Fix various issues detected by megacheck (#880)

* Fix various issues detected by megacheck

I've ran honnef.co/go/tools/cmd/megacheck and fixed a few of the
things that came up there.

* Cleanup using Gogland

cmd/dlv/cmds/commands.go

@@ -404,7 +404,7 @@ func coreCmd(cmd *cobra.Command, args []string) {
 func connectCmd(cmd *cobra.Command, args []string) {
 	addr := args[0]
 	if addr == "" {
-		fmt.Fprintf(os.Stderr, "An empty address was provided. You must provide an address as the first argument.\n")
+		fmt.Fprint(os.Stderr, "An empty address was provided. You must provide an address as the first argument.\n")
 		os.Exit(1)
 	}
 	os.Exit(connect(addr, conf))
@@ -419,8 +419,7 @@ func splitArgs(cmd *cobra.Command, args []string) ([]string, []string) {
 
 func connect(addr string, conf *config.Config) int {
 	// Create and start a terminal - attach to running instance
-	var client service.Client
+	client := rpc2.NewClient(addr)
-	client = rpc2.NewClient(addr)
 	term := terminal.New(client, conf)
 	status, err := term.Run()
 	if err != nil {
@@ -447,7 +446,7 @@ func execute(attachPid int, processArgs []string, conf *config.Config, coreFile
 	defer listener.Close()
 
 	if Headless && (InitFile != "") {
-		fmt.Fprintf(os.Stderr, "Warning: init file ignored\n")
+		fmt.Fprint(os.Stderr, "Warning: init file ignored\n")
 	}
 
 	var server interface {
@@ -498,7 +497,7 @@ func execute(attachPid int, processArgs []string, conf *config.Config, coreFile
 	if Headless {
 		// Print listener address
 		fmt.Printf("API server listening at: %s\n", listener.Addr())
-		ch := make(chan os.Signal)
+		ch := make(chan os.Signal, 1)
 		signal.Notify(ch, syscall.SIGINT)
 		select {
 		case <-ch:
@@ -507,8 +506,7 @@ func execute(attachPid int, processArgs []string, conf *config.Config, coreFile
 		err = server.Stop(true)
 	} else {
 		// Create and start a terminal
-		var client service.Client
+		client := rpc2.NewClient(listener.Addr().String())
-		client = rpc2.NewClient(listener.Addr().String())
 		term := terminal.New(client, conf)
 		term.InitFile = InitFile
 		status, err = term.Run()

pkg/config/config.go

@@ -7,7 +7,7 @@ import (
 	"os/user"
 	"path"
 
-	yaml "gopkg.in/yaml.v2"
+	"gopkg.in/yaml.v2"
 )
 
 const (

pkg/dwarf/frame/entries.go

@@ -32,10 +32,7 @@ type FrameDescriptionEntry struct {
 // Returns whether or not the given address is within the
 // bounds of this frame.
 func (fde *FrameDescriptionEntry) Cover(addr uint64) bool {
-	if (addr - fde.begin) < fde.end {
+	return (addr - fde.begin) < fde.end
-		return true
-	}
-	return false
 }
 
 // Address of first location for this frame.

pkg/proc/disasm_amd64.go

@@ -33,7 +33,6 @@ func patchPCRel(pc uint64, inst *x86asm.Inst) {
 			inst.Args[i] = x86asm.Imm(int64(pc) + int64(rel) + int64(inst.Len))
 		}
 	}
-	return
 }
 
 func (inst *AsmInstruction) Text(flavour AssemblyFlavour) string {

pkg/proc/gdbserial/gdbserver.go

@@ -739,11 +739,7 @@ func (p *Process) Restart(pos string) error {
 		p.conn.setBreakpoint(addr)
 	}
 
-	if err := p.setCurrentBreakpoints(); err != nil {
+	return p.setCurrentBreakpoints()
-		return err
-	}
-
-	return nil
 }
 
 func (p *Process) When() (string, error) {
@@ -1274,7 +1270,7 @@ func (t *Thread) reloadGAtPC() error {
 	// around by clearing and re-setting the breakpoint in a specific sequence
 	// with the memory writes.
 	// Additionally all breakpoints in [pc, pc+len(movinstr)] need to be removed
-	for addr, _ := range t.p.breakpoints {
+	for addr := range t.p.breakpoints {
 		if addr >= pc && addr <= pc+uint64(len(movinstr)) {
 			err := t.p.conn.clearBreakpoint(addr)
 			if err != nil {

pkg/proc/gdbserial/gdbserver_conn.go

@@ -50,7 +50,6 @@ const (
 )
 
 var ErrTooManyAttempts = errors.New("too many transmit attempts")
-var ErrNoTargetDescrption = errors.New("target description not supported")
 
