Merge pull request #22602 from mlugg/incr-embedfile

incremental: handle `@embedFile`

19 files changed, 467 insertions, 208 deletions

diff --git a/lib/std/fs/path.zig b/lib/std/fs/path.zig
index 3376771313..b2f95a937f 100644
--- a/lib/std/fs/path.zig
+++ b/lib/std/fs/path.zig
@@ -18,7 +18,6 @@ const debug = std.debug;
 const assert = debug.assert;
 const testing = std.testing;
 const mem = std.mem;
-const fmt = std.fmt;
 const ascii = std.ascii;
 const Allocator = mem.Allocator;
 const math = std.math;
@@ -147,6 +146,36 @@ pub fn joinZ(allocator: Allocator, paths: []const []const u8) ![:0]u8 {
     return out[0 .. out.len - 1 :0];
 }
 
+pub fn fmtJoin(paths: []const []const u8) std.fmt.Formatter(formatJoin) {
+    return .{ .data = paths };
+}
+
+fn formatJoin(paths: []const []const u8, comptime fmt: []const u8, options: std.fmt.FormatOptions, w: anytype) !void {
+    _ = fmt;
+    _ = options;
+
+    const first_path_idx = for (paths, 0..) |p, idx| {
+        if (p.len != 0) break idx;
+    } else return;
+
+    try w.writeAll(paths[first_path_idx]); // first component
+    var prev_path = paths[first_path_idx];
+    for (paths[first_path_idx + 1 ..]) |this_path| {
+        if (this_path.len == 0) continue; // skip empty components
+        const prev_sep = isSep(prev_path[prev_path.len - 1]);
+        const this_sep = isSep(this_path[0]);
+        if (!prev_sep and !this_sep) {
+            try w.writeByte(sep);
+        }
+        if (prev_sep and this_sep) {
+            try w.writeAll(this_path[1..]); // skip redundant separator
+        } else {
+            try w.writeAll(this_path);
+        }
+        prev_path = this_path;
+    }
+}
+
 fn testJoinMaybeZUefi(paths: []const []const u8, expected: []const u8, zero: bool) !void {
     const uefiIsSep = struct {
         fn isSep(byte: u8) bool {
diff --git a/src/Compilation.zig b/src/Compilation.zig
index 75b7f5e602..22bd0f1d59 100644
--- a/src/Compilation.zig
+++ b/src/Compilation.zig
@@ -154,10 +154,6 @@ win32_resource_work_queue: if (dev.env.supports(.win32_resource)) std.fifo.Linea
 /// since the last compilation, as well as scan for `@import` and queue up
 /// additional jobs corresponding to those new files.
 astgen_work_queue: std.fifo.LinearFifo(Zcu.File.Index, .Dynamic),
-/// These jobs are to inspect the file system stat() and if the embedded file has changed
-/// on disk, mark the corresponding Decl outdated and queue up an `analyze_decl`
-/// task for it.
-embed_file_work_queue: std.fifo.LinearFifo(*Zcu.EmbedFile, .Dynamic),
 
 /// The ErrorMsg memory is owned by the `CObject`, using Compilation's general purpose allocator.
 /// This data is accessed by multiple threads and is protected by `mutex`.
@@ -1465,7 +1461,6 @@ pub fn create(gpa: Allocator, arena: Allocator, options: CreateOptions) !*Compil
             .c_object_work_queue = std.fifo.LinearFifo(*CObject, .Dynamic).init(gpa),
             .win32_resource_work_queue = if (dev.env.supports(.win32_resource)) std.fifo.LinearFifo(*Win32Resource, .Dynamic).init(gpa) else .{},
             .astgen_work_queue = std.fifo.LinearFifo(Zcu.File.Index, .Dynamic).init(gpa),
-            .embed_file_work_queue = std.fifo.LinearFifo(*Zcu.EmbedFile, .Dynamic).init(gpa),
             .c_source_files = options.c_source_files,
             .rc_source_files = options.rc_source_files,
             .cache_parent = cache,
@@ -1920,7 +1915,6 @@ pub fn destroy(comp: *Compilation) void {
     comp.c_object_work_queue.deinit();
     comp.win32_resource_work_queue.deinit();
     comp.astgen_work_queue.deinit();
-    comp.embed_file_work_queue.deinit();
 
     comp.windows_libs.deinit(gpa);
 
@@ -2235,11 +2229,6 @@ pub fn update(comp: *Compilation, main_progress_node: std.Progress.Node) !void {
             }
         }
 
-        // Put a work item in for checking if any files used with `@embedFile` changed.
-        try comp.embed_file_work_queue.ensureUnusedCapacity(zcu.embed_table.count());
-        for (zcu.embed_table.values()) |embed_file| {
-            comp.embed_file_work_queue.writeItemAssumeCapacity(embed_file);
-        }
         if (comp.file_system_inputs) |fsi| {
             const ip = &zcu.intern_pool;
             for (zcu.embed_table.values()) |embed_file| {
@@ -3223,9 +3212,6 @@ pub fn getAllErrorsAlloc(comp: *Compilation) !ErrorBundle {
                 try addZirErrorMessages(&bundle, file);
             }
         }
-        for (zcu.failed_embed_files.values()) |error_msg| {
-            try addModuleErrorMsg(zcu, &bundle, error_msg.*);
-        }
         var sorted_failed_analysis: std.AutoArrayHashMapUnmanaged(InternPool.AnalUnit, *Zcu.ErrorMsg).DataList.Slice = s: {
             const SortOrder = struct {
                 zcu: *Zcu,
@@ -3804,9 +3790,10 @@ fn performAllTheWorkInner(
                 }
             }
 
-            while (comp.embed_file_work_queue.readItem()) |embed_file| {
-                comp.thread_pool.spawnWg(&astgen_wait_group, workerCheckEmbedFile, .{
-                    comp, embed_file,
+            for (0.., zcu.embed_table.values()) |ef_index_usize, ef| {
+                const ef_index: Zcu.EmbedFile.Index = @enumFromInt(ef_index_usize);
+                comp.thread_pool.spawnWgId(&astgen_wait_group, workerCheckEmbedFile, .{
+                    comp, ef_index, ef,
                 });
             }
         }
@@ -4369,33 +4356,33 @@ fn workerUpdateBuiltinZigFile(
     };
 }
 
