Example #1
0
// isPackageLevel reports whether obj is a package-level object.
func isPackageLevel(obj types.Object) bool {
	// TODO(adonovan): fix go/types bug:
	//   obj.Parent().Parent() == obj.Pkg().Scope()
	// doesn't work because obj.Parent() gets mutated during
	// dot-imports.
	return obj.Pkg().Scope().Lookup(obj.Name()) == obj
}
Example #2
0
// lookup returns the address of the named variable identified by obj
// that is local to function f or one of its enclosing functions.
// If escaping, the reference comes from a potentially escaping pointer
// expression and the referent must be heap-allocated.
//
func (f *Function) lookup(obj types.Object, escaping bool) Value {
	if v, ok := f.objects[obj]; ok {
		if alloc, ok := v.(*Alloc); ok && escaping {
			alloc.Heap = true
		}
		return v // function-local var (address)
	}

	// Definition must be in an enclosing function;
	// plumb it through intervening closures.
	if f.Enclosing == nil {
		panic("no Value for type.Object " + obj.Name())
	}
	outer := f.Enclosing.lookup(obj, true) // escaping
	v := &Capture{
		name:   obj.Name(),
		typ:    outer.Type(),
		pos:    outer.Pos(),
		outer:  outer,
		parent: f,
	}
	f.objects[obj] = v
	f.FreeVars = append(f.FreeVars, v)
	return v
}
Example #3
0
// checkSelection checks that all uses and selections that resolve to
// the specified object would continue to do so after the renaming.
func (r *renamer) checkSelections(from types.Object) {
	for pkg, info := range r.packages {
		if id := someUse(info, from); id != nil {
			if !r.checkExport(id, pkg, from) {
				return
			}
		}

		for syntax, sel := range info.Selections {
			// There may be extant selections of only the old
			// name or only the new name, so we must check both.
			// (If neither, the renaming is sound.)
			//
			// In both cases, we wish to compare the lengths
			// of the implicit field path (Selection.Index)
			// to see if the renaming would change it.
			//
			// If a selection that resolves to 'from', when renamed,
			// would yield a path of the same or shorter length,
			// this indicates ambiguity or a changed referent,
			// analogous to same- or sub-block lexical conflict.
			//
			// If a selection using the name 'to' would
			// yield a path of the same or shorter length,
			// this indicates ambiguity or shadowing,
			// analogous to same- or super-block lexical conflict.

			// TODO(adonovan): fix: derive from Types[syntax.X].Mode
			// TODO(adonovan): test with pointer, value, addressable value.
			isAddressable := true

			if sel.Obj() == from {
				if obj, indices, _ := types.LookupFieldOrMethod(sel.Recv(), isAddressable, from.Pkg(), r.to); obj != nil {
					// Renaming this existing selection of
					// 'from' may block access to an existing
					// type member named 'to'.
					delta := len(indices) - len(sel.Index())
					if delta > 0 {
						continue // no ambiguity
					}
					r.selectionConflict(from, delta, syntax, obj)
					return
				}

			} else if sel.Obj().Name() == r.to {
				if obj, indices, _ := types.LookupFieldOrMethod(sel.Recv(), isAddressable, from.Pkg(), from.Name()); obj == from {
					// Renaming 'from' may cause this existing
					// selection of the name 'to' to change
					// its meaning.
					delta := len(indices) - len(sel.Index())
					if delta > 0 {
						continue //  no ambiguity
					}
					r.selectionConflict(from, -delta, syntax, sel.Obj())
					return
				}
			}
		}
	}
}
Example #4
0
// isLocal reports whether obj is local to some function.
// Precondition: not a struct field or interface method.
func isLocal(obj types.Object) bool {
	// [... 5=stmt 4=func 3=file 2=pkg 1=universe]
	var depth int
	for scope := obj.Parent(); scope != nil; scope = scope.Parent() {
		depth++
	}
	return depth >= 4
}
Example #5
0
// same reports whether x and y are identical, or both are PkgNames
// referring to the same Package.
//
func sameObj(x, y types.Object) bool {
	if x == y {
		return true
	}
	if _, ok := x.(*types.PkgName); ok {
		if _, ok := y.(*types.PkgName); ok {
			return x.Pkg() == y.Pkg()
		}
	}
	return false
}
Example #6
0
func (r *resolver) defineObject(b *Block, name string, obj types.Object) {
	if obj.Name() == "_" {
		return
	}
	i := len(b.bindings)
	b.bindings = append(b.bindings, obj)
	b.index[name] = i
	if trace {
		logf("def %s = %s in %s\n", name, types.ObjectString(r.pkg, obj), b)
	}
	r.result.Defs[obj] = b
}
Example #7
0
func (r *renamer) checkInLocalScope(from types.Object) {
	info := r.packages[from.Pkg()]

