Commit 0bf44c30934bced6fc8f6451cf418ae40db665e6 | zig

author	Jacob Young <jacobly@ziglang.org> 2025-01-05 04:59:31-05:00
committer	Andrew Kelley <andrew@ziglang.org> 2025-01-05 17:15:56-05:00
log	0bf44c30934bced6fc8f6451cf418ae40db665e6
tree	c9d715c9907060ef77c1cd807c3ce42e1e133f15
parent	137787edbb1320ce50bd4193d69f21ffaf8593e8

x86_64: fix `@errorName` data

The final offset was clobbering the first error name, which is revealed
by an out of bounds when the global error set is empty.

Closes #22362

4 files changed, 44 insertions(+), 9 deletions(-)

src
- codegen.zig
test
- standalone
  - build.zig.zon
  - empty_global_error_set
    build.zig
    main.zig

src/codegen.zig+13-9

 @@ -148,19 +148,23 @@ pub fn generateLazySymbol(
     if (lazy_sym.ty == .anyerror_type) {
         alignment.* = .@"4";
         const err_names = ip.global_error_set.getNamesFromMainThread();
-        mem.writeInt(u32, try code.addManyAsArray(4), @intCast(err_names.len), endian);
+        var offset_index: u32 = @intCast(code.items.len);
-        var offset = code.items.len;
+        var string_index: u32 = @intCast(4 * (1 + err_names.len + @intFromBool(err_names.len > 0)));
-        try code.resize((err_names.len + 1) * 4);
+        try code.resize(offset_index + string_index);
+        mem.writeInt(u32, code.items[offset_index..][0..4], @intCast(err_names.len), endian);
+        if (err_names.len == 0) return .ok;
+        offset_index += 4;
         for (err_names) |err_name_nts| {
             const err_name = err_name_nts.toSlice(ip);
-            mem.writeInt(u32, code.items[offset..][0..4], @intCast(code.items.len), endian);
+            mem.writeInt(u32, code.items[offset_index..][0..4], string_index, endian);
-            offset += 4;
+            offset_index += 4;
             try code.ensureUnusedCapacity(err_name.len + 1);
             code.appendSliceAssumeCapacity(err_name);
             code.appendAssumeCapacity(0);
+            string_index += @intCast(err_name.len + 1);
         }
-        mem.writeInt(u32, code.items[offset..][0..4], @intCast(code.items.len), endian);
+        mem.writeInt(u32, code.items[offset_index..][0..4], string_index, endian);
-        return Result.ok;
+        return .ok;
     } else if (Type.fromInterned(lazy_sym.ty).zigTypeTag(pt.zcu) == .@"enum") {
         alignment.* = .@"1";
         const enum_ty = Type.fromInterned(lazy_sym.ty);
 @@ -171,8 +175,8 @@ pub fn generateLazySymbol(
             code.appendSliceAssumeCapacity(tag_name);
             code.appendAssumeCapacity(0);
         }
-        return Result.ok;
+        return .ok;
-    } else return .{ .fail = try ErrorMsg.create(
+    } else return .{ .fail = try .create(
         gpa,
         src_loc,
         "TODO implement generateLazySymbol for {s} {}",

test/standalone/build.zig.zon+3

 @@ -180,6 +180,9 @@
         .run_output_caching = .{
             .path = "run_output_caching",
         },
+        .empty_global_error_set = .{
+            .path = "empty_global_error_set",
+        },
     },
     .paths = .{
         "build.zig",

test/standalone/empty_global_error_set/build.zig created+24

...	@@ -0,0 +1,24 @@
1	const std = @import("std");
2	const builtin = @import("builtin");
3
4	pub fn build(b: *std.Build) void {
5	const test_step = b.step("test", "Test it");
6	b.default_step = test_step;
7
8	for ([_]bool{ false, true }) \|use_llvm\| {
9	const main = b.addObject(.{
10	.name = "main",
11	.root_module = b.createModule(.{
12	.root_source_file = b.path("main.zig"),
13	.target = b.resolveTargetQuery(.{
14	.cpu_arch = .x86_64,
15	.os_tag = .linux,
16	}),
17	}),
18	.use_llvm = use_llvm,
19	.use_lld = use_llvm,
20	});
21	_ = main.getEmittedBin();
22	test_step.dependOn(&main.step);
23	}
24	}

test/standalone/empty_global_error_set/main.zig created+4

...	@@ -0,0 +1,4 @@
1	fn errorName(err: anyerror) [:0]const u8 {
2	return @errorName(err);
3	}
4	export const error_name: *const anyopaque = &errorName;