CI

some more discussion @ https://github.com/ceph/ceph-build/issues/656

Does git diff <range> --submodule=log | grep Submodule work for you?

still has to have a git submodule update, but maybe

As a piece of this puzzle: a generic method for specifying the range of commits in the pull request is

git fetch origin $ghprbTargetBranch
git log --oneline refs/remotes/origin/$ghprbTargetBranch..$ghprbActualCommit

TargetBranch is the branch into which the PR wants to merge, and ActualCommit is the SHA1 of the tip of the PR's branch, so this shows all commits in the PR branch that are not already in the existing branch. This should be the set of commits that are searched for changes to submodules.

This is what I'm looking at:

--- a/ceph-pr-submodules/build/build
+++ b/ceph-pr-submodules/build/build
@@ -4,12 +4,11 @@ set -ex

 cd "$WORKSPACE" 

-# The command below has access to the variables $name, $path, $sha1 and $toplevel:
-# $name is the name of the relevant submodule section in .gitmodules, $path is
-# the name of the submodule directory relative to the superproject, $sha1 is
-# the commit as recorded in the superproject, and $toplevel is the absolute
-# path to the top-level of the superproject.
-modified_submodules=$(git submodule foreach 'cd $toplevel; git diff --ignore-submodules=dirty origin/master -- $path')
+# show diffs between $ghprbTargetBranch (where the merge is going) and
+# $ghprbActiveCommit (the tip of the branch that's merging) with '...',
+# which is equivalent to diff $(git merge-base TB AC) AC.  With 
+# --submodule, also show detail of diff in submodules.
+modified_submodules="$(git diff --submodule=log $ghprbTargetBranch...$ghprbActiveCommit | grep ^Submodule)" 

 if [[ $modified_submodules ]]; then
     echo "Project has modified submodules!" 

That looks a lot better than the current implementation