From c94dec5d0ec0987938fb5d2b6181e856e4cba746 Mon Sep 17 00:00:00 2001
From: Johannes Altmanninger <aclopte@gmail.com>
Date: Sun, 31 Oct 2021 13:44:38 +0100
Subject: [PATCH] Fix assertion error trying to highlight cmdsubs inside
 unbalanced quotes

I initially put this logic + assertion in another function, where we
always get balanced quotes. Not for highlighting.
---
 src/fish_tests.cpp |  8 ++++++++
 src/parse_util.cpp | 13 ++++++++++---
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/fish_tests.cpp b/src/fish_tests.cpp
index 931c56cfc..e1b213bff 100644
--- a/src/fish_tests.cpp
+++ b/src/fish_tests.cpp
@@ -5296,6 +5296,14 @@ static void test_highlighting() {
         {L"after\"", highlight_role_t::quote},
         {L"param2", highlight_role_t::param},
     });
+    highlight_tests.push_back({
+        {L"true", highlight_role_t::command},
+        {L"\"", highlight_role_t::error},
+        {L"unclosed quote", highlight_role_t::quote},
+        {L"$(", highlight_role_t::operat},
+        {L"true", highlight_role_t::command},
+        {L")", highlight_role_t::operat},
+    });
 
     // Redirections substitutions.
     highlight_tests.push_back({
diff --git a/src/parse_util.cpp b/src/parse_util.cpp
index 595fe621d..be9d30843 100644
--- a/src/parse_util.cpp
+++ b/src/parse_util.cpp
@@ -275,9 +275,16 @@ int parse_util_locate_cmdsubst_range(const wcstring &str, size_t *inout_cursor_o
         // quoted but the naïve next caller wouldn't know. Since next caller only cares about
         // the next command substitution - (C) - and not about the B part, just advance the
         // cursor to the closing quote.
-        const wchar_t *q_end = quote_end(bracket_range_end, L'"');
-        assert(q_end && "expect balanced quotes");
-        *inout_cursor_offset = 1 + q_end - buff;
+        if (auto *q_end = quote_end(bracket_range_end, L'"')) {
+            *inout_cursor_offset = 1 + q_end - buff;
+        } else {
+            if (accept_incomplete) {
+                // We want to skip quoted text, so if there is no closing quote, skip to the end.
+                *inout_cursor_offset = bracket_range_end + std::wcslen(bracket_range_end) - buff;
+            } else {
+                return -1;
+            }
+        }
     }
 
     return ret;