| 1 | // Copyright 2014 The Go Authors. All rights reserved. |
|---|---|
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package rename |
| 6 | |
| 7 | // This file defines the safety checks for each kind of renaming. |
| 8 | |
| 9 | import ( |
| 10 | "fmt" |
| 11 | "go/ast" |
| 12 | "go/token" |
| 13 | "go/types" |
| 14 | |
| 15 | "golang.org/x/tools/go/loader" |
| 16 | "golang.org/x/tools/refactor/satisfy" |
| 17 | ) |
| 18 | |
| 19 | // errorf reports an error (e.g. conflict) and prevents file modification. |
| 20 | func (r *renamer) errorf(pos token.Pos, format string, args ...interface{}) { |
| 21 | r.hadConflicts = true |
| 22 | reportError(r.iprog.Fset.Position(pos), fmt.Sprintf(format, args...)) |
| 23 | } |
| 24 | |
| 25 | // check performs safety checks of the renaming of the 'from' object to r.to. |
| 26 | func (r *renamer) check(from types.Object) { |
| 27 | if r.objsToUpdate[from] { |
| 28 | return |
| 29 | } |
| 30 | r.objsToUpdate[from] = true |
| 31 | |
| 32 | // NB: order of conditions is important. |
| 33 | if from_, ok := from.(*types.PkgName); ok { |
| 34 | r.checkInFileBlock(from_) |
| 35 | } else if from_, ok := from.(*types.Label); ok { |
| 36 | r.checkLabel(from_) |
| 37 | } else if isPackageLevel(from) { |
| 38 | r.checkInPackageBlock(from) |
| 39 | } else if v, ok := from.(*types.Var); ok && v.IsField() { |
| 40 | r.checkStructField(v) |
| 41 | } else if f, ok := from.(*types.Func); ok && recv(f) != nil { |
| 42 | r.checkMethod(f) |
| 43 | } else if isLocal(from) { |
| 44 | r.checkInLocalScope(from) |
| 45 | } else { |
| 46 | r.errorf(from.Pos(), "unexpected %s object %q (please report a bug)\n", |
| 47 | objectKind(from), from) |
| 48 | } |
| 49 | } |
| 50 | |
| 51 | // checkInFileBlock performs safety checks for renames of objects in the file block, |
| 52 | // i.e. imported package names. |
| 53 | func (r *renamer) checkInFileBlock(from *types.PkgName) { |
| 54 | // Check import name is not "init". |
| 55 | if r.to == "init" { |
| 56 | r.errorf(from.Pos(), "%q is not a valid imported package name", r.to) |
| 57 | } |
| 58 | |
| 59 | // Check for conflicts between file and package block. |
| 60 | if prev := from.Pkg().Scope().Lookup(r.to); prev != nil { |
| 61 | r.errorf(from.Pos(), "renaming this %s %q to %q would conflict", |
| 62 | objectKind(from), from.Name(), r.to) |
| 63 | r.errorf(prev.Pos(), "\twith this package member %s", |
| 64 | objectKind(prev)) |
| 65 | return // since checkInPackageBlock would report redundant errors |
| 66 | } |
| 67 | |
| 68 | // Check for conflicts in lexical scope. |
| 69 | r.checkInLexicalScope(from, r.packages[from.Pkg()]) |
| 70 | |
| 71 | // Finally, modify ImportSpec syntax to add or remove the Name as needed. |
| 72 | info, path, _ := r.iprog.PathEnclosingInterval(from.Pos(), from.Pos()) |
| 73 | if from.Imported().Name() == r.to { |
| 74 | // ImportSpec.Name not needed |
| 75 | path[1].(*ast.ImportSpec).Name = nil |
| 76 | } else { |
| 77 | // ImportSpec.Name needed |
| 78 | if spec := path[1].(*ast.ImportSpec); spec.Name == nil { |
| 79 | spec.Name = &ast.Ident{NamePos: spec.Path.Pos(), Name: r.to} |
| 80 | info.Defs[spec.Name] = from |
| 81 | } |
| 82 | } |
| 83 | } |
| 84 | |
| 85 | // checkInPackageBlock performs safety checks for renames of |
| 86 | // func/var/const/type objects in the package block. |
| 87 | func (r *renamer) checkInPackageBlock(from types.Object) { |
| 88 | // Check that there are no references to the name from another |
| 89 | // package if the renaming would make it unexported. |
| 90 | if ast.IsExported(from.Name()) && !ast.IsExported(r.to) { |
| 91 | for pkg, info := range r.packages { |
| 92 | if pkg == from.Pkg() { |
| 93 | continue |
| 94 | } |
| 95 | if id := someUse(info, from); id != nil && |
| 96 | !r.checkExport(id, pkg, from) { |
| 97 | break |
| 98 | } |
| 99 | } |
| 100 | } |
| 101 | |
| 102 | info := r.packages[from.Pkg()] |
| 103 | |
| 104 | // Check that in the package block, "init" is a function, and never referenced. |
| 105 | if r.to == "init" { |
| 106 | kind := objectKind(from) |
| 107 | if kind == "func" { |
| 108 | // Reject if intra-package references to it exist. |
