pull --rebase/remote rename: document and honor single-letter abbreviations rebase types

When 46af44b07d (pull --rebase=<type>: allow single-letter abbreviations
for the type, 2018-08-04) landed in Git, it had the side effect that
not only 'pull --rebase=<type>' accepted the single-letter abbreviations
but also the 'pull.rebase' and 'branch.<name>.rebase' configurations.

However, 'git remote rename' did not honor these single-letter
abbreviations when reading the 'branch.*.rebase' configurations.

We now document the single-letter abbreviations and both code places
share a common function to parse the values of 'git pull --rebase=*',
'pull.rebase', and 'branches.*.rebase'.

The only functional change is the handling of the `branch_info::rebase`
value. Before it was an unsigned enum, thus the truth value could be
checked with `branch_info::rebase != 0`. But `enum rebase_type` is
signed, thus the truth value must now be checked with
`branch_info::rebase >= REBASE_TRUE`

Signed-off-by: Bert Wesarg <bert.wesarg@googlemail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/rebase.c b/rebase.c
new file mode 100644
index 0000000..f8137d8
--- /dev/null
+++ b/rebase.c
@@ -0,0 +1,35 @@
+#include "rebase.h"
+#include "config.h"
+
+/*
+ * Parses textual value for pull.rebase, branch.<name>.rebase, etc.
+ * Unrecognised value yields REBASE_INVALID, which traditionally is
+ * treated the same way as REBASE_FALSE.
+ *
+ * The callers that care if (any) rebase is requested should say
+ *   if (REBASE_TRUE <= rebase_parse_value(string))
+ *
+ * The callers that want to differenciate an unrecognised value and
+ * false can do so by treating _INVALID and _FALSE differently.
+ */
+enum rebase_type rebase_parse_value(const char *value)
+{
+	int v = git_parse_maybe_bool(value);
+
+	if (!v)
+		return REBASE_FALSE;
+	else if (v > 0)
+		return REBASE_TRUE;
+	else if (!strcmp(value, "preserve") || !strcmp(value, "p"))
+		return REBASE_PRESERVE;
+	else if (!strcmp(value, "merges") || !strcmp(value, "m"))
+		return REBASE_MERGES;
+	else if (!strcmp(value, "interactive") || !strcmp(value, "i"))
+		return REBASE_INTERACTIVE;
+	/*
+	 * Please update _git_config() in git-completion.bash when you
+	 * add new rebase modes.
+	 */
+
+	return REBASE_INVALID;
+}