	// Is this object an implicit local var for a type switch?
	// Each case has its own var, whose position is the decl of y,
	// but Ident in that decl does not appear in the Uses map.
	//
	//   switch y := x.(type) {	 // Defs[Ident(y)] is undefined
	//   case int:    print(y)       // Implicits[CaseClause(int)]    = Var(y_int)
	//   case string: print(y)       // Implicits[CaseClause(string)] = Var(y_string)
	//   }
	//
	var isCaseVar bool
	for syntax, obj := range info.Implicits {
		if _, ok := syntax.(*ast.CaseClause); ok && obj.Pos() == from.Pos() {
			isCaseVar = true
			r.check(obj)
		}
	}

	r.checkInLexicalScope(from, info)

	// Finally, if this was a type switch, change the variable y.
	if isCaseVar {
		_, path, _ := r.iprog.PathEnclosingInterval(from.Pos(), from.Pos())
		path[0].(*ast.Ident).Name = r.to // path is [Ident AssignStmt TypeSwitchStmt...]
	}
}
Example #8
0
File: var.go Project: qioixiy/llgo
func (c *compiler) newStackVarEx(argument int, stackf *LLVMValue, v types.Object, value llvm.Value, name string) (stackvalue llvm.Value, stackvar *LLVMValue) {
	typ := v.Type()

	// We need to put alloca instructions in the top block or the values
	// displayed when inspecting these variables in a debugger will be
	// completely messed up.
	curBlock := c.builder.GetInsertBlock()
	if p := curBlock.Parent(); !p.IsNil() {
		fb := p.FirstBasicBlock()
		fi := fb.FirstInstruction()
		if !fb.IsNil() && !fi.IsNil() {
			c.builder.SetInsertPointBefore(fi)
		}
	}
	old := c.builder.CurrentDebugLocation()
	c.builder.SetCurrentDebugLocation(llvm.Value{})
	stackvalue = c.builder.CreateAlloca(c.types.ToLLVM(typ), name)

	// For arguments we want to insert the store instruction
	// without debug information to ensure that they are executed
	// (and hence have proper values) before the debugger hits the
	// first line in a function.
	if argument == 0 {
		c.builder.SetCurrentDebugLocation(old)
		c.builder.SetInsertPointAtEnd(curBlock)
	}

	if !value.IsNil() {
		c.builder.CreateStore(value, stackvalue)
	}
	c.builder.SetCurrentDebugLocation(old)
	c.builder.SetInsertPointAtEnd(curBlock)

	ptrvalue := c.NewValue(stackvalue, types.NewPointer(typ))
	stackvar = ptrvalue.makePointee()
	stackvar.stack = stackf
	c.objectdata[v].Value = stackvar