-fn workerCheckEmbedFile(comp: *Compilation, embed_file: *Zcu.EmbedFile) void {
-    comp.detectEmbedFileUpdate(embed_file) catch |err| {
-        comp.reportRetryableEmbedFileError(embed_file, err) catch |oom| switch (oom) {
-            // Swallowing this error is OK because it's implied to be OOM when
-            // there is a missing `failed_embed_files` error message.
-            error.OutOfMemory => {},
-        };
-        return;
+fn workerCheckEmbedFile(tid: usize, comp: *Compilation, ef_index: Zcu.EmbedFile.Index, ef: *Zcu.EmbedFile) void {
+    comp.detectEmbedFileUpdate(@enumFromInt(tid), ef_index, ef) catch |err| switch (err) {
+        error.OutOfMemory => {
+            comp.mutex.lock();
+            defer comp.mutex.unlock();
+            comp.setAllocFailure();
+        },
     };
 }
 
-fn detectEmbedFileUpdate(comp: *Compilation, embed_file: *Zcu.EmbedFile) !void {
+fn detectEmbedFileUpdate(comp: *Compilation, tid: Zcu.PerThread.Id, ef_index: Zcu.EmbedFile.Index, ef: *Zcu.EmbedFile) !void {
     const zcu = comp.zcu.?;
-    const ip = &zcu.intern_pool;
-    var file = try embed_file.owner.root.openFile(embed_file.sub_file_path.toSlice(ip), .{});
-    defer file.close();
+    const pt: Zcu.PerThread = .activate(zcu, tid);
+    defer pt.deactivate();
+
+    const old_val = ef.val;
+    const old_err = ef.err;
 
-    const stat = try file.stat();
+    try pt.updateEmbedFile(ef, null);
 
-    const unchanged_metadata =
-        stat.size == embed_file.stat.size and
-        stat.mtime == embed_file.stat.mtime and
-        stat.inode == embed_file.stat.inode;
+    if (ef.val != .none and ef.val == old_val) return; // success, value unchanged
+    if (ef.val == .none and old_val == .none and ef.err == old_err) return; // failure, error unchanged
 
-    if (unchanged_metadata) return;
+    comp.mutex.lock();
+    defer comp.mutex.unlock();
 
-    @panic("TODO: handle embed file incremental update");
+    try zcu.markDependeeOutdated(.not_marked_po, .{ .embed_file = ef_index });
 }
 
 pub fn obtainCObjectCacheManifest(
@@ -4797,30 +4784,6 @@ fn reportRetryableWin32ResourceError(
     }
 }
 
-fn reportRetryableEmbedFileError(
-    comp: *Compilation,
-    embed_file: *Zcu.EmbedFile,
-    err: anyerror,
-) error{OutOfMemory}!void {
-    const zcu = comp.zcu.?;
-    const gpa = zcu.gpa;
-    const src_loc = embed_file.src_loc;
-    const ip = &zcu.intern_pool;
-    const err_msg = try Zcu.ErrorMsg.create(gpa, src_loc, "unable to load '{}/{s}': {s}", .{
-        embed_file.owner.root,
-        embed_file.sub_file_path.toSlice(ip),
-        @errorName(err),
-    });
-
-    errdefer err_msg.destroy(gpa);
-
-    {
-        comp.mutex.lock();
-        defer comp.mutex.unlock();
-        try zcu.failed_embed_files.putNoClobber(gpa, embed_file, err_msg);
-    }
-}
-
 fn updateCObject(comp: *Compilation, c_object: *CObject, c_obj_prog_node: std.Progress.Node) !void {
     if (comp.config.c_frontend == .aro) {
         return comp.failCObj(c_object, "aro does not support compiling C objects yet", .{});
diff --git a/src/InternPool.zig b/src/InternPool.zig
index 6d0c0a0885..ed585a0393 100644
--- a/src/InternPool.zig
+++ b/src/InternPool.zig
@@ -42,6 +42,10 @@ nav_ty_deps: std.AutoArrayHashMapUnmanaged(Nav.Index, DepEntry.Index),
 /// * a container type requiring resolution (invalidated when the type must be recreated at a new index)
 /// Value is index into `dep_entries` of the first dependency on this interned value.
 interned_deps: std.AutoArrayHashMapUnmanaged(Index, DepEntry.Index),
+/// Dependencies on an embedded file.
+/// Introduced by `@embedFile`; invalidated when the file changes.
+/// Value is index into `dep_entries` of the first dependency on this `Zcu.EmbedFile`.
+embed_file_deps: std.AutoArrayHashMapUnmanaged(Zcu.EmbedFile.Index, DepEntry.Index),
 /// Dependencies on the full set of names in a ZIR namespace.
 /// Key refers to a `struct_decl`, `union_decl`, etc.
 /// Value is index into `dep_entries` of the first dependency on this namespace.
@@ -90,6 +94,7 @@ pub const empty: InternPool = .{
     .nav_val_deps = .empty,
     .nav_ty_deps = .empty,
     .interned_deps = .empty,
+    .embed_file_deps = .empty,
     .namespace_deps = .empty,
     .namespace_name_deps = .empty,
     .memoized_state_main_deps = .none,
@@ -824,6 +829,7 @@ pub const Dependee = union(enum) {
     nav_val: Nav.Index,
     nav_ty: Nav.Index,
     interned: Index,
+    embed_file: Zcu.EmbedFile.Index,
     namespace: TrackedInst.Index,
     namespace_name: NamespaceNameKey,
     memoized_state: MemoizedStateStage,
@@ -875,6 +881,7 @@ pub fn dependencyIterator(ip: *const InternPool, dependee: Dependee) DependencyI
         .nav_val => |x| ip.nav_val_deps.get(x),
         .nav_ty => |x| ip.nav_ty_deps.get(x),
         .interned => |x| ip.interned_deps.get(x),
+        .embed_file => |x| ip.embed_file_deps.get(x),
         .namespace => |x| ip.namespace_deps.get(x),
         .namespace_name => |x| ip.namespace_name_deps.get(x),
         .memoized_state => |stage| switch (stage) {
@@ -945,6 +952,7 @@ pub fn addDependency(ip: *InternPool, gpa: Allocator, depender: AnalUnit, depend
                 .nav_val => ip.nav_val_deps,
                 .nav_ty => ip.nav_ty_deps,
                 .interned => ip.interned_deps,
+                .embed_file => ip.embed_file_deps,
                 .namespace => ip.namespace_deps,
                 .namespace_name => ip.namespace_name_deps,
                 .memoized_state => comptime unreachable,
@@ -6682,6 +6690,7 @@ pub fn deinit(ip: *InternPool, gpa: Allocator) void {
     ip.nav_val_deps.deinit(gpa);
     ip.nav_ty_deps.deinit(gpa);
     ip.interned_deps.deinit(gpa);
+    ip.embed_file_deps.deinit(gpa);
     ip.namespace_deps.deinit(gpa);
     ip.namespace_name_deps.deinit(gpa);
 
