From c6a37fdf1dca8fd8ecbedd4907f4261520745ddb Mon Sep 17 00:00:00 2001
From: Max Schaefer <max@semmle.com>
Date: Thu, 9 Apr 2020 16:44:03 +0100
Subject: [PATCH] Add consistency query flagging unexpected frontend errors.

---
 .../UnexpectedFrontendErrors.expected            |  0
 ql/test/consistency/UnexpectedFrontendErrors.ql  | 16 ++++++++++++++++
 ql/test/consistency/test.go                      |  7 +++++++
 3 files changed, 23 insertions(+)
 create mode 100644 ql/test/consistency/UnexpectedFrontendErrors.expected
 create mode 100644 ql/test/consistency/UnexpectedFrontendErrors.ql
 create mode 100644 ql/test/consistency/test.go

diff --git a/ql/test/consistency/UnexpectedFrontendErrors.expected b/ql/test/consistency/UnexpectedFrontendErrors.expected
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/ql/test/consistency/UnexpectedFrontendErrors.ql b/ql/test/consistency/UnexpectedFrontendErrors.ql
new file mode 100644
index 00000000000..f75e2c6bf21
--- /dev/null
+++ b/ql/test/consistency/UnexpectedFrontendErrors.ql
@@ -0,0 +1,16 @@
+/**
+ * @name Unexpected frontend error
+ * @description This query produces a list of all errors produced by the Go frontend
+ *              during extraction, except for those occurring in files annotated with
+ *              "// codeql test: expect frontend errors".
+ * @id go/unexpected-frontend-error
+ */
+
+import go
+
+from Error e
+where
+  not exists(Comment c | c.getFile() = e.getFile() |
+    c.getText().trim() = "codeql test: expect frontend errors"
+  )
+select e
diff --git a/ql/test/consistency/test.go b/ql/test/consistency/test.go
new file mode 100644
index 00000000000..ca40bd0f601
--- /dev/null
+++ b/ql/test/consistency/test.go
@@ -0,0 +1,7 @@
+package main
+
+// Example file with a syntax error to demonstrate use of "expect frontend errors" directive
+
+// codeql test: expect frontend errors
+
+This is not a valid Go program