Zcu: remove *_loaded fields on File

Instead, `source`, `tree`, and `zir` should all be optional. This is
precisely what we're actually trying to model here; and `File` isn't
optimized for memory consumption or serializability anyway, so it's fine
to use a couple of extra bytes on actual optionals here.

src/Builtin.zig

@@ -264,14 +264,12 @@ pub fn append(opts: @This(), buffer: *std.ArrayList(u8)) Allocator.Error!void {
 }
 
 pub fn populateFile(comp: *Compilation, mod: *Module, file: *File) !void {
-    assert(file.source_loaded == true);
-
     if (mod.root.statFile(mod.root_src_path)) |stat| {
-        if (stat.size != file.source.len) {
+        if (stat.size != file.source.?.len) {
             std.log.warn(
                 "the cached file '{}{s}' had the wrong size. Expected {d}, found {d}. " ++
                     "Overwriting with correct file contents now",
-                .{ mod.root, mod.root_src_path, file.source.len, stat.size },
+                .{ mod.root, mod.root_src_path, file.source.?.len, stat.size },
             );
 
             try writeFile(file, mod);
@@ -296,15 +294,13 @@ pub fn populateFile(comp: *Compilation, mod: *Module, file: *File) !void {
 
     log.debug("parsing and generating '{s}'", .{mod.root_src_path});
 
-    file.tree = try std.zig.Ast.parse(comp.gpa, file.source, .zig);
+    file.tree = try std.zig.Ast.parse(comp.gpa, file.source.?, .zig);
-    assert(file.tree.errors.len == 0); // builtin.zig must parse
+    assert(file.tree.?.errors.len == 0); // builtin.zig must parse
-    file.tree_loaded = true;
 
-    file.zir = try AstGen.generate(comp.gpa, file.tree);
+    file.zir = try AstGen.generate(comp.gpa, file.tree.?);
-    assert(!file.zir.hasCompileErrors()); // builtin.zig must not have astgen errors
+    assert(!file.zir.?.hasCompileErrors()); // builtin.zig must not have astgen errors
-    file.zir_loaded = true;
     file.status = .success_zir;
-    // Note that whilst we set `zir_loaded` here, we populated `path_digest`
+    // Note that whilst we set `zir` here, we populated `path_digest`
     // all the way back in `Package.Module.create`.
 }
 
@@ -312,7 +308,7 @@ fn writeFile(file: *File, mod: *Module) !void {
     var buf: [std.fs.max_path_bytes]u8 = undefined;
     var af = try mod.root.atomicFile(mod.root_src_path, .{ .make_path = true }, &buf);
     defer af.deinit();
-    try af.file.writeAll(file.source);
+    try af.file.writeAll(file.source.?);
     af.finish() catch |err| switch (err) {
         error.AccessDenied => switch (builtin.os.tag) {
             .windows => {
@@ -326,7 +322,7 @@ fn writeFile(file: *File, mod: *Module) !void {
     };
 
     file.stat = .{
-        .size = file.source.len,
+        .size = file.source.?.len,
         .inode = 0, // dummy value
         .mtime = 0, // dummy value
     };

src/Compilation.zig

@@ -3211,7 +3211,7 @@ pub fn getAllErrorsAlloc(comp: *Compilation) !ErrorBundle {
             } else {
                 // Must be ZIR or Zoir errors. Note that this may include AST errors.
                 _ = try file.getTree(gpa); // Tree must be loaded.
-                if (file.zir_loaded) {
+                if (file.zir != null) {
                     try addZirErrorMessages(&bundle, file);
                 } else if (file.zoir != null) {
                     try addZoirErrorMessages(&bundle, file);
@@ -3623,22 +3623,17 @@ pub fn addModuleErrorMsg(
 }
 
 pub fn addZirErrorMessages(eb: *ErrorBundle.Wip, file: *Zcu.File) !void {
-    assert(file.zir_loaded);
-    assert(file.tree_loaded);
-    assert(file.source_loaded);
     const gpa = eb.gpa;
     const src_path = try file.fullPath(gpa);
     defer gpa.free(src_path);
-    return eb.addZirErrorMessages(file.zir, file.tree, file.source, src_path);
+    return eb.addZirErrorMessages(file.zir.?, file.tree.?, file.source.?, src_path);
 }
 
 pub fn addZoirErrorMessages(eb: *ErrorBundle.Wip, file: *Zcu.File) !void {
-    assert(file.source_loaded);
-    assert(file.tree_loaded);
     const gpa = eb.gpa;
     const src_path = try file.fullPath(gpa);
     defer gpa.free(src_path);
-    return eb.addZoirErrorMessages(file.zoir.?, file.tree, file.source, src_path);
+    return eb.addZoirErrorMessages(file.zoir.?, file.tree.?, file.source.?, src_path);
 }
 
 pub fn performAllTheWork(
@@ -4312,18 +4307,17 @@ fn workerAstGenFile(
     // Pre-emptively look for `@import` paths and queue them up.
     // If we experience an error preemptively fetching the
     // file, just ignore it and let it happen again later during Sema.
-    assert(file.zir_loaded);
+    const imports_index = file.zir.?.extra[@intFromEnum(Zir.ExtraIndex.imports)];
-    const imports_index = file.zir.extra[@intFromEnum(Zir.ExtraIndex.imports)];
     if (imports_index != 0) {
-        const extra = file.zir.extraData(Zir.Inst.Imports, imports_index);
+        const extra = file.zir.?.extraData(Zir.Inst.Imports, imports_index);
         var import_i: u32 = 0;
         var extra_index = extra.end;
 
         while (import_i < extra.data.imports_len) : (import_i += 1) {
-            const item = file.zir.extraData(Zir.Inst.Imports.Item, extra_index);
+            const item = file.zir.?.extraData(Zir.Inst.Imports.Item, extra_index);
             extra_index = item.end;
 
-            const import_path = file.zir.nullTerminatedString(item.data.name);
+            const import_path = file.zir.?.nullTerminatedString(item.data.name);
             // `@import("builtin")` is handled specially.
             if (mem.eql(u8, import_path, "builtin")) continue;
 

src/Package/Module.zig

@@ -482,13 +482,11 @@ pub fn create(arena: Allocator, options: CreateOptions) !*Package.Module {
         };
         new_file.* = .{
             .sub_file_path = "builtin.zig",
-            .source = generated_builtin_source,
-            .source_loaded = true,
-            .tree_loaded = false,
-            .zir_loaded = false,
             .stat = undefined,
-            .tree = undefined,
+            .source = generated_builtin_source,
-            .zir = undefined,
+            .tree = null,
+            .zir = null,
+            .zoir = null,
             .status = .never_loaded,
             .prev_status = .never_loaded,
             .mod = new,

src/Sema.zig

@@ -7649,9 +7649,8 @@ fn analyzeCall(
         const nav = ip.getNav(info.owner_nav);
         const resolved_func_inst = info.zir_body_inst.resolveFull(ip) orelse return error.AnalysisFail;
         const file = zcu.fileByIndex(resolved_func_inst.file);
-        assert(file.zir_loaded);
+        const zir_info = file.zir.?.getFnInfo(resolved_func_inst.inst);
-        const zir_info = file.zir.getFnInfo(resolved_func_inst.inst);
+        break :b .{ nav, file.zir.?, info.zir_body_inst, resolved_func_inst.inst, zir_info };
-        break :b .{ nav, file.zir, info.zir_body_inst, resolved_func_inst.inst, zir_info };
     } else .{ undefined, undefined, undefined, undefined, undefined };
 
     // This is the `inst_map` used when evaluating generic parameters and return types.
@@ -35328,7 +35327,7 @@ fn backingIntType(
         break :blk accumulator;
     };
 
