internal/lsp: change generated variable names to be more verbose

If new functions or variables need to be created during an extract
call, then we choose the new names. This change makes those names
more descriptive to make the generated names easier to read and
understand.

Before:
cond0, ret0 := fn0()
if cond0 {
    return ret0
}

After
shouldReturn, returnValue := newFunction()
if shouldReturn {
    return returnValue
}

Change-Id: I44795dc45185c75d5bf65e48378aa54d6c156212
Reviewed-on: https://go-review.googlesource.com/c/tools/+/326112
Trust: Suzy Mueller <[email protected]>
Run-TryBot: Suzy Mueller <[email protected]>
gopls-CI: kokoro <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Rebecca Stambler <[email protected]>

Author: suzmue

internal/lsp/source/extract.go

@@ -139,7 +139,10 @@ func calculateIndentation(content []byte, tok *token.File, insertBeforeStmt ast.
 // Possible collisions include other function and variable names. Returns the next index to check for prefix.
 func generateAvailableIdentifier(pos token.Pos, file *ast.File, path []ast.Node, info *types.Info, prefix string, idx int) (string, int) {
 	scopes := CollectScopes(info, path, pos)
-	name := prefix + fmt.Sprintf("%d", idx)
+	name := prefix
+	if idx != 0 {
+		name += fmt.Sprintf("%d", idx)
+	}
 	for file.Scope.Lookup(name) != nil || !isValidName(name, scopes) {
 		idx++
 		name = fmt.Sprintf("%v%d", prefix, idx)
@@ -468,7 +471,7 @@ func extractFunction(fset *token.FileSet, rng span.Range, src []byte, file *ast.
 	if canDefine {
 		sym = token.DEFINE
 	}
-	funName, _ := generateAvailableIdentifier(rng.Start, file, path, info, "fn", 0)
+	funName, _ := generateAvailableIdentifier(rng.Start, file, path, info, "newFunction", 0)
 	extractedFunCall := generateFuncCall(hasNonNestedReturn, hasReturnValues, params,
 		append(returns, getNames(retVars)...), funName, sym)
 
@@ -999,7 +1002,7 @@ func generateReturnInfo(enclosing *ast.FuncType, pkg *types.Package, path []ast.
 	var cond *ast.Ident
 	if !hasNonNestedReturns {
 		// Generate information for the added bool value.
-		name, _ := generateAvailableIdentifier(pos, file, path, info, "cond", 0)
+		name, _ := generateAvailableIdentifier(pos, file, path, info, "shouldReturn", 0)
 		cond = &ast.Ident{Name: name}
 		retVars = append(retVars, &returnVariable{
 			name:    cond,
@@ -1022,7 +1025,7 @@ func generateReturnInfo(enclosing *ast.FuncType, pkg *types.Package, path []ast.
 			}
 			var name string
 			name, idx = generateAvailableIdentifier(pos, file,
-				path, info, "ret", idx)
+				path, info, "returnValue", idx)
 			retVars = append(retVars, &returnVariable{
 				name: ast.NewIdent(name),
 				decl: &ast.Field{Type: expr},

internal/lsp/testdata/extract/extract_function/extract_args_returns.go.golden

@@ -4,14 +4,14 @@ package extract
 func _() {
 	a := 1
 	//@mark(exSt0, "a")
-	a = fn0(a) //@mark(exEn0, "2")
+	a = newFunction(a) //@mark(exEn0, "2")
 	//@extractfunc(exSt0, exEn0)
 	b := a * 2 //@mark(exB, "	b")
 	_ = 3 + 4  //@mark(exEnd, "4")
 	//@extractfunc(exB, exEnd)
 }
 
-func fn0(a int) int {
+func newFunction(a int) int {
 	a = 5
 	a = a + 2
 	return a
@@ -26,11 +26,11 @@ func _() {
 	a = a + 2 //@mark(exEn0, "2")
 	//@extractfunc(exSt0, exEn0)
 	//@mark(exB, "	b")
-	fn0(a)  //@mark(exEnd, "4")
+	newFunction(a)  //@mark(exEnd, "4")
 	//@extractfunc(exB, exEnd)
 }
 
