pathspec: stop --*-pathspecs impact on internal parse_pathspec() uses

Normally parse_pathspec() is used on command line arguments where it
can do fancy thing like parsing magic on each argument or adding magic
for all pathspecs based on --*-pathspecs options.

There's another use of parse_pathspec(), where pathspec is needed, but
the input is known to be pure paths. In this case we usually don't
want --*-pathspecs to interfere. And we definitely do not want to
parse magic in these paths, regardless of --literal-pathspecs.

Add new flag PATHSPEC_LITERAL_PATH for this purpose. When it's set,
--*-pathspecs are ignored, no magic is parsed. And if the caller
allows PATHSPEC_LITERAL (i.e. the next calls can take literal magic),
then PATHSPEC_LITERAL will be set.

This fixes cases where git chokes when GIT_*_PATHSPECS are set because
parse_pathspec() indicates it won't take any magic. But
GIT_*_PATHSPECS add them anyway. These are

   export GIT_LITERAL_PATHSPECS=1
   git blame -- something
   git log --follow something
   git log --merge

"git ls-files --with-tree=path" (aka parse_pathspec() in
overlay_tree_on_cache()) is safe because the input is empty, and
producing one pathspec due to PATHSPEC_PREFER_CWD does not take any
magic into account.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/tree-diff.c b/tree-diff.c
index ccf9d7c8f..456660c7a 100644
--- a/tree-diff.c
+++ b/tree-diff.c
@@ -254,7 +254,9 @@ static void try_to_follow_renames(struct tree_desc *t1, struct tree_desc *t2, co
 			path[0] = p->one->path;
 			path[1] = NULL;
 			free_pathspec(&opt->pathspec);
-			parse_pathspec(&opt->pathspec, PATHSPEC_ALL_MAGIC, 0, "", path);
+			parse_pathspec(&opt->pathspec,
+				       PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
+				       PATHSPEC_LITERAL_PATH, "", path);
 
 			/*
 			 * The caller expects us to return a set of vanilla