diff --git a/src/cmd/compile/internal/syntax/testdata/issue20789.src b/src/cmd/compile/internal/syntax/testdata/issue20789.src
new file mode 100644
index 0000000000..5f150db7e6
--- /dev/null
+++ b/src/cmd/compile/internal/syntax/testdata/issue20789.src
@@ -0,0 +1,9 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Make sure this doesn't crash the compiler.
+// Line 9 must end in EOF for this test (no newline).
+
+package e
+func([<-chan<-[func /* ERROR unexpected u */ u){go /* ERROR must be function call */
\ No newline at end of file
diff --git a/src/cmd/compile/internal/syntax/testdata/issue23385.src b/src/cmd/compile/internal/syntax/testdata/issue23385.src
new file mode 100644
index 0000000000..44abcd7e23
--- /dev/null
+++ b/src/cmd/compile/internal/syntax/testdata/issue23385.src
@@ -0,0 +1,12 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Check error message for use of = instead of == .
+
+package p
+
+func f() {
+	if true || 0 = 1 /* ERROR assignment .* used as value */ {
+	}
+}
diff --git a/src/cmd/compile/internal/syntax/testdata/issue23434.src b/src/cmd/compile/internal/syntax/testdata/issue23434.src
new file mode 100644
index 0000000000..5a72a7f4ed
--- /dev/null
+++ b/src/cmd/compile/internal/syntax/testdata/issue23434.src
@@ -0,0 +1,31 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test case for issue 23434: Better synchronization of
+// parser after missing type. There should be exactly
+// one error each time, with now follow errors.
+
+package p
+
+type T /* ERROR unexpected newline */
+
+type Map map[int] /* ERROR unexpected newline */
+
+// Examples from #23434:
+
+func g() {
+	m := make(map[string] /* ERROR unexpected ! */ !)
+	for {
+		x := 1
+		print(x)
+	}
+}
+
+func f() {
+	m := make(map[string] /* ERROR unexpected \) */ )
+	for {
+		x := 1
+		print(x)
+	}
+}