Source file src/runtime/type.go

Documentation: runtime

     1  // Copyright 2009 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  // Runtime type representation.
     6  
     7  package runtime
     8  
     9  import "unsafe"
    10  
    11  // tflag is documented in reflect/type.go.
    12  //
    13  // tflag values must be kept in sync with copies in:
    14  //	cmd/compile/internal/gc/reflect.go
    15  //	cmd/link/internal/ld/decodesym.go
    16  //	reflect/type.go
    17  type tflag uint8
    18  
    19  const (
    20  	tflagUncommon  tflag = 1 << 0
    21  	tflagExtraStar tflag = 1 << 1
    22  	tflagNamed     tflag = 1 << 2
    23  )
    24  
    25  // Needs to be in sync with ../cmd/link/internal/ld/decodesym.go:/^func.commonsize,
    26  // ../cmd/compile/internal/gc/reflect.go:/^func.dcommontype and
    27  // ../reflect/type.go:/^type.rtype.
    28  type _type struct {
    29  	size       uintptr
    30  	ptrdata    uintptr // size of memory prefix holding all pointers
    31  	hash       uint32
    32  	tflag      tflag
    33  	align      uint8
    34  	fieldalign uint8
    35  	kind       uint8
    36  	alg        *typeAlg
    37  	// gcdata stores the GC type data for the garbage collector.
    38  	// If the KindGCProg bit is set in kind, gcdata is a GC program.
    39  	// Otherwise it is a ptrmask bitmap. See mbitmap.go for details.
    40  	gcdata    *byte
    41  	str       nameOff
    42  	ptrToThis typeOff
    43  }
    44  
    45  func (t *_type) string() string {
    46  	s := t.nameOff(t.str).name()
    47  	if t.tflag&tflagExtraStar != 0 {
    48  		return s[1:]
    49  	}
    50  	return s
    51  }
    52  
    53  func (t *_type) uncommon() *uncommontype {
    54  	if t.tflag&tflagUncommon == 0 {
    55  		return nil
    56  	}
    57  	switch t.kind & kindMask {
    58  	case kindStruct:
    59  		type u struct {
    60  			structtype
    61  			u uncommontype
    62  		}
    63  		return &(*u)(unsafe.Pointer(t)).u
    64  	case kindPtr:
    65  		type u struct {
    66  			ptrtype
    67  			u uncommontype
    68  		}
    69  		return &(*u)(unsafe.Pointer(t)).u
    70  	case kindFunc:
    71  		type u struct {
    72  			functype
    73  			u uncommontype
    74  		}
    75  		return &(*u)(unsafe.Pointer(t)).u
    76  	case kindSlice:
    77  		type u struct {
    78  			slicetype
    79  			u uncommontype
    80  		}
    81  		return &(*u)(unsafe.Pointer(t)).u
    82  	case kindArray:
    83  		type u struct {
    84  			arraytype
    85  			u uncommontype
    86  		}
    87  		return &(*u)(unsafe.Pointer(t)).u
    88  	case kindChan:
    89  		type u struct {
    90  			chantype
    91  			u uncommontype
    92  		}
    93  		return &(*u)(unsafe.Pointer(t)).u
    94  	case kindMap:
    95  		type u struct {
    96  			maptype
    97  			u uncommontype
    98  		}
    99  		return &(*u)(unsafe.Pointer(t)).u
   100  	case kindInterface:
   101  		type u struct {
   102  			interfacetype
   103  			u uncommontype
   104  		}
   105  		return &(*u)(unsafe.Pointer(t)).u
   106  	default:
   107  		type u struct {
   108  			_type
   109  			u uncommontype
   110  		}
   111  		return &(*u)(unsafe.Pointer(t)).u
   112  	}
   113  }
   114  
   115  func (t *_type) name() string {
   116  	if t.tflag&tflagNamed == 0 {
   117  		return ""
   118  	}
   119  	s := t.string()
   120  	i := len(s) - 1
   121  	for i >= 0 && s[i] != '.' {
   122  		i--
   123  	}
   124  	return s[i+1:]
   125  }
   126  
   127  // pkgpath returns the path of the package where t was defined, if
   128  // available. This is not the same as the reflect package's PkgPath
   129  // method, in that it returns the package path for struct and interface
   130  // types, not just named types.