-func fn0(a int) {
+func newFunction(a int) {
 	b := a * 2
 	_ = 3 + 4
 }

internal/lsp/testdata/extract/extract_function/extract_basic.go.golden

@@ -3,11 +3,11 @@ package extract
 
 func _() {
 	//@mark(exSt1, "a")
-	fn0() //@mark(exEn1, "4")
+	newFunction() //@mark(exEn1, "4")
 	//@extractfunc(exSt1, exEn1)
 }
 
-func fn0() {
+func newFunction() {
 	a := 1
 	_ = 3 + 4
 }

internal/lsp/testdata/extract/extract_function/extract_basic_comment.go.golden

@@ -5,11 +5,11 @@ func _() {
 	/* comment in the middle of a line */
 	//@mark(exSt18, "a")
 	// Comment on its own line
-	fn0() //@mark(exEn18, "4")
+	newFunction() //@mark(exEn18, "4")
 	//@extractfunc(exSt18, exEn18)
 }
 
-func fn0() {
+func newFunction() {
 	a := 1
 
 	_ = 3 + 4

internal/lsp/testdata/extract/extract_function/extract_issue_44813.go.golden

@@ -5,12 +5,12 @@ import "fmt"
 
 func main() {
 	//@mark(exSt9, "x")
-	x := fn0() //@mark(exEn9, "}")
+	x := newFunction() //@mark(exEn9, "}")
 	//@extractfunc(exSt9, exEn9)
 	fmt.Printf("%x\n", x)
 }
 
-func fn0() []rune {
+func newFunction() []rune {
 	x := []rune{}
 	s := "HELLO"
 	for _, c := range s {

internal/lsp/testdata/extract/extract_function/extract_redefine.go.golden

@@ -5,13 +5,13 @@ import "strconv"
 
 func _() {
 	i, err := strconv.Atoi("1")
-	u, err := fn0() //@extractfunc("u", ")")
+	u, err := newFunction() //@extractfunc("u", ")")
 	if i == u || err == nil {
 		return
 	}
 }
 
-func fn0() (int, error) {
+func newFunction() (int, error) {
 	u, err := strconv.Atoi("2")
 	return u, err
 }

internal/lsp/testdata/extract/extract_function/extract_return_basic.go.golden

@@ -4,15 +4,15 @@ package extract
 func _() bool {
 	x := 1
 	//@mark(exSt2, "if")
-	cond0, ret0 := fn0(x)
-	if cond0 {
-		return ret0
+	shouldReturn, returnValue := newFunction(x)
+	if shouldReturn {
+		return returnValue
 	} //@mark(exEn2, "}")
 	return false
 	//@extractfunc(exSt2, exEn2)
 }
 
-func fn0(x int) (bool, bool) {
+func newFunction(x int) (bool, bool) {
 	if x == 0 {
 		return true, true
 	}

internal/lsp/testdata/extract/extract_function/extract_return_basic_nonnested.go.golden

@@ -3,11 +3,11 @@ package extract
 
 func _() bool {
 	//@mark(exSt13, "x")
-	return fn0() //@mark(exEn13, "false")
+	return newFunction() //@mark(exEn13, "false")
 	//@extractfunc(exSt13, exEn13)
 }
 
-func fn0() bool {
+func newFunction() bool {
 	x := 1
 	if x == 0 {
 		return true

internal/lsp/testdata/extract/extract_function/extract_return_complex.go.golden

@@ -7,15 +7,15 @@ func _() (int, string, error) {
 	x := 1
 	y := "hello"
 	//@mark(exSt3, "z")
-	z, cond0, ret0, ret1, ret2 := fn0(y, x)
-	if cond0 {
-		return ret0, ret1, ret2
+	z, shouldReturn, returnValue, returnValue1, returnValue2 := newFunction(y, x)
+	if shouldReturn {
+		return returnValue, returnValue1, returnValue2
 	} //@mark(exEn3, "}")
 	return x, z, nil
 	//@extractfunc(exSt3, exEn3)
 }
 
-func fn0(y string, x int) (string, bool, int, string, error) {
+func newFunction(y string, x int) (string, bool, int, string, error) {
 	z := "bye"
 	if y == z {
 		return "", true, x, y, fmt.Errorf("same")

internal/lsp/testdata/extract/extract_function/extract_return_complex_nonnested.go.golden