| 109 | for id, obj := range info.Uses { |
| 110 | if obj == from { |
| 111 | r.errorf(from.Pos(), |
| 112 | "renaming this func %q to %q would make it a package initializer", |
| 113 | from.Name(), r.to) |
| 114 | r.errorf(id.Pos(), "\tbut references to it exist") |
| 115 | break |
| 116 | } |
| 117 | } |
| 118 | } else { |
| 119 | r.errorf(from.Pos(), "you cannot have a %s at package level named %q", |
| 120 | kind, r.to) |
| 121 | } |
| 122 | } |
| 123 | |
| 124 | // Check for conflicts between package block and all file blocks. |
| 125 | for _, f := range info.Files { |
| 126 | fileScope := info.Info.Scopes[f] |
| 127 | b, prev := fileScope.LookupParent(r.to, token.NoPos) |
| 128 | if b == fileScope { |
| 129 | r.errorf(from.Pos(), "renaming this %s %q to %q would conflict", |
| 130 | objectKind(from), from.Name(), r.to) |
| 131 | r.errorf(prev.Pos(), "\twith this %s", |
| 132 | objectKind(prev)) |
| 133 | return // since checkInPackageBlock would report redundant errors |
| 134 | } |
| 135 | } |
| 136 | |
| 137 | // Check for conflicts in lexical scope. |
| 138 | if from.Exported() { |
| 139 | for _, info := range r.packages { |
| 140 | r.checkInLexicalScope(from, info) |
| 141 | } |
| 142 | } else { |
| 143 | r.checkInLexicalScope(from, info) |
| 144 | } |
| 145 | } |
| 146 | |
| 147 | func (r *renamer) checkInLocalScope(from types.Object) { |
| 148 | info := r.packages[from.Pkg()] |
| 149 | |
| 150 | // Is this object an implicit local var for a type switch? |
| 151 | // Each case has its own var, whose position is the decl of y, |
| 152 | // but Ident in that decl does not appear in the Uses map. |
| 153 | // |
| 154 | // switch y := x.(type) { // Defs[Ident(y)] is undefined |
| 155 | // case int: print(y) // Implicits[CaseClause(int)] = Var(y_int) |
| 156 | // case string: print(y) // Implicits[CaseClause(string)] = Var(y_string) |
| 157 | // } |
| 158 | // |
| 159 | var isCaseVar bool |
| 160 | for syntax, obj := range info.Implicits { |
| 161 | if _, ok := syntax.(*ast.CaseClause); ok && obj.Pos() == from.Pos() { |
| 162 | isCaseVar = true |
| 163 | r.check(obj) |
| 164 | } |
| 165 | } |
| 166 | |
| 167 | r.checkInLexicalScope(from, info) |
| 168 | |
| 169 | // Finally, if this was a type switch, change the variable y. |
| 170 | if isCaseVar { |
| 171 | _, path, _ := r.iprog.PathEnclosingInterval(from.Pos(), from.Pos()) |
| 172 | path[0].(*ast.Ident).Name = r.to // path is [Ident AssignStmt TypeSwitchStmt...] |
| 173 | } |
| 174 | } |
| 175 | |
| 176 | // checkInLexicalScope performs safety checks that a renaming does not |
| 177 | // change the lexical reference structure of the specified package. |
| 178 | // |
| 179 | // For objects in lexical scope, there are three kinds of conflicts: |
| 180 | // same-, sub-, and super-block conflicts. We will illustrate all three |
| 181 | // using this example: |
| 182 | // |
| 183 | // var x int |
| 184 | // var z int |
| 185 | // |
| 186 | // func f(y int) { |
| 187 | // print(x) |
| 188 | // print(y) |
| 189 | // } |
| 190 | // |
| 191 | // Renaming x to z encounters a SAME-BLOCK CONFLICT, because an object |
| 192 | // with the new name already exists, defined in the same lexical block |
| 193 | // as the old object. |
| 194 | // |
| 195 | // Renaming x to y encounters a SUB-BLOCK CONFLICT, because there exists |
| 196 | // a reference to x from within (what would become) a hole in its scope. |
| 197 | // The definition of y in an (inner) sub-block would cast a shadow in |
| 198 | // the scope of the renamed variable. |
| 199 | // |
| 200 | // Renaming y to x encounters a SUPER-BLOCK CONFLICT. This is the |
| 201 | // converse situation: there is an existing definition of the new name |
| 202 | // (x) in an (enclosing) super-block, and the renaming would create a |
| 203 | // hole in its scope, within which there exist references to it. The |
| 204 | // new name casts a shadow in scope of the existing definition of x in |
| 205 | // the super-block. |
| 206 | // |
| 207 | // Removing the old name (and all references to it) is always safe, and |
| 208 | // requires no checks. |
