From c7884af063791211544c6595a4900bbfcd5d96b6 Mon Sep 17 00:00:00 2001
From: Veikka Tuominen <git@vexu.eu>
Date: Sat, 3 Sep 2022 01:55:01 +0300
Subject: [PATCH] translate-c: do not translate packed C structs as packed Zig
 structs in stage2

Zig's integer backed packed structs are not compatible with C's packed structs.
---
 src/translate_c.zig       |  4 ++++
 test/run_translated_c.zig | 26 ++++++++++++++------------
 test/translate_c.zig      | 30 ++++++++++++++++--------------
 3 files changed, 34 insertions(+), 26 deletions(-)

diff --git a/src/translate_c.zig b/src/translate_c.zig
index b0fae81475..faa8a456f5 100644
--- a/src/translate_c.zig
+++ b/src/translate_c.zig
@@ -1166,6 +1166,10 @@ fn transRecordDecl(c: *Context, scope: *Scope, record_decl: *const clang.RecordD
             });
         }
 
+        if (!c.zig_is_stage1 and is_packed) {
+            return failDecl(c, record_loc, bare_name, "cannot translate packed record union", .{});
+        }
+
         const record_payload = try c.arena.create(ast.Payload.Record);
         record_payload.* = .{
             .base = .{ .tag = ([2]Tag{ .@"struct", .@"union" })[@boolToInt(is_union)] },
diff --git a/test/run_translated_c.zig b/test/run_translated_c.zig
index 4345625dc1..5aa72e2d1f 100644
--- a/test/run_translated_c.zig
+++ b/test/run_translated_c.zig
@@ -250,18 +250,20 @@ pub fn addCases(cases: *tests.RunTranslatedCContext) void {
         \\}
     , "");
 
-    cases.add("struct initializer - packed",
-        \\#define _NO_CRT_STDIO_INLINE 1
-        \\#include <stdint.h>
-        \\#include <stdlib.h>
-        \\struct s {uint8_t x,y;
-        \\          uint32_t z;} __attribute__((packed)) s0 = {1, 2};
-        \\int main() {
-        \\  /* sizeof nor offsetof currently supported */
-        \\  if (((intptr_t)&s0.z - (intptr_t)&s0.x) != 2) abort();
-        \\  return 0;
-        \\}
-    , "");
+    if (@import("builtin").zig_backend == .stage1) {
+        cases.add("struct initializer - packed",
+            \\#define _NO_CRT_STDIO_INLINE 1
+            \\#include <stdint.h>
+            \\#include <stdlib.h>
+            \\struct s {uint8_t x,y;
+            \\          uint32_t z;} __attribute__((packed)) s0 = {1, 2};
+            \\int main() {
+            \\  /* sizeof nor offsetof currently supported */
+            \\  if (((intptr_t)&s0.z - (intptr_t)&s0.x) != 2) abort();
+            \\  return 0;
+            \\}
+        , "");
+    }
 
     cases.add("cast signed array index to unsigned",
         \\#include <stdlib.h>
diff --git a/test/translate_c.zig b/test/translate_c.zig
index 637d491f49..54b4ad6081 100644
--- a/test/translate_c.zig
+++ b/test/translate_c.zig
@@ -728,20 +728,22 @@ pub fn addCases(cases: *tests.TranslateCContext) void {
         \\}
     });
 
-    cases.add("struct initializer - packed",
-        \\struct {int x,y,z;} __attribute__((packed)) s0 = {1, 2};
-    , &[_][]const u8{
-        \\const struct_unnamed_1 = packed struct {
-        \\    x: c_int,
-        \\    y: c_int,
-        \\    z: c_int,
-        \\};
-        \\pub export var s0: struct_unnamed_1 = struct_unnamed_1{
-        \\    .x = @as(c_int, 1),
-        \\    .y = @as(c_int, 2),
-        \\    .z = 0,
-        \\};
-    });
+    if (builtin.zig_backend == .stage1) {
+        cases.add("struct initializer - packed",
+            \\struct {int x,y,z;} __attribute__((packed)) s0 = {1, 2};
+        , &[_][]const u8{
+            \\const struct_unnamed_1 = packed struct {
+            \\    x: c_int,
+            \\    y: c_int,
+            \\    z: c_int,
+            \\};
+            \\pub export var s0: struct_unnamed_1 = struct_unnamed_1{
+            \\    .x = @as(c_int, 1),
+            \\    .y = @as(c_int, 2),
+            \\    .z = 0,
+            \\};
+        });
+    }
 
     // Test case temporarily disabled:
     // https://github.com/ziglang/zig/issues/12055