Compiler segmentation fault with cImport #31034

brickmonster commented 2026年01月28日 08:16:36 +01:00

Zig Version

0.16.0-dev.2261+d6b3dd25a

Steps to Reproduce and Observed Behavior

build

~/zig-0.16/zig build-exe -lc repro.zig

repro.zig

comptime {
 _ = &badVersion;
 _ = &goodVersion;
}
fn badVersion() void {
 const puts = @cImport({
 @cInclude("stdio.h");
 }).puts;
 _ = puts("");
}
fn goodVersion() void {
 const c = @cImport({
 @cInclude("stdio.h");
 });
 _ = c.puts("");
}

behavior

Compiler crashes with a segmentation fault if badVersion is analysed.
Does NOT crash with zig 0.15.2.

Expected Behavior

Successful build.

### Zig Version 0.16.0-dev.2261+d6b3dd25a ### Steps to Reproduce and Observed Behavior ## build `~/zig-0.16/zig build-exe -lc repro.zig` ## repro.zig ``` comptime { _ = &badVersion; _ = &goodVersion; } fn badVersion() void { const puts = @cImport({ @cInclude("stdio.h"); }).puts; _ = puts(""); } fn goodVersion() void { const c = @cImport({ @cInclude("stdio.h"); }); _ = c.puts(""); } ``` ## behavior Compiler crashes with a segmentation fault if `badVersion` is analysed. **Does NOT crash with zig `0.15.2`.** ### Expected Behavior Successful build.

alexrp commented 2026年01月30日 23:32:18 +01:00

Looks like a frontend bug:

