golang.org/x/tools@v0.21.1-0.20240520172518-788d39e776b1/refactor/rename/check.go (about) 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/internal/typeparams" 17 "golang.org/x/tools/internal/typesinternal" 18 "golang.org/x/tools/refactor/satisfy" 19 ) 20 21 // errorf reports an error (e.g. conflict) and prevents file modification. 22 func (r *renamer) errorf(pos token.Pos, format string, args ...interface{}) { 23 r.hadConflicts = true 24 reportError(r.iprog.Fset.Position(pos), fmt.Sprintf(format, args...)) 25 } 26 27 // check performs safety checks of the renaming of the 'from' object to r.to. 28 func (r *renamer) check(from types.Object) { 29 if r.objsToUpdate[from] { 30 return 31 } 32 r.objsToUpdate[from] = true 33 34 // NB: order of conditions is important. 35 if from_, ok := from.(*types.PkgName); ok { 36 r.checkInFileBlock(from_) 37 } else if from_, ok := from.(*types.Label); ok { 38 r.checkLabel(from_) 39 } else if isPackageLevel(from) { 40 r.checkInPackageBlock(from) 41 } else if v, ok := from.(*types.Var); ok && v.IsField() { 42 r.checkStructField(v) 43 } else if f, ok := from.(*types.Func); ok && recv(f) != nil { 44 r.checkMethod(f) 45 } else if isLocal(from) { 46 r.checkInLocalScope(from) 47 } else { 48 r.errorf(from.Pos(), "unexpected %s object %q (please report a bug)\n", 49 objectKind(from), from) 50 } 51 } 52 53 // checkInFileBlock performs safety checks for renames of objects in the file block, 54 // i.e. imported package names. 55 func (r *renamer) checkInFileBlock(from *types.PkgName) { 56 // Check import name is not "init". 57 if r.to == "init" { 58 r.errorf(from.Pos(), "%q is not a valid imported package name", r.to) 59 } 60 61 // Check for conflicts between file and package block. 62 if prev := from.Pkg().Scope().Lookup(r.to); prev != nil { 63 r.errorf(from.Pos(), "renaming this %s %q to %q would conflict", 64 objectKind(from), from.Name(), r.to) 65 r.errorf(prev.Pos(), "\twith this package member %s", 66 objectKind(prev)) 67 return // since checkInPackageBlock would report redundant errors 68 } 69 70 // Check for conflicts in lexical scope. 71 r.checkInLexicalScope(from, r.packages[from.Pkg()]) 72 73 // Finally, modify ImportSpec syntax to add or remove the Name as needed. 74 info, path, _ := r.iprog.PathEnclosingInterval(from.Pos(), from.Pos()) 75 if from.Imported().Name() == r.to { 76 // ImportSpec.Name not needed 77 path[1].(*ast.ImportSpec).Name = nil 78 } else { 79 // ImportSpec.Name needed 80 if spec := path[1].(*ast.ImportSpec); spec.Name == nil { 81 spec.Name = &ast.Ident{NamePos: spec.Path.Pos(), Name: r.to} 82 info.Defs[spec.Name] = from 83 } 84 } 85 } 86 87 // checkInPackageBlock performs safety checks for renames of 88 // func/var/const/type objects in the package block. 89 func (r *renamer) checkInPackageBlock(from types.Object) { 90 // Check that there are no references to the name from another 91 // package if the renaming would make it unexported. 92 if ast.IsExported(from.Name()) && !ast.IsExported(r.to) { 93 for pkg, info := range r.packages { 94 if pkg == from.Pkg() { 95 continue 96 } 97 if id := someUse(info, from); id != nil && 98 !r.checkExport(id, pkg, from) { 99 break 100 } 101 } 102 } 103 104 info := r.packages[from.Pkg()] 105 106 // Check that in the package block, "init" is a function, and never referenced. 107 if r.to == "init" { 108 kind := objectKind(from) 109 if kind == "func" { 110 // Reject if intra-package references to it exist. 