Add more details to divergent vndk lib error.

Bash better broadcast better build-backstop baggage because baffled
beings' bewilderement begets badness.

Fixes: 162379658
Test: view error by removing "libbinder" from
  VndkMustUseVendorVariantList.
Change-Id: Ib425e30bc7b5388b78af4bfab84dd24072d550a6

1 files changed, 14 insertions, 2 deletions

diff --git a/tools/check_identical_lib.sh b/tools/check_identical_lib.sh
index c3aa41a722..c9f436f0bb 100755
--- a/tools/check_identical_lib.sh
+++ b/tools/check_identical_lib.sh
@@ -26,7 +26,19 @@ function strip_lib() {
 strip_lib ${CORE} ${stripped_core}
 strip_lib ${VENDOR} ${stripped_vendor}
 if ! cmp -s ${stripped_core} ${stripped_vendor}; then
-  echo "VNDK library not in vndkMustUseVendorVariantList but has different core and vendor variant: $(basename ${CORE})"
-  echo "If the two variants need to have different runtime behavior, consider using libvndksupport."
+  echo "ERROR: VNDK library $(basename ${CORE%.so}) has different core and" \
+    "vendor variants! This means that the copy used in the system.img/etc" \
+    "and vendor.img/etc images are different. In order to preserve space on" \
+    "some devices, it is helpful if they are the same. Frequently, " \
+    "libraries are different because they or their dependencies compile" \
+    "things based on the macro '__ANDROID_VNDK__' or they specify custom" \
+    "options under 'target: { vendor: { ... } }'. Here are some possible" \
+    "resolutions:"
+  echo "ERROR: 1). Remove differences, possibly using the libvndksupport" \
+    "function android_is_in_vendor_process in order to turn this into a" \
+    "runtime difference."
+  echo "ERROR: 2). Add the library to the VndkMustUseVendorVariantList" \
+    "variable in build/soong/cc/config/vndk.go, which is used to" \
+    "acknowledge this difference."
   exit 1
 fi