Compiler crash context:
Analyzing 'repro.zig'
 %8 = dbg_stmt(2, 5)
 %9 = c_import({
 %10 = str("stdio.h")
 %11 = extended(c_include(%10)) node_offset:8:9 to :8:29
 %12 = ensure_result_used(@void_value) node_offset:7:18 to :7:26
 %13 = break_inline(%9, @void_value)
 }) node_offset:7:18 to :7:26
 %14 = dbg_stmt(4, 7)
 > %15 = field_ptr_load(%9, "puts") node_offset:9:7 to :9:12
 %16 = validate_const(%15) node_offset:9:7 to :9:12
 %17 = dbg_var_val(%15, "puts")
 %18 = save_err_ret_index(%15)
 %19 = dbg_stmt(6, 13)
 %20 = call(.auto, %15, [
 {
 %21 = str("")
 %22 = break_inline(%20, %21)
 },
 ]) node_offset:11:9 to :11:17
 %23 = ensure_result_non_error(%20) node_offset:11:9 to :11:17
 %24 = restore_err_ret_index_unconditional(.none) node_offset:6:1 to :6:3
 %25 = ret_implicit(@void_value) token_offset:12:1 to :12:1
 For full context, use the command
 zig4 ast-check -t repro.zig
thread 156596 panic: reached unreachable code
/home/alexrp/Sources/ziglang/zig/src/InternPool.zig:10666:17: 0x28daf21 in childType (main.zig)
 else => unreachable,
 ^
/home/alexrp/Sources/ziglang/zig/src/Type.zig:1947:42: 0x23c4925 in childTypeIp (main.zig)
 return Type.fromInterned(ip.childType(ty.toIntern()));
 ^
/home/alexrp/Sources/ziglang/zig/src/Type.zig:1943:23: 0x21abe90 in childType (main.zig)
 return childTypeIp(ty, &zcu.intern_pool);
 ^
/home/alexrp/Sources/ziglang/zig/src/Sema.zig:26544:47: 0x417a51a in fieldPtrLoad (main.zig)
 const pointee_ty = object_ptr_ty.childType(zcu);
 ^
/home/alexrp/Sources/ziglang/zig/src/Sema.zig:9921:24: 0x3a5124e in zirFieldPtrLoad (main.zig)
 return fieldPtrLoad(sema, block, src, object_ptr, field_name, field_name_src);
 ^
/home/alexrp/Sources/ziglang/zig/src/Sema.zig:1218:70: 0x33acb90 in analyzeBodyInner (main.zig)
 .field_ptr_load => try sema.zirFieldPtrLoad(block, inst),
 ^
/home/alexrp/Sources/ziglang/zig/src/Sema.zig:1047:26: 0x2d5cfe1 in analyzeFnBody (main.zig)
 sema.analyzeBodyInner(block, body) catch |err| switch (err) {
 ^
/home/alexrp/Sources/ziglang/zig/src/Zcu/PerThread.zig:2982:23: 0x2d60f8f in analyzeFnBodyInner (main.zig)
 sema.analyzeFnBody(&inner_block, fn_info.body) catch |err| switch (err) {
 ^
/home/alexrp/Sources/ziglang/zig/src/Zcu/PerThread.zig:1747:40: 0x2888ba2 in analyzeFuncBody (main.zig)
 var air = try pt.analyzeFnBodyInner(func_index);
 ^
/home/alexrp/Sources/ziglang/zig/src/Zcu/PerThread.zig:1666:66: 0x2379a2e in ensureFuncBodyUpToDate (main.zig)
 const ies_outdated, const new_failed = if (pt.analyzeFuncBody(func_index)) |result|
 ^
/home/alexrp/Sources/ziglang/zig/src/Compilation.zig:5192:38: 0x21a7470 in processOneJob (main.zig)
 pt.ensureFuncBodyUpToDate(func) catch |err| switch (err) {
 ^
/home/alexrp/Sources/ziglang/zig/src/Compilation.zig:4848:30: 0x20264ac in performAllTheWork (main.zig)
 try processOneJob(
 ^
/home/alexrp/Sources/ziglang/zig/src/Compilation.zig:3117:31: 0x1f26daf in update (main.zig)
 try comp.performAllTheWork(main_progress_node, arena);
 ^
/home/alexrp/Sources/ziglang/zig/src/main.zig:4626:20: 0x1f3742b in updateModule (main.zig)
 try comp.update(prog_node);
 ^
/home/alexrp/Sources/ziglang/zig/src/main.zig:3722:21: 0x1e1f7ae in buildOutputType (main.zig)
 updateModule(comp, color, root_prog_node) catch |err| switch (err) {
 ^
/home/alexrp/Sources/ziglang/zig/src/main.zig:263:31: 0x1e6bf52 in mainArgs (main.zig)
 return buildOutputType(gpa, arena, io, args, .{ .build = .Exe }, environ_map);
 ^
/home/alexrp/Sources/ziglang/zig/src/main.zig:216:20: 0x1dc388f in main (main.zig)
 return mainArgs(gpa, arena, io, args, &environ_map);
 ^
/home/alexrp/Sources/ziglang/zig/lib/std/start.zig:680:88: 0x1dc2e9b in callMain (std.zig)
 if (fn_info.params[0].type.? == std.process.Init.Minimal) return wrapMain(root.main(.{
 ^
../sysdeps/nptl/libc_start_call_main.h:58:16: 0x715f36e2a574 in __libc_start_call_main (../sysdeps/x86/libc-start.c)
../csu/libc-start.c:360:3: 0x715f36e2a627 in __libc_start_main_impl (../sysdeps/x86/libc-start.c)
???:?:?: 0x696f224 in ??? (???)