111 for id, obj := range info.Uses { 112 if obj == from { 113 r.errorf(from.Pos(), 114 "renaming this func %q to %q would make it a package initializer", 115 from.Name(), r.to) 116 r.errorf(id.Pos(), "\tbut references to it exist") 117 break 118 } 119 } 120 } else { 121 r.errorf(from.Pos(), "you cannot have a %s at package level named %q", 122 kind, r.to) 123 } 124 } 125 126 // Check for conflicts between package block and all file blocks. 127 for _, f := range info.Files { 128 fileScope := info.Info.Scopes[f] 129 b, prev := fileScope.LookupParent(r.to, token.NoPos) 130 if b == fileScope { 131 r.errorf(from.Pos(), "renaming this %s %q to %q would conflict", 132 objectKind(from), from.Name(), r.to) 133 r.errorf(prev.Pos(), "\twith this %s", 134 objectKind(prev)) 135 return // since checkInPackageBlock would report redundant errors 136 } 137 } 138 139 // Check for conflicts in lexical scope. 140 if from.Exported() { 141 for _, info := range r.packages { 142 r.checkInLexicalScope(from, info) 143 } 144 } else { 145 r.checkInLexicalScope(from, info) 146 } 147 } 148 149 func (r *renamer) checkInLocalScope(from types.Object) { 150 info := r.packages[from.Pkg()] 151 152 // Is this object an implicit local var for a type switch? 153 // Each case has its own var, whose position is the decl of y, 154 // but Ident in that decl does not appear in the Uses map. 155 // 156 // switch y := x.(type) { // Defs[Ident(y)] is undefined 157 // case int: print(y) // Implicits[CaseClause(int)] = Var(y_int) 158 // case string: print(y) // Implicits[CaseClause(string)] = Var(y_string) 159 // } 160 // 161 var isCaseVar bool 162 for syntax, obj := range info.Implicits { 163 if _, ok := syntax.(*ast.CaseClause); ok && obj.Pos() == from.Pos() { 164 isCaseVar = true 165 r.check(obj) 166 } 167 } 168 169 r.checkInLexicalScope(from, info) 170 171 // Finally, if this was a type switch, change the variable y. 172 if isCaseVar { 173 _, path, _ := r.iprog.PathEnclosingInterval(from.Pos(), from.Pos()) 174 path[0].(*ast.Ident).Name = r.to // path is [Ident AssignStmt TypeSwitchStmt...] 175 } 176 } 177 178 // checkInLexicalScope performs safety checks that a renaming does not 179 // change the lexical reference structure of the specified package. 180 // 181 // For objects in lexical scope, there are three kinds of conflicts: 182 // same-, sub-, and super-block conflicts. We will illustrate all three 183 // using this example: 184 // 185 // var x int 186 // var z int 187 // 188 // func f(y int) { 189 // print(x) 190 // print(y) 191 // } 192 // 193 // Renaming x to z encounters a SAME-BLOCK CONFLICT, because an object 194 // with the new name already exists, defined in the same lexical block 195 // as the old object. 196 // 197 // Renaming x to y encounters a SUB-BLOCK CONFLICT, because there exists 198 // a reference to x from within (what would become) a hole in its scope. 199 // The definition of y in an (inner) sub-block would cast a shadow in 200 // the scope of the renamed variable. 201 // 202 // Renaming y to x encounters a SUPER-BLOCK CONFLICT. This is the 203 // converse situation: there is an existing definition of the new name 204 // (x) in an (enclosing) super-block, and the renaming would create a 205 // hole in its scope, within which there exist references to it. The 206 // new name casts a shadow in scope of the existing definition of x in 207 // the super-block. 208 // 209 // Removing the old name (and all references to it) is always safe, and 210 // requires no checks. 