From 17cf255bf7f765c9510f88a6fcebca701519d20d Mon Sep 17 00:00:00 2001
From: Kurtis Rader <krader@skepticism.us>
Date: Fri, 28 Jul 2017 14:11:14 -0700
Subject: [PATCH] warn when people try to do `set -ex var`

A person asked in issue #4263 why `set -ex fish_greeting` didn't work.
So issue an error to let people know that combination doesn't make sense.
---
 src/builtin_set.cpp | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/builtin_set.cpp b/src/builtin_set.cpp
index 51e103b11..fca3bfff4 100644
--- a/src/builtin_set.cpp
+++ b/src/builtin_set.cpp
@@ -170,6 +170,13 @@ static int validate_cmd_opts(const wchar_t *cmd, set_cmd_opts_t &opts, int argc,
         return STATUS_INVALID_ARGS;
     }
 
+    // Trying to erase and (un)export at the same time doesn't make sense.
+    if (opts.erase && (opts.exportv || opts.unexport)) {
+        streams.err.append_format(BUILTIN_ERR_COMBO, cmd);
+        builtin_print_help(parser, streams, cmd, streams.err);
+        return STATUS_INVALID_ARGS;
+    }
+
     if (argc == 0 && opts.erase) {
         streams.err.append_format(BUILTIN_SET_ERASE_NO_VAR, cmd);
         builtin_print_help(parser, streams, cmd, streams.err);