-    const zir = zcu.namespacePtr(struct_type.namespace).fileScope(zcu).zir;
+    const zir = zcu.namespacePtr(struct_type.namespace).fileScope(zcu).zir.?;
     const zir_index = struct_type.zir_index.resolve(ip) orelse return error.AnalysisFail;
     const extended = zir.instructions.items(.data)[@intFromEnum(zir_index)].extended;
     assert(extended.opcode == .struct_decl);
@@ -35948,7 +35947,7 @@ fn structFields(
     const gpa = zcu.gpa;
     const ip = &zcu.intern_pool;
     const namespace_index = struct_type.namespace;
-    const zir = zcu.namespacePtr(namespace_index).fileScope(zcu).zir;
+    const zir = zcu.namespacePtr(namespace_index).fileScope(zcu).zir.?;
     const zir_index = struct_type.zir_index.resolve(ip) orelse return error.AnalysisFail;
 
     const fields_len, _, var extra_index = structZirInfo(zir, zir_index);
@@ -36149,7 +36148,7 @@ fn structFieldInits(
     assert(!struct_type.haveFieldInits(ip));
 
     const namespace_index = struct_type.namespace;
-    const zir = zcu.namespacePtr(namespace_index).fileScope(zcu).zir;
+    const zir = zcu.namespacePtr(namespace_index).fileScope(zcu).zir.?;
     const zir_index = struct_type.zir_index.resolve(ip) orelse return error.AnalysisFail;
     const fields_len, _, var extra_index = structZirInfo(zir, zir_index);
 
@@ -36268,7 +36267,7 @@ fn unionFields(
     const zcu = pt.zcu;
     const gpa = zcu.gpa;
     const ip = &zcu.intern_pool;
-    const zir = zcu.namespacePtr(union_type.namespace).fileScope(zcu).zir;
+    const zir = zcu.namespacePtr(union_type.namespace).fileScope(zcu).zir.?;
     const zir_index = union_type.zir_index.resolve(ip) orelse return error.AnalysisFail;
     const extended = zir.instructions.items(.data)[@intFromEnum(zir_index)].extended;
     assert(extended.opcode == .union_decl);

src/Type.zig

@@ -3587,8 +3587,7 @@ pub fn typeDeclSrcLine(ty: Type, zcu: *Zcu) ?u32 {
     };
     const info = tracked.resolveFull(&zcu.intern_pool) orelse return null;
     const file = zcu.fileByIndex(info.file);
-    assert(file.zir_loaded);
+    const zir = file.zir.?;
-    const zir = file.zir;
     const inst = zir.instructions.get(@intFromEnum(info.inst));
     return switch (inst.tag) {
         .struct_init, .struct_init_ref => zir.extraData(Zir.Inst.StructInit, inst.data.pl_node.payload_index).data.abs_line,
@@ -3905,7 +3904,7 @@ fn resolveStructInner(
     var comptime_err_ret_trace = std.ArrayList(Zcu.LazySrcLoc).init(gpa);
     defer comptime_err_ret_trace.deinit();
 
-    const zir = zcu.namespacePtr(struct_obj.namespace).fileScope(zcu).zir;
+    const zir = zcu.namespacePtr(struct_obj.namespace).fileScope(zcu).zir.?;
     var sema: Sema = .{
         .pt = pt,
         .gpa = gpa,
@@ -3959,7 +3958,7 @@ fn resolveUnionInner(
     var comptime_err_ret_trace = std.ArrayList(Zcu.LazySrcLoc).init(gpa);
     defer comptime_err_ret_trace.deinit();
 
-    const zir = zcu.namespacePtr(union_obj.namespace).fileScope(zcu).zir;
+    const zir = zcu.namespacePtr(union_obj.namespace).fileScope(zcu).zir.?;
     var sema: Sema = .{
         .pt = pt,
         .gpa = gpa,

src/Zcu.zig

@@ -660,22 +660,17 @@ pub const Namespace = struct {
 pub const File = struct {
     status: Status,
     prev_status: Status,
-    source_loaded: bool,
-    tree_loaded: bool,
-    zir_loaded: bool,
     /// Relative to the owning package's root source directory.
     /// Memory is stored in gpa, owned by File.
     sub_file_path: []const u8,
-    /// Whether this is populated depends on `source_loaded`.
-    source: [:0]const u8,
     /// Whether this is populated depends on `status`.
     stat: Cache.File.Stat,
-    /// Whether this is populated or not depends on `tree_loaded`.
+
-    tree: Ast,
+    source: ?[:0]const u8,
-    /// Whether this is populated or not depends on `zir_loaded`.
+    tree: ?Ast,
-    zir: Zir,
+    zir: ?Zir,
-    /// Cached Zoir, generated lazily.
+    zoir: ?Zoir,
-    zoir: ?Zoir = null,
+
     /// Module that this file is a part of, managed externally.
     mod: *Package.Module,
     /// Whether this file is a part of multiple packages. This is an error condition which will be reported after AstGen.
@@ -727,23 +722,23 @@ pub const File = struct {
     }
 
     pub fn unloadTree(file: *File, gpa: Allocator) void {
-        if (file.tree_loaded) {
+        if (file.tree) |*tree| {
-            file.tree_loaded = false;
+            tree.deinit(gpa);
-            file.tree.deinit(gpa);
+            file.tree = null;
         }
     }
 
     pub fn unloadSource(file: *File, gpa: Allocator) void {
-        if (file.source_loaded) {
+        if (file.source) |source| {
-            file.source_loaded = false;
+            gpa.free(source);
-            gpa.free(file.source);
+            file.source = null;
         }
     }
 
     pub fn unloadZir(file: *File, gpa: Allocator) void {
-        if (file.zir_loaded) {
+        if (file.zir) |*zir| {
-            file.zir_loaded = false;
+            zir.deinit(gpa);
-            file.zir.deinit(gpa);
+            file.zir = null;
         }
     }
 
@@ -753,8 +748,8 @@ pub const File = struct {
     };
 
     pub fn getSource(file: *File, gpa: Allocator) !Source {
-        if (file.source_loaded) return Source{
+        if (file.source) |source| return .{
-            .bytes = file.source,
+            .bytes = source,
             .stat = file.stat,
         };
 
@@ -769,7 +764,8 @@ pub const File = struct {
             return error.FileTooBig;
 
         const source = try gpa.allocSentinel(u8, @as(usize, @intCast(stat.size)), 0);
-        defer if (!file.source_loaded) gpa.free(source);
+        defer gpa.free(source);
+
         const amt = try f.readAll(source);
         if (amt != stat.size)
             return error.UnexpectedEndOfFile;
@@ -778,9 +774,9 @@ pub const File = struct {
         // used for error reporting. We need to keep the stat fields stale so that
         // astGenFile can know to regenerate ZIR.
 