	// Generate debug metadata (will return nil
	// if debug-data generation is disabled).
	if descriptor := c.createLocalVariableMetadata(v, argument); descriptor != nil {
		c.builder.InsertDeclare(
			c.module.Module,
			llvm.MDNode([]llvm.Value{stackvalue}),
			c.debug_info.MDNode(descriptor),
		)
	}
	return stackvalue, stackvar
}
// ssaValueForIdent returns the ssa.Value for the ast.Ident whose path
// to the root of the AST is path.  isAddr reports whether the
// ssa.Value is the address denoted by the ast.Ident, not its value.
//
func ssaValueForIdent(prog *ssa.Program, qinfo *importer.PackageInfo, obj types.Object, path []ast.Node) (value ssa.Value, isAddr bool, err error) {
	switch obj := obj.(type) {
	case *types.Var:
		pkg := prog.Package(qinfo.Pkg)
		pkg.Build()
		if v, addr := prog.VarValue(obj, pkg, path); v != nil {
			return v, addr, nil
		}
		return nil, false, fmt.Errorf("can't locate SSA Value for var %s", obj.Name())

	case *types.Func:
		return prog.FuncValue(obj), false, nil
	}
	panic(obj)
}
Example #10
0
// ssaValueForIdent returns the ssa.Value for the ast.Ident whose path
// to the root of the AST is path.  It may return a nil Value without
// an error to indicate the pointer analysis is not appropriate.
//
func ssaValueForIdent(prog *ssa.Program, qinfo *importer.PackageInfo, obj types.Object, path []ast.Node) (ssa.Value, error) {
	if obj, ok := obj.(*types.Var); ok {
		pkg := prog.Package(qinfo.Pkg)
		pkg.Build()
		if v := prog.VarValue(obj, pkg, path); v != nil {
			// Don't run pointer analysis on a ref to a const expression.
			if _, ok := v.(*ssa.Const); ok {
				v = nil
			}
			return v, nil
		}
		return nil, fmt.Errorf("can't locate SSA Value for var %s", obj.Name())
	}

	// Don't run pointer analysis on const/func objects.
	return nil, nil
}
Example #11
0
func (c *funcContext) initType(o types.Object) {
	if _, isInterface := o.Type().Underlying().(*types.Interface); !isInterface {
		writeMethodSet := func(t types.Type) {
			methodSet := types.NewMethodSet(t)
			if methodSet.Len() == 0 {
				return
			}
			methods := make([]string, methodSet.Len())
			for i := range methods {
				method := methodSet.At(i)
				pkgPath := ""
				if !method.Obj().Exported() {
					pkgPath = method.Obj().Pkg().Path()
				}
				t := method.Type().(*types.Signature)
				embeddedIndex := -1
				if len(method.Index()) > 1 {
					embeddedIndex = method.Index()[0]
				}
				methods[i] = fmt.Sprintf(`["%s", "%s", %s, %s, %t, %d]`, method.Obj().Name(), pkgPath, c.typeArray(t.Params()), c.typeArray(t.Results()), t.Variadic(), embeddedIndex)
			}
			c.Printf("%s.methods = [%s];", c.typeName(t), strings.Join(methods, ", "))
		}
		writeMethodSet(o.Type())
		writeMethodSet(types.NewPointer(o.Type()))
	}
	switch t := o.Type().Underlying().(type) {
	case *types.Array, *types.Chan, *types.Interface, *types.Map, *types.Pointer, *types.Slice, *types.Signature, *types.Struct:
		c.Printf("%s.init(%s);", c.objectName(o), c.initArgs(t))
	}
}
Example #12
0
func (w *Walker) emitObj(obj types.Object) {
	switch obj := obj.(type) {
	case *types.Const:
		w.emitf("const %s %s", obj.Name(), w.typeString(obj.Type()))

	case *types.Var:
		w.emitf("var %s %s", obj.Name(), w.typeString(obj.Type()))

	case *types.TypeName:
		w.emitType(obj)

	case *types.Func:
		w.emitFunc(obj)

