44030: prompt: Return error for unrecognised colour name

ChangeLog

+2019-02-03  dana  <dana@dana.is>
+
+	* 44030: Src/prompt.c, Test/D01prompt.ztst: Return error for
+	unrecognised colour name
+
 2019-01-28  Fredric Silberberg  <fred@silberberg.xyz>
 
 	* github #32: Completion/Unix/Command/_git: Fix a typo in the

Src/prompt.c

@@ -1663,6 +1663,8 @@ match_colour(const char **teststrp, int is_fg, int colour)
 		/* default */
 		return is_fg ? TXTNOFGCOLOUR : TXTNOBGCOLOUR;
 	    }
+	    if (colour < 0)
+		return TXT_ERROR;
 	}
 	else {
 	    colour = (int)zstrtol(*teststrp, (char **)teststrp, 10);

Test/D01prompt.ztst

@@ -221,3 +221,11 @@
   print ${(%U)Y-%(v}
 0:Regression test for test on empty psvar
 >
+
+# Unrecognised colour strings should produce the default sequence
+  f=${(%):-'%f'} # Recognised
+  Fdefault=${(%):-'%F{default}'} # Recognised
+  Freset=${(%):-'%F{reset}'} # Unrecognised
+  Ffoo=${(%):-'%F{foo}'} # Unrecognised
+  [[ $f == $Fdefault && $Fdefault == $Freset && $Freset == $Ffoo ]]
+0:Regression test for workers/44029