 // GdbProtocolError is an error response (Exx) of Gdb Remote Serial Protocol
 // or an "unsupported command" response (empty packet).
@@ -526,7 +525,7 @@ func (conn *gdbConn) resume(sig uint8, tu *threadUpdater) (string, uint8, error)
 	if conn.direction == proc.Forward {
 		conn.outbuf.Reset()
 		if sig == 0 {
-			fmt.Fprintf(&conn.outbuf, "$vCont;c")
+			fmt.Fprint(&conn.outbuf, "$vCont;c")
 		} else {
 			fmt.Fprintf(&conn.outbuf, "$vCont;C%02x", sig)
 		}
@@ -535,7 +534,7 @@ func (conn *gdbConn) resume(sig uint8, tu *threadUpdater) (string, uint8, error)
 			return "", 0, err
 		}
 		conn.outbuf.Reset()
-		fmt.Fprintf(&conn.outbuf, "$bc")
+		fmt.Fprint(&conn.outbuf, "$bc")
 	}
 	if err := conn.send(conn.outbuf.Bytes()); err != nil {
 		return "", 0, err
@@ -561,7 +560,7 @@ func (conn *gdbConn) step(threadID string, tu *threadUpdater) (string, uint8, er
 			return "", 0, err
 		}
 		conn.outbuf.Reset()
-		fmt.Fprintf(&conn.outbuf, "$bs")
+		fmt.Fprint(&conn.outbuf, "$bs")
 	}
 	if err := conn.send(conn.outbuf.Bytes()); err != nil {
 		return "", 0, err
@@ -698,7 +697,7 @@ func (conn *gdbConn) queryProcessInfo(pid int) (map[string]string, error) {
 	if pid != 0 {
 		fmt.Fprintf(&conn.outbuf, "$qProcessInfoPID:%d", pid)
 	} else {
-		fmt.Fprintf(&conn.outbuf, "$qProcessInfo")
+		fmt.Fprint(&conn.outbuf, "$qProcessInfo")
 	}
 	resp, err := conn.exec(conn.outbuf.Bytes(), "process info for pid")
 	if err != nil {
@@ -886,9 +885,9 @@ func (conn *gdbConn) threadStopInfo(threadID string) (sig uint8, reason string,
 // restart executes a 'vRun' command.
 func (conn *gdbConn) restart(pos string) error {
 	conn.outbuf.Reset()
-	fmt.Fprintf(&conn.outbuf, "$vRun;")
+	fmt.Fprint(&conn.outbuf, "$vRun;")
 	if pos != "" {
-		fmt.Fprintf(&conn.outbuf, ";")
+		fmt.Fprint(&conn.outbuf, ";")
 		writeAsciiBytes(&conn.outbuf, []byte(pos))
 	}
 	_, err := conn.exec(conn.outbuf.Bytes(), "restart")
@@ -901,9 +900,9 @@ func (conn *gdbConn) qRRCmd(args ...string) (string, error) {
 		panic("must specify at least one argument for qRRCmd")
 	}
 	conn.outbuf.Reset()
-	fmt.Fprintf(&conn.outbuf, "$qRRCmd")
+	fmt.Fprint(&conn.outbuf, "$qRRCmd")
 	for _, arg := range args {
-		fmt.Fprintf(&conn.outbuf, ":")
+		fmt.Fprint(&conn.outbuf, ":")
 		writeAsciiBytes(&conn.outbuf, []byte(arg))
 	}
 	resp, err := conn.exec(conn.outbuf.Bytes(), "qRRCmd")

pkg/proc/go_version.go

@@ -78,7 +78,7 @@ func ParseVersionString(ver string) (GoVersion, bool) {
 			r.Major, err1 = strconv.Atoi(v[0])
 			r.Minor, err2 = strconv.Atoi(v[1])
 			r.Rev, err3 = strconv.Atoi(v[2])
-			r.Proposal = v[3];
+			r.Proposal = v[3]
 			if err1 != nil || err2 != nil || err3 != nil || r.Proposal == "" {
 				return GoVersion{}, false
 			}

pkg/proc/native/threads.go

@@ -169,7 +169,7 @@ func (thread *Thread) clearBreakpointState() {
 }
 
 func (th *Thread) Breakpoint() (*proc.Breakpoint, bool, error) {
-	return th.CurrentBreakpoint, (th.CurrentBreakpoint != nil && th.BreakpointConditionMet), th.BreakpointConditionError
+	return th.CurrentBreakpoint, th.CurrentBreakpoint != nil && th.BreakpointConditionMet, th.BreakpointConditionError
 }
 
 func (th *Thread) ThreadID() int {

pkg/proc/proc.go

@@ -5,7 +5,6 @@ import (
 	"errors"
 	"fmt"
 	"go/ast"
-	"go/constant"
 	"go/token"
 	"path/filepath"
 	"strconv"
@@ -397,6 +396,9 @@ func GoroutinesInfo(dbp Process) ([]*G, error) {
 	}
 	faddr := make([]byte, dbp.BinInfo().Arch.PtrSize())
 	_, err = dbp.CurrentThread().ReadMemory(faddr, uintptr(allgentryaddr))
+	if err != nil {
+		return nil, err
+	}
 	allgptr := binary.LittleEndian.Uint64(faddr)
 
 	for i := uint64(0); i < allglen; i++ {
@@ -429,24 +431,6 @@ func GoroutinesInfo(dbp Process) ([]*G, error) {
 	return allg, nil
 }
 