	default:
		panic("unknown object: " + obj.String())
	}
}
Example #13
0
func objectKind(obj types.Object) string {
	switch obj := obj.(type) {
	case *types.PkgName:
		return "imported package name"
	case *types.TypeName:
		return "type"
	case *types.Var:
		if obj.IsField() {
			return "field"
		}
	case *types.Func:
		if obj.Type().(*types.Signature).Recv() != nil {
			return "method"
		}
	}
	// label, func, var, const
	return strings.ToLower(strings.TrimPrefix(reflect.TypeOf(obj).String(), "*types."))
}
Example #14
0
// addSpilledParam declares a parameter that is pre-spilled to the
// stack; the function body will load/store the spilled location.
// Subsequent lifting will eliminate spills where possible.
//
func (f *Function) addSpilledParam(obj types.Object) {
	name := obj.Name()
	param := f.addParam(name, obj.Type())
	spill := &Alloc{
		Name_: name + "~", // "~" means "spilled"
		Type_: pointer(obj.Type()),
		pos:   obj.Pos(),
	}
	f.objects[obj] = spill
	f.Locals = append(f.Locals, spill)
	f.emit(spill)
	f.emit(&Store{Addr: spill, Val: param})
}
Example #15
0
// ssaValueForIdent returns the ssa.Value for the ast.Ident whose path
// to the root of the AST is path.  isAddr reports whether the
// ssa.Value is the address denoted by the ast.Ident, not its value.
//
func ssaValueForIdent(prog *ssa.Program, qinfo *loader.PackageInfo, obj types.Object, path []ast.Node) (value ssa.Value, isAddr bool, err error) {
	switch obj := obj.(type) {
	case *types.Var:
		pkg := prog.Package(qinfo.Pkg)
		pkg.Build()
		if v, addr := prog.VarValue(obj, pkg, path); v != nil {
			return v, addr, nil
		}
		return nil, false, fmt.Errorf("can't locate SSA Value for var %s", obj.Name())

	case *types.Func:
		fn := prog.FuncValue(obj)
		if fn == nil {
			return nil, false, fmt.Errorf("%s is an interface method", obj)
		}
		// TODO(adonovan): there's no point running PTA on a *Func ident.
		// Eliminate this feature.
		return fn, false, nil
	}
	panic(obj)
}
Example #16
0
func (f *File) checkNilFuncComparison(e *ast.BinaryExpr) {
	if !vet("nilfunc") {
		return
	}

	// Only want == or != comparisons.
	if e.Op != token.EQL && e.Op != token.NEQ {
		return
	}

	// Only want comparisons with a nil identifier on one side.
	var e2 ast.Expr
	switch {
	case f.isNil(e.X):
		e2 = e.Y
	case f.isNil(e.Y):
		e2 = e.X
	default:
		return
	}

	// Only want identifiers or selector expressions.
	var obj types.Object
	switch v := e2.(type) {
	case *ast.Ident:
		obj = f.pkg.idents[v]
	case *ast.SelectorExpr:
		obj = f.pkg.idents[v.Sel]
	default:
		return
	}

	// Only want functions.
	if _, ok := obj.(*types.Func); !ok {
		return
	}

	f.Badf(e.Pos(), "comparison of function %v %v nil is always %v", obj.Name(), e.Op, e.Op == token.NEQ)
}
Example #17
0
func (r *renamer) selectionConflict(from types.Object, delta int, syntax *ast.SelectorExpr, obj types.Object) {
	r.errorf(from.Pos(), "renaming this %s %q to %q",
		objectKind(from), from.Name(), r.to)

