Add zero test for ir package

experimental/ast/zero_test.go

@@ -104,7 +104,7 @@ func testZero[Node source.Spanner](t *testing.T) {
 					r = m.Call(nil)[0]
 				}
 
-				assert.Zero(t, r.Interface(), "non-zero return #%d %#v of %T.%s", i, r, z, m.Name)
+				assert.Zero(t, r.Interface(), "non-zero return %#d %#v of %T.%s", i, r, z, m.Name)
 			}
 		}
 	})

experimental/ir/export_test.go

@@ -36,5 +36,8 @@ func GetImports(f *File) *Imports {
 }
 
 func (s Symbol) RawData() arena.Untyped {
+	if s.IsZero() {
+		return arena.Nil()
+	}
 	return s.Raw().data
 }

experimental/ir/ir_file.go

@@ -148,6 +148,9 @@ func (f *File) InternedPath() intern.ID {
 // google/protobuf/descriptor.proto, which is given special treatment in
 // the language.
 func (f *File) IsDescriptorProto() bool {
+	if f == nil {
+		return false
+	}
 	return f.InternedPath() == f.session.builtins.DescriptorFile
 }
 
@@ -176,15 +179,23 @@ func (f *File) InternedPackage() intern.ID {
 
 // Imports returns an indexer over the imports declared in this file.
 func (f *File) Imports() seq.Indexer[Import] {
-	return f.imports.Directs()
+	var imp imports
+	if f != nil {
+		imp = f.imports
+	}
+	return imp.Directs()
 }
 
 // TransitiveImports returns an indexer over the transitive imports for this
 // file.
 //
 // This function does not report whether those imports are weak or not.
 func (f *File) TransitiveImports() seq.Indexer[Import] {
-	return f.imports.Transitive()
+	var imp imports
+	if f != nil {
+		imp = f.imports
+	}
+	return imp.Transitive()
 }
 
 // ImportFor returns import metadata for a given file, if this file imports it.
@@ -199,8 +210,12 @@ func (f *File) ImportFor(that *File) Import {
 
 // Types returns the top level types of this file.
 func (f *File) Types() seq.Indexer[Type] {
+	var types []id.ID[Type]
+	if f != nil {
+		types = f.types[:f.topLevelTypesEnd]
+	}
 	return seq.NewFixedSlice(
-		f.types[:f.topLevelTypesEnd],
+		types,
 		func(_ int, p id.ID[Type]) Type {
 			return id.Wrap(f, p)
 		},
@@ -209,8 +224,12 @@ func (f *File) Types() seq.Indexer[Type] {
 
 // AllTypes returns all types defined in this file.
 func (f *File) AllTypes() seq.Indexer[Type] {
+	var types []id.ID[Type]
+	if f != nil {
+		types = f.types
+	}
 	return seq.NewFixedSlice(
-		f.types,
+		types,
 		func(_ int, p id.ID[Type]) Type {
 			return id.Wrap(f, p)
 		},
@@ -220,8 +239,12 @@ func (f *File) AllTypes() seq.Indexer[Type] {
 // Extensions returns the top level extensions defined in this file (i.e.,
 // the contents of any top-level `extends` blocks).
 func (f *File) Extensions() seq.Indexer[Member] {
+	var slice []id.ID[Member]
+	if f != nil {
+		slice = f.extns[:f.topLevelExtnsEnd]
+	}
 	return seq.NewFixedSlice(
-		f.extns[:f.topLevelExtnsEnd],
+		slice,
 		func(_ int, p id.ID[Member]) Member {
 			return id.Wrap(f, p)
 		},
@@ -230,8 +253,12 @@ func (f *File) Extensions() seq.Indexer[Member] {
 
 // AllExtensions returns all extensions defined in this file.
 func (f *File) AllExtensions() seq.Indexer[Member] {
+	var extns []id.ID[Member]
+	if f != nil {
+		extns = f.extns
+	}
 	return seq.NewFixedSlice(
-		f.extns,
+		extns,
 		func(_ int, p id.ID[Member]) Member {
 			return id.Wrap(f, p)
 		},
@@ -240,8 +267,12 @@ func (f *File) AllExtensions() seq.Indexer[Member] {
 
 // Extends returns the top level extend blocks in this file.
 func (f *File) Extends() seq.Indexer[Extend] {
+	var slice []id.ID[Extend]
+	if f != nil {
+		slice = f.extends[:f.topLevelExtendsEnd]
+	}
 	return seq.NewFixedSlice(
-		f.extends[:f.topLevelExtendsEnd],
+		slice,
 		func(_ int, p id.ID[Extend]) Extend {
 			return id.Wrap(f, p)
 		},
@@ -250,8 +281,12 @@ func (f *File) Extends() seq.Indexer[Extend] {
 