Looks like a frontend bug: ``` Compiler crash context: Analyzing 'repro.zig' %8 = dbg_stmt(2, 5) %9 = c_import({ %10 = str("stdio.h") %11 = extended(c_include(%10)) node_offset:8:9 to :8:29 %12 = ensure_result_used(@void_value) node_offset:7:18 to :7:26 %13 = break_inline(%9, @void_value) }) node_offset:7:18 to :7:26 %14 = dbg_stmt(4, 7) > %15 = field_ptr_load(%9, "puts") node_offset:9:7 to :9:12 %16 = validate_const(%15) node_offset:9:7 to :9:12 %17 = dbg_var_val(%15, "puts") %18 = save_err_ret_index(%15) %19 = dbg_stmt(6, 13) %20 = call(.auto, %15, [ { %21 = str("") %22 = break_inline(%20, %21) }, ]) node_offset:11:9 to :11:17 %23 = ensure_result_non_error(%20) node_offset:11:9 to :11:17 %24 = restore_err_ret_index_unconditional(.none) node_offset:6:1 to :6:3 %25 = ret_implicit(@void_value) token_offset:12:1 to :12:1 For full context, use the command zig4 ast-check -t repro.zig thread 156596 panic: reached unreachable code /home/alexrp/Sources/ziglang/zig/src/InternPool.zig:10666:17: 0x28daf21 in childType (main.zig) else => unreachable, ^ /home/alexrp/Sources/ziglang/zig/src/Type.zig:1947:42: 0x23c4925 in childTypeIp (main.zig) return Type.fromInterned(ip.childType(ty.toIntern())); ^ /home/alexrp/Sources/ziglang/zig/src/Type.zig:1943:23: 0x21abe90 in childType (main.zig) return childTypeIp(ty, &zcu.intern_pool); ^ /home/alexrp/Sources/ziglang/zig/src/Sema.zig:26544:47: 0x417a51a in fieldPtrLoad (main.zig) const pointee_ty = object_ptr_ty.childType(zcu); ^ /home/alexrp/Sources/ziglang/zig/src/Sema.zig:9921:24: 0x3a5124e in zirFieldPtrLoad (main.zig) return fieldPtrLoad(sema, block, src, object_ptr, field_name, field_name_src); ^ /home/alexrp/Sources/ziglang/zig/src/Sema.zig:1218:70: 0x33acb90 in analyzeBodyInner (main.zig) .field_ptr_load => try sema.zirFieldPtrLoad(block, inst), ^ /home/alexrp/Sources/ziglang/zig/src/Sema.zig:1047:26: 0x2d5cfe1 in analyzeFnBody (main.zig) sema.analyzeBodyInner(block, body) catch |err| switch (err) { ^ /home/alexrp/Sources/ziglang/zig/src/Zcu/PerThread.zig:2982:23: 0x2d60f8f in analyzeFnBodyInner (main.zig) sema.analyzeFnBody(&inner_block, fn_info.body) catch |err| switch (err) { ^ /home/alexrp/Sources/ziglang/zig/src/Zcu/PerThread.zig:1747:40: 0x2888ba2 in analyzeFuncBody (main.zig) var air = try pt.analyzeFnBodyInner(func_index); ^ /home/alexrp/Sources/ziglang/zig/src/Zcu/PerThread.zig:1666:66: 0x2379a2e in ensureFuncBodyUpToDate (main.zig) const ies_outdated, const new_failed = if (pt.analyzeFuncBody(func_index)) |result| ^ /home/alexrp/Sources/ziglang/zig/src/Compilation.zig:5192:38: 0x21a7470 in processOneJob (main.zig) pt.ensureFuncBodyUpToDate(func) catch |err| switch (err) { ^ /home/alexrp/Sources/ziglang/zig/src/Compilation.zig:4848:30: 0x20264ac in performAllTheWork (main.zig) try processOneJob( ^ /home/alexrp/Sources/ziglang/zig/src/Compilation.zig:3117:31: 0x1f26daf in update (main.zig) try comp.performAllTheWork(main_progress_node, arena); ^ /home/alexrp/Sources/ziglang/zig/src/main.zig:4626:20: 0x1f3742b in updateModule (main.zig) try comp.update(prog_node); ^ /home/alexrp/Sources/ziglang/zig/src/main.zig:3722:21: 0x1e1f7ae in buildOutputType (main.zig) updateModule(comp, color, root_prog_node) catch |err| switch (err) { ^ /home/alexrp/Sources/ziglang/zig/src/main.zig:263:31: 0x1e6bf52 in mainArgs (main.zig) return buildOutputType(gpa, arena, io, args, .{ .build = .Exe }, environ_map); ^ /home/alexrp/Sources/ziglang/zig/src/main.zig:216:20: 0x1dc388f in main (main.zig) return mainArgs(gpa, arena, io, args, &environ_map); ^ /home/alexrp/Sources/ziglang/zig/lib/std/start.zig:680:88: 0x1dc2e9b in callMain (std.zig) if (fn_info.params[0].type.? == std.process.Init.Minimal) return wrapMain(root.main(.{ ^ ../sysdeps/nptl/libc_start_call_main.h:58:16: 0x715f36e2a574 in __libc_start_call_main (../sysdeps/x86/libc-start.c) ../csu/libc-start.c:360:3: 0x715f36e2a627 in __libc_start_main_impl (../sysdeps/x86/libc-start.c) ???:?:?: 0x696f224 in ??? (???) ```

alexrp commented 2026年06月02日 00:46:33 +02:00

#31892

https://codeberg.org/ziglang/zig/pulls/31892