| 209 | func (r *renamer) checkInLexicalScope(from types.Object, info *loader.PackageInfo) { |
| 210 | b := from.Parent() // the block defining the 'from' object |
| 211 | if b != nil { |
| 212 | toBlock, to := b.LookupParent(r.to, from.Parent().End()) |
| 213 | if toBlock == b { |
| 214 | // same-block conflict |
| 215 | r.errorf(from.Pos(), "renaming this %s %q to %q", |
| 216 | objectKind(from), from.Name(), r.to) |
| 217 | r.errorf(to.Pos(), "\tconflicts with %s in same block", |
| 218 | objectKind(to)) |
| 219 | return |
| 220 | } else if toBlock != nil { |
| 221 | // Check for super-block conflict. |
| 222 | // The name r.to is defined in a superblock. |
| 223 | // Is that name referenced from within this block? |
| 224 | forEachLexicalRef(info, to, func(id *ast.Ident, block *types.Scope) bool { |
| 225 | _, obj := lexicalLookup(block, from.Name(), id.Pos()) |
| 226 | if obj == from { |
| 227 | // super-block conflict |
| 228 | r.errorf(from.Pos(), "renaming this %s %q to %q", |
| 229 | objectKind(from), from.Name(), r.to) |
| 230 | r.errorf(id.Pos(), "\twould shadow this reference") |
| 231 | r.errorf(to.Pos(), "\tto the %s declared here", |
| 232 | objectKind(to)) |
| 233 | return false // stop |
| 234 | } |
| 235 | return true |
| 236 | }) |
| 237 | } |
| 238 | } |
| 239 | |
| 240 | // Check for sub-block conflict. |
| 241 | // Is there an intervening definition of r.to between |
| 242 | // the block defining 'from' and some reference to it? |
| 243 | forEachLexicalRef(info, from, func(id *ast.Ident, block *types.Scope) bool { |
| 244 | // Find the block that defines the found reference. |
| 245 | // It may be an ancestor. |
| 246 | fromBlock, _ := lexicalLookup(block, from.Name(), id.Pos()) |
| 247 | |
| 248 | // See what r.to would resolve to in the same scope. |
| 249 | toBlock, to := lexicalLookup(block, r.to, id.Pos()) |
| 250 | if to != nil { |
| 251 | // sub-block conflict |
| 252 | if deeper(toBlock, fromBlock) { |
| 253 | r.errorf(from.Pos(), "renaming this %s %q to %q", |
| 254 | objectKind(from), from.Name(), r.to) |
| 255 | r.errorf(id.Pos(), "\twould cause this reference to become shadowed") |
| 256 | r.errorf(to.Pos(), "\tby this intervening %s definition", |
| 257 | objectKind(to)) |
| 258 | return false // stop |
| 259 | } |
| 260 | } |
| 261 | return true |
| 262 | }) |
| 263 | |
| 264 | // Renaming a type that is used as an embedded field |
| 265 | // requires renaming the field too. e.g. |
| 266 | // type T int // if we rename this to U.. |
| 267 | // var s struct {T} |
| 268 | // print(s.T) // ...this must change too |
| 269 | if _, ok := from.(*types.TypeName); ok { |
| 270 | for id, obj := range info.Uses { |
| 271 | if obj == from { |
| 272 | if field := info.Defs[id]; field != nil { |
| 273 | r.check(field) |
| 274 | } |
| 275 | } |
| 276 | } |
| 277 | } |
| 278 | } |
| 279 | |
| 280 | // lexicalLookup is like (*types.Scope).LookupParent but respects the |
| 281 | // environment visible at pos. It assumes the relative position |
| 282 | // information is correct with each file. |
| 283 | func lexicalLookup(block *types.Scope, name string, pos token.Pos) (*types.Scope, types.Object) { |
| 284 | for b := block; b != nil; b = b.Parent() { |
| 285 | obj := b.Lookup(name) |
| 286 | // The scope of a package-level object is the entire package, |
| 287 | // so ignore pos in that case. |
| 288 | // No analogous clause is needed for file-level objects |
| 289 | // since no reference can appear before an import decl. |
| 290 | if obj != nil && (b == obj.Pkg().Scope() || obj.Pos() < pos) { |
| 291 | return b, obj |
| 292 | } |
| 293 | } |
| 294 | return nil, nil |
| 295 | } |
| 296 | |
| 297 | // deeper reports whether block x is lexically deeper than y. |
| 298 | func deeper(x, y *types.Scope) bool { |
| 299 | if x == y || x == nil { |
| 300 | return false |
| 301 | } else if y == nil { |
| 302 | return true |
| 303 | } else { |
| 304 | return deeper(x.Parent(), y.Parent()) |
| 305 | } |
| 306 | } |
| 307 | |
| 308 | // forEachLexicalRef calls fn(id, block) for each identifier id in package |
| 309 | // info that is a reference to obj in lexical scope. block is the |