 // AllExtends returns all extend blocks in this file.
 func (f *File) AllExtends() seq.Indexer[Extend] {
+	var extends []id.ID[Extend]
+	if f != nil {
+		extends = f.extends
+	}
 	return seq.NewFixedSlice(
-		f.extends,
+		extends,
 		func(_ int, p id.ID[Extend]) Extend {
 			return id.Wrap(f, p)
 		},
@@ -261,17 +296,25 @@ func (f *File) AllExtends() seq.Indexer[Extend] {
 // AllMembers returns all fields defined in this file, including extensions
 // and enum values.
 func (f *File) AllMembers() iter.Seq[Member] {
+	var raw iter.Seq[*rawMember]
+	if f != nil {
+		raw = f.arenas.members.Values()
+	}
 	i := 0
-	return iterx.Map(f.arenas.members.Values(), func(raw *rawMember) Member {
+	return iterx.Map(raw, func(raw *rawMember) Member {
 		i++
 		return id.WrapRaw(f, id.ID[Member](i), raw)
 	})
 }
 
 // Services returns all services defined in this file.
 func (f *File) Services() seq.Indexer[Service] {
+	var services []id.ID[Service]
+	if f != nil {
+		services = f.services
+	}
 	return seq.NewFixedSlice(
-		f.services,
+		services,
 		func(_ int, p id.ID[Service]) Service {
 			return id.Wrap(f, p)
 		},
@@ -280,11 +323,18 @@ func (f *File) Services() seq.Indexer[Service] {
 
 // Options returns the top level options applied to this file.
 func (f *File) Options() MessageValue {
-	return id.Wrap(f, f.options).AsMessage()
+	var options id.ID[Value]
+	if f != nil {
+		options = f.options
+	}
+	return id.Wrap(f, options).AsMessage()
 }
 
 // FeatureSet returns the Editions features associated with this file.
 func (f *File) FeatureSet() FeatureSet {
+	if f == nil {
+		return FeatureSet{}
+	}
 	return id.Wrap(f, f.features)
 }
 
@@ -308,8 +358,12 @@ func (f *File) Deprecated() Value {
 // imported by the file. The symbols are returned in an arbitrary but fixed
 // order.
 func (f *File) Symbols() seq.Indexer[Symbol] {
+	var symbols []Ref[Symbol]
+	if f != nil {
+		symbols = f.imported
+	}
 	return seq.NewFixedSlice(
-		f.imported,
+		symbols,
 		func(_ int, r Ref[Symbol]) Symbol {
 			return GetRef(f, r)
 		},

experimental/ir/ir_imports.go

@@ -193,14 +193,21 @@ func (i *imports) MarkUsed(file *File) {
 
 // DescriptorProto returns the file for descriptor.proto.
 func (i *imports) DescriptorProto() *File {
+	if i == nil {
+		return nil
+	}
 	imported, _ := slicesx.Last(i.files)
 	return imported.file
 }
 
 // Directs returns an indexer over the Directs imports.
 func (i *imports) Directs() seq.Indexer[Import] {
+	var slice []imported
+	if i != nil {
+		slice = i.files[:i.importEnd]
+	}
 	return seq.NewFixedSlice(
-		i.files[:i.importEnd],
+		slice,
 		func(j int, imported imported) Import {
 			n := uint32(j)
 			public := n < i.publicEnd
@@ -223,8 +230,12 @@ func (i *imports) Directs() seq.Indexer[Import] {
 //
 // This function does not report whether those imports are weak or used.
 func (i *imports) Transitive() seq.Indexer[Import] {
+	var slice []imported
+	if i != nil {
+		slice = i.files[:max(0, len(i.files)-1)] // Exclude the implicit descriptor.proto
+	}
 	return seq.NewFixedSlice(
-		i.files[:max(0, len(i.files)-1)], // Exclude the implicit descriptor.proto.
+		slice,
 		func(j int, imported imported) Import {
 			n := uint32(j)
 			return Import{

experimental/ir/ir_member.go

@@ -336,6 +336,10 @@ func (m Member) Oneof() Oneof {
 
 // Options returns the options applied to this member.
 func (m Member) Options() MessageValue {
+	if m.IsZero() {
+		return MessageValue{}
+	}
+
 	return id.Wrap(m.Context(), m.Raw().options).AsMessage()
 }
 
@@ -587,12 +591,13 @@ func (o Oneof) Index() int {
 
 // Members returns this oneof's member fields.
 func (o Oneof) Members() seq.Indexer[Member] {
-	return seq.NewFixedSlice(
-		o.Raw().members,
-		func(_ int, p id.ID[Member]) Member {
-			return id.Wrap(o.Context(), p)
-		},
-	)
+	var members []id.ID[Member]
+	if !o.IsZero() {
+		members = o.Raw().members
+	}
+	return seq.NewFixedSlice(members, func(_ int, p id.ID[Member]) Member {
+		return id.Wrap(o.Context(), p)
+	})
 }
 
 // Parent returns the type that this oneof is declared within,.
@@ -715,6 +720,9 @@ type rawReservedName struct {
 