   131  func (t *_type) pkgpath() string {
   132  	if u := t.uncommon(); u != nil {
   133  		return t.nameOff(u.pkgpath).name()
   134  	}
   135  	switch t.kind & kindMask {
   136  	case kindStruct:
   137  		st := (*structtype)(unsafe.Pointer(t))
   138  		return st.pkgPath.name()
   139  	case kindInterface:
   140  		it := (*interfacetype)(unsafe.Pointer(t))
   141  		return it.pkgpath.name()
   142  	}
   143  	return ""
   144  }
   145  
   146  // reflectOffs holds type offsets defined at run time by the reflect package.
   147  //
   148  // When a type is defined at run time, its *rtype data lives on the heap.
   149  // There are a wide range of possible addresses the heap may use, that
   150  // may not be representable as a 32-bit offset. Moreover the GC may
   151  // one day start moving heap memory, in which case there is no stable
   152  // offset that can be defined.
   153  //
   154  // To provide stable offsets, we add pin *rtype objects in a global map
   155  // and treat the offset as an identifier. We use negative offsets that
   156  // do not overlap with any compile-time module offsets.
   157  //
   158  // Entries are created by reflect.addReflectOff.
   159  var reflectOffs struct {
   160  	lock mutex
   161  	next int32
   162  	m    map[int32]unsafe.Pointer
   163  	minv map[unsafe.Pointer]int32
   164  }
   165  
   166  func reflectOffsLock() {
   167  	lock(&reflectOffs.lock)
   168  	if raceenabled {
   169  		raceacquire(unsafe.Pointer(&reflectOffs.lock))
   170  	}
   171  }
   172  
   173  func reflectOffsUnlock() {
   174  	if raceenabled {
   175  		racerelease(unsafe.Pointer(&reflectOffs.lock))
   176  	}
   177  	unlock(&reflectOffs.lock)
   178  }
   179  
   180  func resolveNameOff(ptrInModule unsafe.Pointer, off nameOff) name {
   181  	if off == 0 {
   182  		return name{}
   183  	}
   184  	base := uintptr(ptrInModule)
   185  	for md := &firstmoduledata; md != nil; md = md.next {
   186  		if base >= md.types && base < md.etypes {
   187  			res := md.types + uintptr(off)
   188  			if res > md.etypes {
   189  				println("runtime: nameOff", hex(off), "out of range", hex(md.types), "-", hex(md.etypes))
   190  				throw("runtime: name offset out of range")
   191  			}
   192  			return name{(*byte)(unsafe.Pointer(res))}
   193  		}
   194  	}
   195  
   196  	// No module found. see if it is a run time name.
   197  	reflectOffsLock()
   198  	res, found := reflectOffs.m[int32(off)]
   199  	reflectOffsUnlock()
   200  	if !found {
   201  		println("runtime: nameOff", hex(off), "base", hex(base), "not in ranges:")
   202  		for next := &firstmoduledata; next != nil; next = next.next {
   203  			println("\ttypes", hex(next.types), "etypes", hex(next.etypes))
   204  		}
   205  		throw("runtime: name offset base pointer out of range")
   206  	}
   207  	return name{(*byte)(res)}
   208  }
   209  
   210  func (t *_type) nameOff(off nameOff) name {
   211  	return resolveNameOff(unsafe.Pointer(t), off)
   212  }
   213  
   214  func resolveTypeOff(ptrInModule unsafe.Pointer, off typeOff) *_type {
   215  	if off == 0 {
   216  		return nil
   217  	}
   218  	base := uintptr(ptrInModule)
   219  	var md *moduledata
   220  	for next := &firstmoduledata; next != nil; next = next.next {
   221  		if base >= next.types && base < next.etypes {
   222  			md = next
   223  			break
   224  		}
   225  	}
   226  	if md == nil {
   227  		reflectOffsLock()
   228  		res := reflectOffs.m[int32(off)]
   229  		reflectOffsUnlock()
   230  		if res == nil {
   231  			println("runtime: typeOff", hex(off), "base", hex(base), "not in ranges:")
   232  			for next := &firstmoduledata; next != nil; next = next.next {
   233  				println("\ttypes", hex(next.types), "etypes", hex(next.etypes))
   234  			}
   235  			throw("runtime: type offset base pointer out of range")
   236  		}
   237  		return (*_type)(res)
   238  	}
   239  	if t := md.typemap[off]; t != nil {
   240  		return t
   241  	}
   242  	res := md.types + uintptr(off)
   243  	if res > md.etypes {
   244  		println("runtime: typeOff", hex(off), "out of range", hex(md.types), "-", hex(md.etypes))
   245  		throw("runtime: type offset out of range")
   246  	}
   247  	return (*_type)(unsafe.Pointer(res))
   248  }
   249  
   250  func (t *_type) typeOff(off typeOff) *_type {
   251  	return resolveTypeOff(unsafe.Pointer(t), off)
   252  }
   253  
   254  func (t *_type) textOff(off textOff) unsafe.Pointer {
   255  	base := uintptr(unsafe.Pointer(t))