| 310 | // lexical block enclosing the reference. If fn returns false the |
| 311 | // iteration is terminated and findLexicalRefs returns false. |
| 312 | func forEachLexicalRef(info *loader.PackageInfo, obj types.Object, fn func(id *ast.Ident, block *types.Scope) bool) bool { |
| 313 | ok := true |
| 314 | var stack []ast.Node |
| 315 | |
| 316 | var visit func(n ast.Node) bool |
| 317 | visit = func(n ast.Node) bool { |
| 318 | if n == nil { |
| 319 | stack = stack[:len(stack)-1] // pop |
| 320 | return false |
| 321 | } |
| 322 | if !ok { |
| 323 | return false // bail out |
| 324 | } |
| 325 | |
| 326 | stack = append(stack, n) // push |
| 327 | switch n := n.(type) { |
| 328 | case *ast.Ident: |
| 329 | if info.Uses[n] == obj { |
| 330 | block := enclosingBlock(&info.Info, stack) |
| 331 | if !fn(n, block) { |
| 332 | ok = false |
| 333 | } |
| 334 | } |
| 335 | return visit(nil) // pop stack |
| 336 | |
| 337 | case *ast.SelectorExpr: |
| 338 | // don't visit n.Sel |
| 339 | ast.Inspect(n.X, visit) |
| 340 | return visit(nil) // pop stack, don't descend |
| 341 | |
| 342 | case *ast.CompositeLit: |
| 343 | // Handle recursion ourselves for struct literals |
| 344 | // so we don't visit field identifiers. |
| 345 | tv := info.Types[n] |
| 346 | if _, ok := deref(tv.Type).Underlying().(*types.Struct); ok { |
| 347 | if n.Type != nil { |
| 348 | ast.Inspect(n.Type, visit) |
| 349 | } |
| 350 | for _, elt := range n.Elts { |
| 351 | if kv, ok := elt.(*ast.KeyValueExpr); ok { |
| 352 | ast.Inspect(kv.Value, visit) |
| 353 | } else { |
| 354 | ast.Inspect(elt, visit) |
| 355 | } |
| 356 | } |
| 357 | return visit(nil) // pop stack, don't descend |
| 358 | } |
| 359 | } |
| 360 | return true |
| 361 | } |
| 362 | |
| 363 | for _, f := range info.Files { |
| 364 | ast.Inspect(f, visit) |
| 365 | if len(stack) != 0 { |
| 366 | panic(stack) |
| 367 | } |
| 368 | if !ok { |
| 369 | break |
| 370 | } |
| 371 | } |
| 372 | return ok |
| 373 | } |
| 374 | |
| 375 | // enclosingBlock returns the innermost block enclosing the specified |
| 376 | // AST node, specified in the form of a path from the root of the file, |
| 377 | // [file...n]. |
| 378 | func enclosingBlock(info *types.Info, stack []ast.Node) *types.Scope { |
| 379 | for i := range stack { |
| 380 | n := stack[len(stack)-1-i] |
| 381 | // For some reason, go/types always associates a |
| 382 | // function's scope with its FuncType. |
| 383 | // TODO(adonovan): feature or a bug? |
| 384 | switch f := n.(type) { |
| 385 | case *ast.FuncDecl: |
| 386 | n = f.Type |
| 387 | case *ast.FuncLit: |
| 388 | n = f.Type |
| 389 | } |
| 390 | if b := info.Scopes[n]; b != nil { |
| 391 | return b |
| 392 | } |
| 393 | } |
| 394 | panic("no Scope for *ast.File") |
| 395 | } |
| 396 | |
| 397 | func (r *renamer) checkLabel(label *types.Label) { |
| 398 | // Check there are no identical labels in the function's label block. |
| 399 | // (Label blocks don't nest, so this is easy.) |
| 400 | if prev := label.Parent().Lookup(r.to); prev != nil { |
| 401 | r.errorf(label.Pos(), "renaming this label %q to %q", label.Name(), prev.Name()) |
| 402 | r.errorf(prev.Pos(), "\twould conflict with this one") |
| 403 | } |
| 404 | } |
| 405 | |
| 406 | // checkStructField checks that the field renaming will not cause |
| 407 | // conflicts at its declaration, or ambiguity or changes to any selection. |
| 408 | func (r *renamer) checkStructField(from *types.Var) { |
| 409 | // Check that the struct declaration is free of field conflicts, |
| 410 | // and field/method conflicts. |
| 411 | |
| 412 | // go/types offers no easy way to get from a field (or interface |
| 413 | // method) to its declaring struct (or interface), so we must |
| 414 | // ascend the AST. |
| 415 | info, path, _ := r.iprog.PathEnclosingInterval(from.Pos(), from.Pos()) |
| 416 | // path matches this pattern: |
| 417 | // [Ident SelectorExpr? StarExpr? Field FieldList StructType ParenExpr* ... File] |
| 418 | |
| 419 | // Ascend to FieldList. |
| 420 | var i int |
| 421 | for { |
| 422 | if _, ok := path[i].(*ast.FieldList); ok { |
| 423 | break |
| 424 | } |
| 425 | i++ |
| 426 | } |
| 427 | i++ |
