diff options
Diffstat (limited to 'src/cmd/compile/internal/types2/typeset.go')
| -rw-r--r-- | src/cmd/compile/internal/types2/typeset.go | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/src/cmd/compile/internal/types2/typeset.go b/src/cmd/compile/internal/types2/typeset.go index da364699ce..5955bbe805 100644 --- a/src/cmd/compile/internal/types2/typeset.go +++ b/src/cmd/compile/internal/types2/typeset.go @@ -268,9 +268,9 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *T pos = (*ityp.embedPos)[i] } var terms termlist - switch t := under(typ).(type) { + switch u := under(typ).(type) { case *Interface: - tset := computeInterfaceTypeSet(check, pos, t) + tset := computeInterfaceTypeSet(check, pos, u) if tset.comparable { ityp.tset.comparable = true } @@ -279,7 +279,10 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *T } terms = tset.terms case *Union: - tset := computeUnionTypeSet(check, pos, t) + tset := computeUnionTypeSet(check, pos, u) + if tset == &invalidTypeSet { + continue // ignore invalid unions + } terms = tset.terms case *TypeParam: // Embedding stand-alone type parameters is not permitted. @@ -297,6 +300,8 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *T } // The type set of an interface is the intersection // of the type sets of all its elements. + // Intersection cannot produce longer termlists and + // thus cannot overflow. allTerms = allTerms.intersect(terms) } ityp.embedPos = nil // not needed anymore (errors have been reported) @@ -339,7 +344,13 @@ func (a byUniqueMethodName) Len() int { return len(a) } func (a byUniqueMethodName) Less(i, j int) bool { return a[i].less(&a[j].object) } func (a byUniqueMethodName) Swap(i, j int) { a[i], a[j] = a[j], a[i] } +// invalidTypeSet is a singleton type set to signal an invalid type set +// due to an error. It's also a valid empty type set, so consumers of +// type sets may choose to ignore it. +var invalidTypeSet TypeSet + // computeUnionTypeSet may be called with check == nil. +// The result is &invalidTypeSet if the union overflows. func computeUnionTypeSet(check *Checker, pos syntax.Pos, utyp *Union) *TypeSet { if utyp.tset != nil { return utyp.tset @@ -359,11 +370,21 @@ func computeUnionTypeSet(check *Checker, pos syntax.Pos, utyp *Union) *TypeSet { // This case is handled during union parsing. unreachable() default: + if t.typ == Typ[Invalid] { + continue + } terms = termlist{(*term)(t)} } // The type set of a union expression is the union // of the type sets of each term. allTerms = allTerms.union(terms) + if len(allTerms) > maxTermCount { + if check != nil { + check.errorf(pos, "cannot handle more than %d union terms (implementation limitation)", maxTermCount) + } + utyp.tset = &invalidTypeSet + return utyp.tset + } } utyp.tset.terms = allTerms |