Revert "cmd/link: skip symbol references when looking for missing symbols"

This reverts commit 8adc1e00.

Reason for revert: The test added in this commit fails on several
builders.

Fixes #36389. Re-opens #33979.

Change-Id: I31191098c36af00f7688749b3376686673b3ac68
Reviewed-on: https://go-review.googlesource.com/c/go/+/213417
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alberto Donizetti <alb.donizetti@gmail.com>

src/cmd/link/internal/ld/link.go

@@ -136,7 +136,7 @@ func (ctxt *Link) ErrorUnresolved(s *sym.Symbol, r *sym.Reloc) {
 				if v == -1 {
 					continue
 				}
-				if rs := ctxt.Syms.ROLookup(r.Sym.Name, v); rs != nil && rs.Type != sym.Sxxx && rs.Type != sym.SXREF {
+				if rs := ctxt.Syms.ROLookup(r.Sym.Name, v); rs != nil && rs.Type != sym.Sxxx {
 					haveABI = abi
 				}
 			}

src/cmd/link/link_test.go

@@ -172,85 +172,6 @@ main.x: relocation target main.zero not defined
 	}
 }
 
-func TestIssue33979(t *testing.T) {
-	testenv.MustHaveGoBuild(t)
-	testenv.MustHaveCGO(t)
-
-	tmpdir, err := ioutil.TempDir("", "unresolved-")
-	if err != nil {
-		t.Fatalf("failed to create temp dir: %v", err)
-	}
-	defer os.RemoveAll(tmpdir)
-
-	write := func(name, content string) {
-		err := ioutil.WriteFile(filepath.Join(tmpdir, name), []byte(content), 0666)
-		if err != nil {
-			t.Fatal(err)
-		}
-	}
-
-	run := func(name string, args ...string) string {
-		cmd := exec.Command(name, args...)
-		cmd.Dir = tmpdir
-		out, err := cmd.CombinedOutput()
-		if err != nil {
-			t.Fatalf("'go %s' failed: %v, output: %s", strings.Join(args, " "), err, out)
-		}
-		return string(out)
-	}
-	runGo := func(args ...string) string {
-		return run(testenv.GoToolPath(t), args...)
-	}
-
-	// Test object with undefined reference that was not generated
-	// by Go, resulting in an SXREF symbol being loaded during linking.
-	// Because of issue #33979, the SXREF symbol would be found during
-	// error reporting, resulting in confusing error messages.
-
-	write("main.go", `package main
-func main() {
-        x()
-}
-func x()
-`)
-	// The following assembly must work on all architectures.
-	write("x.s", `
-TEXT ·x(SB),0,$0
-        CALL foo(SB)
-        RET
-`)
-	write("x.c", `
-void undefined();
-
-void foo() {
-        undefined();
-}
-`)
-
-	cc := strings.TrimSpace(runGo("env", "CC"))
-	cflags := strings.Fields(runGo("env", "GOGCCFLAGS"))
-
-	// Compile, assemble and pack the Go and C code.
-	runGo("tool", "asm", "-gensymabis", "-o", "symabis", "x.s")
-	runGo("tool", "compile", "-symabis", "symabis", "-p", "main", "-o", "x1.o", "main.go")
-	runGo("tool", "asm", "-o", "x2.o", "x.s")
-	run(cc, append(cflags, "-c", "-o", "x3.o", "x.c")...)
-	runGo("tool", "pack", "c", "x.a", "x1.o", "x2.o", "x3.o")
-
-	// Now attempt to link using the internal linker.
-	cmd := exec.Command(testenv.GoToolPath(t), "tool", "link", "-linkmode=internal", "x.a")
-	cmd.Dir = tmpdir
-	out, err := cmd.CombinedOutput()
-	if err == nil {
-		t.Fatalf("expected link to fail, but it succeeded")
-	}
-	got := string(out)
-	want := "main(.text): relocation target undefined not defined\n"
-	if !strings.Contains(got, want) {
-		t.Fatalf("got:\n%swant:\n%s", got, want)
-	}
-}
-
 func TestBuildForTvOS(t *testing.T) {
 	testenv.MustHaveCGO(t)
 	testenv.MustHaveGoBuild(t)