rev-parse: better error message for ambiguous arguments

Currently, if git-rev-parse encounters an argument that is neither a
recognizable revision name nor the name of an existing file or
directory, and it hasn't encountered a "--" argument, it prints an
error message saying "No such file or directory".  This can be
confusing for users, including users of programs such as gitk that
use git-rev-parse, who may then think that they can't ask about the
history of files that no longer exist.

This makes it print a better error message, one that points out the
ambiguity and tells the user what to do to fix it.

Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/rev-parse.c b/rev-parse.c
index e956cd5..7f66ae2 100644 (file)
--- a/rev-parse.c
+++ b/rev-parse.c
@@ -160,6 +160,14 @@ static int show_file(const char *arg)
        return 0;
 }
 
+static void die_badfile(const char *arg)
+{
+       if (errno != ENOENT)
+               die("'%s': %s", arg, strerror(errno));
+       die("'%s' is ambiguous - revision name or file/directory name?\n"
+           "Please put '--' before the list of filenames.", arg);
+}
+
 int main(int argc, char **argv)
 {
        int i, as_is = 0, verify = 0;
@@ -176,7 +184,7 @@ int main(int argc, char **argv)
                if (as_is) {
                        if (show_file(arg) && as_is < 2)
                                if (lstat(arg, &st) < 0)
-                                       die("'%s': %s", arg, strerror(errno));
+                                       die_badfile(arg);
                        continue;
                }
                if (!strcmp(arg,"-n")) {
@@ -343,7 +351,7 @@ int main(int argc, char **argv)
                if (verify)
                        die("Needed a single revision");
                if (lstat(arg, &st) < 0)
-                       die("'%s': %s", arg, strerror(errno));
+                       die_badfile(arg);
        }
        show_default();
        if (verify && revs_count != 1)