	switch {
	case delta < 0:
		// analogous to sub-block conflict
		r.errorf(syntax.Sel.Pos(),
			"\twould change the referent of this selection")
		r.errorf(obj.Pos(), "\tto this %s", objectKind(obj))
	case delta == 0:
		// analogous to same-block conflict
		r.errorf(syntax.Sel.Pos(),
			"\twould make this reference ambiguous")
		r.errorf(obj.Pos(), "\twith this %s", objectKind(obj))
	case delta > 0:
		// analogous to super-block conflict
		r.errorf(syntax.Sel.Pos(),
			"\twould shadow this selection")
		r.errorf(obj.Pos(), "\tto the %s declared here",
			objectKind(obj))
	}
}
Example #18
0
func (f *Function) addParamObj(obj types.Object) *Parameter {
	name := obj.Name()
	if name == "" {
		name = fmt.Sprintf("arg%d", len(f.Params))
	}
	param := f.addParam(name, obj.Type(), obj.Pos())
	param.object = obj
	return param
}
Example #19
0
func (p *printer) printObj(obj types.Object) {
	p.print(obj.Name())

	typ, basic := obj.Type().Underlying().(*types.Basic)
	if basic && typ.Info()&types.IsUntyped != 0 {
		// don't write untyped types
	} else {
		p.print(" ")
		p.writeType(p.pkg, obj.Type())
	}

	if obj, ok := obj.(*types.Const); ok {
		floatFmt := basic && typ.Info()&(types.IsFloat|types.IsComplex) != 0
		p.print(" = ")
		p.print(valString(obj.Val(), floatFmt))
	}
}
Example #20
0
// check performs safety checks of the renaming of the 'from' object to r.to.
func (r *renamer) check(from types.Object) {
	if r.objsToUpdate[from] {
		return
	}
	r.objsToUpdate[from] = true

	// NB: order of conditions is important.
	if from_, ok := from.(*types.PkgName); ok {
		r.checkInFileBlock(from_)
	} else if from_, ok := from.(*types.Label); ok {
		r.checkLabel(from_)
	} else if isPackageLevel(from) {
		r.checkInPackageBlock(from)
	} else if v, ok := from.(*types.Var); ok && v.IsField() {
		r.checkStructField(v)
	} else if f, ok := from.(*types.Func); ok && f.Type().(*types.Signature).Recv() != nil {
		r.checkMethod(f)
	} else if isLocal(from) {
		r.checkInLocalScope(from)
	} else {
		r.errorf(from.Pos(), "unexpected %s object %q (please report a bug)\n",
			objectKind(from), from)
	}
}
Example #21
0
// addSpilledParam declares a parameter that is pre-spilled to the
// stack; the function body will load/store the spilled location.
// Subsequent lifting will eliminate spills where possible.
//
func (f *Function) addSpilledParam(obj types.Object) {
	param := f.addParamObj(obj)
	spill := &Alloc{Comment: obj.Name()}
	spill.setType(types.NewPointer(obj.Type()))
	spill.setPos(obj.Pos())
	f.objects[obj] = spill
	f.Locals = append(f.Locals, spill)
	f.emit(spill)
	f.emit(&Store{Addr: spill, Val: param})
}
Example #22
0
func (p *printer) printObj(obj types.Object) {
	p.printf("%s", obj.Name())
	// don't write untyped types (for constants)
	if typ := obj.Type(); typed(typ) {
		p.print(" ")
		p.writeType(p.pkg, typ)
	}
	// write constant value
	if obj, ok := obj.(*types.Const); ok {
		p.printf(" = %s", obj.Val())
	}
}
Example #23
0
func (c *compiler) newStackVarEx(argument int, stackf *LLVMValue, v types.Object, value llvm.Value, name string) (stackvalue llvm.Value, stackvar *LLVMValue) {
	typ := v.Type()

	// We need to put alloca instructions in the top block or the values
	// displayed when inspecting these variables in a debugger will be
	// completely messed up.
	curBlock := c.builder.GetInsertBlock()
	if p := curBlock.Parent(); !p.IsNil() {
		fb := p.FirstBasicBlock()
		fi := fb.FirstInstruction()
		if !fb.IsNil() && !fi.IsNil() {
			c.builder.SetInsertPointBefore(fi)
		}
	}
	old := c.builder.CurrentDebugLocation()
	c.builder.SetCurrentDebugLocation(llvm.Value{})
	stackvalue = c.builder.CreateAlloca(c.types.ToLLVM(typ), name)