| 428 | tStruct := path[i].(*ast.StructType) |
| 429 | i++ |
| 430 | // Ascend past parens (unlikely). |
| 431 | for { |
| 432 | _, ok := path[i].(*ast.ParenExpr) |
| 433 | if !ok { |
| 434 | break |
| 435 | } |
| 436 | i++ |
| 437 | } |
| 438 | if spec, ok := path[i].(*ast.TypeSpec); ok { |
| 439 | // This struct is also a named type. |
| 440 | // We must check for direct (non-promoted) field/field |
| 441 | // and method/field conflicts. |
| 442 | named := info.Defs[spec.Name].Type() |
| 443 | prev, indices, _ := types.LookupFieldOrMethod(named, true, info.Pkg, r.to) |
| 444 | if len(indices) == 1 { |
| 445 | r.errorf(from.Pos(), "renaming this field %q to %q", |
| 446 | from.Name(), r.to) |
| 447 | r.errorf(prev.Pos(), "\twould conflict with this %s", |
| 448 | objectKind(prev)) |
| 449 | return // skip checkSelections to avoid redundant errors |
| 450 | } |
| 451 | } else { |
| 452 | // This struct is not a named type. |
| 453 | // We need only check for direct (non-promoted) field/field conflicts. |
| 454 | T := info.Types[tStruct].Type.Underlying().(*types.Struct) |
| 455 | for i := 0; i < T.NumFields(); i++ { |
| 456 | if prev := T.Field(i); prev.Name() == r.to { |
| 457 | r.errorf(from.Pos(), "renaming this field %q to %q", |
| 458 | from.Name(), r.to) |
| 459 | r.errorf(prev.Pos(), "\twould conflict with this field") |
| 460 | return // skip checkSelections to avoid redundant errors |
| 461 | } |
| 462 | } |
| 463 | } |
| 464 | |
| 465 | // Renaming an anonymous field requires renaming the type too. e.g. |
| 466 | // print(s.T) // if we rename T to U, |
| 467 | // type T int // this and |
| 468 | // var s struct {T} // this must change too. |
| 469 | if from.Anonymous() { |
| 470 | if named, ok := from.Type().(*types.Named); ok { |
| 471 | r.check(named.Obj()) |
| 472 | } else if named, ok := deref(from.Type()).(*types.Named); ok { |
| 473 | r.check(named.Obj()) |
| 474 | } |
| 475 | } |
| 476 | |
| 477 | // Check integrity of existing (field and method) selections. |
| 478 | r.checkSelections(from) |
| 479 | } |
| 480 | |
| 481 | // checkSelection checks that all uses and selections that resolve to |
| 482 | // the specified object would continue to do so after the renaming. |
| 483 | func (r *renamer) checkSelections(from types.Object) { |
| 484 | for pkg, info := range r.packages { |
| 485 | if id := someUse(info, from); id != nil { |
| 486 | if !r.checkExport(id, pkg, from) { |
| 487 | return |
| 488 | } |
| 489 | } |
| 490 | |
| 491 | for syntax, sel := range info.Selections { |
| 492 | // There may be extant selections of only the old |
| 493 | // name or only the new name, so we must check both. |
| 494 | // (If neither, the renaming is sound.) |
| 495 | // |
| 496 | // In both cases, we wish to compare the lengths |
| 497 | // of the implicit field path (Selection.Index) |
| 498 | // to see if the renaming would change it. |
| 499 | // |
| 500 | // If a selection that resolves to 'from', when renamed, |
| 501 | // would yield a path of the same or shorter length, |
| 502 | // this indicates ambiguity or a changed referent, |
| 503 | // analogous to same- or sub-block lexical conflict. |
| 504 | // |
| 505 | // If a selection using the name 'to' would |
| 506 | // yield a path of the same or shorter length, |
| 507 | // this indicates ambiguity or shadowing, |
| 508 | // analogous to same- or super-block lexical conflict. |
| 509 | |
| 510 | // TODO(adonovan): fix: derive from Types[syntax.X].Mode |
| 511 | // TODO(adonovan): test with pointer, value, addressable value. |
| 512 | isAddressable := true |
| 513 | |
| 514 | if sel.Obj() == from { |
| 515 | if obj, indices, _ := types.LookupFieldOrMethod(sel.Recv(), isAddressable, from.Pkg(), r.to); obj != nil { |
| 516 | // Renaming this existing selection of |
| 517 | // 'from' may block access to an existing |
| 518 | // type member named 'to'. |
| 519 | delta := len(indices) - len(sel.Index()) |
| 520 | if delta > 0 { |
| 521 | continue // no ambiguity |
| 522 | } |
| 523 | r.selectionConflict(from, delta, syntax, obj) |
| 524 | return |
| 525 | } |
| 526 | |
| 527 | } else if sel.Obj().Name() == r.to { |
