From 7e70c26faac2dfae2855fb9148fcc7205c6cfd02 Mon Sep 17 00:00:00 2001
From: Basile Burg <basile.b@gmx.com>
Date: Sat, 24 Feb 2018 12:29:23 +0100
Subject: [PATCH] fix #442 - Prevent crash when cursor is in the middle of a
 UTF sequence

---
 src/dcd/server/autocomplete/complete.d | 9 ++++++++-
 tests/tc_middle_of_utf/expected1.txt   | 0
 tests/tc_middle_of_utf/file.d          | 1 +
 tests/tc_middle_of_utf/run.sh          | 5 +++++
 4 files changed, 14 insertions(+), 1 deletion(-)
 create mode 100644 tests/tc_middle_of_utf/expected1.txt
 create mode 100644 tests/tc_middle_of_utf/file.d
 create mode 100755 tests/tc_middle_of_utf/run.sh

diff --git a/src/dcd/server/autocomplete/complete.d b/src/dcd/server/autocomplete/complete.d
index b3a9b4c..9012ad0 100644
--- a/src/dcd/server/autocomplete/complete.d
+++ b/src/dcd/server/autocomplete/complete.d
@@ -114,8 +114,15 @@ AutocompleteResponse dotCompletion(T)(T beforeTokens, const(Token)[] tokenArray,
 		// of at the end
 		auto t = beforeTokens[$ - 1];
 		if (cursorPosition - t.index >= 0 && cursorPosition - t.index <= t.text.length)
+		{
 			partial = t.text[0 .. cursorPosition - t.index];
-		significantTokenType = tok!"identifier";
+			// issue 442 - prevent `partial` to start in the middle of a MBC
+			// since later there's a non-nothrow call to `toUpper`
+			import std.utf : validate, UTFException;
+			try validate(partial);
+			catch (UTFException) partial = "";
+		}
+		significantTokenType = partial.length ? tok!"identifier" : tok!"";
 		beforeTokens = beforeTokens[0 .. $ - 1];
 	}
 	else if (beforeTokens.length >= 2 && beforeTokens[$ - 1] == tok!".")
diff --git a/tests/tc_middle_of_utf/expected1.txt b/tests/tc_middle_of_utf/expected1.txt
new file mode 100644
index 0000000..e69de29
diff --git a/tests/tc_middle_of_utf/file.d b/tests/tc_middle_of_utf/file.d
new file mode 100644
index 0000000..e520836
--- /dev/null
+++ b/tests/tc_middle_of_utf/file.d
@@ -0,0 +1 @@
+ß
diff --git a/tests/tc_middle_of_utf/run.sh b/tests/tc_middle_of_utf/run.sh
new file mode 100755
index 0000000..9e6d161
--- /dev/null
+++ b/tests/tc_middle_of_utf/run.sh
@@ -0,0 +1,5 @@
+set -e
+set -u
+
+../../bin/dcd-client $1 file.d -c1 > actual1.txt
+diff actual1.txt expected1.txt