	// For arguments we want to insert the store instruction
	// without debug information to ensure that they are executed
	// (and hence have proper values) before the debugger hits the
	// first line in a function.
	if argument == 0 {
		c.builder.SetCurrentDebugLocation(old)
		c.builder.SetInsertPointAtEnd(curBlock)
	}

	if !value.IsNil() {
		c.builder.CreateStore(value, stackvalue)
	}
	c.builder.SetCurrentDebugLocation(old)
	c.builder.SetInsertPointAtEnd(curBlock)

	ptrvalue := c.NewValue(stackvalue, types.NewPointer(typ))
	stackvar = ptrvalue.makePointee()
	stackvar.stack = stackf
	c.objectdata[v].Value = stackvar

	file := c.fileset.File(v.Pos())
	tag := llvm.DW_TAG_auto_variable
	if argument > 0 {
		tag = llvm.DW_TAG_arg_variable
	}
	ld := llvm.NewLocalVariableDescriptor(tag)
	ld.Argument = uint32(argument)
	ld.Line = uint32(file.Line(v.Pos()))
	ld.Name = name
	ld.File = &llvm.ContextDescriptor{llvm.FileDescriptor(file.Name())}
	ld.Type = c.tollvmDebugDescriptor(typ)
	ld.Context = c.currentDebugContext()
	c.builder.InsertDeclare(c.module.Module, llvm.MDNode([]llvm.Value{stackvalue}), c.debug_info.MDNode(ld))
	return stackvalue, stackvar
}
Example #24
0
func (r *renamer) checkExport(id *ast.Ident, pkg *types.Package, from types.Object) bool {
	// Reject cross-package references if r.to is unexported.
	// (Such references may be qualified identifiers or field/method
	// selections.)
	if !ast.IsExported(r.to) && pkg != from.Pkg() {
		r.errorf(from.Pos(),
			"renaming this %s %q to %q would make it unexported",
			objectKind(from), from.Name(), r.to)
		r.errorf(id.Pos(), "\tbreaking references from packages such as %q",
			pkg.Path())
		return false
	}
	return true
}
Example #25
0
func (cdd *CDD) Name(w *bytes.Buffer, obj types.Object, direct bool) {
	if obj == nil {
		w.WriteByte('_')
		return
	}
	switch o := obj.(type) {
	case *types.PkgName:
		// Imported package name in SelectorExpr: pkgname.Name
		w.WriteString(upath(o.Pkg().Path()))
		return

	case *types.Func:
		s := o.Type().(*types.Signature)
		if r := s.Recv(); r != nil {
			t := r.Type()
			if p, ok := t.(*types.Pointer); ok {
				t = p.Elem()
				direct = false
			}
			cdd.Type(w, t)
			w.WriteByte('$')
			w.WriteString(o.Name())
			if !cdd.gtc.isLocal(t.(*types.Named).Obj()) {
				cdd.addObject(o, direct)
			}
			return
		}
	}

	if p := obj.Pkg(); p != nil && !cdd.gtc.isLocal(obj) {
		cdd.addObject(obj, direct)
		w.WriteString(upath(obj.Pkg().Path()))
		w.WriteByte('$')
	}
	name := obj.Name()
	switch name {
	case "init":
		w.WriteString(cdd.gtc.uniqueId() + name)