+        errdefer comptime unreachable; // don't error after populating `source`
         file.source = source;
-        file.source_loaded = true;
+        return .{
-        return Source{
             .bytes = source,
             .stat = .{
                 .size = stat.size,
@@ -791,20 +787,20 @@ pub const File = struct {
     }
 
     pub fn getTree(file: *File, gpa: Allocator) !*const Ast {
-        if (file.tree_loaded) return &file.tree;
+        if (file.tree) |*tree| return tree;
 
         const source = try file.getSource(gpa);
-        file.tree = try Ast.parse(gpa, source.bytes, file.getMode());
+        file.tree = try .parse(gpa, source.bytes, file.getMode());
-        file.tree_loaded = true;
+        return &file.tree.?;
-        return &file.tree;
     }
 
     pub fn getZoir(file: *File, zcu: *Zcu) !*const Zoir {
         if (file.zoir) |*zoir| return zoir;
 
-        assert(file.tree_loaded);
+        const tree = file.tree.?;
-        assert(file.tree.mode == .zon);
+        assert(tree.mode == .zon);
-        file.zoir = try ZonGen.generate(zcu.gpa, file.tree, .{});
+
+        file.zoir = try ZonGen.generate(zcu.gpa, tree, .{});
         if (file.zoir.?.hasCompileErrors()) {
             try zcu.failed_files.putNoClobber(zcu.gpa, file, null);
             return error.AnalysisFail;
@@ -900,18 +896,18 @@ pub const File = struct {
 
         // We can only mark children as failed if the ZIR is loaded, which may not
         // be the case if there were other astgen failures in this file
-        if (!file.zir_loaded) return;
+        if (file.zir == null) return;
 
-        const imports_index = file.zir.extra[@intFromEnum(Zir.ExtraIndex.imports)];
+        const imports_index = file.zir.?.extra[@intFromEnum(Zir.ExtraIndex.imports)];
         if (imports_index == 0) return;
-        const extra = file.zir.extraData(Zir.Inst.Imports, imports_index);
+        const extra = file.zir.?.extraData(Zir.Inst.Imports, imports_index);
 
         var extra_index = extra.end;
         for (0..extra.data.imports_len) |_| {
-            const item = file.zir.extraData(Zir.Inst.Imports.Item, extra_index);
+            const item = file.zir.?.extraData(Zir.Inst.Imports.Item, extra_index);
             extra_index = item.end;
 
-            const import_path = file.zir.nullTerminatedString(item.data.name);
+            const import_path = file.zir.?.nullTerminatedString(item.data.name);
             if (mem.eql(u8, import_path, "builtin")) continue;
 
             const res = pt.importFile(file, import_path) catch continue;
@@ -1012,7 +1008,7 @@ pub const SrcLoc = struct {
     lazy: LazySrcLoc.Offset,
 
     pub fn baseSrcToken(src_loc: SrcLoc) Ast.TokenIndex {
-        const tree = src_loc.file_scope.tree;
+        const tree = src_loc.file_scope.tree.?;
         return tree.firstToken(src_loc.base_node);
     }
 
@@ -1057,7 +1053,6 @@ pub const SrcLoc = struct {
                 const node_off = traced_off.x;
                 const tree = try src_loc.file_scope.getTree(gpa);
                 const node = src_loc.relativeToNodeIndex(node_off);
-                assert(src_loc.file_scope.tree_loaded);
                 return tree.nodeToSpan(node);
             },
             .node_offset_main_token => |node_off| {
@@ -1069,7 +1064,6 @@ pub const SrcLoc = struct {
             .node_offset_bin_op => |node_off| {
                 const tree = try src_loc.file_scope.getTree(gpa);
                 const node = src_loc.relativeToNodeIndex(node_off);
-                assert(src_loc.file_scope.tree_loaded);
                 return tree.nodeToSpan(node);
             },
             .node_offset_initializer => |node_off| {
@@ -2408,9 +2402,8 @@ pub const LazySrcLoc = struct {
         if (zir_inst == .main_struct_inst) return .{ file, 0 };
 
         // Otherwise, make sure ZIR is loaded.
-        assert(file.zir_loaded);
+        const zir = file.zir.?;
 
-        const zir = file.zir;
         const inst = zir.instructions.get(@intFromEnum(zir_inst));
         const base_node: Ast.Node.Index = switch (inst.tag) {
             .declaration => inst.data.declaration.src_node,
@@ -3671,7 +3664,7 @@ fn resolveReferencesInner(zcu: *Zcu) !std.AutoHashMapUnmanaged(AnalUnit, ?Resolv
                 const inst_info = nav.analysis.?.zir_index.resolveFull(ip) orelse continue;
                 const file = zcu.fileByIndex(inst_info.file);
                 // If the file failed AstGen, the TrackedInst refers to the old ZIR.
-                const zir = if (file.status == .success_zir) file.zir else file.prev_zir.?.*;
+                const zir = if (file.status == .success_zir) file.zir.? else file.prev_zir.?.*;
                 const decl = zir.getDeclaration(inst_info.inst);
 
                 if (!comp.config.is_test or file.mod != zcu.main_mod) continue;
@@ -3703,7 +3696,7 @@ fn resolveReferencesInner(zcu: *Zcu) !std.AutoHashMapUnmanaged(AnalUnit, ?Resolv
                 const inst_info = ip.getNav(nav).analysis.?.zir_index.resolveFull(ip) orelse continue;
                 const file = zcu.fileByIndex(inst_info.file);
                 // If the file failed AstGen, the TrackedInst refers to the old ZIR.
-                const zir = if (file.status == .success_zir) file.zir else file.prev_zir.?.*;
+                const zir = if (file.status == .success_zir) file.zir.? else file.prev_zir.?.*;
                 const decl = zir.getDeclaration(inst_info.inst);
                 if (decl.linkage == .@"export") {
                     const unit: AnalUnit = .wrap(.{ .nav_val = nav });
@@ -3721,7 +3714,7 @@ fn resolveReferencesInner(zcu: *Zcu) !std.AutoHashMapUnmanaged(AnalUnit, ?Resolv
                 const inst_info = ip.getNav(nav).analysis.?.zir_index.resolveFull(ip) orelse continue;
                 const file = zcu.fileByIndex(inst_info.file);
                 // If the file failed AstGen, the TrackedInst refers to the old ZIR.
-                const zir = if (file.status == .success_zir) file.zir else file.prev_zir.?.*;
+                const zir = if (file.status == .success_zir) file.zir.? else file.prev_zir.?.*;
                 const decl = zir.getDeclaration(inst_info.inst);
                 if (decl.linkage == .@"export") {
                     const unit: AnalUnit = .wrap(.{ .nav_val = nav });
@@ -3858,7 +3851,7 @@ pub fn navSrcLine(zcu: *Zcu, nav_index: InternPool.Nav.Index) u32 {
     const ip = &zcu.intern_pool;
     const inst_info = ip.getNav(nav_index).srcInst(ip).resolveFull(ip).?;
     const zir = zcu.fileByIndex(inst_info.file).zir;
-    return zir.getDeclaration(inst_info.inst).src_line;
+    return zir.?.getDeclaration(inst_info.inst).src_line;
 }
 
 pub fn navValue(zcu: *const Zcu, nav_index: InternPool.Nav.Index) Value {

src/Zcu/PerThread.zig

@@ -209,7 +209,6 @@ pub fn astGenFile(
                 },
                 else => |e| return e,
             };
-            file.zir_loaded = true;
             file.stat = .{
                 .size = header.stat_size,
                 .inode = header.stat_inode,
@@ -219,12 +218,12 @@ pub fn astGenFile(
             file.status = .success_zir;
             log.debug("AstGen cached success: {s}", .{file.sub_file_path});
 
-            if (file.zir.hasCompileErrors()) {
+            if (file.zir.?.hasCompileErrors()) {
                 comp.mutex.lock();
                 defer comp.mutex.unlock();
                 try zcu.failed_files.putNoClobber(gpa, file, null);
             }
-            if (file.zir.loweringFailed()) {
+            if (file.zir.?.loweringFailed()) {
                 file.status = .astgen_failure;
                 return error.AnalysisFail;
             }
@@ -261,13 +260,12 @@ pub fn astGenFile(
     //    single-threaded context, so we need to keep both versions around
     //    until that point in the pipeline. Previous ZIR data is freed after
     //    that.
-    if (file.zir_loaded and !file.zir.loweringFailed()) {
+    if (file.zir != null and !file.zir.?.loweringFailed()) {
         assert(file.prev_zir == null);
         const prev_zir_ptr = try gpa.create(Zir);
         file.prev_zir = prev_zir_ptr;
-        prev_zir_ptr.* = file.zir;
+        prev_zir_ptr.* = file.zir.?;
-        file.zir = undefined;
+        file.zir = null;
-        file.zir_loaded = false;
     }
     file.unload(gpa);
 
