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[PATCH v3 2/3] read-tree -m: make error message for merging 0 trees less smart aleck

From
Jean-Noel Avila <jn.avila@free.fr>
Date
May 11, 2017, 12:06 UTC
Message-ID
<20170511120634.17683-2-jn.avila@free.fr>
In-Reply-To
<20170511120634.17683-1-jn.avila@free.fr>

"git read-tree -m" requires a tree argument to name the tree to be merged in. Git uses a cutesy error message to say so and why:

    $ git read-tree -m
    warning: read-tree: emptying the index with no arguments is
    deprecated; use --empty
    fatal: just how do you expect me to merge 0 trees?
    $ git read-tree -m --empty
    fatal: just how do you expect me to merge 0 trees?

When lucky, that could produce an ah-hah moment for the user, but it's more likely to irritate and distract them.

Instead, tell the user plainly that the tree argument is required. Also document this requirement in the git-read-tree(1) manpage where there is room to explain it in a more straightforward way.

Signed-off-by: Jean-Noel Avila <jn.avila@free.fr>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
 Documentation/git-read-tree.txt | 8 ++++----
 builtin/read-tree.c             | 7 ++++---
 2 files changed, 8 insertions(+), 7 deletions(-)
diff --git a/Documentation/git-read-tree.txt b/Documentation/git-read-tree.txt
index ed9d63ef4..97df00043 100644
--- a/Documentation/git-read-tree.txt
+++ b/Documentation/git-read-tree.txt
@@ -135,10 +135,10 @@ OPTIONS
 
 Merging
 -------
-If `-m` is specified, 'git read-tree' can perform 3 kinds of
-merge, a single tree merge if only 1 tree is given, a
-fast-forward merge with 2 trees, or a 3-way merge if 3 trees are
-provided.
+If `-m` is specified, at least one tree must be given on the command
+line. 'git read-tree' can perform 3 kinds of merge, a single tree
+merge if only 1 tree is given, a fast-forward merge with 2 trees, or a
+3-way merge if 3 or more trees are provided.
 
 
 Single Tree Merge
diff --git a/builtin/read-tree.c b/builtin/read-tree.c
index 23e212ee8..de1a58d17 100644
--- a/builtin/read-tree.c
+++ b/builtin/read-tree.c
@@ -132,7 +132,7 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 		OPT_BOOL(0, "empty", &read_empty,
 			    N_("only empty the index")),
 		OPT__VERBOSE(&opts.verbose_update, N_("be verbose")),
-		OPT_GROUP(N_("Merging")),
+		OPT_GROUP(N_("Merging (needs at least one tree-ish")),
 		OPT_BOOL('m', NULL, &opts.merge,
 			 N_("perform a merge in addition to a read")),
 		OPT_BOOL(0, "trivial", &opts.trivial_merges_only,
@@ -226,9 +226,10 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 		setup_work_tree();
 
 	if (opts.merge) {
-		if (stage < 2)
-			die("just how do you expect me to merge %d trees?", stage-1);
 		switch (stage - 1) {
+		case 0:
+			die(_("you must specify at least one tree to merge"));
+			break;
 		case 1:
 			opts.fn = opts.prefix ? bind_merge : oneway_merge;
 			break;
-- 
2.13.0
Previous: Jean-Noel AvilaNext: Jonathan Nieder
Message 30 of 41 in “usability: don't ask questions if no reply is required”
  1. 1/4 usability: don't ask questions if no reply is requiredJean-Noel Avila, May 3, 2017
  2. 2/4 usability: fix am and checkout for nevermind questionsJean-Noel Avila, May 3, 2017
  3. Jonathan NiederMay 3, 2017
  4. Jean-Noël AVILAMay 3, 2017
  5. 3/4 read-tree.c: rework UI when merging no treesJean-Noel Avila, May 3, 2017
  6. Jonathan NiederMay 3, 2017
  7. Jean-Noël AVILAMay 3, 2017
  8. 4/4 git-filter-branch: be assertative on dying messageJean-Noel Avila, May 3, 2017
  9. Jonathan NiederMay 3, 2017
  10. Jonathan NiederMay 3, 2017
  11. Stefan BellerMay 3, 2017
  12. Jean-Noël AVILAMay 3, 2017
  13. 1/3 usability: don't ask questions if no reply is requiredJean-Noel Avila, May 3, 2017
  14. 2/3 read-tree -m: make error message for merging 0 trees less smart aleckJean-Noel Avila, May 3, 2017
  15. Junio C HamanoMay 11, 2017
  16. read-tree: "read-tree -m --empty" does not make senseJunio C Hamano, May 11, 2017
  17. 3/3 git-filter-branch: make the error msg when missing branch more openJean-Noel Avila, May 3, 2017
  18. Junio C HamanoMay 11, 2017
  19. Kerry, RichardMay 4, 2017
  20. Ævar Arnfjörð BjarmasonMay 4, 2017
  21. Kerry, RichardMay 4, 2017
  22. Jean-Noël AVILAMay 9, 2017
  23. Ævar Arnfjörð BjarmasonMay 9, 2017
  24. Jean-Noël AVILAMay 4, 2017
  25. Junio C HamanoMay 11, 2017
  26. Kerry, RichardMay 11, 2017
  27. Konstantin KhomoutovMay 11, 2017
  28. Ævar Arnfjörð BjarmasonMay 11, 2017
  29. 1/3 usability: don't ask questions if no reply is requiredJean-Noel Avila, May 11, 2017
  30. 2/3 read-tree -m: make error message for merging 0 trees less smart aleckJean-Noel Avila, May 11, 2017
  31. Jonathan NiederMay 11, 2017
  32. Junio C HamanoMay 12, 2017
  33. Jean-Noël AVILAMay 12, 2017
  34. 3/3 git-filter-branch:Jean-Noel Avila, May 11, 2017
  35. Junio C HamanoMay 12, 2017
  36. 1/3 usability: don't ask questions if no reply is requiredJean-Noel Avila, May 12, 2017
  37. 2/3 read-tree -m: make error message for merging 0 trees less smart aleckJean-Noel Avila, May 12, 2017
  38. 3/3 git-filter-branch: be more direct in an error messageJean-Noel Avila, May 12, 2017
  39. Junio C HamanoMay 12, 2017
  40. Johannes SixtMay 13, 2017
  41. Junio C HamanoMay 15, 2017

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