diff options
Diffstat (limited to 'src/cmd/compile/internal/types2/subst.go')
| -rw-r--r-- | src/cmd/compile/internal/types2/subst.go | 105 |
1 files changed, 38 insertions, 67 deletions
diff --git a/src/cmd/compile/internal/types2/subst.go b/src/cmd/compile/internal/types2/subst.go index c67538d4f0..87c1d7872b 100644 --- a/src/cmd/compile/internal/types2/subst.go +++ b/src/cmd/compile/internal/types2/subst.go @@ -6,10 +6,7 @@ package types2 -import ( - "bytes" - "cmd/compile/internal/syntax" -) +import "cmd/compile/internal/syntax" type substMap map[*TypeParam]Type @@ -40,8 +37,8 @@ func (m substMap) lookup(tpar *TypeParam) Type { // incoming type. If a substitution took place, the result type is different // from the incoming type. // -// If the given typMap is non-nil, it is used in lieu of check.typMap. -func (check *Checker) subst(pos syntax.Pos, typ Type, smap substMap, typMap map[string]*Named) Type { +// If the given environment is non-nil, it is used in lieu of check.env. +func (check *Checker) subst(pos syntax.Pos, typ Type, smap substMap, env *Environment) Type { if smap.empty() { return typ } @@ -61,27 +58,27 @@ func (check *Checker) subst(pos syntax.Pos, typ Type, smap substMap, typMap map[ if check != nil { subst.check = check - if typMap == nil { - typMap = check.typMap + if env == nil { + env = check.conf.Environment } } - if typMap == nil { + if env == nil { // If we don't have a *Checker and its global type map, // use a local version. Besides avoiding duplicate work, // the type map prevents infinite recursive substitution // for recursive types (example: type T[P any] *T[P]). - typMap = make(map[string]*Named) + env = NewEnvironment() } - subst.typMap = typMap + subst.env = env return subst.typ(typ) } type subster struct { - pos syntax.Pos - smap substMap - check *Checker // nil if called via Instantiate - typMap map[string]*Named + pos syntax.Pos + smap substMap + check *Checker // nil if called via Instantiate + env *Environment } func (subst *subster) typ(typ Type) Type { @@ -182,13 +179,19 @@ func (subst *subster) typ(typ Type) Type { } } - if t.TParams().Len() == 0 { + // subst is called by expandNamed, so in this function we need to be + // careful not to call any methods that would cause t to be expanded: doing + // so would result in deadlock. + // + // So we call t.orig.TypeParams() rather than t.TypeParams() here and + // below. + if t.orig.TypeParams().Len() == 0 { dump(">>> %s is not parameterized", t) return t // type is not parameterized } var newTArgs []Type - assert(t.targs.Len() == t.TParams().Len()) + assert(t.targs.Len() == t.orig.TypeParams().Len()) // already instantiated dump(">>> %s already instantiated", t) @@ -201,7 +204,7 @@ func (subst *subster) typ(typ Type) Type { if new_targ != targ { dump(">>> substituted %d targ %s => %s", i, targ, new_targ) if newTArgs == nil { - newTArgs = make([]Type, t.TParams().Len()) + newTArgs = make([]Type, t.orig.TypeParams().Len()) copy(newTArgs, t.targs.list()) } newTArgs[i] = new_targ @@ -214,32 +217,29 @@ func (subst *subster) typ(typ Type) Type { } // before creating a new named type, check if we have this one already - h := typeHash(t, newTArgs) + h := subst.env.TypeHash(t.orig, newTArgs) dump(">>> new type hash: %s", h) - if named, found := subst.typMap[h]; found { + if named := subst.env.typeForHash(h, nil); named != nil { dump(">>> found %s", named) return named } - // Create a new named type and populate typMap to avoid endless recursion. - // The position used here is irrelevant because validation only occurs on t - // (we don't call validType on named), but we use subst.pos to help with - // debugging. - tname := NewTypeName(subst.pos, t.obj.pkg, t.obj.name, nil) - t.load() - // It's ok to provide a nil *Checker because the newly created type - // doesn't need to be (lazily) expanded; it's expanded below. - named := (*Checker)(nil).newNamed(tname, t.orig, nil, t.tparams, t.methods) // t is loaded, so tparams and methods are available - named.targs = NewTypeList(newTArgs) - subst.typMap[h] = named - t.expand(subst.typMap) // must happen after typMap update to avoid infinite recursion - - // do the substitution - dump(">>> subst %s with %s (new: %s)", t.underlying, subst.smap, newTArgs) - named.underlying = subst.typOrNil(t.underlying) - dump(">>> underlying: %v", named.underlying) + t.orig.resolve(subst.env) + // Create a new instance and populate the environment to avoid endless + // recursion. The position used here is irrelevant because validation only + // occurs on t (we don't call validType on named), but we use subst.pos to + // help with debugging. + named := subst.check.instance(subst.pos, t.orig, newTArgs, subst.env).(*Named) + // TODO(rfindley): we probably don't need to resolve here. Investigate if + // this can be removed. + named.resolve(subst.env) assert(named.underlying != nil) - named.fromRHS = named.underlying // for consistency, though no cycle detection is necessary + + // Note that if we were to expose substitution more generally (not just in + // the context of a declaration), we'd have to substitute in + // named.underlying as well. + // + // But this is unnecessary for now. return named @@ -253,35 +253,6 @@ func (subst *subster) typ(typ Type) Type { return typ } -// typeHash returns a string representation of typ, which can be used as an exact -// type hash: types that are identical produce identical string representations. -// If typ is a *Named type and targs is not empty, typ is printed as if it were -// instantiated with targs. -func typeHash(typ Type, targs []Type) string { - assert(typ != nil) - var buf bytes.Buffer - - h := newTypeHasher(&buf) - if named, _ := typ.(*Named); named != nil && len(targs) > 0 { - // Don't use WriteType because we need to use the provided targs - // and not any targs that might already be with the *Named type. - h.typeName(named.obj) - h.typeList(targs) - } else { - assert(targs == nil) - h.typ(typ) - } - - if debug { - // there should be no instance markers in type hashes - for _, b := range buf.Bytes() { - assert(b != instanceMarker) - } - } - - return buf.String() -} - // typOrNil is like typ but if the argument is nil it is replaced with Typ[Invalid]. // A nil type may appear in pathological cases such as type T[P any] []func(_ T([]_)) // where an array/slice element is accessed before it is set up. |