multiple c bindgen issues

[kavoc-brown]

Summary

This issue buckets several problems in wit-bindgen c to avoid opening many separate issues at once.

Each sub-item is independently reproducible and either:

• triggers a panic, or
• exhibits timeout (potential DoS).

If you prefer, I can split this bucket into separate issues.

Environment

• wit-bindgen-cli: 0.47.0
• OS: Ubuntu 22.04.5 LTS (x86_64)

Sub-issues (details in comments)

1. Slowdown on deep option<...> type aliases.
2. Panic on flags with >64 fields.
3. world import/export same name triggers duplicate symbol panic.
4. Resource method vs free-function name collision triggers duplicate symbol panic.
5. Semver sanitization collision (- vs +) triggers duplicate symbol panic.
6. Very deep direct option<...> nesting causes hang (even stack overflow).

[kavoc-brown]

Sub-issue 1: Slowdown on deep option<...> nesting

Reproduction

python3 - <<'PY' > /tmp/deep_option_800.wit
depth=800
print('package poc:deep-option-perf-hang;\\n\\nworld w {')
print('  type t0 = u8;')
for i in range(1, depth+1):
    print(f'  type t{i} = option<t{i-1}>;')
print(f'\\n  export f: func(x: t{depth});\\n}')
PY

Observed (on my machine)

• Depth 400: ~1.5s
• Depth 600: ~4.9s
• Depth 800: killed by timeout 10s (exit 124)

[kavoc-brown]

Sub-issue 2: flags with >64 fields panics

Reproduction

package poc:flags-gt64;

world w {
  flags big {
    b0, b1, b2, b3, b4, b5, b6, b7,
    b8, b9, b10, b11, b12, b13, b14, b15,
    b16, b17, b18, b19, b20, b21, b22, b23,
    b24, b25, b26, b27, b28, b29, b30, b31,
    b32, b33, b34, b35, b36, b37, b38, b39,
    b40, b41, b42, b43, b44, b45, b46, b47,
    b48, b49, b50, b51, b52, b53, b54, b55,
    b56, b57, b58, b59, b60, b61, b62, b63,
    b64,
  }

  export f: func(x: big);
}

[kavoc-brown]

Sub-issue 3: world import/export same name triggers duplicate symbol panic

Reproduction

package poc:import-export-same-name;

world w {
  import same: interface {
    record r { a: u32 }
    foo: func(x: r);
  }

  export same: interface {
    record r { b: u32 }
    foo: func(x: r);
  }
}

[kavoc-brown]

Sub-issue 4: resource method vs free-function name collision triggers duplicate symbol panic

Reproduction

package poc:resource-method-collision;

world w {
  export api: interface {
    resource foo { bar: func(); }
    method-foo-bar: func();
  }
}

[kavoc-brown]

Sub-issue 5: semver sanitization collision triggers duplicate symbol panic

Reproduction

package poc:version-string-collision;

package dep:pkg@1.0.0-alpha {
  interface i { foo: func(); }
}

package dep:pkg@1.0.0+alpha {
  interface i { foo: func(); }
}

use dep:pkg/i@1.0.0-alpha as i1;
use dep:pkg/i@1.0.0+alpha as i2;

world w {
  import i1;
  import i2;
}

[kavoc-brown]

Sub-issue 6: deep direct option<...> nesting causes timeout (even stack overflow)

Reproduction

python3 - <<'PY' > /tmp/deep_option_direct.wit
depth=10000
print('package poc:deep-option-stack-overflow;\\n\\nworld w {')
ty='u8'
for _ in range(depth):
    ty=f'option<{ty}>'
print(f'  export f: func(x: {ty});\\n}')
PY