   256  	var md *moduledata
   257  	for next := &firstmoduledata; next != nil; next = next.next {
   258  		if base >= next.types && base < next.etypes {
   259  			md = next
   260  			break
   261  		}
   262  	}
   263  	if md == nil {
   264  		reflectOffsLock()
   265  		res := reflectOffs.m[int32(off)]
   266  		reflectOffsUnlock()
   267  		if res == nil {
   268  			println("runtime: textOff", hex(off), "base", hex(base), "not in ranges:")
   269  			for next := &firstmoduledata; next != nil; next = next.next {
   270  				println("\ttypes", hex(next.types), "etypes", hex(next.etypes))
   271  			}
   272  			throw("runtime: text offset base pointer out of range")
   273  		}
   274  		return res
   275  	}
   276  	res := uintptr(0)
   277  
   278  	// The text, or instruction stream is generated as one large buffer.  The off (offset) for a method is
   279  	// its offset within this buffer.  If the total text size gets too large, there can be issues on platforms like ppc64 if
   280  	// the target of calls are too far for the call instruction.  To resolve the large text issue, the text is split
   281  	// into multiple text sections to allow the linker to generate long calls when necessary.  When this happens, the vaddr
   282  	// for each text section is set to its offset within the text.  Each method's offset is compared against the section
   283  	// vaddrs and sizes to determine the containing section.  Then the section relative offset is added to the section's
   284  	// relocated baseaddr to compute the method addess.
   285  
   286  	if len(md.textsectmap) > 1 {
   287  		for i := range md.textsectmap {
   288  			sectaddr := md.textsectmap[i].vaddr
   289  			sectlen := md.textsectmap[i].length
   290  			if uintptr(off) >= sectaddr && uintptr(off) < sectaddr+sectlen {
   291  				res = md.textsectmap[i].baseaddr + uintptr(off) - uintptr(md.textsectmap[i].vaddr)
   292  				break
   293  			}
   294  		}
   295  	} else {
   296  		// single text section
   297  		res = md.text + uintptr(off)
   298  	}
   299  
   300  	if res > md.etext && GOARCH != "wasm" { // on wasm, functions do not live in the same address space as the linear memory
   301  		println("runtime: textOff", hex(off), "out of range", hex(md.text), "-", hex(md.etext))
   302  		throw("runtime: text offset out of range")
   303  	}
   304  	return unsafe.Pointer(res)
   305  }
   306  
   307  func (t *functype) in() []*_type {
   308  	// See funcType in reflect/type.go for details on data layout.
   309  	uadd := uintptr(unsafe.Sizeof(functype{}))
   310  	if t.typ.tflag&tflagUncommon != 0 {
   311  		uadd += unsafe.Sizeof(uncommontype{})
   312  	}
   313  	return (*[1 << 20]*_type)(add(unsafe.Pointer(t), uadd))[:t.inCount]
   314  }
   315  
   316  func (t *functype) out() []*_type {
   317  	// See funcType in reflect/type.go for details on data layout.
   318  	uadd := uintptr(unsafe.Sizeof(functype{}))
   319  	if t.typ.tflag&tflagUncommon != 0 {
   320  		uadd += unsafe.Sizeof(uncommontype{})
   321  	}
   322  	outCount := t.outCount & (1<<15 - 1)
   323  	return (*[1 << 20]*_type)(add(unsafe.Pointer(t), uadd))[t.inCount : t.inCount+outCount]
   324  }
   325  
   326  func (t *functype) dotdotdot() bool {
   327  	return t.outCount&(1<<15) != 0
   328  }
   329  
   330  type nameOff int32
   331  type typeOff int32
   332  type textOff int32
   333  
   334  type method struct {
   335  	name nameOff
   336  	mtyp typeOff
   337  	ifn  textOff
   338  	tfn  textOff
   339  }
   340  
   341  type uncommontype struct {
   342  	pkgpath nameOff
   343  	mcount  uint16 // number of methods
   344  	xcount  uint16 // number of exported methods
   345  	moff    uint32 // offset from this uncommontype to [mcount]method
   346  	_       uint32 // unused
   347  }
   348  
   349  type imethod struct {
   350  	name nameOff
   351  	ityp typeOff
   352  }
   353  
   354  type interfacetype struct {
   355  	typ     _type
   356  	pkgpath name
   357  	mhdr    []imethod
   358  }
   359  
   360  type maptype struct {
   361  	typ        _type
   362  	key        *_type
   363  	elem       *_type
   364  	bucket     *_type // internal type representing a hash bucket
   365  	keysize    uint8  // size of key slot
   366  	elemsize   uint8  // size of elem slot
   367  	bucketsize uint16 // size of bucket
   368  	flags      uint32
   369  }
   370  
   371  // Note: flag values must match those used in the TMAP case
   372  // in ../cmd/compile/internal/gc/reflect.go:dtypesym.