diff --git a/src/Sema.zig b/src/Sema.zig
index 52f3ae2101..6ad12d1382 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -13964,6 +13964,8 @@ fn zirEmbedFile(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!A
     defer tracy.end();
 
     const pt = sema.pt;
+    const zcu = pt.zcu;
+
     const inst_data = sema.code.instructions.items(.data)[@intFromEnum(inst)].un_node;
     const operand_src = block.builtinCallArgSrc(inst_data.src_node, 0);
     const name = try sema.resolveConstString(block, operand_src, inst_data.operand, .{ .simple = .operand_embedFile });
@@ -13972,18 +13974,24 @@ fn zirEmbedFile(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!A
         return sema.fail(block, operand_src, "file path name cannot be empty", .{});
     }
 
-    const val = pt.embedFile(block.getFileScope(pt.zcu), name, operand_src) catch |err| switch (err) {
+    const ef_idx = pt.embedFile(block.getFileScope(zcu), name) catch |err| switch (err) {
         error.ImportOutsideModulePath => {
             return sema.fail(block, operand_src, "embed of file outside package path: '{s}'", .{name});
         },
-        else => {
-            // TODO: these errors are file system errors; make sure an update() will
-            // retry this and not cache the file system error, which may be transient.
-            return sema.fail(block, operand_src, "unable to open '{s}': {s}", .{ name, @errorName(err) });
+        error.CurrentWorkingDirectoryUnlinked => {
+            // TODO: this should be some kind of retryable failure, in case the cwd is put back
+            return sema.fail(block, operand_src, "unable to resolve '{s}': working directory has been unlinked", .{name});
         },
+        error.OutOfMemory => |e| return e,
     };
+    try sema.declareDependency(.{ .embed_file = ef_idx });
+
+    const result = ef_idx.get(zcu);
+    if (result.val == .none) {
+        return sema.fail(block, operand_src, "unable to open '{s}': {s}", .{ name, @errorName(result.err.?) });
+    }
 
-    return Air.internedToRef(val);
+    return Air.internedToRef(result.val);
 }
 
 fn zirRetErrValueCode(sema: *Sema, inst: Zir.Inst.Index) CompileError!Air.Inst.Ref {
diff --git a/src/Zcu.zig b/src/Zcu.zig
index e13f62f0da..0f279440b2 100644
--- a/src/Zcu.zig
+++ b/src/Zcu.zig
@@ -143,8 +143,6 @@ compile_log_sources: std.AutoArrayHashMapUnmanaged(AnalUnit, extern struct {
 /// Using a map here for consistency with the other fields here.
 /// The ErrorMsg memory is owned by the `File`, using Module's general purpose allocator.
 failed_files: std.AutoArrayHashMapUnmanaged(*File, ?*ErrorMsg) = .empty,
-/// The ErrorMsg memory is owned by the `EmbedFile`, using Module's general purpose allocator.
-failed_embed_files: std.AutoArrayHashMapUnmanaged(*EmbedFile, *ErrorMsg) = .empty,
 failed_exports: std.AutoArrayHashMapUnmanaged(Export.Index, *ErrorMsg) = .empty,
 /// If analysis failed due to a cimport error, the corresponding Clang errors
 /// are stored here.
@@ -898,13 +896,23 @@ pub const File = struct {
 };
 
 pub const EmbedFile = struct {
-    /// Relative to the owning module's root directory.
-    sub_file_path: InternPool.NullTerminatedString,
     /// Module that this file is a part of, managed externally.
     owner: *Package.Module,
-    stat: Cache.File.Stat,
+    /// Relative to the owning module's root directory.
+    sub_file_path: InternPool.NullTerminatedString,
+
+    /// `.none` means the file was not loaded, so `stat` is undefined.
     val: InternPool.Index,
-    src_loc: LazySrcLoc,
+    /// If this is `null` and `val` is `.none`, the file has never been loaded.
+    err: ?(std.fs.File.OpenError || std.fs.File.StatError || std.fs.File.ReadError || error{UnexpectedEof}),
+    stat: Cache.File.Stat,
+
+    pub const Index = enum(u32) {
+        _,
+        pub fn get(idx: Index, zcu: *const Zcu) *EmbedFile {
+            return zcu.embed_table.values()[@intFromEnum(idx)];
+        }
+    };
 };
 
 /// This struct holds data necessary to construct API-facing `AllErrors.Message`.
@@ -2464,11 +2472,6 @@ pub fn deinit(zcu: *Zcu) void {
         }
         zcu.failed_files.deinit(gpa);
 
-        for (zcu.failed_embed_files.values()) |msg| {
-            msg.destroy(gpa);
-        }
-        zcu.failed_embed_files.deinit(gpa);
-
         for (zcu.failed_exports.values()) |value| {
             value.destroy(gpa);
         }
@@ -3887,6 +3890,14 @@ fn formatDependee(data: struct { dependee: InternPool.Dependee, zcu: *Zcu }, com
             .func => |f| return writer.print("ies('{}')", .{ip.getNav(f.owner_nav).fqn.fmt(ip)}),
             else => unreachable,
         },
+        .embed_file => |ef_idx| {
+            const ef = ef_idx.get(zcu);
+            return writer.print("embed_file('{s}')", .{std.fs.path.fmtJoin(&.{
+                ef.owner.root.root_dir.path orelse "",
+                ef.owner.root.sub_path,
+                ef.sub_file_path.toSlice(ip),
+            })});
+        },
         .namespace => |ti| {
             const info = ti.resolveFull(ip) orelse {
                 return writer.writeAll("namespace(<lost>)");
diff --git a/src/Zcu/PerThread.zig b/src/Zcu/PerThread.zig
index 0529a7fb2a..2c8dc54809 100644
--- a/src/Zcu/PerThread.zig
+++ b/src/Zcu/PerThread.zig
@@ -2117,32 +2117,32 @@ pub fn embedFile(
     pt: Zcu.PerThread,
     cur_file: *Zcu.File,
     import_string: []const u8,
-    src_loc: Zcu.LazySrcLoc,
-) !InternPool.Index {
+) error{
+    OutOfMemory,
+    ImportOutsideModulePath,
+    CurrentWorkingDirectoryUnlinked,
+}!Zcu.EmbedFile.Index {
     const zcu = pt.zcu;
     const gpa = zcu.gpa;
 
-    if (cur_file.mod.deps.get(import_string)) |pkg| {
+    if (cur_file.mod.deps.get(import_string)) |mod| {
         const resolved_path = try std.fs.path.resolve(gpa, &.{
-            pkg.root.root_dir.path orelse ".",
-            pkg.root.sub_path,
-            pkg.root_src_path,
+            mod.root.root_dir.path orelse ".",
+            mod.root.sub_path,
+            mod.root_src_path,
         });
-        var keep_resolved_path = false;
-        defer if (!keep_resolved_path) gpa.free(resolved_path);
+        errdefer gpa.free(resolved_path);
 
         const gop = try zcu.embed_table.getOrPut(gpa, resolved_path);
-        errdefer {
-            assert(std.mem.eql(u8, zcu.embed_table.pop().key, resolved_path));
-            keep_resolved_path = false;
-        }
-        if (gop.found_existing) return gop.value_ptr.*.val;
-        keep_resolved_path = true;
+        errdefer assert(std.mem.eql(u8, zcu.embed_table.pop().key, resolved_path));
 
-        const sub_file_path = try gpa.dupe(u8, pkg.root_src_path);
-        errdefer gpa.free(sub_file_path);
+        if (gop.found_existing) {
+            gpa.free(resolved_path); // we're not using this key
+            return @enumFromInt(gop.index);
+        }
 
-        return pt.newEmbedFile(pkg, sub_file_path, resolved_path, gop.value_ptr, src_loc);
+        gop.value_ptr.* = try pt.newEmbedFile(mod, mod.root_src_path, resolved_path);
+        return @enumFromInt(gop.index);
     }
 
     // The resolved path is used as the key in the table, to detect if a file
@@ -2154,17 +2154,15 @@ pub fn embedFile(
         "..",
         import_string,
     });
-
-    var keep_resolved_path = false;
-    defer if (!keep_resolved_path) gpa.free(resolved_path);
+    errdefer gpa.free(resolved_path);
 
     const gop = try zcu.embed_table.getOrPut(gpa, resolved_path);
-    errdefer {
-        assert(std.mem.eql(u8, zcu.embed_table.pop().key, resolved_path));
-        keep_resolved_path = false;
+    errdefer assert(std.mem.eql(u8, zcu.embed_table.pop().key, resolved_path));
+
+    if (gop.found_existing) {
+        gpa.free(resolved_path); // we're not using this key
+        return @enumFromInt(gop.index);
     }
-    if (gop.found_existing) return gop.value_ptr.*.val;
-    keep_resolved_path = true;
 
     const resolved_root_path = try std.fs.path.resolve(gpa, &.{
         cur_file.mod.root.root_dir.path orelse ".",
@@ -2172,101 +2170,156 @@ pub fn embedFile(
     });
     defer gpa.free(resolved_root_path);
 
-    const sub_file_path = p: {
-        const relative = try std.fs.path.relative(gpa, resolved_root_path, resolved_path);
-        errdefer gpa.free(relative);
-
-        if (!isUpDir(relative) and !std.fs.path.isAbsolute(relative)) {
-            break :p relative;
-        }
-        return error.ImportOutsideModulePath;
+    const sub_file_path = std.fs.path.relative(gpa, resolved_root_path, resolved_path) catch |err| switch (err) {
+        error.Unexpected => unreachable,
+        else => |e| return e,
     };
     defer gpa.free(sub_file_path);
 
-    return pt.newEmbedFile(cur_file.mod, sub_file_path, resolved_path, gop.value_ptr, src_loc);
+    if (isUpDir(sub_file_path) or std.fs.path.isAbsolute(sub_file_path)) {
+        return error.ImportOutsideModulePath;
+    }
+
+    gop.value_ptr.* = try pt.newEmbedFile(cur_file.mod, sub_file_path, resolved_path);
+    return @enumFromInt(gop.index);
 }
 
-/// https://github.com/ziglang/zig/issues/14307
-fn newEmbedFile(
+pub fn updateEmbedFile(
     pt: Zcu.PerThread,
-    pkg: *Module,
-    sub_file_path: []const u8,
-    resolved_path: []const u8,
-    result: **Zcu.EmbedFile,
-    src_loc: Zcu.LazySrcLoc,
-) !InternPool.Index {
+    ef: *Zcu.EmbedFile,
+    /// If not `null`, the interned file data is stored here, if it was loaded.
+    /// `newEmbedFile` uses this to add the file to the `whole` cache manifest.
+    ip_str_out: ?*?InternPool.String,
+) Allocator.Error!void {
+    pt.updateEmbedFileInner(ef, ip_str_out) catch |err| switch (err) {
+        error.OutOfMemory => |e| return e,
+        else => |e| {
+            ef.val = .none;
+            ef.err = e;
+            ef.stat = undefined;
+        },
+    };
+}
+
+fn updateEmbedFileInner(
+    pt: Zcu.PerThread,
+    ef: *Zcu.EmbedFile,
+    ip_str_out: ?*?InternPool.String,
+) !void {
+    const tid = pt.tid;
     const zcu = pt.zcu;
     const gpa = zcu.gpa;
     const ip = &zcu.intern_pool;
 
-    const new_file = try gpa.create(Zcu.EmbedFile);
-    errdefer gpa.destroy(new_file);
-
-    var file = try pkg.root.openFile(sub_file_path, .{});
+    var file = try ef.owner.root.openFile(ef.sub_file_path.toSlice(ip), .{});
     defer file.close();
 
-    const actual_stat = try file.stat();
-    const stat: Cache.File.Stat = .{
-        .size = actual_stat.size,
-        .inode = actual_stat.inode,
-        .mtime = actual_stat.mtime,
-    };
-    const size = std.math.cast(usize, actual_stat.size) orelse return error.Overflow;
-
-    const strings = ip.getLocal(pt.tid).getMutableStrings(gpa);
-    const bytes = try strings.addManyAsSlice(try std.math.add(usize, size, 1));
-    const actual_read = try file.readAll(bytes[0][0..size]);
-    if (actual_read != size) return error.UnexpectedEndOfFile;
-    bytes[0][size] = 0;
+    const stat: Cache.File.Stat = .fromFs(try file.stat());
 
