Missing error for runtime `@ptrFromInt` to comptime-only type

[silbinarywolf]

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Zig Version

0.13.0-dev.267+793f820b3

Steps to Reproduce and Observed Behavior

1. Clone down this repo: https://github.com/silbinarywolf/Zig-PSP/tree/repro/mipsel-psp-sdk-llvm-bug
2. Run zig build
3. Exits with error code in release builds with no additional information.

See debug build output below.

Expected Behavior

I'd expect it to either compile successfully or give me a nicer error explaining what went wrong.

Investigation notes

Looks like this Zig-PSP code utilizes comptime{ asm() } directives in various places, and after inlining certain comptime executions of those assembly strings, and getting compilation to get further, I think the issue is these are falling over within comptime.

Debug output

In Debug build:

$ /c/zig/zig/stage3/bin/zig build
install
└─ install main
   └─ zig build-exe main ReleaseSmall mipsel-freestanding failure
error: thread 9740 panic: attempt to use null value
C:\zig\zig\src\codegen\llvm.zig:4857:79: 0xba8976 in resolveInst (zig.exe.obj)
        const llvm_val = try self.resolveValue((try self.air.value(inst, mod)).?);
                                                                              ^
C:\zig\zig\src\codegen\llvm.zig:5260:45: 0xbf0e6f in airCall (zig.exe.obj)
        const llvm_fn = try self.resolveInst(pl_op.operand);
                                            ^
C:\zig\zig\src\codegen\llvm.zig:5041:55: 0x847cbe in genBody (zig.exe.obj)
                .call              => try self.airCall(inst, .auto),
                                                      ^
C:\zig\zig\src\codegen\llvm.zig:5151:48: 0xbd4c8b in genBodyDebugScope (zig.exe.obj)
        if (self.wip.strip) return self.genBody(body);
                                               ^
C:\zig\zig\src\codegen\llvm.zig:6009:35: 0xbdad75 in airCondBr (zig.exe.obj)
        try self.genBodyDebugScope(null, then_body);
                                  ^
C:\zig\zig\src\codegen\llvm.zig:5021:54: 0x846fd9 in genBody (zig.exe.obj)
                .cond_br        => try self.airCondBr(inst),
                                                     ^
C:\zig\zig\src\codegen\llvm.zig:5151:48: 0xbd4c8b in genBodyDebugScope (zig.exe.obj)
        if (self.wip.strip) return self.genBody(body);
                                               ^
C:\zig\zig\src\codegen\llvm.zig:5950:35: 0xbd43ca in lowerBlock (zig.exe.obj)
        try self.genBodyDebugScope(maybe_inline_func, body);
                                  ^
C:\zig\zig\src\codegen\llvm.zig:5920:31: 0xbd6c1b in airBlock (zig.exe.obj)
        return self.lowerBlock(inst, null, @ptrCast(self.air.extra[extra.end..][0..extra.data.body_len]));
                              ^
C:\zig\zig\src\codegen\llvm.zig:5014:53: 0x846bd4 in genBody (zig.exe.obj)
                .block          => try self.airBlock(inst),
                                                    ^
C:\zig\zig\src\codegen\llvm.zig:1740:19: 0x840e7e in updateFunc (zig.exe.obj)
        fg.genBody(air.getMainBody()) catch |err| switch (err) {
                  ^
C:\zig\zig\src\link\Elf.zig:2993:70: 0xb948d7 in updateFunc (zig.exe.obj)
    if (self.llvm_object) |llvm_object| return llvm_object.updateFunc(mod, func_index, air, liveness);
                                                                     ^
C:\zig\zig\src\link.zig:422:82: 0x85003f in updateFunc (zig.exe.obj)
                return @as(*tag.Type(), @fieldParentPtr("base", base)).updateFunc(module, func_index, air, liveness);
                                                                                 ^
C:\zig\zig\src\Module.zig:3219:22: 0x5b5dc9 in ensureFuncBodyAnalyzed (zig.exe.obj)
        lf.updateFunc(zcu, func_index, air, liveness) catch |err| switch (err) {
                     ^
C:\zig\zig\src\Compilation.zig:3414:42: 0x5b2bdb in processOneJob (zig.exe.obj)
            module.ensureFuncBodyAnalyzed(func) catch |err| switch (err) {
                                         ^
C:\zig\zig\src\Compilation.zig:3354:30: 0x3e7a2e in performAllTheWork (zig.exe.obj)
            try processOneJob(comp, work_item, main_progress_node);
                             ^
C:\zig\zig\src\Compilation.zig:2132:31: 0x3e32e3 in update (zig.exe.obj)
    try comp.performAllTheWork(main_progress_node);
                              ^
C:\zig\zig\src\main.zig:4091:36: 0x45f039 in serve (zig.exe.obj)
                    try comp.update(main_progress_node);
                                   ^
C:\zig\zig\src\main.zig:3368:22: 0x47c79f in buildOutputType (zig.exe.obj)
            try serve(
                     ^
C:\zig\zig\src\main.zig:262:31: 0x2b93f9 in mainArgs (zig.exe.obj)
        return buildOutputType(gpa, arena, args, .{ .build = .Exe });
                              ^
C:\zig\zig\src\main.zig:208:20: 0x2b6aae in main (zig.exe.obj)
    return mainArgs(gpa, arena, args);
                   ^
C:\zig\zig\lib\std\start.zig:497:75: 0x2b67da in main (zig.exe.obj)
    return callMainWithArgs(@as(usize, @intCast(c_argc)), @as([*][*:0]u8, @ptrCast(c_argv)), envp);
                                                                          ^
C:\zig\zig\lib\libc\mingw\crt\crtexe.c:267:0: 0x2bd89a1 in __tmainCRTStartup (crt2.obj)
    mainret = _tmain (argc, argv, envp);

