diff: avoid some nesting

diff --git a/builtin/diff.c b/builtin/diff.c
index adb93a9efa5ed9b97a08224e46f6fbaf680343e6..24d6271625d02b5aba877ac17b13daf36f5db0aa 100644 (file)
--- a/builtin/diff.c
+++ b/builtin/diff.c
@@ -16,6 +16,9 @@
 #include "submodule.h"
 #include "sha1-array.h"
 
+#define DIFF_NO_INDEX_EXPLICIT 1
+#define DIFF_NO_INDEX_IMPLICIT 2
+
 struct blobinfo {
        unsigned char sha1[20];
        const char *name;
@@ -257,7 +260,7 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
        int blobs = 0, paths = 0;
        const char *path = NULL;
        struct blobinfo blob[2];
-       int nongit;
+       int nongit = 0, no_index = 0;
        int result = 0;
 
        /*
@@ -283,14 +286,59 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
         * Other cases are errors.
         */
 
-       prefix = setup_git_directory_gently(&nongit);
-       gitmodules_config();
+       /* Were we asked to do --no-index explicitly? */
+       for (i = 1; i < argc; i++) {
+               if (!strcmp(argv[i], "--")) {
+                       i++;
+                       break;
+               }
+               if (!strcmp(argv[i], "--no-index"))
+                       no_index = DIFF_NO_INDEX_EXPLICIT;
+               if (argv[i][0] != '-')
+                       break;
+       }
+
+       if (!no_index)
+               prefix = setup_git_directory_gently(&nongit);
+
+       /*
+        * Treat git diff with at least one path outside of the
+        * repo the same as if the command would have been executed
+        * outside of a git repository.  In this case it behaves
+        * the same way as "git diff --no-index <a> <b>", which acts
+        * as a colourful "diff" replacement.
+        */
+       if (nongit || ((argc == i + 2) &&
+                      (!path_inside_repo(prefix, argv[i]) ||
+                       !path_inside_repo(prefix, argv[i + 1]))))
+               no_index = DIFF_NO_INDEX_IMPLICIT;
+
+       if (!no_index)
+               gitmodules_config();
        git_config(git_diff_ui_config, NULL);
 
        init_revisions(&rev, prefix);
 
-       /* If this is a no-index diff, just run it and exit there. */
-       diff_no_index(&rev, argc, argv, nongit, prefix);
+       if (no_index && argc != i + 2) {
+               if (no_index == DIFF_NO_INDEX_IMPLICIT) {
+                       /*
+                        * There was no --no-index and there were not two
+                        * paths. It is possible that the user intended
+                        * to do an inside-repository operation.
+                        */
+                       fprintf(stderr, "Not a git repository\n");
+                       fprintf(stderr,
+                               "To compare two paths outside a working tree:\n");
+               }
+               /* Give the usage message for non-repository usage and exit. */
+               usagef("git diff %s <path> <path>",
+                      no_index == DIFF_NO_INDEX_EXPLICIT ?
+                      "--no-index" : "[--no-index]");
+
+       }
+       if (no_index)
+               /* If this is a no-index diff, just run it and exit there. */
+               diff_no_index(&rev, argc, argv, prefix);
 
        /* Otherwise, we are doing the usual "git" diff */
        rev.diffopt.skip_stat_unmatch = !!diff_auto_refresh_index;