WIP: add callgraph package

go.mod

@@ -37,6 +37,7 @@ require (
 	golang.org/x/net v0.0.0-20211005001312-d4b1ae081e3b
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c
 	google.golang.org/grpc v1.41.0
+	golang.org/x/tools v0.1.5
 	gopkg.in/check.v1 v1.0.0-20200902074654-038fdea0a05b // indirect
 	pgregory.net/rapid v0.4.7
 )

tools/panic/callgraph/callgraph.go

@@ -0,0 +1,115 @@
+package callgraph
+
+import (
+	"fmt"
+	"go/ast"
+	"go/types"
+	"sort"
+
+	"golang.org/x/tools/go/loader"
+)
+
+type Triple struct {
+	Caller Entry
+	Target Entry
+	Site   Location
+}
+
+type Entry struct {
+	Package string // canonical import path
+	Name    string // name relative to the package ("" for calls at file scope)
+}
+
+type Location struct {
+	Path      string
+	Offset    int // 0-based
+	Line, Col int // 1-based line, 0-based byte offset
+}
+
+type Graph struct {
+	cfg *loader.Config
+}
+
+func New() *Graph {
+	cfg := new(loader.Config)
+	cfg.TypeCheckFuncBodies = func(ip string) bool {
+		_, ok := cfg.ImportPkgs[ip]
+		return ok
+	}
+	return &Graph{cfg: cfg}
+}
+
+func (g *Graph) Import(ipath string) { g.cfg.Import(ipath) }
+
+func (g *Graph) ImportWithTests(ipath string) { g.cfg.ImportWithTests(ipath) }
+
+func (g *Graph) Process(f func(*Triple)) error {
+	pgm, err := g.cfg.Load()
+	if err != nil {
+		return fmt.Errorf("loading program: %v", err)
+	}
+	var pkgs []*loader.PackageInfo
+	for _, pkg := range pgm.Imported {
+		pkgs = append(pkgs, pkg)
+	}
+	sort.Slice(pkgs, func(i, j int) bool {
+		return pkgs[i].Pkg.Path() < pkgs[j].Pkg.Path()
+	})
+
+	for _, pkg := range pkgs {
+		for _, file := range pkg.Files {
+			fname := g.cfg.Fset.Position(file.Pos()).Filename
+
+			var nodes []ast.Node
+			parent := func() string {
+				for i := len(nodes) - 1; i >= 0; i-- {
+					switch t := nodes[i].(type) {
+					case *ast.FuncDecl:
+						return t.Name.Name
+					}
+				}
+				return fname
+			}
+
+			ast.Walk(visitFunc(func(node ast.Node) {
+				if node == nil {
+					nodes = nodes[:len(nodes)-1]
+					return
+				}
+				nodes = append(nodes, node)
+
+				switch t := node.(type) {
+				case *ast.Ident:
+					ref := pkg.Info.Uses[t]
+					if ref == nil {
+						return // no referent
+					}
+					var refPath string
+					if _, ok := ref.Type().(*types.Signature); ok {
+						refPath = ref.Pkg().Path() // OK, function
+					} else if _, ok := ref.(*types.Builtin); ok {
+						// OK, builtin
+					} else {
+						return // not a function call or reference
+					}
+					pos := g.cfg.Fset.Position(t.Pos())
+					f(&Triple{
+						Caller: Entry{Package: pkg.Pkg.Path(), Name: parent()},
+						Target: Entry{Package: refPath, Name: ref.Name()},
+						Site: Location{
+							Path:   pos.Filename,
+							Offset: pos.Offset,
+							Line:   pos.Line,
+							Col:    pos.Column - 1,
+						},
+					})
+				}
+			}), file)
+		}
+	}
+	return nil
+}
+
+type visitFunc func(ast.Node)
+
+func (v visitFunc) Visit(n ast.Node) ast.Visitor { v(n); return v }

tools/panic/callgraph/callgraph_test.go

@@ -0,0 +1,19 @@
+package callgraph_test
+
+import (
+	"testing"
+
+	"github.com/tendermint/tendermint/tools/panic/callgraph"
+)
+
+func TestStub(t *testing.T) {
+	g := callgraph.New()
+	g.ImportWithTests("github.com/tendermint/tendermint/internal/consensus")
+	if err := g.Process(func(cg *callgraph.Triple) {
+		if cg.Target.Name == "panic" {
+			t.Logf("Panic call at %v", cg.Site)
+		}
+	}); err != nil {
+		t.Fatal(err)
+	}
+}