@@ -7,11 +7,11 @@ func _() (int, string, error) {
 	x := 1
 	y := "hello"
 	//@mark(exSt10, "z")
-	return fn0(y, x) //@mark(exEn10, "nil")
+	return newFunction(y, x) //@mark(exEn10, "nil")
 	//@extractfunc(exSt10, exEn10)
 }
 
-func fn0(y string, x int) (int, string, error) {
+func newFunction(y string, x int) (int, string, error) {
 	z := "bye"
 	if y == z {
 		return x, y, fmt.Errorf("same")

internal/lsp/testdata/extract/extract_function/extract_return_func_lit.go.golden

@@ -6,16 +6,16 @@ import "go/ast"
 func _() {
 	ast.Inspect(ast.NewIdent("a"), func(n ast.Node) bool {
 		//@mark(exSt4, "if")
-		cond0, ret0 := fn0(n)
-		if cond0 {
-			return ret0
+		shouldReturn, returnValue := newFunction(n)
+		if shouldReturn {
+			return returnValue
 		} //@mark(exEn4, "}")
 		return false
 	})
 	//@extractfunc(exSt4, exEn4)
 }
 
-func fn0(n ast.Node) (bool, bool) {
+func newFunction(n ast.Node) (bool, bool) {
 	if n == nil {
 		return true, true
 	}

internal/lsp/testdata/extract/extract_function/extract_return_func_lit_nonnested.go.golden

@@ -6,12 +6,12 @@ import "go/ast"
 func _() {
 	ast.Inspect(ast.NewIdent("a"), func(n ast.Node) bool {
 		//@mark(exSt11, "if")
-		return fn0(n) //@mark(exEn11, "false")
+		return newFunction(n) //@mark(exEn11, "false")
 	})
 	//@extractfunc(exSt11, exEn11)
 }
 
-func fn0(n ast.Node) bool {
+func newFunction(n ast.Node) bool {
 	if n == nil {
 		return true
 	}

internal/lsp/testdata/extract/extract_function/extract_return_init.go.golden

@@ -4,16 +4,16 @@ package extract
 func _() string {
 	x := 1
 	//@mark(exSt5, "if")
-	cond0, ret0 := fn0(x)
-	if cond0 {
-		return ret0
+	shouldReturn, returnValue := newFunction(x)
+	if shouldReturn {
+		return returnValue
 	} //@mark(exEn5, "}")
 	x = 2
 	return "b"
 	//@extractfunc(exSt5, exEn5)
 }
 
-func fn0(x int) (bool, string) {
+func newFunction(x int) (bool, string) {
 	if x == 0 {
 		x = 3
 		return true, "a"

internal/lsp/testdata/extract/extract_function/extract_return_init_nonnested.go.golden

@@ -4,11 +4,11 @@ package extract
 func _() string {
 	x := 1
 	//@mark(exSt12, "if")
-	return fn0(x) //@mark(exEn12, "\"b\"")
+	return newFunction(x) //@mark(exEn12, "\"b\"")
 	//@extractfunc(exSt12, exEn12)
 }
 
-func fn0(x int) string {
+func newFunction(x int) string {
 	if x == 0 {
 		x = 3
 		return "a"

internal/lsp/testdata/extract/extract_function/extract_scope.go.golden

@@ -3,10 +3,10 @@ package extract
 
 func _() {
 	fn0 := 1
-	fn2(fn0) //@extractfunc("a", "fn0")
+	newFunction(fn0) //@extractfunc("a", "fn0")
 }
 
-func fn2(fn0 int) {
+func newFunction(fn0 int) {
 	a := fn0
 }
 

internal/lsp/testdata/extract/extract_function/extract_smart_initialization.go.golden

@@ -4,12 +4,12 @@ package extract
 func _() {
 	var a []int
 	//@mark(exSt6, "a")
-	a, b := fn0(a)           //@mark(exEn6, "4")
+	a, b := newFunction(a)           //@mark(exEn6, "4")
 	//@extractfunc(exSt6, exEn6)
 	a = append(a, b)
 }
 
