cmd/internal/goobj2: add referenced symbol names to object file

Currently, for symbols defined in other packages and referenced
by index, we don't record its name in the object file, as the
linker doesn't need the name, only the index. As a consequence,
tools like objdump and nm also don't know the referenced symbol
names and cannot dump it properly.

This CL adds referenced symbol names to the object file. So the
object file is self-contained. And tools can retrieve referenced
symbol names properly.

Tools now should work as good for new object files as for old
object files.

Fixes #38875.

Change-Id: I16c685c1fd83273ab1faef474e19acf4af46396f
Reviewed-on: https://go-review.googlesource.com/c/go/+/236168
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/cmd/link/internal/loader/loader.go b/src/cmd/link/internal/loader/loader.go
index 8e6451d270..ab38bc3f5c 100644
--- a/src/cmd/link/internal/loader/loader.go
+++ b/src/cmd/link/internal/loader/loader.go
@@ -1914,7 +1914,7 @@ func (l *Loader) FuncInfo(i Sym) FuncInfo {
 // Does not read symbol data.
 // Returns the fingerprint of the object.
 func (l *Loader) Preload(syms *sym.Symbols, f *bio.Reader, lib *sym.Library, unit *sym.CompilationUnit, length int64) goobj2.FingerprintType {
-	roObject, readonly, err := f.Slice(uint64(length))
+	roObject, readonly, err := f.Slice(uint64(length)) // TODO: no need to map blocks that are for tools only (e.g. RefName)
 	if err != nil {
 		log.Fatal("cannot read object file:", err)
 	}