	default:
		w.WriteString(name)
		if cdd.gtc.isLocal(obj) {
			w.WriteByte('$')
		}
	}
}
Example #26
0
// createLocalVariableMetadata creates and returns a debug descriptor for
// a local variable in a function.
//
// obj is the go/types object for the var.
// paramIndex is 0 for "auto" variables (non-parameter stack vars), and a
// 1-based index for parameter vars.
func (c *compiler) createLocalVariableMetadata(obj types.Object, paramIndex int) llvm.DebugDescriptor {
	ctx := c.currentDebugContext()
	if ctx == nil {
		return nil
	}
	tag := llvm.DW_TAG_auto_variable
	if paramIndex > 0 {
		tag = llvm.DW_TAG_arg_variable
	}
	position := c.fileset.Position(obj.Pos())
	ld := llvm.NewLocalVariableDescriptor(tag)
	ld.Argument = uint32(paramIndex)
	ld.Line = uint32(position.Line)
	ld.Name = obj.Name()
	ld.File = &llvm.ContextDescriptor{llvm.FileDescriptor(position.Filename)}
	ld.Type = c.tollvmDebugDescriptor(obj.Type())
	ld.Context = ctx
	return ld
}
Example #27
0
func isAccessibleFrom(obj types.Object, pkg *types.Package) bool {
	return ast.IsExported(obj.Name()) || obj.Pkg() == pkg
}
Example #28
0
func formatMember(obj types.Object, maxname int) string {
	var buf bytes.Buffer
	fmt.Fprintf(&buf, "%-5s %-*s", tokenOf(obj), maxname, obj.Name())
	switch obj := obj.(type) {
	case *types.Const:
		fmt.Fprintf(&buf, " %s = %s", types.TypeString(obj.Pkg(), obj.Type()), obj.Val().String())

	case *types.Func:
		fmt.Fprintf(&buf, " %s", types.TypeString(obj.Pkg(), obj.Type()))

	case *types.TypeName:
		// Abbreviate long aggregate type names.
		var abbrev string
		switch t := obj.Type().Underlying().(type) {
		case *types.Interface:
			if t.NumMethods() > 1 {
				abbrev = "interface{...}"
			}
		case *types.Struct:
			if t.NumFields() > 1 {
				abbrev = "struct{...}"
			}
		}
		if abbrev == "" {
			fmt.Fprintf(&buf, " %s", types.TypeString(obj.Pkg(), obj.Type().Underlying()))
		} else {
			fmt.Fprintf(&buf, " %s", abbrev)
		}

	case *types.Var:
		fmt.Fprintf(&buf, " %s", types.TypeString(obj.Pkg(), obj.Type()))
	}
	return buf.String()
}
Example #29
0
// checkInPackageBlock performs safety checks for renames of
// func/var/const/type objects in the package block.
func (r *renamer) checkInPackageBlock(from types.Object) {
	// Check that there are no references to the name from another
	// package if the renaming would make it unexported.
	if ast.IsExported(from.Name()) && !ast.IsExported(r.to) {
		for pkg, info := range r.packages {
			if pkg == from.Pkg() {
				continue
			}
			if id := someUse(info, from); id != nil &&
				!r.checkExport(id, pkg, from) {
				break
			}
		}
	}

	info := r.packages[from.Pkg()]
	lexinfo := lexical.Structure(r.iprog.Fset, from.Pkg(), &info.Info, info.Files)

	// Check that in the package block, "init" is a function, and never referenced.
	if r.to == "init" {
		kind := objectKind(from)
		if kind == "func" {
			// Reject if intra-package references to it exist.
			if refs := lexinfo.Refs[from]; len(refs) > 0 {
				r.errorf(from.Pos(),
					"renaming this func %q to %q would make it a package initializer",
					from.Name(), r.to)
				r.errorf(refs[0].Id.Pos(), "\tbut references to it exist")
			}
		} else {
			r.errorf(from.Pos(), "you cannot have a %s at package level named %q",
				kind, r.to)
		}
	}

	// Check for conflicts between package block and all file blocks.
	for _, f := range info.Files {
		if prev, b := lexinfo.Blocks[f].Lookup(r.to); b == lexinfo.Blocks[f] {
			r.errorf(from.Pos(), "renaming this %s %q to %q would conflict",
				objectKind(from), from.Name(), r.to)
			r.errorf(prev.Pos(), "\twith this %s",
				objectKind(prev))
			return // since checkInPackageBlock would report redundant errors
		}
	}