211 func (r *renamer) checkInLexicalScope(from types.Object, info *loader.PackageInfo) { 212 b := from.Parent() // the block defining the 'from' object 213 if b != nil { 214 toBlock, to := b.LookupParent(r.to, from.Parent().End()) 215 if toBlock == b { 216 // same-block conflict 217 r.errorf(from.Pos(), "renaming this %s %q to %q", 218 objectKind(from), from.Name(), r.to) 219 r.errorf(to.Pos(), "\tconflicts with %s in same block", 220 objectKind(to)) 221 return 222 } else if toBlock != nil { 223 // Check for super-block conflict. 224 // The name r.to is defined in a superblock. 225 // Is that name referenced from within this block? 226 forEachLexicalRef(info, to, func(id *ast.Ident, block *types.Scope) bool { 227 _, obj := lexicalLookup(block, from.Name(), id.Pos()) 228 if obj == from { 229 // super-block conflict 230 r.errorf(from.Pos(), "renaming this %s %q to %q", 231 objectKind(from), from.Name(), r.to) 232 r.errorf(id.Pos(), "\twould shadow this reference") 233 r.errorf(to.Pos(), "\tto the %s declared here", 234 objectKind(to)) 235 return false // stop 236 } 237 return true 238 }) 239 } 240 } 241 242 // Check for sub-block conflict. 243 // Is there an intervening definition of r.to between 244 // the block defining 'from' and some reference to it? 245 forEachLexicalRef(info, from, func(id *ast.Ident, block *types.Scope) bool { 246 // Find the block that defines the found reference. 247 // It may be an ancestor. 248 fromBlock, _ := lexicalLookup(block, from.Name(), id.Pos()) 249 250 // See what r.to would resolve to in the same scope. 251 toBlock, to := lexicalLookup(block, r.to, id.Pos()) 252 if to != nil { 253 // sub-block conflict 254 if deeper(toBlock, fromBlock) { 255 r.errorf(from.Pos(), "renaming this %s %q to %q", 256 objectKind(from), from.Name(), r.to) 257 r.errorf(id.Pos(), "\twould cause this reference to become shadowed") 258 r.errorf(to.Pos(), "\tby this intervening %s definition", 259 objectKind(to)) 260 return false // stop 261 } 262 } 263 return true 264 }) 265 266 // Renaming a type that is used as an embedded field 267 // requires renaming the field too. e.g. 268 // type T int // if we rename this to U.. 269 // var s struct {T} 270 // print(s.T) // ...this must change too 271 if _, ok := from.(*types.TypeName); ok { 272 for id, obj := range info.Uses { 273 if obj == from { 274 if field := info.Defs[id]; field != nil { 275 r.check(field) 276 } 277 } 278 } 279 } 280 } 281 282 // lexicalLookup is like (*types.Scope).LookupParent but respects the 283 // environment visible at pos. It assumes the relative position 284 // information is correct with each file. 285 func lexicalLookup(block *types.Scope, name string, pos token.Pos) (*types.Scope, types.Object) { 286 for b := block; b != nil; b = b.Parent() { 287 obj := b.Lookup(name) 288 // The scope of a package-level object is the entire package, 289 // so ignore pos in that case. 290 // No analogous clause is needed for file-level objects 291 // since no reference can appear before an import decl. 292 if obj != nil && (b == obj.Pkg().Scope() || obj.Pos() < pos) { 293 return b, obj 294 } 295 } 296 return nil, nil 297 } 298 299 // deeper reports whether block x is lexically deeper than y. 300 func deeper(x, y *types.Scope) bool { 301 if x == y || x == nil { 302 return false 303 } else if y == nil { 304 return true 305 } else { 306 return deeper(x.Parent(), y.Parent()) 307 } 308 } 309 310 // forEachLexicalRef calls fn(id, block) for each identifier id in package 311 // info that is a reference to obj in lexical scope. block is the 312 // lexical block enclosing the reference. If fn returns false the 313 // iteration is terminated and findLexicalRefs returns false. 