   373  func (mt *maptype) indirectkey() bool { // store ptr to key instead of key itself
   374  	return mt.flags&1 != 0
   375  }
   376  func (mt *maptype) indirectelem() bool { // store ptr to elem instead of elem itself
   377  	return mt.flags&2 != 0
   378  }
   379  func (mt *maptype) reflexivekey() bool { // true if k==k for all keys
   380  	return mt.flags&4 != 0
   381  }
   382  func (mt *maptype) needkeyupdate() bool { // true if we need to update key on an overwrite
   383  	return mt.flags&8 != 0
   384  }
   385  func (mt *maptype) hashMightPanic() bool { // true if hash function might panic
   386  	return mt.flags&16 != 0
   387  }
   388  
   389  type arraytype struct {
   390  	typ   _type
   391  	elem  *_type
   392  	slice *_type
   393  	len   uintptr
   394  }
   395  
   396  type chantype struct {
   397  	typ  _type
   398  	elem *_type
   399  	dir  uintptr
   400  }
   401  
   402  type slicetype struct {
   403  	typ  _type
   404  	elem *_type
   405  }
   406  
   407  type functype struct {
   408  	typ      _type
   409  	inCount  uint16
   410  	outCount uint16
   411  }
   412  
   413  type ptrtype struct {
   414  	typ  _type
   415  	elem *_type
   416  }
   417  
   418  type structfield struct {
   419  	name       name
   420  	typ        *_type
   421  	offsetAnon uintptr
   422  }
   423  
   424  func (f *structfield) offset() uintptr {
   425  	return f.offsetAnon >> 1
   426  }
   427  
   428  type structtype struct {
   429  	typ     _type
   430  	pkgPath name
   431  	fields  []structfield
   432  }
   433  
   434  // name is an encoded type name with optional extra data.
   435  // See reflect/type.go for details.
   436  type name struct {
   437  	bytes *byte
   438  }
   439  
   440  func (n name) data(off int) *byte {
   441  	return (*byte)(add(unsafe.Pointer(n.bytes), uintptr(off)))
   442  }
   443  
   444  func (n name) isExported() bool {
   445  	return (*n.bytes)&(1<<0) != 0
   446  }
   447  
   448  func (n name) nameLen() int {
   449  	return int(uint16(*n.data(1))<<8 | uint16(*n.data(2)))
   450  }
   451  
   452  func (n name) tagLen() int {
   453  	if *n.data(0)&(1<<1) == 0 {
   454  		return 0
   455  	}
   456  	off := 3 + n.nameLen()
   457  	return int(uint16(*n.data(off))<<8 | uint16(*n.data(off + 1)))
   458  }
   459  
   460  func (n name) name() (s string) {
   461  	if n.bytes == nil {
   462  		return ""
   463  	}
   464  	nl := n.nameLen()
   465  	if nl == 0 {
   466  		return ""
   467  	}
   468  	hdr := (*stringStruct)(unsafe.Pointer(&s))
   469  	hdr.str = unsafe.Pointer(n.data(3))
   470  	hdr.len = nl
   471  	return s
   472  }
   473  
   474  func (n name) tag() (s string) {
   475  	tl := n.tagLen()
   476  	if tl == 0 {
   477  		return ""
   478  	}
   479  	nl := n.nameLen()
   480  	hdr := (*stringStruct)(unsafe.Pointer(&s))
   481  	hdr.str = unsafe.Pointer(n.data(3 + nl + 2))
   482  	hdr.len = tl
   483  	return s
   484  }
   485  
   486  func (n name) pkgPath() string {
   487  	if n.bytes == nil || *n.data(0)&(1<<2) == 0 {
   488  		return ""
   489  	}
   490  	off := 3 + n.nameLen()
   491  	if tl := n.tagLen(); tl > 0 {
   492  		off += 2 + tl
   493  	}
   494  	var nameOff nameOff
   495  	copy((*[4]byte)(unsafe.Pointer(&nameOff))[:], (*[4]byte)(unsafe.Pointer(n.data(off)))[:])
   496  	pkgPathName := resolveNameOff(unsafe.Pointer(n.bytes), nameOff)
   497  	return pkgPathName.name()
   498  }
   499  
   500  // typelinksinit scans the types from extra modules and builds the
   501  // moduledata typemap used to de-duplicate type pointers.
   502  func typelinksinit() {
   503  	if firstmoduledata.next == nil {
   504  		return
   505  	}
   506  	typehash := make(map[uint32][]*_type, len(firstmoduledata.typelinks))
   507  
   508  	modules := activeModules()
   509  	prev := modules[0]
   510  	for _, md := range modules[1:] {
   511  		// Collect types from the previous module into typehash.
   512  	collect:
   513  		for _, tl := range prev.typelinks {
   514  			var t *_type
   515  			if prev.typemap == nil {
   516  				t = (*_type)(unsafe.Pointer(prev.types + uintptr(tl)))
   517  			} else {
   518  				t = prev.typemap[typeOff(tl)]
   519  			}
   520  			// Add to typehash if not seen before.
   521  			tlist := typehash[t.hash]
   522  			for _, tcur := range tlist {
   523  				if tcur == t {
   524  					continue collect
   525  				}
   526  			}
   527  			typehash[t.hash] = append(tlist, t)
   528  		}
   529  
   530  		if md.typemap == nil {
   531  			// If any of this module's typelinks match a type from a
   532  			// prior module, prefer that prior type by adding the offset
   533  			// to this module's typemap.
   534  			tm := make(map[typeOff]*_type, len(md.typelinks))
   535  			pinnedTypemaps = append(pinnedTypemaps, tm)
   536  			md.typemap = tm
   537  			for _, tl := range md.typelinks {
   538  				t := (*_type)(unsafe.Pointer(md.types + uintptr(tl)))
   539  				for _, candidate := range typehash[t.hash] {
   540  					seen := map[_typePair]struct{}{}
   541  					if typesEqual(t, candidate, seen) {
   542  						t = candidate
   543  						break
   544  					}
   545  				}
   546  				md.typemap[typeOff(tl)] = t
   547  			}
   548  		}
   549  
   550  		prev = md
   551  	}
   552  }
   553  
   554  type _typePair struct {
   555  	t1 *_type
   556  	t2 *_type
   557  }
   558  
   559  // typesEqual reports whether two types are equal.
   560  //
   561  // Everywhere in the runtime and reflect packages, it is assumed that
   562  // there is exactly one *_type per Go type, so that pointer equality
   563  // can be used to test if types are equal. There is one place that
   564  // breaks this assumption: buildmode=shared. In this case a type can
   565  // appear as two different pieces of memory. This is hidden from the
   566  // runtime and reflect package by the per-module typemap built in
   567  // typelinksinit. It uses typesEqual to map types from later modules
   568  // back into earlier ones.
   569  //
   570  // Only typelinksinit needs this function.