	// Check for conflicts in lexical scope.
	if from.Exported() {
		for _, info := range r.packages {
			r.checkInLexicalScope(from, info)
		}
	} else {
		r.checkInLexicalScope(from, info)
	}
}
Example #30
0
// checkInLexicalScope performs safety checks that a renaming does not
// change the lexical reference structure of the specified package.
//
// For objects in lexical scope, there are three kinds of conflicts:
// same-, sub-, and super-block conflicts.  We will illustrate all three
// using this example:
//
//      var x int
//	var z int
//
//	func f(y int) {
//		print(x)
//		print(y)
//	}
//
// Renaming x to z encounters a SAME-BLOCK CONFLICT, because an object
// with the new name already exists, defined in the same lexical block
// as the old object.
//
// Renaming x to y encounters a SUB-BLOCK CONFLICT, because there exists
// a reference to x from within (what would become) a hole in its scope.
// The definition of y in an (inner) sub-block would cast a shadow in
// the scope of the renamed variable.
//
// Renaming y to x encounters a SUPER-BLOCK CONFLICT.  This is the
// converse situation: there is an existing definition of the new name
// (x) in an (enclosing) super-block, and the renaming would create a
// hole in its scope, within which there exist references to it.  The
// new name casts a shadow in scope of the existing definition of x in
// the super-block.
//
// Removing the old name (and all references to it) is always safe, and
// requires no checks.
//
func (r *renamer) checkInLexicalScope(from types.Object, info *loader.PackageInfo) {
	lexinfo := lexical.Structure(r.iprog.Fset, info.Pkg, &info.Info, info.Files)

	b := lexinfo.Defs[from] // the block defining the 'from' object
	if b != nil {
		to, toBlock := b.Lookup(r.to)
		if toBlock == b {
			// same-block conflict
			r.errorf(from.Pos(), "renaming this %s %q to %q",
				objectKind(from), from.Name(), r.to)
			r.errorf(to.Pos(), "\tconflicts with %s in same block",
				objectKind(to))
			return
		} else if toBlock != nil {
			// Check for super-block conflict.
			// The name r.to is defined in a superblock.
			// Is that name referenced from within this block?
			for _, ref := range lexinfo.Refs[to] {
				if obj, _ := ref.Env.Lookup(from.Name()); obj == from {
					// super-block conflict
					r.errorf(from.Pos(), "renaming this %s %q to %q",
						objectKind(from), from.Name(), r.to)
					r.errorf(ref.Id.Pos(), "\twould shadow this reference")
					r.errorf(to.Pos(), "\tto the %s declared here",
						objectKind(to))
					return
				}
			}
		}
	}

	// Check for sub-block conflict.
	// Is there an intervening definition of r.to between
	// the block defining 'from' and some reference to it?
	for _, ref := range lexinfo.Refs[from] {
		// TODO(adonovan): think about dot imports.
		// (Is b == fromBlock an invariant?)
		_, fromBlock := ref.Env.Lookup(from.Name())
		fromDepth := fromBlock.Depth()

		to, toBlock := ref.Env.Lookup(r.to)
		if to != nil {
			// sub-block conflict
			if toBlock.Depth() > fromDepth {
				r.errorf(from.Pos(), "renaming this %s %q to %q",
					objectKind(from), from.Name(), r.to)
				r.errorf(ref.Id.Pos(), "\twould cause this reference to become shadowed")
				r.errorf(to.Pos(), "\tby this intervening %s definition",
					objectKind(to))
				return
			}
		}
	}

	// Renaming a type that is used as an embedded field
	// requires renaming the field too. e.g.
	// 	type T int // if we rename this to U..
	// 	var s struct {T}
	// 	print(s.T) // ...this must change too
	if _, ok := from.(*types.TypeName); ok {
		for id, obj := range info.Uses {
			if obj == from {
				if field := info.Defs[id]; field != nil {
					r.check(field)
				}
			}
		}
	}
}