// checkInPackageBlock performs safety checks for renames of
// func/var/const/type objects in the package block.
func (e *Export) checkInPackageBlock(from types.Object, to string) {
info := e.u.pkgInfo
lexinfo := lexical.Structure(e.u.prog.Fset, from.Pkg(), &info.Info, info.Files)
// We don't rename anything in the package block to init, as that might
// conflict or otherwise break stuff
if to == "init" {
e.Conflicting = true
return
}
// Check for conflicts between package block and all file blocks.
for _, f := range info.Files {
if _, b := lexinfo.Blocks[f].Lookup(to); b == lexinfo.Blocks[f] {
e.Conflicting = true
return
}
}
if f, ok := from.(*types.Func); ok && recv(f) == nil {
e.checkFunction(f, to)
if e.Conflicting {
return
}
}
// Check for conflicts in lexical scope.
// Do not need to check all imported packages:
// Since it's unnecessarily exported, no one else is going to be sad if I unexport it!
e.checkInLexicalScope(from, to)
}
// 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)
}
}
func (r *Unexporter) lexInfo(info *loader.PackageInfo) *lexical.Info {
r.mutex.Lock()
defer r.mutex.Unlock()
if lexinfo := r.lexinfos[info]; lexinfo != nil {
return lexinfo
} else {
lexinfo := lexical.Structure(r.iprog.Fset, info.Pkg, &info.Info, info.Files)
r.lexinfos[info] = lexinfo
return lexinfo
}
}
func (e *Export) checkInLexicalScope(from types.Object, to string) {
info := e.u.pkgInfo
lexinfo := lexical.Structure(e.u.prog.Fset, info.Pkg, &info.Info, info.Files)
b := lexinfo.Defs[from] // the block defining the 'from' object
if b != nil {
to, toBlock := b.Lookup(to)
if toBlock == b {
e.Conflicting = true
return // same-block conflict
} else if toBlock != nil {
for _, ref := range lexinfo.Refs[to] {
if obj, _ := ref.Env.Lookup(from.Name()); obj == from {
e.Conflicting = true
return // super-block conflict
}
}
}
}
// 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] {
_, fromBlock := ref.Env.Lookup(from.Name())
fromDepth := fromBlock.Depth()
to, toBlock := ref.Env.Lookup(to)
if to != nil {
// sub-block conflict
if toBlock.Depth() > fromDepth {
e.Conflicting = true
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 {
e.check(field, to)
}
}
}
}
}
// 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)
}
}
}
}
}