@@ -275,7 +273,7 @@ pub fn astGenFile(
         return error.FileTooBig;
 
     const source = try gpa.allocSentinel(u8, @as(usize, @intCast(stat.size)), 0);
-    defer if (!file.source_loaded) gpa.free(source);
+    defer if (file.source == null) gpa.free(source);
     const amt = try source_file.readAll(source);
     if (amt != stat.size)
         return error.UnexpectedEndOfFile;
@@ -286,42 +284,39 @@ pub fn astGenFile(
         .mtime = stat.mtime,
     };
     file.source = source;
-    file.source_loaded = true;
 
     file.tree = try Ast.parse(gpa, source, .zig);
-    file.tree_loaded = true;
 
     // Any potential AST errors are converted to ZIR errors here.
-    file.zir = try AstGen.generate(gpa, file.tree);
+    file.zir = try AstGen.generate(gpa, file.tree.?);
-    file.zir_loaded = true;
     file.prev_status = file.status;
     file.status = .success_zir;
     log.debug("AstGen fresh success: {s}", .{file.sub_file_path});
 
     const safety_buffer = if (Zcu.data_has_safety_tag)
-        try gpa.alloc([8]u8, file.zir.instructions.len)
+        try gpa.alloc([8]u8, file.zir.?.instructions.len)
     else
         undefined;
     defer if (Zcu.data_has_safety_tag) gpa.free(safety_buffer);
     const data_ptr = if (Zcu.data_has_safety_tag)
-        if (file.zir.instructions.len == 0)
+        if (file.zir.?.instructions.len == 0)
             @as([*]const u8, undefined)
         else
             @as([*]const u8, @ptrCast(safety_buffer.ptr))
     else
-        @as([*]const u8, @ptrCast(file.zir.instructions.items(.data).ptr));
+        @as([*]const u8, @ptrCast(file.zir.?.instructions.items(.data).ptr));
     if (Zcu.data_has_safety_tag) {
         // The `Data` union has a safety tag but in the file format we store it without.
-        for (file.zir.instructions.items(.data), 0..) |*data, i| {
+        for (file.zir.?.instructions.items(.data), 0..) |*data, i| {
             const as_struct: *const Zcu.HackDataLayout = @ptrCast(data);
             safety_buffer[i] = as_struct.data;
         }
     }
 
     const header: Zir.Header = .{
-        .instructions_len = @as(u32, @intCast(file.zir.instructions.len)),
+        .instructions_len = @as(u32, @intCast(file.zir.?.instructions.len)),
-        .string_bytes_len = @as(u32, @intCast(file.zir.string_bytes.len)),
+        .string_bytes_len = @as(u32, @intCast(file.zir.?.string_bytes.len)),
-        .extra_len = @as(u32, @intCast(file.zir.extra.len)),
+        .extra_len = @as(u32, @intCast(file.zir.?.extra.len)),
 
         .stat_size = stat.size,
         .stat_inode = stat.inode,
@@ -333,20 +328,20 @@ pub fn astGenFile(
             .len = @sizeOf(Zir.Header),
         },
         .{
-            .base = @as([*]const u8, @ptrCast(file.zir.instructions.items(.tag).ptr)),
+            .base = @as([*]const u8, @ptrCast(file.zir.?.instructions.items(.tag).ptr)),
-            .len = file.zir.instructions.len,
+            .len = file.zir.?.instructions.len,
         },
         .{
             .base = data_ptr,
-            .len = file.zir.instructions.len * 8,
+            .len = file.zir.?.instructions.len * 8,
         },
         .{
-            .base = file.zir.string_bytes.ptr,
+            .base = file.zir.?.string_bytes.ptr,
-            .len = file.zir.string_bytes.len,
+            .len = file.zir.?.string_bytes.len,
         },
         .{
-            .base = @as([*]const u8, @ptrCast(file.zir.extra.ptr)),
+            .base = @as([*]const u8, @ptrCast(file.zir.?.extra.ptr)),
-            .len = file.zir.extra.len * 4,
+            .len = file.zir.?.extra.len * 4,
         },
     };
     cache_file.writevAll(&iovecs) catch |err| {
@@ -355,12 +350,12 @@ pub fn astGenFile(
         });
     };
 
-    if (file.zir.hasCompileErrors()) {
+    if (file.zir.?.hasCompileErrors()) {
         comp.mutex.lock();
         defer comp.mutex.unlock();
         try zcu.failed_files.putNoClobber(gpa, file, null);
     }
-    if (file.zir.loweringFailed()) {
+    if (file.zir.?.loweringFailed()) {
         file.status = .astgen_failure;
         return error.AnalysisFail;
     }
@@ -392,7 +387,7 @@ pub fn updateZirRefs(pt: Zcu.PerThread) Allocator.Error!void {
             try zcu.markDependeeOutdated(.not_marked_po, .{ .file = file_index });
         }
         const old_zir = file.prev_zir orelse continue;
-        const new_zir = file.zir;
+        const new_zir = file.zir.?;
         const gop = try updated_files.getOrPut(gpa, file_index);
         assert(!gop.found_existing);
         gop.value_ptr.* = .{
@@ -400,7 +395,7 @@ pub fn updateZirRefs(pt: Zcu.PerThread) Allocator.Error!void {
             .inst_map = .{},
         };
         if (!new_zir.loweringFailed()) {
-            try Zcu.mapOldZirToNew(gpa, old_zir.*, file.zir, &gop.value_ptr.inst_map);
+            try Zcu.mapOldZirToNew(gpa, old_zir.*, new_zir, &gop.value_ptr.inst_map);
         }
     }
 
@@ -426,7 +421,7 @@ pub fn updateZirRefs(pt: Zcu.PerThread) Allocator.Error!void {
                 // Either way, invalidate associated `src_hash` deps.
                 log.debug("tracking failed for %{d}{s}", .{
                     old_inst,
-                    if (file.zir.loweringFailed()) " due to AstGen failure" else "",
+                    if (file.zir.?.loweringFailed()) " due to AstGen failure" else "",
                 });
                 tracked_inst.inst = .lost;
                 try zcu.markDependeeOutdated(.not_marked_po, .{ .src_hash = tracked_inst_index });
@@ -435,7 +430,7 @@ pub fn updateZirRefs(pt: Zcu.PerThread) Allocator.Error!void {
             tracked_inst.inst = InternPool.TrackedInst.MaybeLost.ZirIndex.wrap(new_inst);
 
             const old_zir = file.prev_zir.?.*;
-            const new_zir = file.zir;
+            const new_zir = file.zir.?;
             const old_tag = old_zir.instructions.items(.tag)[@intFromEnum(old_inst)];
             const old_data = old_zir.instructions.items(.data)[@intFromEnum(old_inst)];
 
@@ -532,7 +527,7 @@ pub fn updateZirRefs(pt: Zcu.PerThread) Allocator.Error!void {
 
     for (updated_files.keys(), updated_files.values()) |file_index, updated_file| {
         const file = updated_file.file;
-        if (file.zir.loweringFailed()) {
+        if (file.zir.?.loweringFailed()) {
             // Keep `prev_zir` around: it's the last usable ZIR.
             // Don't update the namespace, as we have no new data to update *to*.
         } else {
@@ -805,7 +800,7 @@ fn analyzeComptimeUnit(pt: Zcu.PerThread, cu_id: InternPool.ComptimeUnit.Id) Zcu
     // unnecessary, and we can move the below `removeDependenciesForDepender` call up with its friends
     // in `ensureComptimeUnitUpToDate`.
     if (file.status != .success_zir) return error.AnalysisFail;
-    const zir = file.zir;
+    const zir = file.zir.?;
 
     // We are about to re-analyze this unit; drop its depenndencies.
     zcu.intern_pool.removeDependenciesForDepender(gpa, anal_unit);
@@ -1002,7 +997,7 @@ fn analyzeNavVal(pt: Zcu.PerThread, nav_id: InternPool.Nav.Index) Zcu.CompileErr
     // unnecessary, and we can move the below `removeDependenciesForDepender` call up with its friends
     // in `ensureComptimeUnitUpToDate`.
     if (file.status != .success_zir) return error.AnalysisFail;
-    const zir = file.zir;
+    const zir = file.zir.?;
 
     // We are about to re-analyze this unit; drop its depenndencies.
     zcu.intern_pool.removeDependenciesForDepender(gpa, anal_unit);
@@ -1380,7 +1375,7 @@ fn analyzeNavType(pt: Zcu.PerThread, nav_id: InternPool.Nav.Index) Zcu.CompileEr
     // unnecessary, and we can move the below `removeDependenciesForDepender` call up with its friends
     // in `ensureComptimeUnitUpToDate`.
     if (file.status != .success_zir) return error.AnalysisFail;
-    const zir = file.zir;
+    const zir = file.zir.?;
 
     // We are about to re-analyze this unit; drop its depenndencies.
     zcu.intern_pool.removeDependenciesForDepender(gpa, anal_unit);
@@ -1758,7 +1753,7 @@ fn createFileRootStruct(
     const gpa = zcu.gpa;
     const ip = &zcu.intern_pool;
     const file = zcu.fileByIndex(file_index);
-    const extended = file.zir.instructions.items(.data)[@intFromEnum(Zir.Inst.Index.main_struct_inst)].extended;
+    const extended = file.zir.?.instructions.items(.data)[@intFromEnum(Zir.Inst.Index.main_struct_inst)].extended;
     assert(extended.opcode == .struct_decl);
     const small: Zir.Inst.StructDecl.Small = @bitCast(extended.small);
     assert(!small.has_captures_len);
@@ -1766,16 +1761,16 @@ fn createFileRootStruct(
     assert(small.layout == .auto);
     var extra_index: usize = extended.operand + @typeInfo(Zir.Inst.StructDecl).@"struct".fields.len;
     const fields_len = if (small.has_fields_len) blk: {
-        const fields_len = file.zir.extra[extra_index];
+        const fields_len = file.zir.?.extra[extra_index];
         extra_index += 1;
         break :blk fields_len;
     } else 0;
     const decls_len = if (small.has_decls_len) blk: {
-        const decls_len = file.zir.extra[extra_index];
+        const decls_len = file.zir.?.extra[extra_index];
         extra_index += 1;
         break :blk decls_len;
     } else 0;
-    const decls = file.zir.bodySlice(extra_index, decls_len);
+    const decls = file.zir.?.bodySlice(extra_index, decls_len);
     extra_index += decls_len;
 
     const tracked_inst = try ip.trackZir(gpa, pt.tid, .{
@@ -1844,17 +1839,17 @@ fn updateFileNamespace(pt: Zcu.PerThread, file_index: Zcu.File.Index) Allocator.
 
     const namespace_index = Type.fromInterned(file_root_type).getNamespaceIndex(zcu);
     const decls = decls: {
-        const extended = file.zir.instructions.items(.data)[@intFromEnum(Zir.Inst.Index.main_struct_inst)].extended;
+        const extended = file.zir.?.instructions.items(.data)[@intFromEnum(Zir.Inst.Index.main_struct_inst)].extended;
         const small: Zir.Inst.StructDecl.Small = @bitCast(extended.small);
 
         var extra_index: usize = extended.operand + @typeInfo(Zir.Inst.StructDecl).@"struct".fields.len;
         extra_index += @intFromBool(small.has_fields_len);
         const decls_len = if (small.has_decls_len) blk: {
-            const decls_len = file.zir.extra[extra_index];
+            const decls_len = file.zir.?.extra[extra_index];
             extra_index += 1;
             break :blk decls_len;
         } else 0;
-        break :decls file.zir.bodySlice(extra_index, decls_len);
+        break :decls file.zir.?.bodySlice(extra_index, decls_len);
     };
     try pt.scanNamespace(namespace_index, decls);
     zcu.namespacePtr(namespace_index).generation = zcu.generation;
@@ -1873,7 +1868,7 @@ fn semaFile(pt: Zcu.PerThread, file_index: Zcu.File.Index) Zcu.SemaError!void {
     if (file.status != .success_zir) {
         return error.AnalysisFail;
     }
-    assert(file.zir_loaded);
+    assert(file.zir != null);
 
     const new_namespace_index = try pt.createNamespace(.{
         .parent = .none,
@@ -1983,13 +1978,11 @@ pub fn importPkg(pt: Zcu.PerThread, mod: *Module) !Zcu.ImportFileResult {
     gop.value_ptr.* = new_file_index;
     new_file.* = .{
         .sub_file_path = sub_file_path,
-        .source = undefined,
-        .source_loaded = false,
-        .tree_loaded = false,
-        .zir_loaded = false,
         .stat = undefined,
-        .tree = undefined,
+        .source = null,
-        .zir = undefined,
+        .tree = null,
+        .zir = null,
+        .zoir = null,
         .status = .never_loaded,
         .prev_status = .never_loaded,
         .mod = mod,
@@ -2096,13 +2089,11 @@ pub fn importFile(
     gop.value_ptr.* = new_file_index;
     new_file.* = .{
         .sub_file_path = sub_file_path,
-        .source = undefined,
-        .source_loaded = false,
-        .tree_loaded = false,
-        .zir_loaded = false,
         .stat = undefined,
-        .tree = undefined,
+        .source = null,
-        .zir = undefined,
+        .tree = null,
+        .zir = null,
+        .zoir = null,
         .status = .never_loaded,
         .prev_status = .never_loaded,
         .mod = mod,
@@ -2441,7 +2432,7 @@ const ScanDeclIter = struct {
         const namespace = zcu.namespacePtr(namespace_index);
         const gpa = zcu.gpa;
         const file = namespace.fileScope(zcu);
-        const zir = file.zir;
+        const zir = file.zir.?;
         const ip = &zcu.intern_pool;
 
         const decl = zir.getDeclaration(decl_inst);
@@ -2591,7 +2582,7 @@ fn analyzeFnBodyInner(pt: Zcu.PerThread, func_index: InternPool.Index) Zcu.SemaE
     const func = zcu.funcInfo(func_index);
     const inst_info = func.zir_body_inst.resolveFull(ip) orelse return error.AnalysisFail;
     const file = zcu.fileByIndex(inst_info.file);
-    const zir = file.zir;
+    const zir = file.zir.?;
 
