[PATCH] Fix 'unset ZLE_RPROMPT_INDENT' not restoring the default behaviour.

[Daniel Shahaf <d.s@daniel.shahaf.name>]

To reproduce:

    RPS1=foo
    ZLE_RPROMPT_INDENT=42
    unset ZLE_RPROMPT_INDENT
---
 Src/init.c   |  2 +-
 Src/params.c | 19 ++++++++++++++++++-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/Src/init.c b/Src/init.c
index 43d274c..98f836f 100644
--- a/Src/init.c
+++ b/Src/init.c
@@ -790,7 +790,7 @@ init_term(void)
 	    tcstr[TCCLEARSCREEN] = ztrdup("\14");
 	    tclen[TCCLEARSCREEN] = 1;
 	}
-	rprompt_indent = 1;
+	rprompt_indent = 1; /* If you change this, update rprompt_indent_unsetfn() */
 	/* The following is an attempt at a heuristic,
 	 * but it fails in some cases */
 	/* rprompt_indent = ((hasam && !hasbw) || hasye || !tccan(TCLEFT)); */
diff --git a/Src/params.c b/Src/params.c
index d09ff21..f01bbfa 100644
--- a/Src/params.c
+++ b/Src/params.c
@@ -128,6 +128,11 @@ struct timeval shtimer;
 /**/
 mod_export int termflags;
 
+/* Forward declaration */
+
+static void
+rprompt_indent_unsetfn(Param pm, UNUSED(int exp));
+
 /* Standard methods for get/set/unset pointers in parameters */
 
 /**/
@@ -241,6 +246,9 @@ static const struct gsu_integer argc_gsu =
 static const struct gsu_array pipestatus_gsu =
 { pipestatgetfn, pipestatsetfn, stdunsetfn };
 
+static const struct gsu_integer rprompt_indent_gsu =
+{ intvargetfn, zlevarsetfn, rprompt_indent_unsetfn };
+
 /* Nodes for special parameters for parameter hash table */
 
 #ifdef HAVE_UNION_INIT
@@ -327,7 +335,7 @@ IPDEF4("ZSH_SUBSHELL", &zsh_subshell),
 #define IPDEF5U(A,B,F) {{NULL,A,PM_INTEGER|PM_SPECIAL|PM_UNSET},BR((void *)B),GSU(F),10,0,NULL,NULL,NULL,0}
 IPDEF5("COLUMNS", &zterm_columns, zlevar_gsu),
 IPDEF5("LINES", &zterm_lines, zlevar_gsu),
-IPDEF5U("ZLE_RPROMPT_INDENT", &rprompt_indent, zlevar_gsu),
+IPDEF5U("ZLE_RPROMPT_INDENT", &rprompt_indent, rprompt_indent_gsu),
 IPDEF5("SHLVL", &shlvl, varinteger_gsu),
 
 /* Don't import internal integer status variables. */
@@ -3733,6 +3741,15 @@ zlevarsetfn(Param pm, zlong x)
 	adjustwinsize(2 + (p == &zterm_columns));
 }
 
+
+/* Implements gsu_integer.unsetfn for ZLE_RPROMPT_INDENT; see stdunsetfn() */
+
+static void
+rprompt_indent_unsetfn(Param pm, UNUSED(int exp))
+{
+    rprompt_indent = 1; /* Keep this in sync with init_term() */
+}
+
 /* Function to set value of generic special scalar    *
  * parameter.  data is pointer to a character pointer *
  * representing the scalar (string).                  */