C:\zig\zig\lib\libc\mingw\crt\crtexe.c:188:0: 0x2bd89fb in mainCRTStartup (crt2.obj)
  ret = __tmainCRTStartup ();

???:?:?: 0x7ff95cc87343 in ??? (KERNEL32.DLL)
???:?:?: 0x7ff95df426b0 in ??? (ntdll.dll)

error: the following command exited with error code 3:
C:\zig\zig\stage3\bin\zig.exe build-exe -OReleaseSmall -target mipsel-freestanding -mcpu mips2+single_float -Mroot=D:\ZigProjects\Zig-PSP-Repro\src\main.zig --cache-dir D:\ZigProjects\Zig-PSP-Repro\zig-cache --global-cache-dir C:\Users\User\AppData\Local\zig --name main --listen=-
Build Summary: 0/3 steps succeeded; 1 failed (disable with --summary none)
install transitive failure
└─ install main transitive failure
   └─ zig build-exe main ReleaseSmall mipsel-freestanding failure
error: the following build command failed with exit code 1:
D:\ZigProjects\Zig-PSP-Repro\zig-cache\o\b8e4e33615e00870368c45052146b4c8\build.exe C:\zig\zig\stage3\bin\zig.exe D:\ZigProjects\Zig-PSP-Repro D:\ZigProjects\Zig-PSP-Repro\zig-cache C:\Users\User\AppData\Local\zig --seed 0x9ce9bd08 -Zd8461fa9d950770a

[Vexu]

Crash fixed by:

diff --git a/src/psp/sdk/pspguimpl.zig b/src/psp/sdk/pspguimpl.zig
index b835002..80e8903 100644
--- a/src/psp/sdk/pspguimpl.zig
+++ b/src/psp/sdk/pspguimpl.zig
@@ -8,7 +8,7 @@ test {
 }
 
 //Internals
-pub const GuCallback = ?fn (c_int) callconv(.C) void;
+pub const GuCallback = ?*const fn (c_int) callconv(.C) void;
 
 const GuSettings = struct {
     sig: GuCallback,

Will make a PR to fix the missing error shortly.

[silbinarywolf]

Thank you very much. I did try to like, print the file/line from resolveInst in llvm.zig but just... I could not figure out how to get that information out 😁