revision parsing: make "rev -- paths" checks stronger.

If you don't have a "--" marker, then:

 - all of the arguments we are going to assume are pathspecs
   must exist in the working tree.

 - none of the arguments we parsed as revisions could be
   interpreted as a filename.

so that there really isn't any possibility of confusion in case
somebody does have a revision that looks like a pathname too.

The former rule has been in effect; this implements the latter.

Signed-off-by: Junio C Hamano <junkio@cox.net>

cache.h

@@ -135,6 +135,7 @@ extern const char *setup_git_directory(void);
 extern const char *prefix_path(const char *prefix, int len, const char *path);
 extern const char *prefix_filename(const char *prefix, int len, const char *path);
 extern void verify_filename(const char *prefix, const char *name);
+extern void verify_non_filename(const char *prefix, const char *name);
 
 #define alloc_nr(x) (((x)+16)*3/2)
 

revision.c

@@ -740,6 +740,11 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 				include = get_reference(revs, next, sha1, flags);
 				if (!exclude || !include)
 					die("Invalid revision range %s..%s", arg, next);
+
+				if (!seen_dashdash) {
+					*dotdot = '.';
+					verify_non_filename(revs->prefix, arg);
+				}
 				add_pending_object(revs, exclude, this);
 				add_pending_object(revs, include, next);
 				continue;
@@ -757,13 +762,20 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 			if (seen_dashdash || local_flags)
 				die("bad revision '%s'", arg);
 
-			/* If we didn't have a "--", all filenames must exist */
+			/* If we didn't have a "--":
+			 * (1) all filenames must exist;
+			 * (2) all rev-args must not be interpretable
+			 *     as a valid filename.
+			 * but the latter we have checked in the main loop.
+			 */
 			for (j = i; j < argc; j++)
 				verify_filename(revs->prefix, argv[j]);
 
 			revs->prune_data = get_pathspec(revs->prefix, argv + i);
 			break;
 		}
+		if (!seen_dashdash)
+			verify_non_filename(revs->prefix, arg);
 		object = get_reference(revs, arg, sha1, flags ^ local_flags);
 		add_pending_object(revs, object, arg);
 	}

setup.c

@@ -80,11 +80,31 @@ void verify_filename(const char *prefix, const char *arg)
 	if (!lstat(name, &st))
 		return;
 	if (errno == ENOENT)
-		die("ambiguous argument '%s': unknown revision or filename\n"
+		die("ambiguous argument '%s': unknown revision or path not in the working tree.\n"
-		    "Use '--' to separate filenames from revisions", arg);
+		    "Use '--' to separate paths from revisions", arg);
 	die("'%s': %s", arg, strerror(errno));
 }
 
+/*
+ * Opposite of the above: the command line did not have -- marker
+ * and we parsed the arg as a refname.  It should not be interpretable
+ * as a filename.
+ */
+void verify_non_filename(const char *prefix, const char *arg)
+{
+	const char *name;
+	struct stat st;
+
+	if (*arg == '-')
+		return; /* flag */
+	name = prefix ? prefix_filename(prefix, strlen(prefix), arg) : arg;
+	if (!lstat(name, &st))
+		die("ambiguous argument '%s': both revision and filename\n"
+		    "Use '--' to separate filenames from revisions", arg);
+	if (errno != ENOENT)
+		die("'%s': %s", arg, strerror(errno));
+}
+
 const char **get_pathspec(const char *prefix, const char **pathspec)
 {
 	const char *entry = *pathspec;