| 528 | if obj, indices, _ := types.LookupFieldOrMethod(sel.Recv(), isAddressable, from.Pkg(), from.Name()); obj == from { |
| 529 | // Renaming 'from' may cause this existing |
| 530 | // selection of the name 'to' to change |
| 531 | // its meaning. |
| 532 | delta := len(indices) - len(sel.Index()) |
| 533 | if delta > 0 { |
| 534 | continue // no ambiguity |
| 535 | } |
| 536 | r.selectionConflict(from, -delta, syntax, sel.Obj()) |
| 537 | return |
| 538 | } |
| 539 | } |
| 540 | } |
| 541 | } |
| 542 | } |
| 543 | |
| 544 | func (r *renamer) selectionConflict(from types.Object, delta int, syntax *ast.SelectorExpr, obj types.Object) { |
| 545 | r.errorf(from.Pos(), "renaming this %s %q to %q", |
| 546 | objectKind(from), from.Name(), r.to) |
| 547 | |
| 548 | switch { |
| 549 | case delta < 0: |
| 550 | // analogous to sub-block conflict |
| 551 | r.errorf(syntax.Sel.Pos(), |
| 552 | "\twould change the referent of this selection") |
| 553 | r.errorf(obj.Pos(), "\tof this %s", objectKind(obj)) |
| 554 | case delta == 0: |
| 555 | // analogous to same-block conflict |
| 556 | r.errorf(syntax.Sel.Pos(), |
| 557 | "\twould make this reference ambiguous") |
| 558 | r.errorf(obj.Pos(), "\twith this %s", objectKind(obj)) |
| 559 | case delta > 0: |
| 560 | // analogous to super-block conflict |
| 561 | r.errorf(syntax.Sel.Pos(), |
| 562 | "\twould shadow this selection") |
| 563 | r.errorf(obj.Pos(), "\tof the %s declared here", |
| 564 | objectKind(obj)) |
| 565 | } |
| 566 | } |
| 567 | |
| 568 | // checkMethod performs safety checks for renaming a method. |
| 569 | // There are three hazards: |
| 570 | // - declaration conflicts |
| 571 | // - selection ambiguity/changes |
| 572 | // - entailed renamings of assignable concrete/interface types. |
| 573 | // |
| 574 | // We reject renamings initiated at concrete methods if it would |
| 575 | // change the assignability relation. For renamings of abstract |
| 576 | // methods, we rename all methods transitively coupled to it via |
| 577 | // assignability. |
| 578 | func (r *renamer) checkMethod(from *types.Func) { |
| 579 | // e.g. error.Error |
| 580 | if from.Pkg() == nil { |
| 581 | r.errorf(from.Pos(), "you cannot rename built-in method %s", from) |
| 582 | return |
| 583 | } |
| 584 | |
| 585 | // ASSIGNABILITY: We reject renamings of concrete methods that |
| 586 | // would break a 'satisfy' constraint; but renamings of abstract |
| 587 | // methods are allowed to proceed, and we rename affected |
| 588 | // concrete and abstract methods as necessary. It is the |
| 589 | // initial method that determines the policy. |
| 590 | |
| 591 | // Check for conflict at point of declaration. |
| 592 | // Check to ensure preservation of assignability requirements. |
| 593 | R := recv(from).Type() |
| 594 | if isInterface(R) { |
| 595 | // Abstract method |
| 596 | |
| 597 | // declaration |
| 598 | prev, _, _ := types.LookupFieldOrMethod(R, false, from.Pkg(), r.to) |
| 599 | if prev != nil { |
| 600 | r.errorf(from.Pos(), "renaming this interface method %q to %q", |
| 601 | from.Name(), r.to) |
| 602 | r.errorf(prev.Pos(), "\twould conflict with this method") |
| 603 | return |
| 604 | } |
| 605 | |
| 606 | // Check all interfaces that embed this one for |
| 607 | // declaration conflicts too. |
| 608 | for _, info := range r.packages { |
| 609 | // Start with named interface types (better errors) |
| 610 | for _, obj := range info.Defs { |
| 611 | if obj, ok := obj.(*types.TypeName); ok && isInterface(obj.Type()) { |
| 612 | f, _, _ := types.LookupFieldOrMethod( |
| 613 | obj.Type(), false, from.Pkg(), from.Name()) |
| 614 | if f == nil { |
| 615 | continue |
| 616 | } |
| 617 | t, _, _ := types.LookupFieldOrMethod( |
| 618 | obj.Type(), false, from.Pkg(), r.to) |
| 619 | if t == nil { |
| 620 | continue |
| 621 | } |
| 622 | r.errorf(from.Pos(), "renaming this interface method %q to %q", |
| 623 | from.Name(), r.to) |
| 624 | r.errorf(t.Pos(), "\twould conflict with this method") |
| 625 | r.errorf(obj.Pos(), "\tin named interface type %q", obj.Name()) |
| 626 | } |
| 627 | } |
| 628 | |
| 629 | // Now look at all literal interface types (includes named ones again). |
