all: use io.{SeekStart, SeekCurrent, SeekEnd}

Currently we include these symbols in bootstrap code.

Change-Id: I19b504237b0344f0e87cda0fbe651811c72daba1
GitHub-Last-Rev: 5134baec387659c5e2ca8c4fc65a5e73c07f00ce
GitHub-Pull-Request: golang/go#62368
Reviewed-on: https://go-review.googlesource.com/c/go/+/524258
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: qiulaidongfeng <2645477756@qq.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

4 files changed, 5 insertions, 8 deletions

diff --git a/src/debug/pe/file.go b/src/debug/pe/file.go
index 06c160105f..e7be4ef1a0 100644
--- a/src/debug/pe/file.go
+++ b/src/debug/pe/file.go
@@ -27,9 +27,6 @@ import (
 	"strings"
 )
 
-// Avoid use of post-Go 1.4 io features, to make safe for toolchain bootstrap.
-const seekStart = 0
-
 // A File represents an open PE file.
 type File struct {
 	FileHeader
@@ -92,7 +89,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 	} else {
 		base = int64(0)
 	}
-	sr.Seek(base, seekStart)
+	sr.Seek(base, io.SeekStart)
 	if err := binary.Read(sr, binary.LittleEndian, &f.FileHeader); err != nil {
 		return nil, err
 	}
@@ -129,7 +126,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 	}
 
 	// Seek past file header.
-	_, err = sr.Seek(base+int64(binary.Size(f.FileHeader)), seekStart)
+	_, err = sr.Seek(base+int64(binary.Size(f.FileHeader)), io.SeekStart)
 	if err != nil {
 		return nil, err
 	}
diff --git a/src/debug/pe/section.go b/src/debug/pe/section.go
index 70d0c220ce..bab067e06b 100644
--- a/src/debug/pe/section.go
+++ b/src/debug/pe/section.go
@@ -54,7 +54,7 @@ func readRelocs(sh *SectionHeader, r io.ReadSeeker) ([]Reloc, error) {
 	if sh.NumberOfRelocations <= 0 {
 		return nil, nil
 	}
-	_, err := r.Seek(int64(sh.PointerToRelocations), seekStart)
+	_, err := r.Seek(int64(sh.PointerToRelocations), io.SeekStart)
 	if err != nil {
 		return nil, fmt.Errorf("fail to seek to %q section relocations: %v", sh.Name, err)
 	}
diff --git a/src/debug/pe/string.go b/src/debug/pe/string.go
index a156bbef05..6cd08aed71 100644
--- a/src/debug/pe/string.go
+++ b/src/debug/pe/string.go
@@ -31,7 +31,7 @@ func readStringTable(fh *FileHeader, r io.ReadSeeker) (StringTable, error) {
 		return nil, nil
 	}
 	offset := fh.PointerToSymbolTable + COFFSymbolSize*fh.NumberOfSymbols
-	_, err := r.Seek(int64(offset), seekStart)
+	_, err := r.Seek(int64(offset), io.SeekStart)
 	if err != nil {
 		return nil, fmt.Errorf("fail to seek to string table: %v", err)
 	}
diff --git a/src/debug/pe/symbol.go b/src/debug/pe/symbol.go
index 2e03af76bd..02f24ec29d 100644
--- a/src/debug/pe/symbol.go
+++ b/src/debug/pe/symbol.go
@@ -55,7 +55,7 @@ func readCOFFSymbols(fh *FileHeader, r io.ReadSeeker) ([]COFFSymbol, error) {
 	if fh.NumberOfSymbols <= 0 {
 		return nil, nil
 	}
-	_, err := r.Seek(int64(fh.PointerToSymbolTable), seekStart)
+	_, err := r.Seek(int64(fh.PointerToSymbolTable), io.SeekStart)
 	if err != nil {
 		return nil, fmt.Errorf("fail to seek to symbol table: %v", err)
 	}