314 func forEachLexicalRef(info *loader.PackageInfo, obj types.Object, fn func(id *ast.Ident, block *types.Scope) bool) bool { 315 ok := true 316 var stack []ast.Node 317 318 var visit func(n ast.Node) bool 319 visit = func(n ast.Node) bool { 320 if n == nil { 321 stack = stack[:len(stack)-1] // pop 322 return false 323 } 324 if !ok { 325 return false // bail out 326 } 327 328 stack = append(stack, n) // push 329 switch n := n.(type) { 330 case *ast.Ident: 331 if info.Uses[n] == obj { 332 block := enclosingBlock(&info.Info, stack) 333 if !fn(n, block) { 334 ok = false 335 } 336 } 337 return visit(nil) // pop stack 338 339 case *ast.SelectorExpr: 340 // don't visit n.Sel 341 ast.Inspect(n.X, visit) 342 return visit(nil) // pop stack, don't descend 343 344 case *ast.CompositeLit: 345 // Handle recursion ourselves for struct literals 346 // so we don't visit field identifiers. 347 tv := info.Types[n] 348 if is[*types.Struct](typeparams.CoreType(typeparams.Deref(tv.Type))) { 349 if n.Type != nil { 350 ast.Inspect(n.Type, visit) 351 } 352 for _, elt := range n.Elts { 353 if kv, ok := elt.(*ast.KeyValueExpr); ok { 354 ast.Inspect(kv.Value, visit) 355 } else { 356 ast.Inspect(elt, visit) 357 } 358 } 359 return visit(nil) // pop stack, don't descend 360 } 361 } 362 return true 363 } 364 365 for _, f := range info.Files { 366 ast.Inspect(f, visit) 367 if len(stack) != 0 { 368 panic(stack) 369 } 370 if !ok { 371 break 372 } 373 } 374 return ok 375 } 376 377 // enclosingBlock returns the innermost block enclosing the specified 378 // AST node, specified in the form of a path from the root of the file, 379 // [file...n]. 380 func enclosingBlock(info *types.Info, stack []ast.Node) *types.Scope { 381 for i := range stack { 382 n := stack[len(stack)-1-i] 383 // For some reason, go/types always associates a 384 // function's scope with its FuncType. 385 // TODO(adonovan): feature or a bug? 386 switch f := n.(type) { 387 case *ast.FuncDecl: 388 n = f.Type 389 case *ast.FuncLit: 390 n = f.Type 391 } 392 if b := info.Scopes[n]; b != nil { 393 return b 394 } 395 } 396 panic("no Scope for *ast.File") 397 } 398 399 func (r *renamer) checkLabel(label *types.Label) { 400 // Check there are no identical labels in the function's label block. 401 // (Label blocks don't nest, so this is easy.) 402 if prev := label.Parent().Lookup(r.to); prev != nil { 403 r.errorf(label.Pos(), "renaming this label %q to %q", label.Name(), prev.Name()) 404 r.errorf(prev.Pos(), "\twould conflict with this one") 405 } 406 } 407 408 // checkStructField checks that the field renaming will not cause 409 // conflicts at its declaration, or ambiguity or changes to any selection. 410 func (r *renamer) checkStructField(from *types.Var) { 411 // Check that the struct declaration is free of field conflicts, 412 // and field/method conflicts. 413 414 // go/types offers no easy way to get from a field (or interface 415 // method) to its declaring struct (or interface), so we must 416 // ascend the AST. 417 info, path, _ := r.iprog.PathEnclosingInterval(from.Pos(), from.Pos()) 418 // path matches this pattern: 419 // [Ident SelectorExpr? StarExpr? Field FieldList StructType ParenExpr* ... File] 420 421 // Ascend to FieldList. 422 var i int 423 for { 424 if _, ok := path[i].