-func GetGoVersion(p Process) (GoVersion, error) {
-	scope := &EvalScope{0, 0, p.CurrentThread(), nil, p.BinInfo(), 0}
-	vv, err := scope.packageVarAddr("runtime.buildVersion")
-	if err != nil {
-		return GoVersion{}, fmt.Errorf("could not determine version number: %v", err)
-	}
-	vv.loadValue(LoadConfig{true, 0, 64, 0, 0})
-	if vv.Unreadable != nil {
-		return GoVersion{}, fmt.Errorf("unreadable version number: %v\n", vv.Unreadable)
-	}
-
-	ver, ok := ParseVersionString(constant.StringVal(vv.Value))
-	if !ok {
-		return GoVersion{}, fmt.Errorf("could not parse version number: %v\n", vv.Value)
-	}
-	return ver, nil
-}
-
 // FindGoroutine returns a G struct representing the goroutine
 // specified by `gid`.
 func FindGoroutine(dbp Process, gid int) (*G, error) {

pkg/proc/proc_test.go

@@ -208,7 +208,7 @@ func setFileBreakpoint(p proc.Process, t *testing.T, fixture protest.Fixture, li
 }
 
 func TestHalt(t *testing.T) {
-	stopChan := make(chan interface{})
+	stopChan := make(chan interface{}, 1)
 	withTestProcess("loopprog", t, func(p proc.Process, fixture protest.Fixture) {
 		_, err := setFunctionBreakpoint(p, "main.loop")
 		assertNoError(err, t, "SetBreakpoint")
@@ -219,18 +219,20 @@ func TestHalt(t *testing.T) {
 				assertNoError(err, t, "Registers")
 			}
 		}
-		resumeChan := make(chan struct{})
+		resumeChan := make(chan struct{}, 1)
 		go func() {
 			<-resumeChan
 			time.Sleep(100 * time.Millisecond)
-			if err := p.RequestManualStop(); err != nil {
+			stopChan <- p.RequestManualStop()
-				t.Fatal(err)
-			}
-			stopChan <- nil
 		}()
 		p.ResumeNotify(resumeChan)
 		assertNoError(proc.Continue(p), t, "Continue")
-		<-stopChan
+		retVal := <-stopChan
+
+		if err, ok := retVal.(error); ok && err != nil {
+			t.Fatal()
+		}
+
 		// Loop through threads and make sure they are all
 		// actually stopped, err will not be nil if the process
 		// is still running.
@@ -870,7 +872,11 @@ func stackMatch(stack []loc, locations []proc.Stackframe, skipRuntime bool) bool
 
 func TestStacktraceGoroutine(t *testing.T) {
 	mainStack := []loc{{13, "main.stacktraceme"}, {26, "main.main"}}
-	agoroutineStacks := [][]loc{[]loc{{8, "main.agoroutine"}}, []loc{{9, "main.agoroutine"}}, []loc{{10, "main.agoroutine"}}}
+	agoroutineStacks := [][]loc{
+		{{8, "main.agoroutine"}},
+		{{9, "main.agoroutine"}},
+		{{10, "main.agoroutine"}},
+	}
 
 	protest.AllowRecording(t)
 	withTestProcess("goroutinestackprog", t, func(p proc.Process, fixture protest.Fixture) {
@@ -940,7 +946,7 @@ func TestKill(t *testing.T) {
 		if err := p.Kill(); err != nil {
 			t.Fatal(err)
 		}
-		if p.Exited() != true {
+		if !p.Exited() {
 			t.Fatal("expected process to have exited")
 		}
 		if runtime.GOOS == "linux" {
@@ -954,7 +960,7 @@ func TestKill(t *testing.T) {
 		if err := p.Detach(true); err != nil {
 			t.Fatal(err)
 		}
-		if p.Exited() != true {
+		if !p.Exited() {
 			t.Fatal("expected process to have exited")
 		}
 		if runtime.GOOS == "linux" {
@@ -1789,6 +1795,9 @@ func TestIssue332_Part2(t *testing.T) {
 		pcAfterPrologue, err := proc.FindFunctionLocation(p, "main.changeMe", true, -1)
 		assertNoError(err, t, "FindFunctionLocation()")
 		pcEntry, err := proc.FindFunctionLocation(p, "main.changeMe", false, 0)
+		if err != nil {
+			t.Fatalf("got error while finding function location: %v", err)
+		}
 		if pcAfterPrologue == pcEntry {
 			t.Fatalf("main.changeMe and main.changeMe:0 are the same (%x)", pcAfterPrologue)
 		}
@@ -1891,7 +1900,7 @@ func TestCmdLineArgs(t *testing.T) {
 			t.Fatalf("Process did not exit: %v", err)
 		} else {
 			if exit.Status != 0 {
-				t.Fatalf("process exited with invalid status", exit.Status)
+				t.Fatalf("process exited with invalid status %d", exit.Status)
 			}
 		}
 	}
@@ -2364,7 +2373,7 @@ func TestStepConcurrentPtr(t *testing.T) {
 
