cmd/compile/internal/syntax: implement regression test harness for syntax errors

R=go1.11

Fixes #20800.

Change-Id: Ifea273521d42a543a43da2f655ace7c295650e30
Reviewed-on: https://go-review.googlesource.com/88335
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/syntax/testdata/sample.src b/src/cmd/compile/internal/syntax/testdata/sample.src
new file mode 100644
index 0000000000..5a2b4bf0c4
--- /dev/null
+++ b/src/cmd/compile/internal/syntax/testdata/sample.src
@@ -0,0 +1,33 @@
+// 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.
+
+// This is a sample test file illustrating the use
+// of error comments with the error test harness.
+
+package p
+
+// The following are invalid error comments; they are
+// silently ignored. The prefix must be exactly one of
+// "/* ERROR " or "// ERROR ".
+//
+/*ERROR*/
+/*ERROR foo*/
+/* ERRORfoo */
+/*  ERROR foo */
+//ERROR
+// ERROR
+// ERRORfoo
+//  ERROR foo
+
+// This is a valid error comment; it applies to the
+// immediately following token. 
+import "math" /* ERROR unexpected comma */ ,
+
+// If there are multiple /*-style error comments before
+// the next token, only the last one is considered.
+type x = /* ERROR ignored */ /* ERROR literal 0 in type declaration */ 0
+
+// A //-style error comment matches any error position
+// on the same line.
+func () foo() // ERROR method has no receiver