9, 0):
diff --git a/bitbake/lib/bb/event.py b/bitbake/lib/bb/event.py
index a12adbc937..b29f0a5568 100644
--- a/bitbake/lib/bb/event.py
+++ b/bitbake/lib/bb/event.py
@@ -431,6 +431,16 @@ class RecipeEvent(Event):
         self.fn = fn
         Event.__init__(self)
 
+class RecipePreDeferredInherits(RecipeEvent):
+    """
+    Called before deferred inherits are processed so code can snoop on class extensions for example
+    Limitations: It won't see inherits of inherited classes and the data is unexpanded
+    """
+    def __init__(self, fn, inherits):
+        self.fn = fn
+        self.inherits = inherits
+        Event.__init__(self)
+
 class RecipePreFinalise(RecipeEvent):
     """ Recipe Parsing Complete but not yet finalised"""
 
diff --git a/bitbake/lib/bb/parse/ast.py b/bitbake/lib/bb/parse/ast.py
index 290ed45048..ea1096f2de 100644
--- a/bitbake/lib/bb/parse/ast.py
+++ b/bitbake/lib/bb/parse/ast.py
@@ -340,9 +340,7 @@ class InheritDeferredNode(AstNode):
         self.inherit = (classes, filename, lineno)
 
     def eval(self, data):
-        inherits = data.getVar('__BBDEFINHERITS', False) or []
-        inherits.append(self.inherit)
-        data.setVar('__BBDEFINHERITS', inherits)
+        bb.parse.BBHandler.inherit_defer(*self.inherit, data)
 
 class AddFragmentsNode(AstNode):
     def __init__(self, filename, lineno, fragments_path_prefix, fragments_variable, flagged_variables_list_variable):
@@ -471,6 +469,17 @@ def finalize(fn, d, variant = None):
         if d.getVar("_FAILPARSINGERRORHANDLED", False) == True:
             raise bb.BBHandledException()
 
+        inherits = [x[0] for x in (d.getVar('__BBDEFINHERITS', False) or [('',)])]
+        bb.event.fire(bb.event.RecipePreDeferredInherits(fn, inherits), d)
+
+        while True:
+            inherits = d.getVar('__BBDEFINHERITS', False) or []
+            if not inherits:
+                break
+            inherit, filename, lineno = inherits.pop(0)
+            d.setVar('__BBDEFINHERITS', inherits)
+            bb.parse.BBHandler.inherit(inherit, filename, lineno, d, deferred=True)
+
         for var in d.getVar('__BBHANDLERS', False) or []:
             # try to add the handler
             handlerfn = d.getVarFlag(var, "filename", False)
@@ -525,14 +534,6 @@ def multi_finalize(fn, d):
         logger.debug("Appending .bbappend file %s to %s", append, fn)
         bb.parse.BBHandler.handle(append, d, True)
 
-    while True:
-        inherits = d.getVar('__BBDEFINHERITS', False) or []
-        if not inherits:
-            break
-        inherit, filename, lineno = inherits.pop(0)
-        d.setVar('__BBDEFINHERITS', inherits)
-        bb.parse.BBHandler.inherit(inherit, filename, lineno, d, deferred=True)
-
     onlyfinalise = d.getVar("__ONLYFINALISE", False)
 
     safe_d = d
@@ -568,7 +569,7 @@ def multi_finalize(fn, d):
                 d.setVar("BBEXTENDVARIANT", variantmap[name])
             else:
                 d.setVar("PN", "%s-%s" % (pn, name))
-            bb.parse.BBHandler.inherit(extendedmap[name], fn, 0, d)
+            bb.parse.BBHandler.inherit_defer(extendedmap[name], fn, 0, d)
 
         safe_d.setVar("BBCLASSEXTEND", extended)
         _create_variants(datastores, extendedmap.keys(), extendfunc, onlyfinalise)
diff --git a/bitbake/lib/bb/parse/parse_py/BBHandler.py b/bitbake/lib/bb/parse/parse_py/BBHandler.py
index 4bdb11994f..008fec2308 100644
--- a/bitbake/lib/bb/parse/parse_py/BBHandler.py
+++ b/bitbake/lib/bb/parse/parse_py/BBHandler.py
@@ -42,12 +42,22 @@ def supports(fn, d):
     """Return True if fn has a supported extension"""
     return os.path.splitext(fn)[-1] in [".bb", ".bbclass", ".inc"]
 
+def inherit_defer(expression, fn, lineno, d):
+    inherit = (expression, fn, lineno)
+    inherits = d.getVar('__BBDEFINHERITS', False) or []
+    inherits.append(inherit)
+    d.setVar('__BBDEFINHERITS', inherits)
+
 def inherit(files, fn, lineno, d, deferred=False):
     __inherit_cache = d.getVar('__inherit_cache', False) or []
     #if "${" in files and not deferred:
     #    bb.warn("%s:%s has non deferred conditional inherit" % (fn, lineno))
     files = d.expand(files).split()
     for file in files:
+        defer = (d.getVar("BB_DEFER_BBCLASSES") or "").split()
+        if not deferred and file in defer:
+            inherit_defer(file, fn, lineno, d)
+            continue
         classtype = d.getVar("__bbclasstype", False)
         origfile = file
         for t in ["classes-" + classtype, "classes"]: