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cmd/compile/internal/types: use Type.LinkString in TypeHash

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Now that Type.LinkString always returns a fully unique string ID, we
can use it in TypeHash to avoid collisions between instantiations of
the same generic type.

Updates #51734.

Change-Id: I38cb396c88259be7afa44bd4333124ca98666c3f
Reviewed-on: https://go-review.googlesource.com/c/go/+/393716
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
This commit is contained in:
Matthew Dempsky 2022-03-17 19:50:47 -07:00
parent d81dd12906
commit a900a176bf
1 changed files with 7 additions and 20 deletions
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27
src/cmd/compile/internal/types/fmt.go
View File

@ -72,7 +72,6 @@ const (
fmtDebug
fmtTypeID
fmtTypeIDName
fmtTypeIDHash
)
// Sym
@ -144,18 +143,6 @@ func symfmt(b *bytes.Buffer, s *Sym, verb rune, mode fmtMode) {
if q := pkgqual(s.Pkg, verb, mode); q != "" {
b.WriteString(q)
b.WriteByte('.')
switch mode {
case fmtTypeIDHash:
// If name is a generic instantiation, don't hash the instantiating types.
// This isn't great, but it is safe. If we hash the instantiating types, then
// we need to make sure they have just the package name. At this point, they
// either have "", or the whole package path, and it is hard to reconcile
// the two without depending on -p (which we might do someday).
// See issue 51250.
if i := strings.Index(name, "["); i >= 0 {
name = name[:i]
}
}
}
b.WriteString(name)
}
@ -183,7 +170,7 @@ func pkgqual(pkg *Pkg, verb rune, mode fmtMode) string {
case fmtDebug:
return pkg.Name
case fmtTypeIDName, fmtTypeIDHash:
case fmtTypeIDName:
// dcommontype, typehash
return pkg.Name
@ -329,7 +316,7 @@ func tconv2(b *bytes.Buffer, t *Type, verb rune, mode fmtMode, visited map[*Type
if t == AnyType || t == ByteType || t == RuneType {
// in %-T mode collapse predeclared aliases with their originals.
switch mode {
case fmtTypeIDName, fmtTypeIDHash, fmtTypeID:
case fmtTypeIDName, fmtTypeID:
t = Types[t.Kind()]
default:
sconv2(b, t.Sym(), 'S', mode)
@ -420,7 +407,7 @@ func tconv2(b *bytes.Buffer, t *Type, verb rune, mode fmtMode, visited map[*Type
case TPTR:
b.WriteByte('*')
switch mode {
case fmtTypeID, fmtTypeIDName, fmtTypeIDHash:
case fmtTypeID, fmtTypeIDName:
if verb == 'S' {
tconv2(b, t.Elem(), 'S', mode, visited)
return
@ -482,7 +469,7 @@ func tconv2(b *bytes.Buffer, t *Type, verb rune, mode fmtMode, visited map[*Type
case IsExported(f.Sym.Name):
sconv2(b, f.Sym, 'S', mode)
default:
if mode != fmtTypeIDName && mode != fmtTypeIDHash {
if mode != fmtTypeIDName {
mode = fmtTypeID
}
sconv2(b, f.Sym, 'v', mode)
@ -552,7 +539,7 @@ func tconv2(b *bytes.Buffer, t *Type, verb rune, mode fmtMode, visited map[*Type
b.WriteByte(byte(open))
fieldVerb := 'v'
switch mode {
case fmtTypeID, fmtTypeIDName, fmtTypeIDHash, fmtGo:
case fmtTypeID, fmtTypeIDName, fmtGo:
// no argument names on function signature, and no "noescape"/"nosplit" tags
fieldVerb = 'S'
}
@ -686,7 +673,7 @@ func fldconv(b *bytes.Buffer, f *Field, verb rune, mode fmtMode, visited map[*Ty
if name == ".F" {
name = "F" // Hack for toolstash -cmp.
}
if !IsExported(name) && mode != fmtTypeIDName && mode != fmtTypeIDHash {
if !IsExported(name) && mode != fmtTypeIDName {
name = sconv(s, 0, mode) // qualify non-exported names (used on structs, not on funarg)
}
} else {
@ -754,7 +741,7 @@ func FmtConst(v constant.Value, sharp bool) string {
// TypeHash computes a hash value for type t to use in type switch statements.
func TypeHash(t *Type) uint32 {
p := tconv(t, 0, fmtTypeIDHash)
p := t.LinkString()
// Using SHA256 is overkill, but reduces accidental collisions.
h := notsha256.Sum256([]byte(p))