| 630 | for e, tv := range info.Types { |
| 631 | if e, ok := e.(*ast.InterfaceType); ok { |
| 632 | _ = e |
| 633 | _ = tv.Type.(*types.Interface) |
| 634 | // TODO(adonovan): implement same check as above. |
| 635 | } |
| 636 | } |
| 637 | } |
| 638 | |
| 639 | // assignability |
| 640 | // |
| 641 | // Find the set of concrete or abstract methods directly |
| 642 | // coupled to abstract method 'from' by some |
| 643 | // satisfy.Constraint, and rename them too. |
| 644 | for key := range r.satisfy() { |
| 645 | // key = (lhs, rhs) where lhs is always an interface. |
| 646 | |
| 647 | lsel := r.msets.MethodSet(key.LHS).Lookup(from.Pkg(), from.Name()) |
| 648 | if lsel == nil { |
| 649 | continue |
| 650 | } |
| 651 | rmethods := r.msets.MethodSet(key.RHS) |
| 652 | rsel := rmethods.Lookup(from.Pkg(), from.Name()) |
| 653 | if rsel == nil { |
| 654 | continue |
| 655 | } |
| 656 | |
| 657 | // If both sides have a method of this name, |
| 658 | // and one of them is m, the other must be coupled. |
| 659 | var coupled *types.Func |
| 660 | switch from { |
| 661 | case lsel.Obj(): |
| 662 | coupled = rsel.Obj().(*types.Func) |
| 663 | case rsel.Obj(): |
| 664 | coupled = lsel.Obj().(*types.Func) |
| 665 | default: |
| 666 | continue |
| 667 | } |
| 668 | |
| 669 | // We must treat concrete-to-interface |
| 670 | // constraints like an implicit selection C.f of |
| 671 | // each interface method I.f, and check that the |
| 672 | // renaming leaves the selection unchanged and |
| 673 | // unambiguous. |
| 674 | // |
| 675 | // Fun fact: the implicit selection of C.f |
| 676 | // type I interface{f()} |
| 677 | // type C struct{I} |
| 678 | // func (C) g() |
| 679 | // var _ I = C{} // here |
| 680 | // yields abstract method I.f. This can make error |
| 681 | // messages less than obvious. |
| 682 | // |
| 683 | if !isInterface(key.RHS) { |
| 684 | // The logic below was derived from checkSelections. |
| 685 | |
| 686 | rtosel := rmethods.Lookup(from.Pkg(), r.to) |
| 687 | if rtosel != nil { |
| 688 | rto := rtosel.Obj().(*types.Func) |
| 689 | delta := len(rsel.Index()) - len(rtosel.Index()) |
| 690 | if delta < 0 { |
| 691 | continue // no ambiguity |
| 692 | } |
| 693 | |
| 694 | // TODO(adonovan): record the constraint's position. |
| 695 | keyPos := token.NoPos |
| 696 | |
| 697 | r.errorf(from.Pos(), "renaming this method %q to %q", |
| 698 | from.Name(), r.to) |
| 699 | if delta == 0 { |
| 700 | // analogous to same-block conflict |
| 701 | r.errorf(keyPos, "\twould make the %s method of %s invoked via interface %s ambiguous", |
| 702 | r.to, key.RHS, key.LHS) |
| 703 | r.errorf(rto.Pos(), "\twith (%s).%s", |
| 704 | recv(rto).Type(), r.to) |
| 705 | } else { |
| 706 | // analogous to super-block conflict |
| 707 | r.errorf(keyPos, "\twould change the %s method of %s invoked via interface %s", |
| 708 | r.to, key.RHS, key.LHS) |
| 709 | r.errorf(coupled.Pos(), "\tfrom (%s).%s", |
| 710 | recv(coupled).Type(), r.to) |
| 711 | r.errorf(rto.Pos(), "\tto (%s).%s", |
| 712 | recv(rto).Type(), r.to) |
| 713 | } |
| 714 | return // one error is enough |
| 715 | } |
| 716 | } |
| 717 | |
| 718 | if !r.changeMethods { |
| 719 | // This should be unreachable. |
| 720 | r.errorf(from.Pos(), "internal error: during renaming of abstract method %s", from) |
| 721 | r.errorf(coupled.Pos(), "\tchangedMethods=false, coupled method=%s", coupled) |
| 722 | r.errorf(from.Pos(), "\tPlease file a bug report") |
| 723 | return |
| 724 | } |
| 725 | |
| 726 | // Rename the coupled method to preserve assignability. |
| 727 | r.check(coupled) |
| 728 | } |
| 729 | } else { |
| 730 | // Concrete method |
| 731 | |
| 732 | // declaration |
| 733 | prev, indices, _ := types.LookupFieldOrMethod(R, true, from.Pkg(), r.to) |
| 734 | if prev != nil && len(indices) == 1 { |
| 735 | r.errorf(from.Pos(), "renaming this method %q to %q", |
| 736 | from.Name(), r.to) |
| 737 | r.errorf(prev.Pos(), "\twould conflict with this %s", |
| 738 | objectKind(prev)) |
| 739 | return |
| 740 | } |
| 741 | |
| 742 | // assignability |
| 743 | // |
| 744 | // Find the set of abstract methods coupled to concrete |