(*ast.FieldList); ok { 425 break 426 } 427 i++ 428 } 429 i++ 430 tStruct := path[i].(*ast.StructType) 431 i++ 432 // Ascend past parens (unlikely). 433 for { 434 _, ok := path[i].(*ast.ParenExpr) 435 if !ok { 436 break 437 } 438 i++ 439 } 440 if spec, ok := path[i].(*ast.TypeSpec); ok && !spec.Assign.IsValid() { 441 // This struct is also a defined type. 442 // We must check for direct (non-promoted) field/field 443 // and method/field conflicts. 444 named := info.Defs[spec.Name].Type() 445 prev, indices, _ := types.LookupFieldOrMethod(named, true, info.Pkg, r.to) 446 if len(indices) == 1 { 447 r.errorf(from.Pos(), "renaming this field %q to %q", 448 from.Name(), r.to) 449 r.errorf(prev.Pos(), "\twould conflict with this %s", 450 objectKind(prev)) 451 return // skip checkSelections to avoid redundant errors 452 } 453 } else { 454 // This struct is not a defined type. (It may be an alias.) 455 // We need only check for direct (non-promoted) field/field conflicts. 456 T := info.Types[tStruct].Type.Underlying().(*types.Struct) 457 for i := 0; i < T.NumFields(); i++ { 458 if prev := T.Field(i); prev.Name() == r.to { 459 r.errorf(from.Pos(), "renaming this field %q to %q", 460 from.Name(), r.to) 461 r.errorf(prev.Pos(), "\twould conflict with this field") 462 return // skip checkSelections to avoid redundant errors 463 } 464 } 465 } 466 467 // Renaming an anonymous field requires renaming the TypeName too. e.g. 468 // print(s.T) // if we rename T to U, 469 // type T int // this and 470 // var s struct {T} // this must change too. 471 if from.Anonymous() { 472 // A TypeParam cannot appear as an anonymous field. 473 if t, ok := typesinternal.Unpointer(from.Type()).(hasTypeName); ok { 474 r.check(t.Obj()) 475 } 476 } 477 478 // Check integrity of existing (field and method) selections. 479 r.checkSelections(from) 480 } 481 482 // hasTypeName abstracts the named types, *types.{Named,Alias,TypeParam}. 483 type hasTypeName interface{ Obj() *types.TypeName } 484 485 // checkSelections checks that all uses and selections that resolve to 486 // the specified object would continue to do so after the renaming. 487 func (r *renamer) checkSelections(from types.Object) { 488 for pkg, info := range r.packages { 489 if id := someUse(info, from); id != nil { 490 if !r.checkExport(id, pkg, from) { 491 return 492 } 493 } 494 495 for syntax, sel := range info.Selections { 496 // There may be extant selections of only the old 497 // name or only the new name, so we must check both. 498 // (If neither, the renaming is sound.) 499 // 500 // In both cases, we wish to compare the lengths 501 // of the implicit field path (Selection.Index) 502 // to see if the renaming would change it. 503 // 504 // If a selection that resolves to 'from', when renamed, 505 // would yield a path of the same or shorter length, 506 // this indicates ambiguity or a changed referent, 507 // analogous to same- or sub-block lexical conflict. 508 // 509 // If a selection using the name 'to' would 510 // yield a path of the same or shorter length, 511 // this indicates ambiguity or shadowing, 512 // analogous to same- or super-block lexical conflict. 513 514 // TODO(adonovan): fix: derive from Types[syntax.X].Mode 515 // TODO(adonovan): test with pointer, value, addressable value. 516 isAddressable := true 517 518 if sel.Obj() == from { 519 if obj, indices, _ := types.LookupFieldOrMethod(sel.Recv(), isAddressable, from.Pkg(), r.to); obj != nil { 520 // Renaming this existing selection of 521 // 'from' may block access to an existing 522 // type member named 'to'. 