cmd: fixed certain vet warnings

Updates #11041

Change-Id: I7f2583d08f344d6622027c5e8a5de1f5d2f2881c
Reviewed-on: https://go-review.googlesource.com/23082
Reviewed-by: Brad Fitzpatrick <[email protected]>
Run-TryBot: Brad Fitzpatrick <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>

Author: valyala

src/cmd/cover/cover.go

@@ -388,7 +388,7 @@ func trimComments(file *ast.File, fset *token.FileSet) []*ast.CommentGroup {
 			}
 		}
 		if list != nil {
-			comments = append(comments, &ast.CommentGroup{list})
+			comments = append(comments, &ast.CommentGroup{List: list})
 		}
 	}
 	return comments

src/cmd/dist/test.go

@@ -699,7 +699,7 @@ func (t *tester) supportedBuildmode(mode string) bool {
 		}
 		return false
 	default:
-		log.Fatal("internal error: unknown buildmode %s", mode)
+		log.Fatalf("internal error: unknown buildmode %s", mode)
 		return false
 	}
 }

src/cmd/internal/pprof/report/report.go

@@ -205,7 +205,9 @@ func nodesPerSymbol(ns nodes, symbols []*objSymbol) map[*objSymbol]nodes {
 // offset to adjust the sample addresses.
 func annotateAssembly(insns []plugin.Inst, samples nodes, base uint64) nodes {
 	// Add end marker to simplify printing loop.
-	insns = append(insns, plugin.Inst{^uint64(0), "", "", 0})
+	insns = append(insns, plugin.Inst{
+		Addr: ^uint64(0),
+	})
 
 	// Ensure samples are sorted by address.
 	samples.sort(addressOrder)

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

@@ -538,7 +538,7 @@ func (r *objReader) readSymName() string {
 		origName = make([]byte, n)
 		r.readFull(origName)
 	} else if err != nil {
-		log.Fatalf("%s: error reading symbol: %v", err)
+		log.Fatalf("%s: error reading symbol: %v", r.pn, err)
 	}
 	adjName := r.rdBuf[:0]
 	for {