| 745 | // method 'from' by some satisfy.Constraint, and rename |
| 746 | // them too. |
| 747 | // |
| 748 | // Coupling may be indirect, e.g. I.f <-> C.f via type D. |
| 749 | // |
| 750 | // type I interface {f()} |
| 751 | // type C int |
| 752 | // type (C) f() |
| 753 | // type D struct{C} |
| 754 | // var _ I = D{} |
| 755 | // |
| 756 | for key := range r.satisfy() { |
| 757 | // key = (lhs, rhs) where lhs is always an interface. |
| 758 | if isInterface(key.RHS) { |
| 759 | continue |
| 760 | } |
| 761 | rsel := r.msets.MethodSet(key.RHS).Lookup(from.Pkg(), from.Name()) |
| 762 | if rsel == nil || rsel.Obj() != from { |
| 763 | continue // rhs does not have the method |
| 764 | } |
| 765 | lsel := r.msets.MethodSet(key.LHS).Lookup(from.Pkg(), from.Name()) |
| 766 | if lsel == nil { |
| 767 | continue |
| 768 | } |
| 769 | imeth := lsel.Obj().(*types.Func) |
| 770 | |
| 771 | // imeth is the abstract method (e.g. I.f) |
| 772 | // and key.RHS is the concrete coupling type (e.g. D). |
| 773 | if !r.changeMethods { |
| 774 | r.errorf(from.Pos(), "renaming this method %q to %q", |
| 775 | from.Name(), r.to) |
| 776 | var pos token.Pos |
| 777 | var iface string |
| 778 | |
| 779 | I := recv(imeth).Type() |
| 780 | if named, ok := I.(*types.Named); ok { |
| 781 | pos = named.Obj().Pos() |
| 782 | iface = "interface " + named.Obj().Name() |
| 783 | } else { |
| 784 | pos = from.Pos() |
| 785 | iface = I.String() |
| 786 | } |
| 787 | r.errorf(pos, "\twould make %s no longer assignable to %s", |
| 788 | key.RHS, iface) |
| 789 | r.errorf(imeth.Pos(), "\t(rename %s.%s if you intend to change both types)", |
| 790 | I, from.Name()) |
| 791 | return // one error is enough |
| 792 | } |
| 793 | |
| 794 | // Rename the coupled interface method to preserve assignability. |
| 795 | r.check(imeth) |
| 796 | } |
| 797 | } |
| 798 | |
| 799 | // Check integrity of existing (field and method) selections. |
| 800 | // We skip this if there were errors above, to avoid redundant errors. |
| 801 | r.checkSelections(from) |
| 802 | } |
| 803 | |
| 804 | func (r *renamer) checkExport(id *ast.Ident, pkg *types.Package, from types.Object) bool { |
| 805 | // Reject cross-package references if r.to is unexported. |
| 806 | // (Such references may be qualified identifiers or field/method |
| 807 | // selections.) |
| 808 | if !ast.IsExported(r.to) && pkg != from.Pkg() { |
| 809 | r.errorf(from.Pos(), |
| 810 | "renaming this %s %q to %q would make it unexported", |
| 811 | objectKind(from), from.Name(), r.to) |
| 812 | r.errorf(id.Pos(), "\tbreaking references from packages such as %q", |
| 813 | pkg.Path()) |
| 814 | return false |
| 815 | } |
| 816 | return true |
| 817 | } |
| 818 | |
| 819 | // satisfy returns the set of interface satisfaction constraints. |
| 820 | func (r *renamer) satisfy() map[satisfy.Constraint]bool { |
| 821 | if r.satisfyConstraints == nil { |
| 822 | // Compute on demand: it's expensive. |
| 823 | var f satisfy.Finder |
| 824 | for _, info := range r.packages { |
| 825 | f.Find(&info.Info, info.Files) |
| 826 | } |
| 827 | r.satisfyConstraints = f.Result |
| 828 | } |
| 829 | return r.satisfyConstraints |
| 830 | } |
| 831 | |
| 832 | // -- helpers ---------------------------------------------------------- |
| 833 | |
| 834 | // recv returns the method's receiver. |
| 835 | func recv(meth *types.Func) *types.Var { |
| 836 | return meth.Type().(*types.Signature).Recv() |
| 837 | } |
| 838 | |
| 839 | // someUse returns an arbitrary use of obj within info. |
| 840 | func someUse(info *loader.PackageInfo, obj types.Object) *ast.Ident { |
| 841 | for id, o := range info.Uses { |
| 842 | if o == obj { |
| 843 | return id |
| 844 | } |
| 845 | } |
| 846 | return nil |
| 847 | } |
| 848 | |
| 849 | // -- Plundered from golang.org/x/tools/go/ssa ----------------- |
| 850 | |
| 851 | func isInterface(T types.Type) bool { return types.IsInterface(T) } |
| 852 | |
| 853 | func deref(typ types.Type) types.Type { |
| 854 | if p, _ := typ.(*types.Pointer); p != nil { |
| 855 | return p.Elem() |
| 856 | } |
| 857 | return typ |
| 858 | } |
| 859 |
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