From 5afd939f3e7558c91404e8c563c53351b71cfb43 Mon Sep 17 00:00:00 2001
From: Aaron Gyes <me@aaron.gy>
Date: Sat, 23 Jul 2016 13:40:01 -0700
Subject: [PATCH] Stop swallowing the cartesian product

This should work:
 > env TERM=vt100 ./fish -c 'echo (set_color red)"hi"'

We do a ::reset() if setting the color doesn't happen.

Fixes #2951
---
 src/builtin_set_color.cpp | 7 ++++++-
 src/output.cpp            | 5 +++--
 src/output.h              | 2 +-
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/builtin_set_color.cpp b/src/builtin_set_color.cpp
index e6679562f..35917a63d 100644
--- a/src/builtin_set_color.cpp
+++ b/src/builtin_set_color.cpp
@@ -179,7 +179,12 @@ int builtin_set_color(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
             write_color(rgb_color_t::black(), true /* is_fg */);
             writembs(tparm(exit_attribute_mode));
         } else {
-            write_color(fg, true /* is_fg */);
+            if (!write_color(fg, true /* is_fg */)) {
+                // We need to do *something* or the lack of any output messes up 
+                // when the cartesian product here would make "foo" disappear:
+                //  $ echo (set_color foo)bar
+                set_color(rgb_color_t::reset(), rgb_color_t::none());
+            }
         }
     }
 
diff --git a/src/output.cpp b/src/output.cpp
index 937e78114..4905c5a50 100644
--- a/src/output.cpp
+++ b/src/output.cpp
@@ -106,12 +106,12 @@ static bool write_background_color(unsigned char idx) {
 }
 
 // Exported for builtin_set_color's usage only.
-void write_color(rgb_color_t color, bool is_fg) {
+bool write_color(rgb_color_t color, bool is_fg) {
     bool supports_term24bit = !!(output_get_color_support() & color_support_term24bit);
     if (!supports_term24bit || !color.is_rgb()) {
         // Indexed or non-24 bit color.
         unsigned char idx = index_for_color(color);
-        (is_fg ? write_foreground_color : write_background_color)(idx);
+        return (is_fg ? write_foreground_color : write_background_color)(idx);
     } else {
         // 24 bit! No tparm here, just ANSI escape sequences.
         // Foreground: ^[38;2;<r>;<g>;<b>m
@@ -127,6 +127,7 @@ void write_color(rgb_color_t color, bool is_fg) {
             }
         }
     }
+    return true;
 }
 
 /// Sets the fg and bg color. May be called as often as you like, since if the new color is the same
diff --git a/src/output.h b/src/output.h
index 71f94de80..6ca31d92c 100644
--- a/src/output.h
+++ b/src/output.h
@@ -51,7 +51,7 @@ void output_set_color_support(color_support_t support);
 
 rgb_color_t best_color(const std::vector<rgb_color_t> &colors, color_support_t support);
 
-void write_color(rgb_color_t color, bool is_fg);
+bool write_color(rgb_color_t color, bool is_fg);
 unsigned char index_for_color(rgb_color_t c);
 
 #endif