Using `@This()` in opaque type hits unreachable

[Jarred-Sumner]

Zig Version

0.14.0-dev.3002+1f2fff682

Steps to Reproduce and Observed Behavior

zir:

❯ zig-debug build check
info: zig compiler v0.14.0-dev.3002+1f2fff682
check
└─ zig build-obj bun-debug Debug native-native.13.0 failure
error: thread 137887556 panic: reached unreachable code
Analyzing src/bun.js/bindings/bindings.zig
    > %6926 = extended(this()) 
      %6927 = break_inline(%6921, %6926)
    For full context, use the command
      zig ast-check -t src/bun.js/bindings/bindings.zig

  in src/bun.js/bindings/bindings.zig
    > %6921 = call(.auto, %6919, [
        {%6922, %6923},
        {%6924, %6925},
        {%6926, %6927},
      ]) 
  in src/bun.js/bindings/bindings.zig
    > %7775 = decl_ref("shim") 

Unable to dump stack trace: AccessDenied

error: the following command terminated unexpectedly:

It appears to be happening in this struct

Relevant commit in Bun: https://github.com/oven-sh/bun/commits/36ea9c6adc0bda9502dd1f9797962100be3a0667

Expected Behavior

zig shouldn't panic in debug builds when compiling bun

[Vexu]

Reduction:

const A = opaque {
    const b = @This();
};
comptime {
    _ = A.b;
}

Unreachable hit in PerThread.ensureTypeUpToDate due to not handling .opaque_type.