func checkVarValue(t *testing.T, prog *ssa.Program, pkg *ssa.Package, ref []ast.Node, obj *types.Var, expKind string, wantAddr bool) {
// The prefix of all assertions messages.
prefix := fmt.Sprintf("VarValue(%s @ L%d)",
obj, prog.Fset.Position(ref[0].Pos()).Line)
v := prog.VarValue(obj, pkg, ref)
// Kind is the concrete type of the ssa Value.
gotKind := "nil"
if v != nil {
gotKind = fmt.Sprintf("%T", v)[len("*ssa."):]
}
// fmt.Printf("%s = %v (kind %q; expect %q) addr=%t\n", prefix, v, gotKind, expKind, wantAddr) // debugging
// Check the kinds match.
// "nil" indicates expected failure (e.g. optimized away).
if expKind != gotKind {
t.Errorf("%s concrete type == %s, want %s", prefix, gotKind, expKind)
}
// Check the types match.
// If wantAddr, the expected type is the object's address.
if v != nil {
expType := obj.Type()
if wantAddr {
expType = types.NewPointer(expType)
}
if !types.IsIdentical(v.Type(), expType) {
t.Errorf("%s.Type() == %s, want %s", prefix, v.Type(), expType)
}
}
}
func (p *exporter) field(f *types.Var) {
// anonymous fields have "" name
name := ""
if !f.Anonymous() {
name = f.Name()
}
// qualifiedName will always emit the field package for
// anonymous fields because "" is not an exported name.
p.qualifiedName(f.Pkg(), name)
p.typ(f.Type())
}
// VarValue returns the SSA Value that corresponds to a specific
// identifier denoting the source-level named variable obj.
//
// VarValue returns nil if a local variable was not found, perhaps
// because its package was not built, the debug information was not
// requested during SSA construction, or the value was optimized away.
//
// ref is the path to an ast.Ident (e.g. from PathEnclosingInterval),
// and that ident must resolve to obj.
//
// pkg is the package enclosing the reference. (A reference to a var
// may result in code, so we need to know where to find that code.)
//
// The Value of a defining (as opposed to referring) identifier is the
// value assigned to it in its definition.
//
// In many cases where the identifier appears in an lvalue context,
// the resulting Value is the var's address, not its value.
// For example, x in all these examples:
// x.y = 0
// x[0] = 0
// _ = x[:]
// x = X{}
// _ = &x
// x.method() (iff method is on &x)
// and all package-level vars. (This situation can be detected by
// comparing the types of the Var and Value.)
//
func (prog *Program) VarValue(obj *types.Var, pkg *Package, ref []ast.Node) Value {
id := ref[0].(*ast.Ident)
// Package-level variable?
if v := prog.packageLevelValue(obj); v != nil {
return v.(*Global)
}
// Must be a function-local variable.
// (e.g. local, parameter, or field selection e.f)
fn := EnclosingFunction(pkg, ref)
if fn == nil {
return nil // e.g. SSA not built
}
// Defining ident of a parameter?
if id.Pos() == obj.Pos() {
for _, param := range fn.Params {
if param.Object() == obj {
return param
}
}
}
// Other ident?
for _, b := range fn.Blocks {
for _, instr := range b.Instrs {
if ref, ok := instr.(*DebugRef); ok {
if ref.Pos() == id.Pos() {
return ref.X
}
}
}
}
return nil // e.g. debug info not requested, or var optimized away
}
// VarValue returns the SSA Value that corresponds to a specific
// identifier denoting the source-level named variable obj.
//
// VarValue returns nil if a local variable was not found, perhaps
// because its package was not built, the debug information was not
// requested during SSA construction, or the value was optimized away.
//
// ref is the path to an ast.Ident (e.g. from PathEnclosingInterval),
// and that ident must resolve to obj.
//
// pkg is the package enclosing the reference. (A reference to a var
// always occurs within a function, so we need to know where to find it.)
//
// The Value of a defining (as opposed to referring) identifier is the
// value assigned to it in its definition. Similarly, the Value of an
// identifier that is the LHS of an assignment is the value assigned
// to it in that statement. In all these examples, VarValue(x) returns
// the value of x and isAddr==false.