-    const comp = zcu.comp;
-    switch (comp.cache_use) {
-        .whole => |whole| if (whole.cache_manifest) |man| {
-            const copied_resolved_path = try gpa.dupe(u8, resolved_path);
-            errdefer gpa.free(copied_resolved_path);
-            whole.cache_manifest_mutex.lock();
-            defer whole.cache_manifest_mutex.unlock();
-            try man.addFilePostContents(copied_resolved_path, bytes[0][0..size], stat);
-        },
-        .incremental => {},
+    if (ef.val != .none) {
+        const old_stat = ef.stat;
+        const unchanged_metadata =
+            stat.size == old_stat.size and
+            stat.mtime == old_stat.mtime and
+            stat.inode == old_stat.inode;
+        if (unchanged_metadata) return;
     }
 
-    const array_ty = try pt.intern(.{ .array_type = .{
+    const size = std.math.cast(usize, stat.size) orelse return error.FileTooBig;
+    const size_plus_one = std.math.add(usize, size, 1) catch return error.FileTooBig;
+
+    // The loaded bytes of the file, including a sentinel 0 byte.
+    const ip_str: InternPool.String = str: {
+        const strings = ip.getLocal(tid).getMutableStrings(gpa);
+        const old_len = strings.mutate.len;
+        errdefer strings.shrinkRetainingCapacity(old_len);
+        const bytes = (try strings.addManyAsSlice(size_plus_one))[0];
+        const actual_read = try file.readAll(bytes[0..size]);
+        if (actual_read != size) return error.UnexpectedEof;
+        bytes[size] = 0;
+        break :str try ip.getOrPutTrailingString(gpa, tid, @intCast(bytes.len), .maybe_embedded_nulls);
+    };
+    if (ip_str_out) |p| p.* = ip_str;
+
+    const array_ty = try pt.arrayType(.{
         .len = size,
         .sentinel = .zero_u8,
         .child = .u8_type,
-    } });
+    });
+    const ptr_ty = try pt.singleConstPtrType(array_ty);
+
     const array_val = try pt.intern(.{ .aggregate = .{
-        .ty = array_ty,
-        .storage = .{ .bytes = try ip.getOrPutTrailingString(gpa, pt.tid, @intCast(bytes[0].len), .maybe_embedded_nulls) },
+        .ty = array_ty.toIntern(),
+        .storage = .{ .bytes = ip_str },
     } });
-
-    const ptr_ty = (try pt.ptrType(.{
-        .child = array_ty,
-        .flags = .{
-            .alignment = .none,
-            .is_const = true,
-            .address_space = .generic,
-        },
-    })).toIntern();
     const ptr_val = try pt.intern(.{ .ptr = .{
-        .ty = ptr_ty,
+        .ty = ptr_ty.toIntern(),
         .base_addr = .{ .uav = .{
             .val = array_val,
-            .orig_ty = ptr_ty,
+            .orig_ty = ptr_ty.toIntern(),
         } },
         .byte_offset = 0,
     } });
 
-    result.* = new_file;
+    ef.val = ptr_val;
+    ef.err = null;
+    ef.stat = stat;
+}
+
+fn newEmbedFile(
+    pt: Zcu.PerThread,
+    mod: *Module,
+    /// The path of the file to embed relative to the root of `mod`.
+    sub_file_path: []const u8,
+    /// The resolved path of the file to embed.
+    resolved_path: []const u8,
+) !*Zcu.EmbedFile {
+    const zcu = pt.zcu;
+    const comp = zcu.comp;
+    const gpa = zcu.gpa;
+    const ip = &zcu.intern_pool;
+
+    if (comp.file_system_inputs) |fsi|
+        try comp.appendFileSystemInput(fsi, mod.root, sub_file_path);
+
+    const new_file = try gpa.create(Zcu.EmbedFile);
+    errdefer gpa.destroy(new_file);
+
     new_file.* = .{
+        .owner = mod,
         .sub_file_path = try ip.getOrPutString(gpa, pt.tid, sub_file_path, .no_embedded_nulls),
-        .owner = pkg,
-        .stat = stat,
-        .val = ptr_val,
-        .src_loc = src_loc,
+        .val = .none,
+        .err = null,
+        .stat = undefined,
     };
-    return ptr_val;
+
+    var opt_ip_str: ?InternPool.String = null;
+    try pt.updateEmbedFile(new_file, &opt_ip_str);
+
+    // Add the file contents to the `whole` cache manifest if necessary.
+    cache: {
+        const whole = switch (zcu.comp.cache_use) {
+            .whole => |whole| whole,
+            .incremental => break :cache,
+        };
+        const man = whole.cache_manifest orelse break :cache;
+        const ip_str = opt_ip_str orelse break :cache;
+
+        const copied_resolved_path = try gpa.dupe(u8, resolved_path);
+        errdefer gpa.free(copied_resolved_path);
+
+        const array_len = Value.fromInterned(new_file.val).typeOf(zcu).childType(zcu).arrayLen(zcu);
+
+        whole.cache_manifest_mutex.lock();
+        defer whole.cache_manifest_mutex.unlock();
+
+        man.addFilePostContents(copied_resolved_path, ip_str.toSlice(array_len, ip), new_file.stat) catch |err| switch (err) {
+            error.Unexpected => unreachable,
+            else => |e| return e,
+        };
+    }
+
+    return new_file;
 }
 
 pub fn scanNamespace(
diff --git a/test/incremental/add_decl b/test/incremental/add_decl
index b842593056..87f33b1c51 100644
--- a/test/incremental/add_decl
+++ b/test/incremental/add_decl
@@ -39,7 +39,7 @@ pub fn main() !void {
 }
 const foo = "good morning\n";
 const bar = "good evening\n";
-#expect_error=ignored
+#expect_error=main.zig:3:37: error: use of undeclared identifier 'qux'
 
 #update=add missing declaration
 #file=main.zig
diff --git a/test/incremental/add_decl_namespaced b/test/incremental/add_decl_namespaced
index a42e5600bc..84472effb5 100644
--- a/test/incremental/add_decl_namespaced
+++ b/test/incremental/add_decl_namespaced
@@ -39,7 +39,8 @@ pub fn main() !void {
 }
 const foo = "good morning\n";
 const bar = "good evening\n";
-#expect_error=ignored
+#expect_error=main.zig:3:44: error: root source file struct 'main' has no member named 'qux'
+#expect_error=main.zig:1:1: note: struct declared here
 
