From c23c0f7c1458cee72ea4ba0967f264739579d533 Mon Sep 17 00:00:00 2001
From: greatroar <61184462+greatroar@users.noreply.github.com>
Date: Thu, 31 Mar 2022 22:30:45 +0200
Subject: [PATCH] Cast unix.Statfs_t.Type to int64 when checking for btrfs

Fixes #3687. Uses the cast suggested by @MichaelEischer, except that the
contant isn't cast along, because it's untyped and will be converted by
the compiler as necessary.
---
 internal/fs/setflags_linux_test.go | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/internal/fs/setflags_linux_test.go b/internal/fs/setflags_linux_test.go
index 7818146ac..089b7c615 100644
--- a/internal/fs/setflags_linux_test.go
+++ b/internal/fs/setflags_linux_test.go
@@ -59,9 +59,13 @@ func supportsNoatime(t *testing.T, f *os.File) bool {
 	err := unix.Fstatfs(int(f.Fd()), &fsinfo)
 	rtest.OK(t, err)
 
-	return fsinfo.Type == unix.BTRFS_SUPER_MAGIC ||
-		fsinfo.Type == unix.EXT2_SUPER_MAGIC ||
-		fsinfo.Type == unix.EXT3_SUPER_MAGIC ||
-		fsinfo.Type == unix.EXT4_SUPER_MAGIC ||
-		fsinfo.Type == unix.TMPFS_MAGIC
+	// The funky cast works around a compiler error on 32-bit archs:
+	// "unix.BTRFS_SUPER_MAGIC (untyped int constant 2435016766) overflows int32".
+	// https://github.com/golang/go/issues/52061
+	typ := int64(uint(fsinfo.Type))
+	return typ == unix.BTRFS_SUPER_MAGIC ||
+		typ == unix.EXT2_SUPER_MAGIC ||
+		typ == unix.EXT3_SUPER_MAGIC ||
+		typ == unix.EXT4_SUPER_MAGIC ||
+		typ == unix.TMPFS_MAGIC
 }