//
// var x X
// var x = X{}
// x := X{}
// x = X{}
//
// When an identifier appears in an lvalue context other than as the
// LHS of an assignment, the resulting Value is the var's address, not
// its value. This situation is reported by isAddr, the second
// component of the result. In these examples, VarValue(x) returns
// the address of x and isAddr==true.
//
// x.y = 0
// x[0] = 0
// _ = x[:] (where x is an array)
// _ = &x
// x.method() (iff method is on &x)
//
func (prog *Program) VarValue(obj *types.Var, pkg *Package, ref []ast.Node) (value Value, isAddr bool) {
// All references to a var are local to some function, possibly init.
fn := EnclosingFunction(pkg, ref)
if fn == nil {
return // e.g. def of struct field; SSA not built?
}
id := ref[0].(*ast.Ident)
// Defining ident of a parameter?
if id.Pos() == obj.Pos() {
for _, param := range fn.Params {
if param.Object() == obj {
return param, false
}
}
}
// Other ident?
for _, b := range fn.Blocks {
for _, instr := range b.Instrs {
if dr, ok := instr.(*DebugRef); ok {
if dr.Pos() == id.Pos() {
return dr.X, dr.IsAddr
}
}
}
}
// Defining ident of package-level var?
if v := prog.packageLevelValue(obj); v != nil {
return v.(*Global), true
}
return // e.g. debug info not requested, or var optimized away
}
func (tr *Transformer) matchWildcard(xobj *types.Var, y ast.Expr) bool {
name := xobj.Name()
if tr.verbose {
fmt.Fprintf(os.Stderr, "%s: wildcard %s -> %s?: ",
tr.fset.Position(y.Pos()), name, astString(tr.fset, y))
}
// Check that y is assignable to the declared type of the param.
if yt := tr.info.TypeOf(y); !types.AssignableTo(yt, xobj.Type()) {
if tr.verbose {
fmt.Fprintf(os.Stderr, "%s not assignable to %s\n", yt, xobj.Type())
}
return false
}
// A wildcard matches any expression.
// If it appears multiple times in the pattern, it must match
// the same expression each time.
if old, ok := tr.env[name]; ok {
// found existing binding
tr.allowWildcards = false
r := tr.matchExpr(old, y)
if tr.verbose {
fmt.Fprintf(os.Stderr, "%t secondary match, primary was %s\n",
r, astString(tr.fset, old))
}
tr.allowWildcards = true
return r
}
if tr.verbose {
fmt.Fprintf(os.Stderr, "primary match\n")
}
tr.env[name] = y // record binding
return true
}
// checkStructField checks that the field renaming will not cause
// conflicts at its declaration, or ambiguity or changes to any selection.
func (r *renamer) checkStructField(from *types.Var) {
// Check that the struct declaration is free of field conflicts,
// and field/method conflicts.
// go/types offers no easy way to get from a field (or interface
// method) to its declaring struct (or interface), so we must
// ascend the AST.
info, path, _ := r.iprog.PathEnclosingInterval(from.Pos(), from.Pos())
// path is [Ident Field FieldList StructType ... File]. Can't fail.
// Ascend past parens (unlikely).
i := 4
for {
_, ok := path[i].(*ast.ParenExpr)
if !ok {
break
}
i++
}
if spec, ok := path[i].(*ast.TypeSpec); ok {
// This struct is also a named type.
// We must check for direct (non-promoted) field/field
// and method/field conflicts.
named := info.Defs[spec.Name].Type()
prev, indices, _ := types.LookupFieldOrMethod(named, true, info.Pkg, r.to)
if len(indices) == 1 {
r.errorf(from.Pos(), "renaming this field %q to %q",
from.Name(), r.to)
r.errorf(prev.Pos(), "\twould conflict with this %s",
objectKind(prev))
return // skip checkSelections to avoid redundant errors
}
} else {
// This struct is not a named type.
// We need only check for direct (non-promoted) field/field conflicts.
T := info.Types[path[3].(*ast.StructType)].Type.Underlying().(*types.Struct)
for i := 0; i < T.NumFields(); i++ {
if prev := T.Field(i); prev.Name() == r.to {
r.errorf(from.Pos(), "renaming this field %q to %q",
from.Name(), r.to)
r.errorf(prev.Pos(), "\twould conflict with this field")
return // skip checkSelections to avoid redundant errors
}
}
}
// Renaming an anonymous field requires renaming the type too. e.g.