 #update=add missing declaration
 #file=main.zig
diff --git a/test/incremental/change_embed_file b/test/incremental/change_embed_file
new file mode 100644
index 0000000000..171e4d3178
--- /dev/null
+++ b/test/incremental/change_embed_file
@@ -0,0 +1,46 @@
+#target=x86_64-linux-selfhosted
+#target=x86_64-linux-cbe
+#target=x86_64-windows-cbe
+#target=wasm32-wasi-selfhosted
+#update=initial version
+#file=main.zig
+const std = @import("std");
+const string = @embedFile("string.txt");
+pub fn main() !void {
+    try std.io.getStdOut().writeAll(string);
+}
+#file=string.txt
+Hello, World!
+#expect_stdout="Hello, World!\n"
+
+#update=change file contents
+#file=string.txt
+Hello again, World!
+#expect_stdout="Hello again, World!\n"
+
+#update=delete file
+#rm_file=string.txt
+#expect_error=main.zig:2:27: error: unable to open 'string.txt': FileNotFound
+
+#update=remove reference to file
+#file=main.zig
+const std = @import("std");
+const string = @embedFile("string.txt");
+pub fn main() !void {
+    try std.io.getStdOut().writeAll("a hardcoded string\n");
+}
+#expect_stdout="a hardcoded string\n"
+
+#update=re-introduce reference to file
+#file=main.zig
+const std = @import("std");
+const string = @embedFile("string.txt");
+pub fn main() !void {
+    try std.io.getStdOut().writeAll(string);
+}
+#expect_error=main.zig:2:27: error: unable to open 'string.txt': FileNotFound
+
+#update=recreate file
+#file=string.txt
+We're back, World!
+#expect_stdout="We're back, World!\n"
diff --git a/test/incremental/change_enum_tag_type b/test/incremental/change_enum_tag_type
index e66728e08d..d3f6c85c37 100644
--- a/test/incremental/change_enum_tag_type
+++ b/test/incremental/change_enum_tag_type
@@ -39,7 +39,7 @@ comptime {
     std.debug.assert(@TypeOf(@intFromEnum(Foo.e)) == Tag);
 }
 const std = @import("std");
-#expect_error=ignored
+#expect_error=main.zig:7:5: error: enumeration value '4' too large for type 'u2'
 #update=increase tag size
 #file=main.zig
 const Tag = u3;
diff --git a/test/incremental/compile_error_then_log b/test/incremental/compile_error_then_log
index 9ab844bb4a..800fb92dfe 100644
--- a/test/incremental/compile_error_then_log
+++ b/test/incremental/compile_error_then_log
@@ -4,19 +4,22 @@
 #target=wasm32-wasi-selfhosted
 #update=initial version with compile error
 #file=main.zig
+pub fn main() void {}
 comptime {
     @compileError("this is an error");
 }
 comptime {
     @compileLog("this is a log");
 }
-#expect_error=ignored
+#expect_error=main.zig:3:5: error: this is an error
+
 #update=remove the compile error
 #file=main.zig
+pub fn main() void {}
 comptime {
     //@compileError("this is an error");
 }
 comptime {
     @compileLog("this is a log");
 }
-#expect_error=ignored
+#expect_error=main.zig:6:5: error: found compile log statement
diff --git a/test/incremental/delete_comptime_decls b/test/incremental/delete_comptime_decls
index 45c77048eb..b5ccd438a2 100644
--- a/test/incremental/delete_comptime_decls
+++ b/test/incremental/delete_comptime_decls
@@ -26,7 +26,10 @@ comptime {
     const slice = array[3..2];
     _ = slice;
 }
-#expect_error=ignored
+#expect_error=main.zig:5:32: error: end index 6 out of bounds for slice of length 4 +1 (sentinel)
+#expect_error=main.zig:10:28: error: end index 6 out of bounds for array of length 4 +1 (sentinel)
+#expect_error=main.zig:15:28: error: end index 5 out of bounds for array of length 4
+#expect_error=main.zig:20:25: error: start index 3 is larger than end index 2
 
 #update=delete and modify comptime decls
 #file=main.zig
@@ -38,4 +41,4 @@ comptime {
     const y = x[0..runtime_len];
     _ = y;
 }
-#expect_error=ignored
+#expect_error=main.zig:6:16: error: slice of null pointer
diff --git a/test/incremental/fix_astgen_failure b/test/incremental/fix_astgen_failure
index a57b1ebde3..51972e9232 100644
--- a/test/incremental/fix_astgen_failure
+++ b/test/incremental/fix_astgen_failure
@@ -11,7 +11,7 @@ pub fn main() !void {
 pub fn hello() !void {
     try std.io.getStdOut().writeAll("Hello, World!\n");
 }
-#expect_error=ignored
+#expect_error=foo.zig:2:9: error: use of undeclared identifier 'std'
 #update=fix the error
 #file=foo.zig
 const std = @import("std");
@@ -25,7 +25,7 @@ const std = @import("std");
 pub fn hello() !void {
     try std.io.getStdOut().writeAll(hello_str);
 }
-#expect_error=ignored
+#expect_error=foo.zig:3:37: error: use of undeclared identifier 'hello_str'
 #update=fix the new error
 #file=foo.zig
 const std = @import("std");
diff --git a/test/incremental/fix_many_errors b/test/incremental/fix_many_errors
index 0722cdfced..1d9446022c 100644
--- a/test/incremental/fix_many_errors
+++ b/test/incremental/fix_many_errors
@@ -24,7 +24,26 @@ export fn f6() void { @compileError("f6"); }
 export fn f7() void { @compileError("f7"); }
 export fn f8() void { @compileError("f8"); }
 export fn f9() void { @compileError("f9"); }
-#expect_error=ignored
+#expect_error=main.zig:2:12: error: c0
+#expect_error=main.zig:3:12: error: c1
+#expect_error=main.zig:4:12: error: c2
+#expect_error=main.zig:5:12: error: c3
+#expect_error=main.zig:6:12: error: c4
+#expect_error=main.zig:7:12: error: c5
+#expect_error=main.zig:8:12: error: c6
+#expect_error=main.zig:9:12: error: c7
+#expect_error=main.zig:10:12: error: c8
+#expect_error=main.zig:11:12: error: c9
+#expect_error=main.zig:12:23: error: f0
+#expect_error=main.zig:13:23: error: f1
+#expect_error=main.zig:14:23: error: f2
+#expect_error=main.zig:15:23: error: f3
+#expect_error=main.zig:16:23: error: f4
+#expect_error=main.zig:17:23: error: f5
+#expect_error=main.zig:18:23: error: f6
+#expect_error=main.zig:19:23: error: f7
+#expect_error=main.zig:20:23: error: f8
+#expect_error=main.zig:21:23: error: f9
 #update=fix all the errors
 #file=main.zig
 pub fn main() !void {}
diff --git a/test/incremental/remove_enum_field b/test/incremental/remove_enum_field
index a1e5e20fd3..8d3796b7c3 100644
--- a/test/incremental/remove_enum_field
+++ b/test/incremental/remove_enum_field
@@ -23,4 +23,5 @@ pub fn main() !void {
     try std.io.getStdOut().writer().print("{}\n", .{@intFromEnum(MyEnum.foo)});
 }
 const std = @import("std");
-#expect_error=ignored
+#expect_error=main.zig:6:73: error: enum 'main.MyEnum' has no member named 'foo'
+#expect_error=main.zig:1:16: note: enum declared here
diff --git a/test/incremental/remove_invalid_union_backing_enum b/test/incremental/remove_invalid_union_backing_enum
index 4308899f9a..1f7ee69b14 100644
--- a/test/incremental/remove_invalid_union_backing_enum
+++ b/test/incremental/remove_invalid_union_backing_enum
@@ -15,7 +15,8 @@ pub fn main() void {
     const u: U = .{ .a = 123 };
     _ = u;
 }
-#expect_error=ignored
+#expect_error=main.zig:6:5: error: no field named 'd' in enum 'main.E'
+#expect_error=main.zig:1:11: note: enum declared here
 #update=remove invalid backing enum
 #file=main.zig
 const U = union {
diff --git a/test/incremental/temporary_parse_error b/test/incremental/temporary_parse_error
index 675232ea94..0933546d33 100644
--- a/test/incremental/temporary_parse_error
+++ b/test/incremental/temporary_parse_error
@@ -11,7 +11,7 @@ pub fn main() !void {}
 #update=introduce parse error
 #file=main.zig
 pub fn main() !void {
-#expect_error=ignored
+#expect_error=main.zig:2:1: error: expected statement, found 'EOF'
 
