Merge branch 'jk/grep-no-index-fix' into maint

The code to parse the command line "git grep <patterns>... <rev>
[[--] <pathspec>...]" has been cleaned up, and a handful of bugs
have been fixed (e.g. we used to check "--" if it is a rev).

* jk/grep-no-index-fix:
  grep: treat revs the same for --untracked as for --no-index
  grep: do not diagnose misspelt revs with --no-index
  grep: avoid resolving revision names in --no-index case
  grep: fix "--" rev/pathspec disambiguation
  grep: re-order rev-parsing loop
  grep: do not unnecessarily query repo for "--"
  grep: move thread initialization a little lower

builtin/grep.c

@@ -967,6 +967,7 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 	int dummy;
 	int use_index = 1;
 	int pattern_type_arg = GREP_PATTERN_TYPE_UNSPECIFIED;
+	int allow_revs;
 
 	struct option options[] = {
 		OPT_BOOL(0, "cached", &cached,
@@ -1149,26 +1150,69 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 
 	compile_grep_patterns(&opt);
 
-	/* Check revs and then paths */
+	/*
+	 * We have to find "--" in a separate pass, because its presence
+	 * influences how we will parse arguments that come before it.
+	 */
+	for (i = 0; i < argc; i++) {
+		if (!strcmp(argv[i], "--")) {
+			seen_dashdash = 1;
+			break;
+		}
+	}
+
+	/*
+	 * Resolve any rev arguments. If we have a dashdash, then everything up
+	 * to it must resolve as a rev. If not, then we stop at the first
+	 * non-rev and assume everything else is a path.
+	 */
+	allow_revs = use_index && !untracked;
 	for (i = 0; i < argc; i++) {
 		const char *arg = argv[i];
 		unsigned char sha1[20];
 		struct object_context oc;
-		/* Is it a rev? */
-		if (!get_sha1_with_context(arg, 0, sha1, &oc)) {
-			struct object *object = parse_object_or_die(sha1, arg);
-			if (!seen_dashdash)
-				verify_non_filename(prefix, arg);
-			add_object_array_with_path(object, arg, &list, oc.mode, oc.path);
-			continue;
-		}
+		struct object *object;
+
 		if (!strcmp(arg, "--")) {
 			i++;
-			seen_dashdash = 1;
+			break;
 		}
-		break;
+
+		if (!allow_revs) {
+			if (seen_dashdash)
+				die(_("--no-index or --untracked cannot be used with revs"));
+			break;
+		}
+
+		if (get_sha1_with_context(arg, 0, sha1, &oc)) {
+			if (seen_dashdash)
+				die(_("unable to resolve revision: %s"), arg);
+			break;
+		}
+
+		object = parse_object_or_die(sha1, arg);
+		if (!seen_dashdash)
+			verify_non_filename(prefix, arg);
+		add_object_array_with_path(object, arg, &list, oc.mode, oc.path);
 	}
 
+	/*
+	 * Anything left over is presumed to be a path. But in the non-dashdash
+	 * "do what I mean" case, we verify and complain when that isn't true.
+	 */
+	if (!seen_dashdash) {
+		int j;
+		for (j = i; j < argc; j++)
+			verify_filename(prefix, argv[j], j == i && allow_revs);
+	}
+
+	parse_pathspec(&pathspec, 0,
+		       PATHSPEC_PREFER_CWD |
+		       (opt.max_depth != -1 ? PATHSPEC_MAXDEPTH_VALID : 0),
+		       prefix, argv + i);
+	pathspec.max_depth = opt.max_depth;
+	pathspec.recursive = 1;
+
 #ifndef NO_PTHREADS
 	if (list.nr || cached || show_in_pager)
 		num_threads = 0;
@@ -1190,20 +1234,6 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 	}
 #endif
 
-	/* The rest are paths */
-	if (!seen_dashdash) {
-		int j;
-		for (j = i; j < argc; j++)
-			verify_filename(prefix, argv[j], j == i);
-	}
-
-	parse_pathspec(&pathspec, 0,
-		       PATHSPEC_PREFER_CWD |
-		       (opt.max_depth != -1 ? PATHSPEC_MAXDEPTH_VALID : 0),
-		       prefix, argv + i);
-	pathspec.max_depth = opt.max_depth;
-	pathspec.recursive = 1;
-
 	if (recurse_submodules) {
 		gitmodules_config();
 		compile_submodule_options(&opt, &pathspec, cached, untracked,
@@ -1245,8 +1275,6 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 
 	if (!use_index || untracked) {
 		int use_exclude = (opt_exclude < 0) ? use_index : !!opt_exclude;
-		if (list.nr)
-			die(_("--no-index or --untracked cannot be used with revs."));
 		hit = grep_directory(&opt, &pathspec, use_exclude, use_index);
 	} else if (0 <= opt_exclude) {
 		die(_("--[no-]exclude-standard cannot be used for tracked contents."));

t/t7810-grep.sh

@@ -982,6 +982,72 @@ test_expect_success 'grep -e -- -- path' '
 	test_cmp expected actual
 '
 
+test_expect_success 'dashdash disambiguates rev as rev' '
+	test_when_finished "rm -f master" &&
+	echo content >master &&
+	echo master:hello.c >expect &&
+	git grep -l o master -- hello.c >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'dashdash disambiguates pathspec as pathspec' '
+	test_when_finished "git rm -f master" &&
+	echo content >master &&
+	git add master &&
+	echo master:content >expect &&
+	git grep o -- master >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'report bogus arg without dashdash' '
+	test_must_fail git grep o does-not-exist
+'
+
+test_expect_success 'report bogus rev with dashdash' '
+	test_must_fail git grep o hello.c --
+'
+
+test_expect_success 'allow non-existent path with dashdash' '
+	# We need a real match so grep exits with success.
+	tree=$(git ls-tree HEAD |
+	       sed s/hello.c/not-in-working-tree/ |
+	       git mktree) &&
+	git grep o "$tree" -- not-in-working-tree
+'
+
+test_expect_success 'grep --no-index pattern -- path' '
+	rm -fr non &&
+	mkdir -p non/git &&
+	(
+		GIT_CEILING_DIRECTORIES="$(pwd)/non" &&
+		export GIT_CEILING_DIRECTORIES &&
+		cd non/git &&
+		echo hello >hello &&
+		echo goodbye >goodbye &&
+		echo hello:hello >expect &&
+		git grep --no-index o -- hello >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'grep --no-index complains of revs' '
+	test_must_fail git grep --no-index o master -- 2>err &&
+	test_i18ngrep "cannot be used with revs" err
+'
+
+test_expect_success 'grep --no-index prefers paths to revs' '
+	test_when_finished "rm -f master" &&
+	echo content >master &&
+	echo master:content >expect &&
+	git grep --no-index o master >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'grep --no-index does not "diagnose" revs' '
+	test_must_fail git grep --no-index o :1:hello.c 2>err &&
+	test_i18ngrep ! -i "did you mean" err
+'
+
 cat >expected <<EOF
 hello.c:int main(int argc, const char **argv)
 hello.c:	printf("Hello world.\n");