 // AST returns the expression that this name was evaluated from, if known.
 func (r ReservedName) AST() ast.ExprAny {
+	if r.IsZero() {
+		return ast.ExprAny{}
+	}
 	return r.raw.ast
 }
 

experimental/ir/ir_type.go

@@ -196,7 +196,7 @@ func (t Type) AllowsAlias() bool {
 // IsAny returns whether this is the type google.protobuf.Any, which gets special
 // treatment in the language.
 func (t Type) IsAny() bool {
-	return t.InternedFullName() == t.Context().session.builtins.AnyPath
+	return !t.IsZero() && t.InternedFullName() == t.Context().session.builtins.AnyPath
 }
 
 // Predeclared returns the predeclared type that this Type corresponds to, if any.
@@ -417,7 +417,10 @@ func (t Type) Extensions() seq.Indexer[Member] {
 //
 // This does not include reserved field names; see [Type.ReservedNames].
 func (t Type) AllRanges() seq.Indexer[ReservedRange] {
-	slice := t.Raw().ranges
+	var slice []id.ID[ReservedRange]
+	if !t.IsZero() {
+		slice = t.Raw().ranges
+	}
 	return seq.NewFixedSlice(slice, func(_ int, p id.ID[ReservedRange]) ReservedRange {
 		return id.Wrap(t.Context(), p)
 	})
@@ -427,24 +430,34 @@ func (t Type) AllRanges() seq.Indexer[ReservedRange] {
 //
 // This does not include reserved field names; see [Type.ReservedNames].
 func (t Type) ReservedRanges() seq.Indexer[ReservedRange] {
-	slice := t.Raw().ranges[:t.Raw().rangesExtnStart]
+	var slice []id.ID[ReservedRange]
+	if !t.IsZero() {
+		slice = t.Raw().ranges[:t.Raw().rangesExtnStart]
+	}
 	return seq.NewFixedSlice(slice, func(_ int, p id.ID[ReservedRange]) ReservedRange {
 		return id.Wrap(t.Context(), p)
 	})
 }
 
 // ExtensionRanges returns the extension ranges declared in this type.
 func (t Type) ExtensionRanges() seq.Indexer[ReservedRange] {
-	slice := t.Raw().ranges[t.Raw().rangesExtnStart:]
+	var slice []id.ID[ReservedRange]
+	if !t.IsZero() {
+		slice = t.Raw().ranges[t.Raw().rangesExtnStart:]
+	}
 	return seq.NewFixedSlice(slice, func(_ int, p id.ID[ReservedRange]) ReservedRange {
 		return id.Wrap(t.Context(), p)
 	})
 }
 
 // ReservedNames returns the reserved named declared in this type.
 func (t Type) ReservedNames() seq.Indexer[ReservedName] {
+	var slice []rawReservedName
+	if !t.IsZero() {
+		slice = t.Raw().reservedNames
+	}
 	return seq.NewFixedSlice(
-		t.Raw().reservedNames,
+		slice,
 		func(i int, _ rawReservedName) ReservedName {
 			return ReservedName{id.WrapContext(t.Context()), &t.Raw().reservedNames[i]}
 		},
@@ -453,8 +466,12 @@ func (t Type) ReservedNames() seq.Indexer[ReservedName] {
 
 // Oneofs returns the options applied to this type.
 func (t Type) Oneofs() seq.Indexer[Oneof] {
+	var oneofs []id.ID[Oneof]
+	if !t.IsZero() {
+		oneofs = t.Raw().oneofs
+	}
 	return seq.NewFixedSlice(
-		t.Raw().oneofs,
+		oneofs,
 		func(_ int, p id.ID[Oneof]) Oneof {
 			return id.Wrap(t.Context(), p)
 		},
@@ -463,8 +480,12 @@ func (t Type) Oneofs() seq.Indexer[Oneof] {
 
 // Extends returns the options applied to this type.
 func (t Type) Extends() seq.Indexer[Extend] {
+	var extends []id.ID[Extend]
+	if !t.IsZero() {
+		extends = t.Raw().extends
+	}
 	return seq.NewFixedSlice(
-		t.Raw().extends,
+		extends,
 		func(_ int, p id.ID[Extend]) Extend {
 			return id.Wrap(t.Context(), p)
 		},
@@ -473,6 +494,9 @@ func (t Type) Extends() seq.Indexer[Extend] {
 
 // Options returns the options applied to this type.
 func (t Type) Options() MessageValue {
+	if t.IsZero() {
+		return MessageValue{}
+	}
 	return id.Wrap(t.Context(), t.Raw().options).AsMessage()
 }
 

experimental/ir/ir_value.go

@@ -571,7 +571,13 @@ func (e Element) AST() ast.ExprAny {
 // this element, e.g.
 //
 //	key := e.Value().MessageKeys().At(e.ValueNodeIndex())
+//
+// If the element is empty, this returns -1.
 func (e Element) ValueNodeIndex() int {
+	if e.IsZero() {
+		return -1
+	}
+
 	// We do O(log n) work here, because this function doesn't get called except
 	// for diagnostics.