Warn about uncommitted files in final summary

Too many times rebuilds have gone unnoticed because the per package
warning gets lost in the debug output. This tries to improve the issue
by adding a summary at the end with the list of directories containing
untracked files.

alibuild_helpers/build.py

@@ -275,6 +275,7 @@ def hash_local_changes(directory):
   If there are untracked files, this function returns a unique hash to force a
   rebuild, and logs a warning, as we cannot detect changes to those files.
   """
+  untrackedFilesDirectories = []
   class UntrackedChangesError(Exception):
     """Signal that we cannot detect code changes due to untracked files."""
   h = Hasher()
@@ -291,6 +292,7 @@ def hash_output(msg, args):
     debug("Command %s returned %d", cmd, err)
     dieOnError(err, "Unable to detect source code changes.")
   except UntrackedChangesError:
+    untrackedFilesDirectories = [directory]
     warning("You have untracked changes in %s, so aliBuild cannot detect "
             "whether it needs to rebuild the package. Therefore, the package "
             "is being rebuilt unconditionally. Please use 'git add' and/or "
@@ -299,7 +301,7 @@ def hash_output(msg, args):
     # and let CMake figure out what needs to be rebuilt. Force a rebuild by
     # changing the hash to something basically random.
     h(str(time.time()))
-  return h.hexdigest()
+  return (h.hexdigest(), untrackedFilesDirectories)
 
 
 def better_tarball(spec, old, new):
@@ -473,6 +475,10 @@ def doBuild(args, parser):
 
   # Clone/update repos
   update_git_repos(args, specs, buildOrder, develPkgs)
+  # This is the list of packages which have untracked files in their
+  # source directory, and which are rebuilt every time. We will warn
+  # about them at the end of the build.
+  untrackedFilesDirectories = []
 
   # Resolve the tag to the actual commit ref
   for p in buildOrder:
@@ -509,7 +515,9 @@ def doBuild(args, parser):
         # Devel package: we get the commit hash from the checked source, not from remote.
         out = git(("rev-parse", "HEAD"), directory=spec["source"])
         spec["commit_hash"] = out.strip()
-        spec["devel_hash"] = spec["commit_hash"] + hash_local_changes(spec["source"])
+        local_hash, untracked = hash_local_changes(spec["source"])
+        untrackedFilesDirectories.extend(untracked)
+        spec["devel_hash"] = spec["commit_hash"] + local_hash
         out = git(("rev-parse", "--abbrev-ref", "HEAD"), directory=spec["source"])
         if out == "HEAD":
           out = git(("rev-parse", "HEAD"), directory=spec["source"])[:10]
@@ -1153,5 +1161,8 @@ def doBuild(args, parser):
   for x in develPkgs:
     banner("Build directory for devel package %s:\n%s/BUILD/%s-latest%s/%s",
            x, abspath(args.workDir), x, "-"+args.develPrefix if "develPrefix" in args else "", x)
+  for x in untrackedFilesDirectories:
+    banner("Untracked files in the following directories resulted in a rebuild of "
+           "the associated package and its dependencies:\n%s\n\nPlease commit or remove them to avoid useless rebuilds.", "\n".join(untrackedFilesDirectories))
   debug("Everything done")
   return 0

tox.ini

@@ -39,6 +39,7 @@ allowlist_externals =
     sh
     git
     test
+    touch
 deps =
     py27: mock
     coverage
@@ -101,6 +102,10 @@ commands =
     # Test for devel packages
     coverage run --source={toxinidir} -a {toxinidir}/aliBuild init zlib
     coverage run --source={toxinidir} -a {toxinidir}/aliBuild --aggressive-cleanup --docker -a slc7_x86-64 --always-prefer-system -d build zlib
+    # Test that we complain if we have a devel package with an untracked file
+    coverage run --source={toxinidir} -a {toxinidir}/aliBuild init zlib
+    touch zlib/foo
+    coverage run --source={toxinidir} -a {toxinidir}/aliBuild build -a slc7_x86-64 --no-system --disable GCC-Toolchain build zlib
 
 [coverage:run]
 branch = True