1 files changed, 36 insertions, 0 deletions

diff --git a/meta/classes/cross.bbclass b/meta/classes/cross.bbclass
index 9d951076a7..a292a98335 100644
--- a/meta/classes/cross.bbclass
+++ b/meta/classes/cross.bbclass
@@ -95,3 +95,39 @@ addtask addto_recipe_sysroot after do_populate_sysroot
 do_addto_recipe_sysroot[deptask] = "do_populate_sysroot"
 
 PATH:prepend = "${COREBASE}/scripts/cross-intercept:"
+
+#
+# Cross task outputs can call native dependencies and even when cross
+# recipe output doesn't change it might produce different results when
+# the called native dependency is changed, e.g. clang-cross-${TARGET_ARCH}
+# contains symlink to clang binary from clang-native, but when clang-native
+# outhash is changed, clang-cross-${TARGET_ARCH} will still be considered
+# equivalent and target recipes aren't rebuilt with new clang binary, see
+# work around in https://github.com/kraj/meta-clang/pull/1140 to make target
+# recipes to depend directly not only on clang-cross-${TARGET_ARCH} but
+# clang-native as well.
+#
+# This can cause poor interactions with hash equivalence, since this recipes
+# output-changing dependency is "hidden" and downstream task only see that this
+# recipe has the same outhash and therefore is equivalent. This can result in
+# different output in different cases.
+#
+# To resolve this, unhide the output-changing dependency by adding its unihash
+# to this tasks outhash calculation. Unfortunately, don't know specifically
+# know which dependencies are output-changing, so we have to add all of them.
+#
+python cross_add_do_populate_sysroot_deps () {
+    current_task = "do_" + d.getVar("BB_CURRENTTASK")
+    if current_task != "do_populate_sysroot":
+        return
+
+    taskdepdata = d.getVar("BB_TASKDEPDATA", False)
+    pn = d.getVar("PN")
+    deps = {
+        dep[0]:dep[6] for dep in taskdepdata.values() if
+            dep[1] == current_task and dep[0] != pn
+    }
+
+    d.setVar("HASHEQUIV_EXTRA_SIGDATA", "\n".join("%s: %s" % (k, deps[k]) for k in sorted(deps.keys())))
+}
+SSTATECREATEFUNCS += "cross_add_do_populate_sysroot_deps"