     try zcu.analysis_in_progress.put(gpa, anal_unit, {});
     errdefer _ = zcu.analysis_in_progress.swapRemove(anal_unit);
@@ -2843,7 +2834,9 @@ pub fn getErrorValueFromSlice(pt: Zcu.PerThread, name: []const u8) Allocator.Err
 /// Removes any entry from `Zcu.failed_files` associated with `file`. Acquires `Compilation.mutex` as needed.
 /// `file.zir` must be unchanged from the last update, as it is used to determine if there is such an entry.
 fn lockAndClearFileCompileError(pt: Zcu.PerThread, file: *Zcu.File) void {
-    if (!file.zir_loaded or !file.zir.hasCompileErrors()) return;
+    const zir = file.zir orelse return;
+    if (zir.hasCompileErrors()) return;
+
     pt.zcu.comp.mutex.lock();
     defer pt.zcu.comp.mutex.unlock();
     if (pt.zcu.failed_files.fetchSwapRemove(file)) |kv| {
@@ -3779,7 +3772,7 @@ fn recreateStructType(
     const inst_info = key.zir_index.resolveFull(ip).?;
     const file = zcu.fileByIndex(inst_info.file);
     assert(file.status == .success_zir); // otherwise inst tracking failed
-    const zir = file.zir;
+    const zir = file.zir.?;
 
     assert(zir.instructions.items(.tag)[@intFromEnum(inst_info.inst)] == .extended);
     const extended = zir.instructions.items(.data)[@intFromEnum(inst_info.inst)].extended;
@@ -3852,7 +3845,7 @@ fn recreateUnionType(
     const inst_info = key.zir_index.resolveFull(ip).?;
     const file = zcu.fileByIndex(inst_info.file);
     assert(file.status == .success_zir); // otherwise inst tracking failed
-    const zir = file.zir;
+    const zir = file.zir.?;
 
     assert(zir.instructions.items(.tag)[@intFromEnum(inst_info.inst)] == .extended);
     const extended = zir.instructions.items(.data)[@intFromEnum(inst_info.inst)].extended;
@@ -3939,7 +3932,7 @@ fn recreateEnumType(
     const inst_info = key.zir_index.resolveFull(ip).?;
     const file = zcu.fileByIndex(inst_info.file);
     assert(file.status == .success_zir); // otherwise inst tracking failed
-    const zir = file.zir;
+    const zir = file.zir.?;
 
     assert(zir.instructions.items(.tag)[@intFromEnum(inst_info.inst)] == .extended);
     const extended = zir.instructions.items(.data)[@intFromEnum(inst_info.inst)].extended;
@@ -4083,7 +4076,7 @@ pub fn ensureNamespaceUpToDate(pt: Zcu.PerThread, namespace_index: Zcu.Namespace
     const inst_info = key.zir_index.resolveFull(ip) orelse return error.AnalysisFail;
     const file = zcu.fileByIndex(inst_info.file);
     if (file.status != .success_zir) return error.AnalysisFail;
-    const zir = file.zir;
+    const zir = file.zir.?;
 
     assert(zir.instructions.items(.tag)[@intFromEnum(inst_info.inst)] == .extended);
     const extended = zir.instructions.items(.data)[@intFromEnum(inst_info.inst)].extended;

src/link.zig

@@ -750,8 +750,7 @@ pub const File = struct {
         {
             const ti = ti_id.resolveFull(&pt.zcu.intern_pool).?;
             const file = pt.zcu.fileByIndex(ti.file);
-            assert(file.zir_loaded);
+            const inst = file.zir.?.instructions.get(@intFromEnum(ti.inst));
-            const inst = file.zir.instructions.get(@intFromEnum(ti.inst));
             assert(inst.tag == .declaration);
         }
 

src/link/Dwarf.zig

@@ -2358,8 +2358,7 @@ fn initWipNavInner(
     const nav = ip.getNav(nav_index);
     const inst_info = nav.srcInst(ip).resolveFull(ip).?;
     const file = zcu.fileByIndex(inst_info.file);
-    assert(file.zir_loaded);
+    const decl = file.zir.?.getDeclaration(inst_info.inst);
-    const decl = file.zir.getDeclaration(inst_info.inst);
     log.debug("initWipNav({s}:{d}:{d} %{d} = {})", .{
         file.sub_file_path,
         decl.src_line + 1,
@@ -2373,7 +2372,7 @@ fn initWipNavInner(
     switch (nav_key) {
         // Ignore @extern
         .@"extern" => |@"extern"| if (decl.linkage != .@"extern" or
-            !@"extern".name.eqlSlice(file.zir.nullTerminatedString(decl.name), ip)) return null,
+            !@"extern".name.eqlSlice(file.zir.?.nullTerminatedString(decl.name), ip)) return null,
         else => {},
     }
 
@@ -2696,8 +2695,7 @@ fn updateComptimeNavInner(dwarf: *Dwarf, pt: Zcu.PerThread, nav_index: InternPoo
     const nav = ip.getNav(nav_index);
     const inst_info = nav.srcInst(ip).resolveFull(ip).?;
     const file = zcu.fileByIndex(inst_info.file);
-    assert(file.zir_loaded);
+    const decl = file.zir.?.getDeclaration(inst_info.inst);
-    const decl = file.zir.getDeclaration(inst_info.inst);
     log.debug("updateComptimeNav({s}:{d}:{d} %{d} = {})", .{
         file.sub_file_path,
         decl.src_line + 1,
@@ -4097,7 +4095,7 @@ pub fn updateContainerType(dwarf: *Dwarf, pt: Zcu.PerThread, type_index: InternP
             // if a newly-tracked instruction can be a type's owner `zir_index`.
             comptime assert(Zir.inst_tracking_version == 0);
 
-            const decl_inst = file.zir.instructions.get(@intFromEnum(inst_info.inst));
+            const decl_inst = file.zir.?.instructions.get(@intFromEnum(inst_info.inst));
             const name_strat: Zir.Inst.NameStrategy = switch (decl_inst.tag) {
                 .struct_init, .struct_init_ref, .struct_init_anon => .anon,
                 .extended => switch (decl_inst.data.extended.opcode) {
@@ -4301,14 +4299,13 @@ pub fn updateLineNumber(dwarf: *Dwarf, zcu: *Zcu, zir_index: InternPool.TrackedI
     const inst_info = zir_index.resolveFull(ip).?;
     assert(inst_info.inst != .main_struct_inst);
     const file = zcu.fileByIndex(inst_info.file);
-    assert(file.zir_loaded);
+    const decl = file.zir.?.getDeclaration(inst_info.inst);
-    const decl = file.zir.getDeclaration(inst_info.inst);
     log.debug("updateLineNumber({s}:{d}:{d} %{d} = {s})", .{
         file.sub_file_path,
         decl.src_line + 1,
         decl.src_column + 1,
         @intFromEnum(inst_info.inst),
-        file.zir.nullTerminatedString(decl.name),
+        file.zir.?.nullTerminatedString(decl.name),
     });
 
     var line_buf: [4]u8 = undefined;
@@ -4661,7 +4658,7 @@ pub fn flushModule(dwarf: *Dwarf, pt: Zcu.PerThread) FlushError!void {
                     .target_unit = StringSection.unit,
                     .target_entry = (try dwarf.debug_line_str.addString(
                         dwarf,
-                        if (file.mod.builtin_file == file) file.source else "",
+                        if (file.mod.builtin_file == file) file.source.? else "",
                     )).toOptional(),
                 });
                 header.appendNTimesAssumeCapacity(0, dwarf.sectionOffsetBytes());

src/main.zig

@@ -3636,7 +3636,7 @@ fn buildOutputType(
 
     if (show_builtin) {
         const builtin_mod = comp.root_mod.getBuiltinDependency();
-        const source = builtin_mod.builtin_file.?.source;
+        const source = builtin_mod.builtin_file.?.source.?;
         return std.io.getStdOut().writeAll(source);
     }
     switch (listen) {
@@ -6135,14 +6135,12 @@ fn cmdAstCheck(
     var file: Zcu.File = .{
         .status = .never_loaded,
         .prev_status = .never_loaded,
-        .source_loaded = false,
-        .tree_loaded = false,
-        .zir_loaded = false,
         .sub_file_path = undefined,
-        .source = undefined,
         .stat = undefined,
-        .tree = undefined,
+        .source = null,
-        .zir = undefined,
+        .tree = null,
+        .zir = null,
+        .zoir = null,
         .mod = undefined,
     };
     if (zig_source_file) |file_name| {
@@ -6163,7 +6161,6 @@ fn cmdAstCheck(
 
         file.sub_file_path = file_name;
         file.source = source;
-        file.source_loaded = true;
         file.stat = .{
             .size = stat.size,
             .inode = stat.inode,
@@ -6176,7 +6173,6 @@ fn cmdAstCheck(
         };
         file.sub_file_path = "<stdin>";
         file.source = source;
-        file.source_loaded = true;
         file.stat.size = source.len;
     }
 
