io: make clear that EOF should not be wrapped

For #40827. Change-Id: Ifd108421abd8d0988dd7b985e4f9e2bd5356964a Reviewed-on: https://go-review.googlesource.com/c/go/+/258524 Trust: Russ Cox <[email protected]> Reviewed-by: Rob Pike <[email protected]>
cloudflare · Oct 1, 2020 · 9b1518a · 9b1518a
1 parent b8ec1d5
commit 9b1518a
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/src/io/io.go b/src/io/io.go
@@ -31,6 +31,8 @@ var ErrShortWrite = errors.New("short write")
 var ErrShortBuffer = errors.New("short buffer")
 
 // EOF is the error returned by Read when no more input is available.
+// (Read must return EOF itself, not an error wrapping EOF,
+// because callers will test for EOF using ==.)
 // Functions should return EOF only to signal a graceful end of input.
 // If the EOF occurs unexpectedly in a structured data stream,
 // the appropriate error is either ErrUnexpectedEOF or some other error