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Segmentation Fault When Using Anonymous Struct Literal Assignment #23190

Open
ArielBenichou opened this issue Mar 10, 2025 · 1 comment · May be fixed by #23263
Open

Segmentation Fault When Using Anonymous Struct Literal Assignment #23190

ArielBenichou opened this issue Mar 10, 2025 · 1 comment · May be fixed by #23263
Labels
bug Observed behavior contradicts documented or intended behavior regression It worked in a previous version of Zig, but stopped working.
Milestone
0.14.1

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@ArielBenichou
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Zig Version

0.14.0

Steps to Reproduce and Observed Behavior

  1. Create a new Zig project (I've used zig init).
  2. Place the following minimal code into your main.zig:
fn createVec(x: f32, y: f32, z: f32) [3]f32 {
    return .{ x, y, z };
}

var camera = .{
    .pos = createVec(0, 0, 0),
};

pub fn main() !void {
    camera.pos = createVec(0, 1, 0);
}
  1. Build and run the project using zig build run.

Observed Behavior
The program terminates with a segmentation fault:

Segmentation fault at address 0xaaaaaaaaaaaaaaaa
aborting due to recursive panic
run
└─ run zig_seg_fault_anony_lit_struct failure
error: the following command terminated unexpectedly:
/Users/arielbenichou/personal/zig-seg-fault-anonymous-literal-struct/zig-out/bin/zig_seg_fault_anony_lit_struct
Build Summary: 3/5 steps succeeded; 1 failed
run transitive failure
└─ run zig_seg_fault_anony_lit_struct failure
error: the following build command failed with exit code 1:
/Users/arielbenichou/personal/zig-seg-fault-anonymous-literal-struct/.zig-cache/o/0bd88885df425ba4769286815bd940e7/build /Users/arielbenichou/.zvm/0.14.0/zig /Users/arielbenichou/.zvm/0.14.0/lib /Users/arielbenichou/personal/zig-seg-fault-anonymous-literal-struct /Users/arielbenichou/personal/zig-seg-fault-anonymous-literal-struct/.zig-cache /Users/arielbenichou/.cache/zig --seed 0x82075a23 -Z0d899954f16beb30 run

Expected Behavior

Now I understand that Anonymous Struct Literals create comptime fields that can't be modified.

But should it compile at all?
@ArielBenichou ArielBenichou added the bug Observed behavior contradicts documented or intended behavior label Mar 10, 2025
@linusg
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linusg commented Mar 10, 2025

Correctly caused a compile error in 0.13:

test.zig:10:11: error: cannot store runtime value in compile time variable
    camera.pos = createVec(0, 1, 0);
    ~~~~~~^~~~

@linusg linusg added the regression It worked in a previous version of Zig, but stopped working. label Mar 10, 2025
mlugg added a commit to mlugg/zig that referenced this issue Mar 16, 2025
@mlugg
Sema: fix pointers to comptime fields of comptime-known aggregate poi…
7730a27 
…nters

Resolves: ziglang#23190
@mlugg mlugg added this to the 0.14.1 milestone Mar 16, 2025
@mlugg mlugg linked a pull request Mar 16, 2025 that will close this issue
Open
mlugg added a commit to mlugg/zig that referenced this issue Mar 17, 2025
@mlugg
Sema: fix pointers to comptime fields of comptime-known aggregate poi…
3b0734a 
…nters

Resolves: ziglang#23190
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Labels
bug Observed behavior contradicts documented or intended behavior regression It worked in a previous version of Zig, but stopped working.
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Milestone
0.14.1
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Sema: fix pointers to comptime fields of comptime-known aggregate pointers mlugg/zig
3 participants
@mlugg @linusg @ArielBenichou