@@ -6196,17 +6192,15 @@ fn cmdAstCheck(
         .fully_qualified_name = "root",
     });
 
-    file.tree = try Ast.parse(gpa, file.source, mode);
+    file.tree = try Ast.parse(gpa, file.source.?, mode);
-    file.tree_loaded = true;
+    defer file.tree.?.deinit(gpa);
-    defer file.tree.deinit(gpa);
 
     switch (mode) {
         .zig => {
-            file.zir = try AstGen.generate(gpa, file.tree);
+            file.zir = try AstGen.generate(gpa, file.tree.?);
-            file.zir_loaded = true;
+            defer file.zir.?.deinit(gpa);
-            defer file.zir.deinit(gpa);
 
-            if (file.zir.hasCompileErrors()) {
+            if (file.zir.?.hasCompileErrors()) {
                 var wip_errors: std.zig.ErrorBundle.Wip = undefined;
                 try wip_errors.init(gpa);
                 defer wip_errors.deinit();
@@ -6215,13 +6209,13 @@ fn cmdAstCheck(
                 defer error_bundle.deinit(gpa);
                 error_bundle.renderToStdErr(color.renderOptions());
 
-                if (file.zir.loweringFailed()) {
+                if (file.zir.?.loweringFailed()) {
                     process.exit(1);
                 }
             }
 
             if (!want_output_text) {
-                if (file.zir.hasCompileErrors()) {
+                if (file.zir.?.hasCompileErrors()) {
                     process.exit(1);
                 } else {
                     return cleanExit();
@@ -6233,18 +6227,18 @@ fn cmdAstCheck(
 
             {
                 const token_bytes = @sizeOf(Ast.TokenList) +
-                    file.tree.tokens.len * (@sizeOf(std.zig.Token.Tag) + @sizeOf(Ast.ByteOffset));
+                    file.tree.?.tokens.len * (@sizeOf(std.zig.Token.Tag) + @sizeOf(Ast.ByteOffset));
-                const tree_bytes = @sizeOf(Ast) + file.tree.nodes.len *
+                const tree_bytes = @sizeOf(Ast) + file.tree.?.nodes.len *
                     (@sizeOf(Ast.Node.Tag) +
                     @sizeOf(Ast.Node.Data) +
                     @sizeOf(Ast.TokenIndex));
-                const instruction_bytes = file.zir.instructions.len *
+                const instruction_bytes = file.zir.?.instructions.len *
                     // Here we don't use @sizeOf(Zir.Inst.Data) because it would include
                     // the debug safety tag but we want to measure release size.
                     (@sizeOf(Zir.Inst.Tag) + 8);
-                const extra_bytes = file.zir.extra.len * @sizeOf(u32);
+                const extra_bytes = file.zir.?.extra.len * @sizeOf(u32);
                 const total_bytes = @sizeOf(Zir) + instruction_bytes + extra_bytes +
-                    file.zir.string_bytes.len * @sizeOf(u8);
+                    file.zir.?.string_bytes.len * @sizeOf(u8);
                 const stdout = io.getStdOut();
                 const fmtIntSizeBin = std.fmt.fmtIntSizeBin;
                 // zig fmt: off
@@ -6258,27 +6252,27 @@ fn cmdAstCheck(
                     \\# Extra Data Items:   {d} ({})
                     \\
                 , .{
-                    fmtIntSizeBin(file.source.len),
+                    fmtIntSizeBin(file.source.?.len),
-                    file.tree.tokens.len, fmtIntSizeBin(token_bytes),
+                    file.tree.?.tokens.len, fmtIntSizeBin(token_bytes),
-                    file.tree.nodes.len, fmtIntSizeBin(tree_bytes),
+                    file.tree.?.nodes.len, fmtIntSizeBin(tree_bytes),
                     fmtIntSizeBin(total_bytes),
-                    file.zir.instructions.len, fmtIntSizeBin(instruction_bytes),
+                    file.zir.?.instructions.len, fmtIntSizeBin(instruction_bytes),
-                    fmtIntSizeBin(file.zir.string_bytes.len),
+                    fmtIntSizeBin(file.zir.?.string_bytes.len),
-                    file.zir.extra.len, fmtIntSizeBin(extra_bytes),
+                    file.zir.?.extra.len, fmtIntSizeBin(extra_bytes),
                 });
                 // zig fmt: on
             }
 
             try @import("print_zir.zig").renderAsTextToFile(gpa, &file, io.getStdOut());
 
-            if (file.zir.hasCompileErrors()) {
+            if (file.zir.?.hasCompileErrors()) {
                 process.exit(1);
             } else {
                 return cleanExit();
             }
         },
         .zon => {
-            const zoir = try ZonGen.generate(gpa, file.tree, .{});
+            const zoir = try ZonGen.generate(gpa, file.tree.?, .{});
             defer zoir.deinit(gpa);
 
             if (zoir.hasCompileErrors()) {
@@ -6289,7 +6283,7 @@ fn cmdAstCheck(
                 {
                     const src_path = try file.fullPath(gpa);
                     defer gpa.free(src_path);
-                    try wip_errors.addZoirErrorMessages(zoir, file.tree, file.source, src_path);
+                    try wip_errors.addZoirErrorMessages(zoir, file.tree.?, file.source.?, src_path);
                 }
 
                 var error_bundle = try wip_errors.toOwnedBundle("");
@@ -6519,26 +6513,24 @@ fn cmdDumpZir(
     var file: Zcu.File = .{
         .status = .never_loaded,
         .prev_status = .never_loaded,
-        .source_loaded = false,
-        .tree_loaded = false,
-        .zir_loaded = true,
         .sub_file_path = undefined,
-        .source = undefined,
         .stat = undefined,
-        .tree = undefined,
+        .source = null,
+        .tree = null,
         .zir = try Zcu.loadZirCache(gpa, f),
+        .zoir = null,
         .mod = undefined,
     };
-    defer file.zir.deinit(gpa);
+    defer file.zir.?.deinit(gpa);
 
