Soft-deprecate prefix-less dirconfig entriesdirconfig-refactor

The implicit "any unprefixed line is an ignore pattern" rule is the
last source of subtle parser surprises — it's the reason why a
single leading space silently changes a +-keep into a literal ignore
pattern, and it makes typo'd comments slip through as ignores.

Mark these lines as :legacy-ignore in the classifier, record them
in a new prefixless-ignore slot on the dirconfig struct, and emit a
one-time warning per project listing the offending entries. The
behavior is unchanged — the lines still go into the ignore list —
but users now get a nudge to write them as -entry. The warning can
be silenced via projectile-warn-on-prefixless-dirconfig-lines.

1 files changed, 7 insertions, 2 deletions

diff --git a/doc/modules/ROOT/pages/projects.adoc b/doc/modules/ROOT/pages/projects.adoc
index f1f4a5f..24e6e31 100644
--- a/doc/modules/ROOT/pages/projects.adoc
+++ b/doc/modules/ROOT/pages/projects.adoc
@@ -813,8 +813,13 @@ If you'd like to instruct Projectile to ignore certain files in a
 project, when indexing it you can do so in the `.projectile` file by
 adding each path to ignore, where the paths all are relative to the
 root directory and start with a slash. Everything ignored should be
-preceded with a `-` sign. Alternatively, not having any prefix at all
-also means to ignore the directory or file pattern that follows.
+preceded with a `-` sign.
+
+NOTE: Lines without any prefix at all are still accepted and treated
+as ignore patterns for backward compatibility, but the implicit form
+is being phased out and Projectile now warns about it once per
+project.  Prefer the explicit `-` prefix in new dirconfigs.
+
 Here's an example for a typical Rails application:
 
 ----