diff options
Diffstat (limited to 'src/cmd/compile/internal/types2/instantiate.go')
| -rw-r--r-- | src/cmd/compile/internal/types2/instantiate.go | 51 |
1 files changed, 21 insertions, 30 deletions
diff --git a/src/cmd/compile/internal/types2/instantiate.go b/src/cmd/compile/internal/types2/instantiate.go index 8bea63ec86..f9cde24dfc 100644 --- a/src/cmd/compile/internal/types2/instantiate.go +++ b/src/cmd/compile/internal/types2/instantiate.go @@ -122,27 +122,26 @@ func (check *Checker) instantiate(pos syntax.Pos, typ Type, targs []Type, posLis // instance creates a type or function instance using the given original type // typ and arguments targs. For Named types the resulting instance will be // unexpanded. -func (check *Checker) instance(pos syntax.Pos, typ Type, targs []Type) (res Type) { - // TODO(gri) What is better here: work with TypeParams, or work with TypeNames? +func (check *Checker) instance(pos syntax.Pos, typ Type, targs []Type) Type { switch t := typ.(type) { case *Named: h := instantiatedHash(t, targs) if check != nil { - // typ may already have been instantiated with identical type arguments. In - // that case, re-use the existing instance. + // typ may already have been instantiated with identical type arguments. + // In that case, re-use the existing instance. if named := check.typMap[h]; named != nil { return named } } - tname := NewTypeName(pos, t.obj.pkg, t.obj.name, nil) named := check.newNamed(tname, t, nil, nil, nil) // methods and tparams are set when named is loaded named.targs = NewTypeList(targs) - named.instance = &instance{pos} + named.instPos = &pos if check != nil { check.typMap[h] = named } - res = named + return named + case *Signature: tparams := t.TParams() if !check.validateTArgLen(pos, tparams.Len(), len(targs)) { @@ -151,30 +150,22 @@ func (check *Checker) instance(pos syntax.Pos, typ Type, targs []Type) (res Type if tparams.Len() == 0 { return typ // nothing to do (minor optimization) } - defer func() { - // If we had an unexpected failure somewhere don't panic below when - // asserting res.(*Signature). Check for *Signature in case Typ[Invalid] - // is returned. - if _, ok := res.(*Signature); !ok { - return - } - // If the signature doesn't use its type parameters, subst - // will not make a copy. In that case, make a copy now (so - // we can set tparams to nil w/o causing side-effects). - if t == res { - copy := *t - res = © - } - // After instantiating a generic signature, it is not generic - // anymore; we need to set tparams to nil. - res.(*Signature).tparams = nil - }() - res = check.subst(pos, typ, makeSubstMap(tparams.list(), targs), nil) - default: - // only types and functions can be generic - panic(fmt.Sprintf("%v: cannot instantiate %v", pos, typ)) + sig := check.subst(pos, typ, makeSubstMap(tparams.list(), targs), nil).(*Signature) + // If the signature doesn't use its type parameters, subst + // will not make a copy. In that case, make a copy now (so + // we can set tparams to nil w/o causing side-effects). + if sig == t { + copy := *sig + sig = © + } + // After instantiating a generic signature, it is not generic + // anymore; we need to set tparams to nil. + sig.tparams = nil + return sig } - return res + + // only types and functions can be generic + panic(fmt.Sprintf("%v: cannot instantiate %v", pos, typ)) } // validateTArgLen verifies that the length of targs and tparams matches, |