cmd/link/internal/sym: add sizeof tests

CL 121916 showed that sym.Symbol matters for linker performance.
Prevent accidental regression.

Change-Id: I5fd998c91fdeef9e721bc3f6e30f775b81103e95
Reviewed-on: https://go-review.googlesource.com/122716
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/cmd/link/internal/sym/sizeof_test.go b/src/cmd/link/internal/sym/sizeof_test.go
new file mode 100644 (file)
index 0000000..2f2dfc7
--- /dev/null
+++ b/src/cmd/link/internal/sym/sizeof_test.go
@@ -0,0 +1,39 @@
+// 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.
+
+// +build !nacl
+
+package sym
+
+import (
+       "reflect"
+       "testing"
+       "unsafe"
+)
+
+// Assert that the size of important structures do not change unexpectedly.
+
+func TestSizeof(t *testing.T) {
+       const nbit = unsafe.Sizeof(uintptr(0)) * 8
+       const _64bit = nbit == 64
+
+       var tests = []struct {
+               val    interface{} // type as a value
+               _32bit uintptr     // size on 32bit platforms
+               _64bit uintptr     // size on 64bit platforms
+       }{
+               {Symbol{}, 132, 216},
+       }
+
+       for _, tt := range tests {
+               want := tt._32bit
+               if _64bit {
+                       want = tt._64bit
+               }
+               got := reflect.TypeOf(tt.val).Size()
+               if want != got {
+                       t.Errorf("%d bit unsafe.Sizeof(%T) = %d, want %d", nbit, tt.val, got, want)
+               }
+       }
+}