   571  func typesEqual(t, v *_type, seen map[_typePair]struct{}) bool {
   572  	tp := _typePair{t, v}
   573  	if _, ok := seen[tp]; ok {
   574  		return true
   575  	}
   576  
   577  	// mark these types as seen, and thus equivalent which prevents an infinite loop if
   578  	// the two types are identical, but recursively defined and loaded from
   579  	// different modules
   580  	seen[tp] = struct{}{}
   581  
   582  	if t == v {
   583  		return true
   584  	}
   585  	kind := t.kind & kindMask
   586  	if kind != v.kind&kindMask {
   587  		return false
   588  	}
   589  	if t.string() != v.string() {
   590  		return false
   591  	}
   592  	ut := t.uncommon()
   593  	uv := v.uncommon()
   594  	if ut != nil || uv != nil {
   595  		if ut == nil || uv == nil {
   596  			return false
   597  		}
   598  		pkgpatht := t.nameOff(ut.pkgpath).name()
   599  		pkgpathv := v.nameOff(uv.pkgpath).name()
   600  		if pkgpatht != pkgpathv {
   601  			return false
   602  		}
   603  	}
   604  	if kindBool <= kind && kind <= kindComplex128 {
   605  		return true
   606  	}
   607  	switch kind {
   608  	case kindString, kindUnsafePointer:
   609  		return true
   610  	case kindArray:
   611  		at := (*arraytype)(unsafe.Pointer(t))
   612  		av := (*arraytype)(unsafe.Pointer(v))
   613  		return typesEqual(at.elem, av.elem, seen) && at.len == av.len
   614  	case kindChan:
   615  		ct := (*chantype)(unsafe.Pointer(t))
   616  		cv := (*chantype)(unsafe.Pointer(v))
   617  		return ct.dir == cv.dir && typesEqual(ct.elem, cv.elem, seen)
   618  	case kindFunc:
   619  		ft := (*functype)(unsafe.Pointer(t))
   620  		fv := (*functype)(unsafe.Pointer(v))
   621  		if ft.outCount != fv.outCount || ft.inCount != fv.inCount {
   622  			return false
   623  		}
   624  		tin, vin := ft.in(), fv.in()
   625  		for i := 0; i < len(tin); i++ {
   626  			if !typesEqual(tin[i], vin[i], seen) {
   627  				return false
   628  			}
   629  		}
   630  		tout, vout := ft.out(), fv.out()
   631  		for i := 0; i < len(tout); i++ {
   632  			if !typesEqual(tout[i], vout[i], seen) {
   633  				return false
   634  			}
   635  		}
   636  		return true
   637  	case kindInterface:
   638  		it := (*interfacetype)(unsafe.Pointer(t))
   639  		iv := (*interfacetype)(unsafe.Pointer(v))
   640  		if it.pkgpath.name() != iv.pkgpath.name() {
   641  			return false
   642  		}
   643  		if len(it.mhdr) != len(iv.mhdr) {
   644  			return false
   645  		}
   646  		for i := range it.mhdr {
   647  			tm := &it.mhdr[i]
   648  			vm := &iv.mhdr[i]
   649  			// Note the mhdr array can be relocated from
   650  			// another module. See #17724.
   651  			tname := resolveNameOff(unsafe.Pointer(tm), tm.name)
   652  			vname := resolveNameOff(unsafe.Pointer(vm), vm.name)
   653  			if tname.name() != vname.name() {
   654  				return false
   655  			}
   656  			if tname.pkgPath() != vname.pkgPath() {
   657  				return false
   658  			}
   659  			tityp := resolveTypeOff(unsafe.Pointer(tm), tm.ityp)
   660  			vityp := resolveTypeOff(unsafe.Pointer(vm), vm.ityp)
   661  			if !typesEqual(tityp, vityp, seen) {
   662  				return false
   663  			}
   664  		}
   665  		return true
   666  	case kindMap:
   667  		mt := (*maptype)(unsafe.Pointer(t))
   668  		mv := (*maptype)(unsafe.Pointer(v))
   669  		return typesEqual(mt.key, mv.key, seen) && typesEqual(mt.elem, mv.elem, seen)
   670  	case kindPtr:
   671  		pt := (*ptrtype)(unsafe.Pointer(t))
   672  		pv := (*ptrtype)(unsafe.Pointer(v))
   673  		return typesEqual(pt.elem, pv.elem, seen)
   674  	case kindSlice:
   675  		st := (*slicetype)(unsafe.Pointer(t))
   676  		sv := (*slicetype)(unsafe.Pointer(v))
   677  		return typesEqual(st.elem, sv.elem, seen)
   678  	case kindStruct:
   679  		st := (*structtype)(unsafe.Pointer(t))
   680  		sv := (*structtype)(unsafe.Pointer(v))
   681  		if len(st.fields) != len(sv.fields) {
   682  			return false
   683  		}
   684  		if st.pkgPath.name() != sv.pkgPath.name() {
   685  			return false
   686  		}
   687  		for i := range st.fields {
   688  			tf := &st.fields[i]
   689  			vf := &sv.fields[i]
   690  			if tf.name.name() != vf.name.name() {
   691  				return false
   692  			}
   693  			if !typesEqual(tf.typ, vf.typ, seen) {
   694  				return false
   695  			}
   696  			if tf.name.tag() != vf.name.tag() {
   697  				return false
   698  			}
   699  			if tf.offsetAnon != vf.offsetAnon {
   700  				return false
   701  			}
   702  		}
   703  		return true
   704  	default:
   705  		println("runtime: impossible type kind", kind)
   706  		throw("runtime: impossible type kind")
   707  		return false
   708  	}
   709  }
   710  

View as plain text