Merge branch 'ar/diff'

* ar/diff:
Add tests for --quiet option of diff programs
try-to-simplify-commit: use diff-tree --quiet machinery.
revision.c: explain what tree_difference does
Teach --quiet to diff backends.
diff --quiet
Remove unused diffcore_std_no_resolve
Allow git-diff exit with codes similar to diff(1)

diff --combined tree-diff.c
index f89b9d31e4542724ff44b6f3c3bc6ae3adcaa1a6,44cde74caf20ded9cd196c4e5d16f4d9ba251a22..3940962e79a5094e61270cd951d5d37c307d11a9
--- 1/tree-diff.c
--- 2/tree-diff.c
+++ b/tree-diff.c
@@@ -5,8 -5,9 +5,8 @@@
  #include "diff.h"
  #include "tree.h"
  
 -static char *malloc_base(const char *base, const char *path, int pathlen)
 +static char *malloc_base(const char *base, int baselen, const char *path, int pathlen)
  {
 -      int baselen = strlen(base);
        char *newbase = xmalloc(baselen + pathlen + 2);
        memcpy(newbase, base, baselen);
        memcpy(newbase + baselen, path, pathlen);
@@@ -15,9 -16,9 +15,9 @@@
  }
  
  static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
 -                     const char *base);
 +                     const char *base, int baselen);
  
 -static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
 +static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, int baselen, struct diff_options *opt)
  {
        unsigned mode1, mode2;
        const char *path1, *path2;
@@@ -27,15 -28,15 +27,15 @@@
        sha1 = tree_entry_extract(t1, &path1, &mode1);
        sha2 = tree_entry_extract(t2, &path2, &mode2);
  
 -      pathlen1 = strlen(path1);
 -      pathlen2 = strlen(path2);
 +      pathlen1 = tree_entry_len(path1, sha1);
 +      pathlen2 = tree_entry_len(path2, sha2);
        cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
        if (cmp < 0) {
 -              show_entry(opt, "-", t1, base);
 +              show_entry(opt, "-", t1, base, baselen);
                return -1;
        }
        if (cmp > 0) {
 -              show_entry(opt, "+", t2, base);
 +              show_entry(opt, "+", t2, base, baselen);
                return 1;
        }
        if (!opt->find_copies_harder && !hashcmp(sha1, sha2) && mode1 == mode2)
@@@ -46,14 -47,14 +46,14 @@@
         * file, we need to consider it a remove and an add.
         */
        if (S_ISDIR(mode1) != S_ISDIR(mode2)) {
 -              show_entry(opt, "-", t1, base);
 -              show_entry(opt, "+", t2, base);
 +              show_entry(opt, "-", t1, base, baselen);
 +              show_entry(opt, "+", t2, base, baselen);
                return 0;
        }
  
        if (opt->recursive && S_ISDIR(mode1)) {
                int retval;
 -              char *newbase = malloc_base(base, path1, pathlen1);
 +              char *newbase = malloc_base(base, baselen, path1, pathlen1);
                if (opt->tree_in_recursive)
                        opt->change(opt, mode1, mode2,
                                    sha1, sha2, base, path1);
@@@ -66,20 -67,20 +66,20 @@@
        return 0;
  }
  
 -static int interesting(struct tree_desc *desc, const char *base, struct diff_options *opt)
 +static int interesting(struct tree_desc *desc, const char *base, int baselen, struct diff_options *opt)
  {
        const char *path;
 +      const unsigned char *sha1;
        unsigned mode;
        int i;
 -      int baselen, pathlen;
 +      int pathlen;
  
        if (!opt->nr_paths)
                return 1;
  
 -      (void)tree_entry_extract(desc, &path, &mode);
 +      sha1 = tree_entry_extract(desc, &path, &mode);
  
 -      pathlen = strlen(path);
 -      baselen = strlen(base);
 +      pathlen = tree_entry_len(path, sha1);
  
        for (i=0; i < opt->nr_paths; i++) {
                const char *match = opt->paths[i];
@@@ -120,18 -121,18 +120,18 @@@
  }
  
  /* A whole sub-tree went away or appeared */
 -static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base)
 +static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base, int baselen)
  {
        while (desc->size) {
 -              if (interesting(desc, base, opt))
 -                      show_entry(opt, prefix, desc, base);
 +              if (interesting(desc, base, baselen, opt))
 +                      show_entry(opt, prefix, desc, base, baselen);
                update_tree_entry(desc);
        }
  }
  
  /* A file entry went away or appeared */
  static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
 -                     const char *base)
 +                     const char *base, int baselen)
  {
        unsigned mode;
        const char *path;
@@@ -139,8 -140,7 +139,8 @@@
  
        if (opt->recursive && S_ISDIR(mode)) {
                enum object_type type;
 -              char *newbase = malloc_base(base, path, strlen(path));
 +              int pathlen = tree_entry_len(path, sha1);
 +              char *newbase = malloc_base(base, baselen, path, pathlen);
                struct tree_desc inner;
                void *tree;
  
@@@ -149,7 -149,7 +149,7 @@@
                        die("corrupt tree sha %s", sha1_to_hex(sha1));
  
                inner.buf = tree;
 -              show_tree(opt, prefix, &inner, newbase);
 +              show_tree(opt, prefix, &inner, newbase, baselen + 1 + pathlen);
  
                free(tree);
                free(newbase);
@@@ -160,28 -160,28 +160,30 @@@
  
  int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
  {
 +      int baselen = strlen(base);
 +
        while (t1->size | t2->size) {
 -              if (opt->nr_paths && t1->size && !interesting(t1, base, opt)) {
+               if (opt->quiet && opt->has_changes)
+                       break;
 +              if (opt->nr_paths && t1->size && !interesting(t1, base, baselen, opt)) {
                        update_tree_entry(t1);
                        continue;
                }
 -              if (opt->nr_paths && t2->size && !interesting(t2, base, opt)) {
 +              if (opt->nr_paths && t2->size && !interesting(t2, base, baselen, opt)) {
                        update_tree_entry(t2);
                        continue;
                }
                if (!t1->size) {
 -                      show_entry(opt, "+", t2, base);
 +                      show_entry(opt, "+", t2, base, baselen);
                        update_tree_entry(t2);
                        continue;
                }
                if (!t2->size) {
 -                      show_entry(opt, "-", t1, base);
 +                      show_entry(opt, "-", t1, base, baselen);
                        update_tree_entry(t1);
                        continue;
                }
 -              switch (compare_tree_entry(t1, t2, base, opt)) {
 +              switch (compare_tree_entry(t1, t2, base, baselen, opt)) {
                case -1:
                        update_tree_entry(t1);
                        continue;