 #update=fix parse error
 #file=main.zig
diff --git a/test/incremental/unreferenced_error b/test/incremental/unreferenced_error
index 29a9a34d97..6025f3fdae 100644
--- a/test/incremental/unreferenced_error
+++ b/test/incremental/unreferenced_error
@@ -18,7 +18,7 @@ pub fn main() !void {
     try std.io.getStdOut().writeAll(a);
 }
 const a = @compileError("bad a");
-#expect_error=ignored
+#expect_error=main.zig:5:11: error: bad a
 
 #update=remove error reference
 #file=main.zig
diff --git a/tools/incr-check.zig b/tools/incr-check.zig
index 144e05ccc4..93d16e1e58 100644
--- a/tools/incr-check.zig
+++ b/tools/incr-check.zig
@@ -340,19 +340,63 @@ const Eval = struct {
     }
 
     fn checkErrorOutcome(eval: *Eval, update: Case.Update, error_bundle: std.zig.ErrorBundle) !void {
-        switch (update.outcome) {
+        const expected_errors = switch (update.outcome) {
             .unknown => return,
-            .compile_errors => |expected_errors| {
-                for (expected_errors) |expected_error| {
-                    _ = expected_error;
-                    @panic("TODO check if the expected error matches the compile errors");
-                }
-            },
+            .compile_errors => |expected_errors| expected_errors,
             .stdout, .exit_code => {
                 const color: std.zig.Color = .auto;
                 error_bundle.renderToStdErr(color.renderOptions());
                 eval.fatal("update '{s}': unexpected compile errors", .{update.name});
             },
+        };
+
+        var expected_idx: usize = 0;
+
+        for (error_bundle.getMessages()) |err_idx| {
+            if (expected_idx == expected_errors.len) {
+                const color: std.zig.Color = .auto;
+                error_bundle.renderToStdErr(color.renderOptions());
+                eval.fatal("update '{s}': more errors than expected", .{update.name});
+            }
+            eval.checkOneError(update, error_bundle, expected_errors[expected_idx], false, err_idx);
+            expected_idx += 1;
+
+            for (error_bundle.getNotes(err_idx)) |note_idx| {
+                if (expected_idx == expected_errors.len) {
+                    const color: std.zig.Color = .auto;
+                    error_bundle.renderToStdErr(color.renderOptions());
+                    eval.fatal("update '{s}': more error notes than expected", .{update.name});
+                }
+                eval.checkOneError(update, error_bundle, expected_errors[expected_idx], true, note_idx);
+                expected_idx += 1;
+            }
+        }
+    }
+
+    fn checkOneError(
+        eval: *Eval,
+        update: Case.Update,
+        eb: std.zig.ErrorBundle,
+        expected: Case.ExpectedError,
+        is_note: bool,
+        err_idx: std.zig.ErrorBundle.MessageIndex,
+    ) void {
+        const err = eb.getErrorMessage(err_idx);
+        if (err.src_loc == .none) @panic("TODO error message with no source location");
+        if (err.count != 1) @panic("TODO error message with count>1");
+        const msg = eb.nullTerminatedString(err.msg);
+        const src = eb.getSourceLocation(err.src_loc);
+        const filename = eb.nullTerminatedString(src.src_path);
+
+        if (expected.is_note != is_note or
+            !std.mem.eql(u8, expected.filename, filename) or
+            expected.line != src.line + 1 or
+            expected.column != src.column + 1 or
+            !std.mem.eql(u8, expected.msg, msg))
+        {
+            const color: std.zig.Color = .auto;
+            eb.renderToStdErr(color.renderOptions());
+            eval.fatal("update '{s}': compile error did not match expected error", .{update.name});
         }
     }
 
