cmd/cgo: use a plausible position for typedef error messages

Fixes #28069

Change-Id: I7e0f96b8b6d123de283325fcb78ec76455050f6d
Reviewed-on: https://go-review.googlesource.com/c/152158
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

2 files changed, 32 insertions, 1 deletions

diff --git a/misc/cgo/errors/errors_test.go b/misc/cgo/errors/errors_test.go
index 118187f23b..0d7ca4cf9d 100644
--- a/misc/cgo/errors/errors_test.go
+++ b/misc/cgo/errors/errors_test.go
@@ -126,7 +126,12 @@ func TestReportsTypeErrors(t *testing.T) {
 	}
 
 	if sizeofLongDouble(t) > 8 {
-		check(t, "err4.go")
+		for _, file := range []string{
+			"err4.go",
+			"issue28069.go",
+		} {
+			check(t, file)
+		}
 	}
 }
 
diff --git a/misc/cgo/errors/src/issue28069.go b/misc/cgo/errors/src/issue28069.go
new file mode 100644
index 0000000000..e19a3b45bd
--- /dev/null
+++ b/misc/cgo/errors/src/issue28069.go
@@ -0,0 +1,26 @@
+// 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 that the error message for an unrepresentable typedef in a
+// union appears on the right line. This test is only run if the size
+// of long double is larger than 64.
+
+package main
+
+/*
+typedef long double             Float128;
+
+typedef struct SV {
+    union {
+        Float128         float128;
+    } value;
+} SV;
+*/
+import "C"
+
+type ts struct {
+	tv *C.SV // ERROR HERE
+}
+
+func main() {}