     {
-        const instruction_bytes = file.zir.instructions.len *
+        const instruction_bytes = file.zir.?.instructions.len *
             // Here we don't use @sizeOf(Zir.Inst.Data) because it would include
             // the debug safety tag but we want to measure release size.
             (@sizeOf(Zir.Inst.Tag) + 8);
-        const extra_bytes = file.zir.extra.len * @sizeOf(u32);
+        const extra_bytes = file.zir.?.extra.len * @sizeOf(u32);
         const total_bytes = @sizeOf(Zir) + instruction_bytes + extra_bytes +
-            file.zir.string_bytes.len * @sizeOf(u8);
+            file.zir.?.string_bytes.len * @sizeOf(u8);
         const stdout = io.getStdOut();
         const fmtIntSizeBin = std.fmt.fmtIntSizeBin;
         // zig fmt: off
@@ -6550,9 +6542,9 @@ fn cmdDumpZir(
             \\
         , .{
             fmtIntSizeBin(total_bytes),
-            file.zir.instructions.len, fmtIntSizeBin(instruction_bytes),
+            file.zir.?.instructions.len, fmtIntSizeBin(instruction_bytes),
-            fmtIntSizeBin(file.zir.string_bytes.len),
+            fmtIntSizeBin(file.zir.?.string_bytes.len),
-            file.zir.extra.len, fmtIntSizeBin(extra_bytes),
+            file.zir.?.extra.len, fmtIntSizeBin(extra_bytes),
         });
         // zig fmt: on
     }
@@ -6587,18 +6579,16 @@ fn cmdChangelist(
     var file: Zcu.File = .{
         .status = .never_loaded,
         .prev_status = .never_loaded,
-        .source_loaded = false,
-        .tree_loaded = false,
-        .zir_loaded = false,
         .sub_file_path = old_source_file,
-        .source = undefined,
         .stat = .{
             .size = stat.size,
             .inode = stat.inode,
             .mtime = stat.mtime,
         },
-        .tree = undefined,
+        .source = null,
-        .zir = undefined,
+        .tree = null,
+        .zir = null,
+        .zoir = null,
         .mod = undefined,
     };
 
@@ -6613,17 +6603,14 @@ fn cmdChangelist(
     if (amt != stat.size)
         return error.UnexpectedEndOfFile;
     file.source = source;
-    file.source_loaded = true;
 
-    file.tree = try Ast.parse(gpa, file.source, .zig);
+    file.tree = try Ast.parse(gpa, file.source.?, .zig);
-    file.tree_loaded = true;
+    defer file.tree.?.deinit(gpa);
-    defer file.tree.deinit(gpa);
 
-    file.zir = try AstGen.generate(gpa, file.tree);
+    file.zir = try AstGen.generate(gpa, file.tree.?);
-    file.zir_loaded = true;
+    defer file.zir.?.deinit(gpa);
-    defer file.zir.deinit(gpa);
 
-    if (file.zir.loweringFailed()) {
+    if (file.zir.?.loweringFailed()) {
         var wip_errors: std.zig.ErrorBundle.Wip = undefined;
         try wip_errors.init(gpa);
         defer wip_errors.deinit();
@@ -6652,13 +6639,12 @@ fn cmdChangelist(
     var new_tree = try Ast.parse(gpa, new_source, .zig);
     defer new_tree.deinit(gpa);
 
-    var old_zir = file.zir;
+    var old_zir = file.zir.?;
     defer old_zir.deinit(gpa);
-    file.zir_loaded = false;
+    file.zir = null;
     file.zir = try AstGen.generate(gpa, new_tree);
-    file.zir_loaded = true;
 
-    if (file.zir.loweringFailed()) {
+    if (file.zir.?.loweringFailed()) {
         var wip_errors: std.zig.ErrorBundle.Wip = undefined;
         try wip_errors.init(gpa);
         defer wip_errors.deinit();
@@ -6672,7 +6658,7 @@ fn cmdChangelist(
     var inst_map: std.AutoHashMapUnmanaged(Zir.Inst.Index, Zir.Inst.Index) = .empty;
     defer inst_map.deinit(gpa);
 
-    try Zcu.mapOldZirToNew(gpa, old_zir, file.zir, &inst_map);
+    try Zcu.mapOldZirToNew(gpa, old_zir, file.zir.?, &inst_map);
 
     var bw = io.bufferedWriter(io.getStdOut().writer());
     const stdout = bw.writer();

src/print_zir.zig

@@ -22,7 +22,7 @@ pub fn renderAsTextToFile(
         .gpa = gpa,
         .arena = arena.allocator(),
         .file = scope_file,
-        .code = scope_file.zir,
+        .code = scope_file.zir.?,
         .indent = 0,
         .parent_decl_node = 0,
         .recurse_decls = true,
@@ -36,18 +36,18 @@ pub fn renderAsTextToFile(
     try stream.print("%{d} ", .{@intFromEnum(main_struct_inst)});
     try writer.writeInstToStream(stream, main_struct_inst);
     try stream.writeAll("\n");
-    const imports_index = scope_file.zir.extra[@intFromEnum(Zir.ExtraIndex.imports)];
+    const imports_index = scope_file.zir.?.extra[@intFromEnum(Zir.ExtraIndex.imports)];
     if (imports_index != 0) {
         try stream.writeAll("Imports:\n");
 
-        const extra = scope_file.zir.extraData(Zir.Inst.Imports, imports_index);
+        const extra = scope_file.zir.?.extraData(Zir.Inst.Imports, imports_index);
         var extra_index = extra.end;
 
         for (0..extra.data.imports_len) |_| {
-            const item = scope_file.zir.extraData(Zir.Inst.Imports.Item, extra_index);
+            const item = scope_file.zir.?.extraData(Zir.Inst.Imports.Item, extra_index);
             extra_index = item.end;
 
-            const import_path = scope_file.zir.nullTerminatedString(item.data.name);
+            const import_path = scope_file.zir.?.nullTerminatedString(item.data.name);
             try stream.print("  @import(\"{}\") ", .{
                 std.zig.fmtEscapes(import_path),
             });
@@ -75,7 +75,7 @@ pub fn renderInstructionContext(
         .gpa = gpa,
         .arena = arena.allocator(),
         .file = scope_file,
-        .code = scope_file.zir,
+        .code = scope_file.zir.?,
         .indent = if (indent < 2) 2 else indent,
         .parent_decl_node = parent_decl_node,
         .recurse_decls = false,
@@ -107,7 +107,7 @@ pub fn renderSingleInstruction(
         .gpa = gpa,
         .arena = arena.allocator(),
         .file = scope_file,
-        .code = scope_file.zir,
+        .code = scope_file.zir.?,
         .indent = indent,
         .parent_decl_node = parent_decl_node,
         .recurse_decls = false,
@@ -2759,8 +2759,7 @@ const Writer = struct {
     }
 
     fn writeSrcNode(self: *Writer, stream: anytype, src_node: i32) !void {
-        if (!self.file.tree_loaded) return;
+        const tree = self.file.tree orelse return;
-        const tree = self.file.tree;
         const abs_node = self.relativeToNodeIndex(src_node);
         const src_span = tree.nodeToSpan(abs_node);
         const start = self.line_col_cursor.find(tree.source, src_span.start);
@@ -2772,8 +2771,7 @@ const Writer = struct {
     }
 
     fn writeSrcTok(self: *Writer, stream: anytype, src_tok: u32) !void {
-        if (!self.file.tree_loaded) return;
+        const tree = self.file.tree orelse return;
-        const tree = self.file.tree;
         const abs_tok = tree.firstToken(self.parent_decl_node) + src_tok;
         const span_start = tree.tokens.items(.start)[abs_tok];
         const span_end = span_start + @as(u32, @intCast(tree.tokenSlice(abs_tok).len));
@@ -2786,8 +2784,7 @@ const Writer = struct {
     }
 
     fn writeSrcTokAbs(self: *Writer, stream: anytype, src_tok: u32) !void {
-        if (!self.file.tree_loaded) return;
+        const tree = self.file.tree orelse return;
-        const tree = self.file.tree;
         const span_start = tree.tokens.items(.start)[src_tok];
         const span_end = span_start + @as(u32, @intCast(tree.tokenSlice(src_tok).len));
         const start = self.line_col_cursor.find(tree.source, span_start);