do not record function multiple times in topproto (#388)

internal/driver/driver_test.go

 		{"text,lines,cum,show=[12]00", "cpu"},
 		{"text,lines,cum,hide=line[X3]0,focus=[12]00", "cpu"},
 		{"topproto,lines,cum,hide=mangled[X3]0", "cpu"},
+		{"topproto,lines", "cpu"},
 		{"tree,lines,cum,focus=[24]00", "heap"},
 		{"tree,relative_percentages,cum,focus=[24]00", "heap"},
 		{"tree,lines,cum,show_from=line2", "cpu"},

internal/driver/testdata/pprof.cpu.lines.topproto

+Showing nodes accounting for 1s, 100% of 1s total
+      flat  flat%   sum%        cum   cum%
+        1s   100%   100%         1s   100%  mangled1000 testdata/file1000.src:1

internal/report/report.go

 	}
 	functionMap := make(functionMap)
 	for i, n := range g.Nodes {
-		f := functionMap.FindOrAdd(n.Info)
+		f, added := functionMap.findOrAdd(n.Info)
+		if added {
+			out.Function = append(out.Function, f)
+		}
 		flat, cum := n.FlatValue(), n.CumValue()
 		l := &profile.Location{
 			ID:      uint64(i + 1),
 			Location: []*profile.Location{l},
 			Value:    []int64{int64(cv), int64(fv)},
 		}
-		out.Function = append(out.Function, f)
 		out.Location = append(out.Location, l)
 		out.Sample = append(out.Sample, s)
 	}
 
 type functionMap map[string]*profile.Function
 
-func (fm functionMap) FindOrAdd(ni graph.NodeInfo) *profile.Function {
+// findOrAdd takes a node representing a function, adds the function
+// represented by the node to the map if the function is not already present,
+// and returns the function the node represents. This also returns a boolean,
+// which is true if the function was added and false otherwise.
+func (fm functionMap) findOrAdd(ni graph.NodeInfo) (*profile.Function, bool) {
 	fName := fmt.Sprintf("%q%q%q%d", ni.Name, ni.OrigName, ni.File, ni.StartLine)
 
 	if f := fm[fName]; f != nil {
-		return f
+		return f, false
 	}
 
 	f := &profile.Function{
 		StartLine:  int64(ni.StartLine),
 	}
 	fm[fName] = f
-	return f
+	return f, true
 }
 
 // printAssembly prints an annotated assembly listing.

internal/report/report_test.go

 		{Name: "fun2", File: "filename2"},
 	}
 
-	want := []profile.Function{
-		{ID: 1, Name: "fun1"},
-		{ID: 2, Name: "fun2", Filename: "filename"},
-		{ID: 1, Name: "fun1"},
-		{ID: 3, Name: "fun2", Filename: "filename2"},
+	want := []struct {
+		wantFunction profile.Function
+		wantAdded    bool
+	}{
+		{profile.Function{ID: 1, Name: "fun1"}, true},
+		{profile.Function{ID: 2, Name: "fun2", Filename: "filename"}, true},
+		{profile.Function{ID: 1, Name: "fun1"}, false},
+		{profile.Function{ID: 3, Name: "fun2", Filename: "filename2"}, true},
 	}
 
 	for i, tc := range nodes {
-		if got, want := fm.FindOrAdd(tc), want[i]; *got != want {
-			t.Errorf("%d: want %v, got %v", i, want, got)
+		gotFunc, gotAdded := fm.findOrAdd(tc)
+		if got, want := gotFunc, want[i].wantFunction; *got != want {
+			t.Errorf("%d: got %v, want %v", i, got, want)
+		}
+		if got, want := gotAdded, want[i].wantAdded; got != want {
+			t.Errorf("%d: got %v, want %v", i, got, want)
 		}
 	}
 }