523 delta := len(indices) - len(sel.Index()) 524 if delta > 0 { 525 continue // no ambiguity 526 } 527 r.selectionConflict(from, delta, syntax, obj) 528 return 529 } 530 531 } else if sel.Obj().Name() == r.to { 532 if obj, indices, _ := types.LookupFieldOrMethod(sel.Recv(), isAddressable, from.Pkg(), from.Name()); obj == from { 533 // Renaming 'from' may cause this existing 534 // selection of the name 'to' to change 535 // its meaning. 536 delta := len(indices) - len(sel.Index()) 537 if delta > 0 { 538 continue // no ambiguity 539 } 540 r.selectionConflict(from, -delta, syntax, sel.Obj()) 541 return 542 } 543 } 544 } 545 } 546 } 547 548 func (r *renamer) selectionConflict(from types.Object, delta int, syntax *ast.SelectorExpr, obj types.Object) { 549 r.errorf(from.Pos(), "renaming this %s %q to %q", 550 objectKind(from), from.Name(), r.to) 551 552 switch { 553 case delta < 0: 554 // analogous to sub-block conflict 555 r.errorf(syntax.Sel.Pos(), 556 "\twould change the referent of this selection") 557 r.errorf(obj.Pos(), "\tof this %s", objectKind(obj)) 558 case delta == 0: 559 // analogous to same-block conflict 560 r.errorf(syntax.Sel.Pos(), 561 "\twould make this reference ambiguous") 562 r.errorf(obj.Pos(), "\twith this %s", objectKind(obj)) 563 case delta > 0: 564 // analogous to super-block conflict 565 r.errorf(syntax.Sel.Pos(), 566 "\twould shadow this selection") 567 r.errorf(obj.Pos(), "\tof the %s declared here", 568 objectKind(obj)) 569 } 570 } 571 572 // checkMethod performs safety checks for renaming a method. 573 // There are three hazards: 574 // - declaration conflicts 575 // - selection ambiguity/changes 576 // - entailed renamings of assignable concrete/interface types. 577 // 578 // We reject renamings initiated at concrete methods if it would 579 // change the assignability relation. For renamings of abstract 580 // methods, we rename all methods transitively coupled to it via 581 // assignability. 582 func (r *renamer) checkMethod(from *types.Func) { 583 // e.g. error.Error 584 if from.Pkg() == nil { 585 r.errorf(from.Pos(), "you cannot rename built-in method %s", from) 586 return 587 } 588 589 // ASSIGNABILITY: We reject renamings of concrete methods that 590 // would break a 'satisfy' constraint; but renamings of abstract 591 // methods are allowed to proceed, and we rename affected 592 // concrete and abstract methods as necessary. It is the 593 // initial method that determines the policy. 594 595 // Check for conflict at point of declaration. 596 // Check to ensure preservation of assignability requirements. 597 R := recv(from).Type() 598 if types.IsInterface(R) { 599 // Abstract method 600 601 // declaration 602 prev, _, _ := types.LookupFieldOrMethod(R, false, from.Pkg(), r.to) 603 if prev != nil { 604 r.errorf(from.Pos(), "renaming this interface method %q to %q", 605 from.Name(), r.to) 606 r.errorf(prev.Pos(), "\twould conflict with this method") 607 return 608 } 609 610 // Check all interfaces that embed this one for 611 // declaration conflicts too. 612 for _, info := range r.packages { 613 // Start with named interface types (better errors) 614 for _, obj := range info.Defs { 615 if obj, ok := obj.