Analyze all usage of `sessionctx.Context` in the "tidb/expression" package.

main.go

package main

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"log"
	"strings"

	"golang.org/x/tools/go/packages"
)

var currentPkg = "expression"

type astVisitor struct {
	pkg  *packages.Package
	file *ast.File

	stack []ast.Node

	allSels  map[string][]token.Position
	allCalls map[string][]token.Position
	others   []token.Position
}

func (v *astVisitor) Visit(n ast.Node) ast.Visitor {
	var parent ast.Node
	if v.stack != nil {
		parent = v.stack[len(v.stack)-1]
	}

	isOthers := true

	switch node := n.(type) {
	case ast.Expr:
		t := v.pkg.TypesInfo.TypeOf(node)
		pos := v.pkg.Fset.Position(node.Pos())
		if sessionctx, ok := t.(*types.Named); ok && strings.Contains(sessionctx.String(), "github.com/pingcap/tidb/sessionctx.Context") {
			if sel, ok := parent.(*ast.SelectorExpr); ok {
				// the parent of ctx is a selector expr, we can see which field/method it used
				v.allSels["ctx."+sel.Sel.String()] = append(v.allSels["ctx."+sel.Sel.String()], pos)
				isOthers = false
			} else {
				for i := len(v.stack) - 1; i >= 0; i-- {
					p := v.stack[i]
					switch pWithTyp := p.(type) {
					case *ast.CallExpr:
						typOfX := v.pkg.TypesInfo.TypeOf(pWithTyp.Fun)
						if !strings.Contains(typOfX.String(), "tidb/"+currentPkg) && types.ExprString(pWithTyp.Fun) != currentPkg {
							funCallStr := types.ExprString(pWithTyp.Fun)
							v.allCalls[funCallStr] = append(v.allCalls[funCallStr], pos)
						}
						isOthers = false
						break
					case *ast.FuncType, *ast.StructType:
						// ignore these cases
						isOthers = false
						break

					}
				}
			}

			if isOthers {
				v.others = append(v.others, pos)
			}

			return nil
		}
	}

	if n == nil {
		// Done with node's children. Pop.
		v.stack = v.stack[:len(v.stack)-1]
	} else {
		// Push the current node for children.
		v.stack = append(v.stack, n)
	}
	return v
}

func main() {
	packages, err := packages.Load(&packages.Config{
		Mode: packages.NeedSyntax | packages.NeedTypes | packages.NeedImports | packages.NeedName | packages.NeedTypesInfo,
		Dir:  "/home/yangkeao/Project/github.com/YangKeao/tidb",
	}, "/home/yangkeao/Project/github.com/YangKeao/tidb/"+currentPkg+"/...")
	if err != nil {
		log.Fatal(err)
	}

	allSels := make(map[string][]token.Position)
	allCalls := make(map[string][]token.Position)
	var others []token.Position
	for _, pkg := range packages {
		for _, file := range pkg.Syntax {
			v := &astVisitor{
				pkg:      pkg,
				file:     file,
				allSels:  allSels,
				allCalls: allCalls,
			}
			ast.Walk(v, file)
			others = append(others, v.others...)
		}
	}
	fmt.Println("Selectors:")
	for sel, poses := range allSels {
		for _, pos := range poses {
			fmt.Printf("%s: %s\n", sel, pos.String())
		}
	}
	fmt.Println("FunctionCalls:")
	for call, poses := range allCalls {
		for _, pos := range poses {
			fmt.Printf("%s: %s\n", call, pos.String())
		}
	}
	fmt.Println("Others:")
	for _, pos := range others {
		fmt.Printf("%s\n", pos.String())
	}
}