 			if oldk, ok := kvals[gid]; ok {
 				if oldk >= k {
-					t.Fatalf("Goroutine %d did not make progress?")
+					t.Fatalf("Goroutine %d did not make progress?", gid)
 				}
 			}
 			kvals[gid] = k
@@ -2752,7 +2761,7 @@ func TestStacktraceWithBarriers(t *testing.T) {
 			}
 
 			if !found {
-				t.Log("Truncated stacktrace for %d\n", goid)
+				t.Logf("Truncated stacktrace for %d\n", goid)
 			}
 		}
 	})
@@ -2824,7 +2833,7 @@ func TestAttachDetach(t *testing.T) {
 	assertNoError(err, t, "Page request after detach")
 	bs, err := ioutil.ReadAll(resp.Body)
 	assertNoError(err, t, "Reading /nobp page")
-	if out := string(bs); strings.Index(out, "hello, world!") < 0 {
+	if out := string(bs); !strings.Contains(out, "hello, world!") {
 		t.Fatalf("/nobp page does not contain \"hello, world!\": %q", out)
 	}
 

pkg/proc/proc_unix_test.go

@@ -3,6 +3,7 @@
 package proc_test
 
 import (
+	"fmt"
 	"runtime"
 	"syscall"
 	"testing"
@@ -12,6 +13,15 @@ import (
 	protest "github.com/derekparker/delve/pkg/proc/test"
 )
 
+type errIssue419 struct {
+	pid int
+	err error
+}
+
+func (npe errIssue419) Error() string {
+	return fmt.Sprintf("Pid is zero or negative: %d", npe.pid)
+}
+
 func TestIssue419(t *testing.T) {
 	if testBackend == "lldb" && runtime.GOOS == "darwin" {
 		// debugserver bug?
@@ -20,29 +30,43 @@ func TestIssue419(t *testing.T) {
 	if testBackend == "rr" {
 		return
 	}
+
+	errChan := make(chan error, 2)
+
 	// SIGINT directed at the inferior should be passed along not swallowed by delve
 	withTestProcess("issue419", t, func(p proc.Process, fixture protest.Fixture) {
+		defer close(errChan)
 		_, err := setFunctionBreakpoint(p, "main.main")
 		assertNoError(err, t, "SetBreakpoint()")
 		assertNoError(proc.Continue(p), t, "Continue()")
-		resumeChan := make(chan struct{})
+		resumeChan := make(chan struct{}, 1)
 		go func() {
 			time.Sleep(500 * time.Millisecond)
 			<-resumeChan
 			if p.Pid() <= 0 {
 				// if we don't stop the inferior the test will never finish
 				p.RequestManualStop()
-				p.Kill()
+				err := p.Kill()
-				t.Fatalf("Pid is zero or negative: %d", p.Pid())
+				errChan <- errIssue419{pid: p.Pid(), err: err}
 				return
 			}
 			err := syscall.Kill(p.Pid(), syscall.SIGINT)
-			assertNoError(err, t, "syscall.Kill")
+			errChan <- errIssue419{pid: p.Pid(), err: err}
 		}()
 		p.ResumeNotify(resumeChan)
-		err = proc.Continue(p)
+		errChan <- proc.Continue(p)
+	})
+
+	for i :=0; i<2; i++ {
+		err := <-errChan
+
+		if v, ok := err.(errIssue419); ok {
+			assertNoError(v.err, t, "syscall.Kill")
+			continue
+		}
+
 		if _, exited := err.(proc.ProcessExitedError); !exited {
 			t.Fatalf("Unexpected error after Continue(): %v\n", err)
 		}
-	})
+	}
 }

pkg/proc/variables.go

@@ -481,7 +481,7 @@ func (g *G) UserCurrent() Location {
 		frame := it.Frame()
 		if frame.Call.Fn != nil {
 			name := frame.Call.Fn.Name
-			if (strings.Index(name, ".") >= 0) && (!strings.HasPrefix(name, "runtime.") || isExportedRuntime(name)) {
+			if strings.Contains(name, ".") && (!strings.HasPrefix(name, "runtime.") || isExportedRuntime(name)) {
 				return frame.Call
 			}
 		}
@@ -712,7 +712,7 @@ func (v *Variable) structMember(memberName string) (*Variable, error) {
 				return nil, err
 			}
 			embeddedVar.Name = structVar.Name
-			embeddedField, err := embeddedVar.structMember(memberName)
+			embeddedField, _ := embeddedVar.structMember(memberName)
 			if embeddedField != nil {
 				return embeddedField, nil
 			}
@@ -1016,8 +1016,6 @@ func (v *Variable) loadSliceInfo(t *dwarf.SliceType) {
 	if t, ok := v.fieldType.(*dwarf.PtrType); ok {
 		v.stride = t.ByteSize
 	}
-
-	return
 }
 
 func (v *Variable) loadArrayValues(recurseLevel int, cfg LoadConfig) {
@@ -1652,7 +1650,6 @@ func (v *Variable) loadInterface(recurseLevel int, loadData bool, cfg LoadConfig
 	} else {
 		v.Children[0].OnlyAddr = true
 	}
-	return
 }
 