(*types.TypeName); ok && types.IsInterface(obj.Type()) { 616 f, _, _ := types.LookupFieldOrMethod( 617 obj.Type(), false, from.Pkg(), from.Name()) 618 if f == nil { 619 continue 620 } 621 t, _, _ := types.LookupFieldOrMethod( 622 obj.Type(), false, from.Pkg(), r.to) 623 if t == nil { 624 continue 625 } 626 r.errorf(from.Pos(), "renaming this interface method %q to %q", 627 from.Name(), r.to) 628 r.errorf(t.Pos(), "\twould conflict with this method") 629 r.errorf(obj.Pos(), "\tin named interface type %q", obj.Name()) 630 } 631 } 632 633 // Now look at all literal interface types (includes named ones again). 634 for e, tv := range info.Types { 635 if e, ok := e.(*ast.InterfaceType); ok { 636 _ = e 637 _ = tv.Type.(*types.Interface) 638 // TODO(adonovan): implement same check as above. 639 } 640 } 641 } 642 643 // assignability 644 // 645 // Find the set of concrete or abstract methods directly 646 // coupled to abstract method 'from' by some 647 // satisfy.Constraint, and rename them too. 648 for key := range r.satisfy() { 649 // key = (lhs, rhs) where lhs is always an interface. 650 651 lsel := r.msets.MethodSet(key.LHS).Lookup(from.Pkg(), from.Name()) 652 if lsel == nil { 653 continue 654 } 655 rmethods := r.msets.MethodSet(key.RHS) 656 rsel := rmethods.Lookup(from.Pkg(), from.Name()) 657 if rsel == nil { 658 continue 659 } 660 661 // If both sides have a method of this name, 662 // and one of them is m, the other must be coupled. 663 var coupled *types.Func 664 switch from { 665 case lsel.Obj(): 666 coupled = rsel.Obj().(*types.Func) 667 case rsel.Obj(): 668 coupled = lsel.Obj().(*types.Func) 669 default: 670 continue 671 } 672 673 // We must treat concrete-to-interface 674 // constraints like an implicit selection C.f of 675 // each interface method I.f, and check that the 676 // renaming leaves the selection unchanged and 677 // unambiguous. 678 // 679 // Fun fact: the implicit selection of C.f 680 // type I interface{f()} 681 // type C struct{I} 682 // func (C) g() 683 // var _ I = C{} // here 684 // yields abstract method I.f. This can make error 685 // messages less than obvious. 686 // 687 if !types.IsInterface(key.RHS) { 688 // The logic below was derived from checkSelections. 689 690 rtosel := rmethods.Lookup(from.Pkg(), r.to) 691 if rtosel != nil { 692 rto := rtosel.Obj().(*types.Func) 693 delta := len(rsel.Index()) - len(rtosel.Index()) 694 if delta < 0 { 695 continue // no ambiguity 696 } 697 698 // TODO(adonovan): record the constraint's position. 699 keyPos := token.NoPos 700 701 r.errorf(from.Pos(), "renaming this method %q to %q", 702 from.Name(), r.to) 703 if delta == 0 { 704 // analogous to same-block conflict 705 r.errorf(keyPos, "\twould make the %s method of %s invoked via interface %s ambiguous", 706 r.to, key.RHS, key.LHS) 707 r.errorf(rto.Pos(), "\twith (%s).%s", 708 recv(rto).Type(), r.to) 709 } else { 710 // analogous to super-block conflict 711 r.errorf(keyPos, "\twould change the %s method of %s invoked via interface %s", 712 r.to, key.RHS, key.LHS) 713 r.errorf(coupled.Pos(), "\tfrom (%s).%s", 714 recv(coupled).Type(), r.to) 715 r.errorf(rto.Pos(), "\tto (%s).%s", 716 recv(rto).Type(), r.to) 717 } 718 return // one error is enough 719 } 720 } 721 722 if !r.changeMethods { 723 // This should be unreachable. 724 r.errorf(from.Pos(), "internal error: during renaming of abstract method %s", from) 725 r.errorf(coupled.Pos(), "\tchangedMethods=false, coupled method=%s", coupled) 726 r.errorf(from.Pos(), "\tPlease file a bug report") 727 return 728 } 729 730 // Rename the coupled method to preserve assignability. 