@@ -595,11 +639,11 @@ const Case = struct {
     };
 
     const ExpectedError = struct {
-        file_name: ?[]const u8 = null,
-        line: ?u32 = null,
-        column: ?u32 = null,
-        msg_exact: ?[]const u8 = null,
-        msg_substring: ?[]const u8 = null,
+        is_note: bool,
+        filename: []const u8,
+        line: u32,
+        column: u32,
+        msg: []const u8,
     };
 
     fn parse(arena: Allocator, bytes: []const u8) !Case {
@@ -608,6 +652,7 @@ const Case = struct {
         var targets: std.ArrayListUnmanaged(Target) = .empty;
         var updates: std.ArrayListUnmanaged(Update) = .empty;
         var changes: std.ArrayListUnmanaged(FullContents) = .empty;
+        var deletes: std.ArrayListUnmanaged([]const u8) = .empty;
         var it = std.mem.splitScalar(u8, bytes, '\n');
         var line_n: usize = 1;
         var root_source_file: ?[]const u8 = null;
@@ -647,33 +692,42 @@ const Case = struct {
                     if (updates.items.len > 0) {
                         const last_update = &updates.items[updates.items.len - 1];
                         last_update.changes = try changes.toOwnedSlice(arena);
+                        last_update.deletes = try deletes.toOwnedSlice(arena);
                     }
                     try updates.append(arena, .{
                         .name = val,
                         .outcome = .unknown,
                     });
                 } else if (std.mem.eql(u8, key, "file")) {
-                    if (updates.items.len == 0) fatal("line {d}: expect directive before update", .{line_n});
+                    if (updates.items.len == 0) fatal("line {d}: file directive before update", .{line_n});
 
                     if (root_source_file == null)
                         root_source_file = val;
 
-                    const start_index = it.index.?;
-                    const src = while (true) : (line_n += 1) {
-                        const old = it;
-                        const next_line = it.next() orelse fatal("line {d}: unexpected EOF", .{line_n});
-                        if (std.mem.startsWith(u8, next_line, "#")) {
-                            const end_index = old.index.?;
-                            const src = bytes[start_index..end_index];
-                            it = old;
-                            break src;
-                        }
-                    };
+                    // Because Windows is so excellent, we need to convert CRLF to LF, so
+                    // can't just slice into the input here. How delightful!
+                    var src: std.ArrayListUnmanaged(u8) = .empty;
+
+                    while (true) {
+                        const next_line_raw = it.peek() orelse fatal("line {d}: unexpected EOF", .{line_n});
+                        const next_line = std.mem.trimRight(u8, next_line_raw, "\r");
+                        if (std.mem.startsWith(u8, next_line, "#")) break;
+
+                        _ = it.next();
+                        line_n += 1;
+
+                        try src.ensureUnusedCapacity(arena, next_line.len + 1);
+                        src.appendSliceAssumeCapacity(next_line);
+                        src.appendAssumeCapacity('\n');
+                    }
 
                     try changes.append(arena, .{
                         .name = val,
-                        .bytes = src,
+                        .bytes = src.items,
                     });
+                } else if (std.mem.eql(u8, key, "rm_file")) {
+                    if (updates.items.len == 0) fatal("line {d}: rm_file directive before update", .{line_n});
+                    try deletes.append(arena, val);
                 } else if (std.mem.eql(u8, key, "expect_stdout")) {
                     if (updates.items.len == 0) fatal("line {d}: expect directive before update", .{line_n});
                     const last_update = &updates.items[updates.items.len - 1];
@@ -687,7 +741,24 @@ const Case = struct {
                     if (updates.items.len == 0) fatal("line {d}: expect directive before update", .{line_n});
                     const last_update = &updates.items[updates.items.len - 1];
                     if (last_update.outcome != .unknown) fatal("line {d}: conflicting expect directive", .{line_n});
-                    last_update.outcome = .{ .compile_errors = &.{} };
+
+                    var errors: std.ArrayListUnmanaged(ExpectedError) = .empty;
+                    try errors.append(arena, parseExpectedError(val, line_n));
+                    while (true) {
+                        const next_line = it.peek() orelse break;
+                        if (!std.mem.startsWith(u8, next_line, "#")) break;
+                        var new_line_it = std.mem.splitScalar(u8, next_line, '=');
+                        const new_key = new_line_it.first()[1..];
+                        const new_val = std.mem.trimRight(u8, new_line_it.rest(), "\r");
+                        if (new_val.len == 0) break;
+                        if (!std.mem.eql(u8, new_key, "expect_error")) break;
+
+                        _ = it.next();
+                        line_n += 1;
+                        try errors.append(arena, parseExpectedError(new_val, line_n));
+                    }
+
+                    last_update.outcome = .{ .compile_errors = errors.items };
                 } else {
                     fatal("line {d}: unrecognized key '{s}'", .{ line_n, key });
                 }
@@ -701,6 +772,7 @@ const Case = struct {
         if (changes.items.len > 0) {
             const last_update = &updates.items[updates.items.len - 1];
             last_update.changes = changes.items; // arena so no need for toOwnedSlice
+            last_update.deletes = deletes.items;
         }
 
         return .{
@@ -736,3 +808,43 @@ fn waitChild(child: *std.process.Child, eval: *Eval) void {
         .Signal, .Stopped, .Unknown => eval.fatal("compiler terminated unexpectedly", .{}),
     }
 }
+
+fn parseExpectedError(str: []const u8, l: usize) Case.ExpectedError {
+    // #expect_error=foo.zig:1:2: error: the error message
+    // #expect_error=foo.zig:1:2: note: and a note
+
+    const fatal = std.process.fatal;
+
+    var it = std.mem.splitScalar(u8, str, ':');
+    const filename = it.first();
+    const line_str = it.next() orelse fatal("line {d}: incomplete error specification", .{l});
+    const column_str = it.next() orelse fatal("line {d}: incomplete error specification", .{l});
+    const error_or_note_str = std.mem.trim(
+        u8,
+        it.next() orelse fatal("line {d}: incomplete error specification", .{l}),
+        " ",
+    );
+    const message = std.mem.trim(u8, it.rest(), " ");
+    if (filename.len == 0) fatal("line {d}: empty filename", .{l});
+    if (message.len == 0) fatal("line {d}: empty error message", .{l});
+    const is_note = if (std.mem.eql(u8, error_or_note_str, "error"))
+        false
+    else if (std.mem.eql(u8, error_or_note_str, "note"))
+        true
+    else
+        fatal("line {d}: expeted 'error' or 'note', found '{s}'", .{ l, error_or_note_str });
+
+    const line = std.fmt.parseInt(u32, line_str, 10) catch
+        fatal("line {d}: invalid line number '{s}'", .{ l, line_str });
+
+    const column = std.fmt.parseInt(u32, column_str, 10) catch
+        fatal("line {d}: invalid column number '{s}'", .{ l, column_str });
+
+    return .{
+        .is_note = is_note,
+        .filename = filename,
+        .line = line,
+        .column = column,
+        .msg = message,
+    };
+}