 // Fetches all variables of a specific type in the current function scope

pkg/terminal/command_test.go

@@ -369,7 +369,7 @@ func TestOnPrefix(t *testing.T) {
 		for {
 			outstr, err := term.Exec("continue")
 			if err != nil {
-				if strings.Index(err.Error(), "exited") < 0 {
+				if !strings.Contains(err.Error(), "exited") {
 					t.Fatalf("Unexpected error executing 'continue': %v", err)
 				}
 				break
@@ -422,7 +422,7 @@ func TestOnPrefixLocals(t *testing.T) {
 		for {
 			outstr, err := term.Exec("continue")
 			if err != nil {
-				if strings.Index(err.Error(), "exited") < 0 {
+				if !strings.Contains(err.Error(), "exited") {
 					t.Fatalf("Unexpected error executing 'continue': %v", err)
 				}
 				break
@@ -476,7 +476,7 @@ func TestIssue387(t *testing.T) {
 			breakpointHitCount += countOccourences(outstr, "issue387.go:8")
 			t.Log(outstr)
 			if err != nil {
-				if strings.Index(err.Error(), "exited") < 0 {
+				if !strings.Contains(err.Error(), "exited") {
 					t.Fatalf("Unexpected error executing 'continue': %v", err)
 				}
 				break
@@ -509,7 +509,7 @@ func listIsAt(t *testing.T, term *FakeTerminal, listcmd string, cur, start, end
 
 	t.Logf("%q: %q", listcmd, outstr)
 
-	if strings.Index(lines[0], fmt.Sprintf(":%d", cur)) < 0 {
+	if !strings.Contains(lines[0], fmt.Sprintf(":%d", cur)) {
 		t.Fatalf("Could not find current line number in first output line: %q", lines[0])
 	}
 

pkg/terminal/disasmprint.go

@@ -3,10 +3,11 @@ package terminal
 import (
 	"bufio"
 	"fmt"
-	"github.com/derekparker/delve/service/api"
 	"io"
 	"path/filepath"
 	"text/tabwriter"
+
+	"github.com/derekparker/delve/service/api"
 )
 
 func DisasmPrint(dv api.AsmInstructions, out io.Writer) {

pkg/terminal/docgen.go

@@ -27,10 +27,10 @@ func replaceDocPath(s string) string {
 }
 
 func (commands *Commands) WriteMarkdown(w io.Writer) {
-	fmt.Fprintf(w, "# Commands\n\n")
+	fmt.Fprint(w, "# Commands\n\n")
 
-	fmt.Fprintf(w, "Command | Description\n")
+	fmt.Fprint(w, "Command | Description\n")
-	fmt.Fprintf(w, "--------|------------\n")
+	fmt.Fprint(w, "--------|------------\n")
 	for _, cmd := range commands.cmds {
 		h := cmd.helpMsg
 		if idx := strings.Index(h, "\n"); idx >= 0 {
@@ -38,17 +38,17 @@ func (commands *Commands) WriteMarkdown(w io.Writer) {
 		}
 		fmt.Fprintf(w, "[%s](#%s) | %s\n", cmd.aliases[0], cmd.aliases[0], h)
 	}
-	fmt.Fprintf(w, "\n")
+	fmt.Fprint(w, "\n")
 
 	for _, cmd := range commands.cmds {
 		fmt.Fprintf(w, "## %s\n%s\n\n", cmd.aliases[0], replaceDocPath(cmd.helpMsg))
 		if len(cmd.aliases) > 1 {
-			fmt.Fprintf(w, "Aliases:")
+			fmt.Fprint(w, "Aliases:")
 			for _, alias := range cmd.aliases[1:] {
 				fmt.Fprintf(w, " %s", alias)
 			}
-			fmt.Fprintf(w, "\n")
+			fmt.Fprint(w, "\n")
 		}
-		fmt.Fprintf(w, "\n")
+		fmt.Fprint(w, "\n")
 	}
 }

service/api/conversions.go

@@ -276,5 +276,5 @@ func ConvertRegisters(in []proc.Register) (out []Register) {
 }
 
 func ConvertCheckpoint(in proc.Checkpoint) (out Checkpoint) {
-	return Checkpoint{ID: in.ID, When: in.When, Where: in.Where}
+	return Checkpoint(in)
 }