731 r.check(coupled) 732 } 733 } else { 734 // Concrete method 735 736 // declaration 737 prev, indices, _ := types.LookupFieldOrMethod(R, true, from.Pkg(), r.to) 738 if prev != nil && len(indices) == 1 { 739 r.errorf(from.Pos(), "renaming this method %q to %q", 740 from.Name(), r.to) 741 r.errorf(prev.Pos(), "\twould conflict with this %s", 742 objectKind(prev)) 743 return 744 } 745 746 // assignability 747 // 748 // Find the set of abstract methods coupled to concrete 749 // method 'from' by some satisfy.Constraint, and rename 750 // them too. 751 // 752 // Coupling may be indirect, e.g. I.f <-> C.f via type D. 753 // 754 // type I interface {f()} 755 // type C int 756 // type (C) f() 757 // type D struct{C} 758 // var _ I = D{} 759 // 760 for key := range r.satisfy() { 761 // key = (lhs, rhs) where lhs is always an interface. 762 if types.IsInterface(key.RHS) { 763 continue 764 } 765 rsel := r.msets.MethodSet(key.RHS).Lookup(from.Pkg(), from.Name()) 766 if rsel == nil || rsel.Obj() != from { 767 continue // rhs does not have the method 768 } 769 lsel := r.msets.MethodSet(key.LHS).Lookup(from.Pkg(), from.Name()) 770 if lsel == nil { 771 continue 772 } 773 imeth := lsel.Obj().(*types.Func) 774 775 // imeth is the abstract method (e.g. I.f) 776 // and key.RHS is the concrete coupling type (e.g. D). 777 if !r.changeMethods { 778 r.errorf(from.Pos(), "renaming this method %q to %q", 779 from.Name(), r.to) 780 var pos token.Pos 781 var iface string 782 783 I := recv(imeth).Type() 784 if named, ok := I.(hasTypeName); ok { 785 pos = named.Obj().Pos() 786 iface = "interface " + named.Obj().Name() 787 } else { 788 pos = from.Pos() 789 iface = I.String() 790 } 791 r.errorf(pos, "\twould make %s no longer assignable to %s", 792 key.RHS, iface) 793 r.errorf(imeth.Pos(), "\t(rename %s.%s if you intend to change both types)", 794 I, from.Name()) 795 return // one error is enough 796 } 797 798 // Rename the coupled interface method to preserve assignability. 799 r.check(imeth) 800 } 801 } 802 803 // Check integrity of existing (field and method) selections. 804 // We skip this if there were errors above, to avoid redundant errors. 805 r.checkSelections(from) 806 } 807 808 func (r *renamer) checkExport(id *ast.Ident, pkg *types.Package, from types.Object) bool { 809 // Reject cross-package references if r.to is unexported. 810 // (Such references may be qualified identifiers or field/method 811 // selections.) 812 if !ast.IsExported(r.to) && pkg != from.Pkg() { 813 r.errorf(from.Pos(), 814 "renaming this %s %q to %q would make it unexported", 815 objectKind(from), from.Name(), r.to) 816 r.errorf(id.Pos(), "\tbreaking references from packages such as %q", 817 pkg.Path()) 818 return false 819 } 820 return true 821 } 822 823 // satisfy returns the set of interface satisfaction constraints. 824 func (r *renamer) satisfy() map[satisfy.Constraint]bool { 825 if r.satisfyConstraints == nil { 826 // Compute on demand: it's expensive. 827 var f satisfy.Finder 828 for _, info := range r.packages { 829 f.Find(&info.Info, info.Files) 830 } 831 r.satisfyConstraints = f.Result 832 } 833 return r.satisfyConstraints 834 } 835 836 // -- helpers ---------------------------------------------------------- 837 838 // recv returns the method's receiver. 839 func recv(meth *types.Func) *types.Var { 840 return meth.Type().(*types.Signature).Recv() 841 } 842 843 // someUse returns an arbitrary use of obj within info. 844 func someUse(info *loader.PackageInfo, obj types.Object) *ast.Ident { 845 for id, o := range info.Uses { 846 if o == obj { 847 return id 848 } 849 } 850 return nil 851 }