// print(s.T) // if we rename T to U,
// type T int // this and
// var s struct {T} // this must change too.
if from.Anonymous() {
if named, ok := from.Type().(*types.Named); ok {
r.check(named.Obj())
} else if named, ok := deref(from.Type()).(*types.Named); ok {
r.check(named.Obj())
}
}
// Check integrity of existing (field and method) selections.
r.checkSelections(from)
}
func (g *Go) pkg_var(v *types.Var) (ret content.Variable) {
ret.Name.Relative = dotre.ReplaceAllString(v.Name(), "")
ret.Type = g.pkg_type(v.Type())
return
}
func (p *exporter) param(v *types.Var) {
p.string(v.Name())
p.typ(v.Type())
}
// makeWrapper returns a synthetic method that delegates to the
// declared method denoted by meth.Obj(), first performing any
// necessary pointer indirections or field selections implied by meth.
//
// The resulting method's receiver type is meth.Recv().
//
// This function is versatile but quite subtle! Consider the
// following axes of variation when making changes:
// - optional receiver indirection
// - optional implicit field selections
// - meth.Obj() may denote a concrete or an interface method
// - the result may be a thunk or a wrapper.
//
// EXCLUSIVE_LOCKS_REQUIRED(prog.methodsMu)
//
func makeWrapper(prog *Program, meth *types.Selection) *Function {
obj := meth.Obj().(*types.Func) // the declared function
sig := meth.Type().(*types.Signature) // type of this wrapper
var recv *types.Var // wrapper's receiver or thunk's params[0]
name := obj.Name()
var description string
var start int // first regular param
if meth.Kind() == types.MethodExpr {
name += "$thunk"
description = "thunk"
recv = sig.Params().At(0)
start = 1
} else {
description = "wrapper"
recv = sig.Recv()
}
description = fmt.Sprintf("%s for %s", description, meth.Obj())
if prog.mode&LogSource != 0 {
defer logStack("make %s to (%s)", description, recv.Type())()
}
fn := &Function{
name: name,
method: meth,
object: obj,
Signature: sig,
Synthetic: description,
Prog: prog,
pos: obj.Pos(),
}
fn.startBody()
fn.addSpilledParam(recv)
createParams(fn, start)
indices := meth.Index()
var v Value = fn.Locals[0] // spilled receiver
if isPointer(meth.Recv()) {
v = emitLoad(fn, v)
// For simple indirection wrappers, perform an informative nil-check:
// "value method (T).f called using nil *T pointer"
if len(indices) == 1 && !isPointer(recvType(obj)) {
var c Call
c.Call.Value = &Builtin{
name: "ssa:wrapnilchk",
sig: types.NewSignature(nil, nil,
types.NewTuple(anonVar(meth.Recv()), anonVar(tString), anonVar(tString)),
types.NewTuple(anonVar(meth.Recv())), false),
}
c.Call.Args = []Value{
v,
stringConst(deref(meth.Recv()).String()),
stringConst(meth.Obj().Name()),
}
c.setType(v.Type())
v = fn.emit(&c)
}
}
// Invariant: v is a pointer, either
// value of *A receiver param, or
// address of A spilled receiver.
// We use pointer arithmetic (FieldAddr possibly followed by
// Load) in preference to value extraction (Field possibly
// preceded by Load).
v = emitImplicitSelections(fn, v, indices[:len(indices)-1])
// Invariant: v is a pointer, either
// value of implicit *C field, or
// address of implicit C field.
var c Call
if r := recvType(obj); !isInterface(r) { // concrete method
if !isPointer(r) {
v = emitLoad(fn, v)
}
c.Call.Value = prog.declaredFunc(obj)
c.Call.Args = append(c.Call.Args, v)
} else {
c.Call.Method = obj
c.Call.Value = emitLoad(fn, v)
}
for _, arg := range fn.Params[1:] {
c.Call.Args = append(c.Call.Args, arg)
}
emitTailCall(fn, &c)
fn.finishBody()
return fn
}