service/api/prettyprint.go

@@ -38,7 +38,7 @@ func (v *Variable) writeTo(buf io.Writer, top, newlines, includeType bool, inden
 		if includeType && v.Type != "void" {
 			fmt.Fprintf(buf, "%s nil", v.Type)
 		} else {
-			fmt.Fprintf(buf, "nil")
+			fmt.Fprint(buf, "nil")
 		}
 		return
 	}
@@ -50,11 +50,11 @@ func (v *Variable) writeTo(buf io.Writer, top, newlines, includeType bool, inden
 		v.writeArrayTo(buf, newlines, includeType, indent)
 	case reflect.Ptr:
 		if v.Type == "" {
-			fmt.Fprintf(buf, "nil")
+			fmt.Fprint(buf, "nil")
 		} else if v.Children[0].OnlyAddr && v.Children[0].Addr != 0 {
 			fmt.Fprintf(buf, "(%s)(0x%x)", v.Type, v.Children[0].Addr)
 		} else {
-			fmt.Fprintf(buf, "*")
+			fmt.Fprint(buf, "*")
 			v.Children[0].writeTo(buf, false, newlines, includeType, indent)
 		}
 	case reflect.UnsafePointer:
@@ -78,7 +78,7 @@ func (v *Variable) writeTo(buf io.Writer, top, newlines, includeType bool, inden
 			if v.Children[0].Kind == reflect.Invalid {
 				fmt.Fprintf(buf, "%s ", v.Type)
 				if v.Children[0].Addr == 0 {
-					fmt.Fprintf(buf, "nil")
+					fmt.Fprint(buf, "nil")
 					return
 				}
 			} else {
@@ -88,9 +88,9 @@ func (v *Variable) writeTo(buf io.Writer, top, newlines, includeType bool, inden
 		data := v.Children[0]
 		if data.Kind == reflect.Ptr {
 			if len(data.Children) == 0 {
-				fmt.Fprintf(buf, "...")
+				fmt.Fprint(buf, "...")
 			} else if data.Children[0].Addr == 0 {
-				fmt.Fprintf(buf, "nil")
+				fmt.Fprint(buf, "nil")
 			} else if data.Children[0].OnlyAddr {
 				fmt.Fprintf(buf, "0x%x", v.Children[0].Addr)
 			} else {
@@ -103,7 +103,7 @@ func (v *Variable) writeTo(buf io.Writer, top, newlines, includeType bool, inden
 		v.writeMapTo(buf, newlines, includeType, indent)
 	case reflect.Func:
 		if v.Value == "" {
-			fmt.Fprintf(buf, "nil")
+			fmt.Fprint(buf, "nil")
 		} else {
 			fmt.Fprintf(buf, "%s", v.Value)
 		}
@@ -152,7 +152,7 @@ func (v *Variable) writeStructTo(buf io.Writer, newlines, includeType bool, inde
 
 	nl := v.shouldNewlineStruct(newlines)
 
-	fmt.Fprintf(buf, "{")
+	fmt.Fprint(buf, "{")
 
 	for i := range v.Children {
 		if nl {
@@ -161,9 +161,9 @@ func (v *Variable) writeStructTo(buf io.Writer, newlines, includeType bool, inde
 		fmt.Fprintf(buf, "%s: ", v.Children[i].Name)
 		v.Children[i].writeTo(buf, false, nl, true, indent+indentString)
 		if i != len(v.Children)-1 || nl {
-			fmt.Fprintf(buf, ",")
+			fmt.Fprint(buf, ",")
 			if !nl {
-				fmt.Fprintf(buf, " ")
+				fmt.Fprint(buf, " ")
 			}
 		}
 	}
@@ -172,12 +172,12 @@ func (v *Variable) writeStructTo(buf io.Writer, newlines, includeType bool, inde
 		if nl {
 			fmt.Fprintf(buf, "\n%s%s", indent, indentString)
 		} else {
-			fmt.Fprintf(buf, ",")
+			fmt.Fprint(buf, ",")
 		}
 		fmt.Fprintf(buf, "...+%d more", int(v.Len)-len(v.Children))
 	}
 
-	fmt.Fprintf(buf, "}")
+	fmt.Fprint(buf, "}")
 }
 
 func (v *Variable) writeMapTo(buf io.Writer, newlines, includeType bool, indent string) {
@@ -187,7 +187,7 @@ func (v *Variable) writeMapTo(buf io.Writer, newlines, includeType bool, indent
 
 	nl := newlines && (len(v.Children) > 0)
 