-func fn0(a []int) ([]int, int) {
+func newFunction(a []int) ([]int, int) {
 	a = append(a, 2)
 	b := 4
 	return a, b

internal/lsp/testdata/extract/extract_function/extract_smart_return.go.golden

@@ -5,12 +5,12 @@ func _() {
 	var b []int
 	var a int
 	//@mark(exSt7, "a")
-	b = fn0(a, b) //@mark(exEn7, ")")
+	b = newFunction(a, b) //@mark(exEn7, ")")
 	b[0] = 1
 	//@extractfunc(exSt7, exEn7)
 }
 
-func fn0(a int, b []int) []int {
+func newFunction(a int, b []int) []int {
 	a = 2
 	b = []int{}
 	b = append(b, a)

internal/lsp/testdata/extract/extract_function/extract_unnecessary_param.go.golden

@@ -5,15 +5,15 @@ func _() {
 	var b []int
 	var a int
 	//@mark(exSt8, "a")
-	a, b = fn0(b) //@mark(exEn8, ")")
+	a, b = newFunction(b) //@mark(exEn8, ")")
 	b[0] = 1
 	if a == 2 {
 		return
 	}
 	//@extractfunc(exSt8, exEn8)
 }
 
-func fn0(b []int) (int, []int) {
+func newFunction(b []int) (int, []int) {
 	a := 2
 	b = []int{}
 	b = append(b, a)

internal/lsp/testdata/extract/extract_variable/extract_basic_lit.go.golden

@@ -2,8 +2,8 @@
 package extract
 
 func _() {
-	x0 := 1
-	var _ = x0 + 2 //@suggestedfix("1", "refactor.extract")
+	x := 1
+	var _ = x + 2 //@suggestedfix("1", "refactor.extract")
 	var _ = 3 + 4 //@suggestedfix("3 + 4", "refactor.extract")
 }
 
@@ -12,7 +12,7 @@ package extract
 
 func _() {
 	var _ = 1 + 2 //@suggestedfix("1", "refactor.extract")
-	x0 := 3 + 4
-	var _ = x0 //@suggestedfix("3 + 4", "refactor.extract")
+	x := 3 + 4
+	var _ = x //@suggestedfix("3 + 4", "refactor.extract")
 }
 

internal/lsp/testdata/extract/extract_variable/extract_func_call.go.golden

@@ -16,8 +16,8 @@ package extract
 import "strconv"
 
 func _() {
-	x1 := append([]int{}, 1)
-	x0 := x1 //@suggestedfix("append([]int{}, 1)", "refactor.extract")
+	x := append([]int{}, 1)
+	x0 := x //@suggestedfix("append([]int{}, 1)", "refactor.extract")
 	str := "1"
 	b, err := strconv.Atoi(str) //@suggestedfix("strconv.Atoi(str)", "refactor.extract")
 }
@@ -30,7 +30,7 @@ import "strconv"
 func _() {
 	x0 := append([]int{}, 1) //@suggestedfix("append([]int{}, 1)", "refactor.extract")
 	str := "1"
-	x1, x2 := strconv.Atoi(str)
-	b, err := x1, x2 //@suggestedfix("strconv.Atoi(str)", "refactor.extract")
+	x, x1 := strconv.Atoi(str)
+	b, err := x, x1 //@suggestedfix("strconv.Atoi(str)", "refactor.extract")
 }
 

internal/lsp/testdata/extract/extract_variable/extract_scope.go.golden

@@ -9,8 +9,8 @@ func _() {
 		y := ast.CompositeLit{} //@suggestedfix("ast.CompositeLit{}", "refactor.extract")
 	}
 	if true {
-		x2 := !false
-		x1 := x2 //@suggestedfix("!false", "refactor.extract")
+		x := !false
+		x1 := x //@suggestedfix("!false", "refactor.extract")
 	}
 }
 
@@ -22,8 +22,8 @@ import "go/ast"
 func _() {
 	x0 := 0
 	if true {
-		x1 := ast.CompositeLit{}
-		y := x1 //@suggestedfix("ast.CompositeLit{}", "refactor.extract")
+		x := ast.CompositeLit{}
+		y := x //@suggestedfix("ast.CompositeLit{}", "refactor.extract")
 	}
 	if true {
 		x1 := !false //@suggestedfix("!false", "refactor.extract")