-	fmt.Fprintf(buf, "[")
+	fmt.Fprint(buf, "[")
 
 	for i := 0; i < len(v.Children); i += 2 {
 		key := &v.Children[i]
@@ -198,10 +198,10 @@ func (v *Variable) writeMapTo(buf io.Writer, newlines, includeType bool, indent
 		}
 
 		key.writeTo(buf, false, false, false, indent+indentString)
-		fmt.Fprintf(buf, ": ")
+		fmt.Fprint(buf, ": ")
 		value.writeTo(buf, false, nl, false, indent+indentString)
 		if i != len(v.Children)-1 || nl {
-			fmt.Fprintf(buf, ", ")
+			fmt.Fprint(buf, ", ")
 		}
 	}
 
@@ -210,18 +210,18 @@ func (v *Variable) writeMapTo(buf io.Writer, newlines, includeType bool, indent
 			if nl {
 				fmt.Fprintf(buf, "\n%s%s", indent, indentString)
 			} else {
-				fmt.Fprintf(buf, ",")
+				fmt.Fprint(buf, ",")
 			}
 			fmt.Fprintf(buf, "...+%d more", int(v.Len)-(len(v.Children)/2))
 		} else {
-			fmt.Fprintf(buf, "...")
+			fmt.Fprint(buf, "...")
 		}
 	}
 
 	if nl {
 		fmt.Fprintf(buf, "\n%s", indent)
 	}
-	fmt.Fprintf(buf, "]")
+	fmt.Fprint(buf, "]")
 }
 
 func (v *Variable) shouldNewlineArray(newlines bool) bool {
@@ -290,7 +290,7 @@ func (v *Variable) shouldNewlineStruct(newlines bool) bool {
 
 func (v *Variable) writeSliceOrArrayTo(buf io.Writer, newlines bool, indent string) {
 	nl := v.shouldNewlineArray(newlines)
-	fmt.Fprintf(buf, "[")
+	fmt.Fprint(buf, "[")
 
 	for i := range v.Children {
 		if nl {
@@ -298,7 +298,7 @@ func (v *Variable) writeSliceOrArrayTo(buf io.Writer, newlines bool, indent stri
 		}
 		v.Children[i].writeTo(buf, false, nl, false, indent+indentString)
 		if i != len(v.Children)-1 || nl {
-			fmt.Fprintf(buf, ",")
+			fmt.Fprint(buf, ",")
 		}
 	}
 
@@ -307,11 +307,11 @@ func (v *Variable) writeSliceOrArrayTo(buf io.Writer, newlines bool, indent stri
 			if nl {
 				fmt.Fprintf(buf, "\n%s%s", indent, indentString)
 			} else {
-				fmt.Fprintf(buf, ",")
+				fmt.Fprint(buf, ",")
 			}
 			fmt.Fprintf(buf, "...+%d more", int(v.Len)-len(v.Children))
 		} else {
-			fmt.Fprintf(buf, "...")
+			fmt.Fprint(buf, "...")
 		}
 	}
 
@@ -319,5 +319,5 @@ func (v *Variable) writeSliceOrArrayTo(buf io.Writer, newlines bool, indent stri
 		fmt.Fprintf(buf, "\n%s", indent)
 	}
 
-	fmt.Fprintf(buf, "]")
+	fmt.Fprint(buf, "]")
 }

service/debugger/debugger_linux.go

@@ -2,10 +2,11 @@ package debugger
 
 import (
 	"fmt"
-	sys "golang.org/x/sys/unix"
 	"io/ioutil"
 	"os"
 	"syscall"
+
+	sys "golang.org/x/sys/unix"
 )
 
 func attachErrorMessage(pid int, err error) error {

service/debugger/locations.go

@@ -178,7 +178,7 @@ func parseFuncLocationSpec(in string) *FuncLocationSpec {
 		r := stripReceiverDecoration(v[0])
 		if r != v[0] {
 			spec.ReceiverName = r
-		} else if strings.Index(r, "/") >= 0 {
+		} else if strings.Contains(r, "/") {
 			spec.PackageName = r
 		} else {
 			spec.PackageOrReceiverName = r
@@ -198,7 +198,7 @@ func parseFuncLocationSpec(in string) *FuncLocationSpec {
 		spec.AbsolutePackage = true
 	}
 
-	if strings.Index(spec.BaseName, "/") >= 0 || strings.Index(spec.ReceiverName, "/") >= 0 {
+	if strings.Contains(spec.BaseName, "/") || strings.Contains(spec.ReceiverName, "/") {
 		return nil
 	}
 

service/rpc1/client.go

@@ -15,7 +15,6 @@ import (
 // Client is a RPC service.Client.
 type RPCClient struct {
 	addr       string
-	processPid int
 	client     *rpc.Client
 	haltMu     sync.Mutex
 	haltReq    bool
@@ -303,10 +302,6 @@ func (c *RPCClient) DisassemblePC(scope api.EvalScope, pc uint64, flavour api.As
 	return r, err
 }
 
-func (c *RPCClient) url(path string) string {
-	return fmt.Sprintf("http://%s%s", c.addr, path)
-}
-
 func (c *RPCClient) call(method string, args, reply interface{}) error {
 	return c.client.Call("RPCServer."+method, args, reply)
 }

service/rpc2/client.go

@@ -14,7 +14,6 @@ import (
 // Client is a RPC service.Client.
 type RPCClient struct {
 	addr       string
-	processPid int
 	client     *rpc.Client
 }
 
@@ -349,10 +348,6 @@ func (c *RPCClient) ClearCheckpoint(id int) error {
 	return err
 }
 
-func (c *RPCClient) url(path string) string {
-	return fmt.Sprintf("http://%s%s", c.addr, path)
-}
-
 func (c *RPCClient) call(method string, args, reply interface{}) error {
 	return c.client.Call("RPCServer."+method, args, reply)
 }

service/rpc2/server.go

@@ -109,7 +109,6 @@ func (s *RPCServer) Command(command api.DebuggerCommand, cb service.RPCCallback)
 	var out CommandOut
 	out.State = *st
 	cb.Return(out, nil)
-	return
 }
 
 type GetBreakpointIn struct {

service/rpccommon/server.go

@@ -244,7 +244,6 @@ func suitableMethods(rcvr interface{}, methods map[string]*methodType) {
 		}
 		methods[sname+"."+mname] = &methodType{method: method, ArgType: argType, ReplyType: replyType, Synchronous: synchronous, Rcvr: rcvrv}
 	}
-	return
 }
 
 func (s *ServerImpl) serveJSONCodec(conn io.ReadWriteCloser) {

service/test/common_test.go

@@ -26,7 +26,7 @@ func assertError(err error, t *testing.T, s string) {
 		t.Fatalf("failed assertion at %s:%d: %s (no error)\n", fname, line, s)
 	}
 
-	if strings.Index(err.Error(), "Internal debugger error") >= 0 {
+	if strings.Contains(err.Error(), "Internal debugger error") {
 		_, file, line, _ := runtime.Caller(1)
 		fname := filepath.Base(file)
 		t.Fatalf("failed assertion at %s:%d: %s internal debugger error: %v\n", fname, line, s, err)

service/test/integration1_test.go

@@ -172,7 +172,7 @@ func Test1ClientServer_exit(t *testing.T) {
 		if !state.Exited {
 			t.Fatalf("Expected exit after continue: %v", state)
 		}
-		state, err = c.GetState()
+		_, err = c.GetState()
 		if err == nil {
 			t.Fatal("Expected error on querying state from exited process")
 		}
@@ -699,6 +699,9 @@ func Test1ClientServer_SetVariable(t *testing.T) {
 		assertNoError(c.SetVariable(api.EvalScope{-1, 0}, "a2", "8"), t, "SetVariable()")
 
 		a2, err := c.EvalVariable(api.EvalScope{-1, 0}, "a2")
+		if err != nil {
+			t.Fatalf("Could not evaluate variable: %v", err)
+		}
 
 		t.Logf("a2: %v", a2)
 
@@ -737,7 +740,7 @@ func Test1ClientServer_FullStacktrace(t *testing.T) {
 					if arg.Name != "i" {
 						continue
 					}
-					t.Logf("frame %d, variable i is %v\n", arg)
+					t.Logf("frame %d, variable i is %v\n", i,  arg)
 					argn, err := strconv.Atoi(arg.Value)
 					if err == nil {
 						found[argn] = true

service/test/integration2_test.go

@@ -196,7 +196,7 @@ func TestClientServer_exit(t *testing.T) {
 		if !state.Exited {
 			t.Fatalf("Expected exit after continue: %v", state)
 		}
-		state, err = c.GetState()
+		_, err = c.GetState()
 		if err == nil {
 			t.Fatal("Expected error on querying state from exited process")
 		}
@@ -762,6 +762,9 @@ func TestClientServer_SetVariable(t *testing.T) {
 		assertNoError(c.SetVariable(api.EvalScope{-1, 0}, "a2", "8"), t, "SetVariable()")
 
 		a2, err := c.EvalVariable(api.EvalScope{-1, 0}, "a2", normalLoadConfig)
+		if err != nil {
+			t.Fatalf("Could not evaluate variable: %v", err)
+		}
 
 		t.Logf("a2: %v", a2)
 

service/test/variables_test.go

@@ -83,6 +83,10 @@ func evalVariable(p proc.Process, symbol string, cfg proc.LoadConfig) (*proc.Var
 		scope, err = proc.GoroutineScope(p.CurrentThread())
 	}
 
+	if err != nil {
+		return nil, err
+	}
+
 	return scope.EvalVariable(symbol, cfg)
 }
 
@@ -100,8 +104,6 @@ func setVariable(p proc.Process, symbol, value string) error {
 	return scope.SetVariable(symbol, value)
 }
 
-const varTestBreakpointLineNumber = 59
-
 func withTestProcess(name string, t *testing.T, fn func(p proc.Process, fixture protest.Fixture)) {
 	fixture := protest.BuildFixture(name)
 	var p proc.Process