/zig-check [file]

/zig-check [file]

Audit Zig source files for common Zig 0.15.x mistakes. If a file path is given, check that file. Otherwise check all src/*.zig files that were modified in the current git diff (staged and unstaged).

Procedure

1. Determine target files

If argument provided:

• Check only that file

If no argument:

• Run git diff --name-only and git diff --cached --name-only
• Filter to src/*.zig files
• If no modified Zig files, report "No modified Zig files to check" and exit

2. Read each target file

Use the Read tool to read the full contents of each file.

3. Check for violations

Search each file for these patterns. Report each violation with file path, line number, and the specific issue.

Critical (must fix):

1. Deleted API usage:

   • std.io.getStdOut or std.io.getStdErr -- use buffered writer pattern
   • usingnamespace -- removed from language
   • async / await -- removed from language
   • std.BoundedArray -- use ArrayListUnmanaged.initBuffer
   • std.json.Parser -- use std.json.parseFromSlice

2. Renamed API usage:

   • std.mem.tokenize( without Any/Scalar/Sequence -- use tokenizeAny, tokenizeScalar, or tokenizeSequence
   • std.process.args() without Alloc -- use std.process.argsAlloc(allocator)

3. takeDelimiterExclusive in while loops:

   • while loop calling takeDelimiterExclusive -- use appendRemaining instead (hangs on stdin)

4. Missing writer flush:

   • stdout_writer or stderr_writer created without a corresponding defer ... flush() catch {}

5. ArrayList without allocator:

   • .append(, .appendSlice(, .deinit() etc. without allocator as first argument (for ArrayListUnmanaged)

6. Ambiguous format strings:

   • "{}" in print/format calls -- must use {s}, {d}, {any}, etc.

7. Signed division without builtins:

   • / or % on runtime signed integer variables -- use @divTrunc, @divFloor, @divExact, @rem, @mod

8. Old for-loop index syntax:

   • for (items) |item, i| without explicit index range -- use for (items, 0..) |item, i|

4. Report results

Format output as:

## /zig-check Results

### <file_path>

CRITICAL: <line>: <description>
CRITICAL: <line>: <description>

### <file_path>

No issues found.

---
Summary: X critical across Z files

If no issues found in any file:

## /zig-check Results

All files pass. No Zig 0.15.x issues found.

5. Suggest fixes

For each critical issue, include a one-line fix suggestion:

• "Replace std.io.getStdOut() with buffered writer pattern (see zig-patterns skill)"
• "Replace while (reader.takeDelimiterExclusive(...)) with reader.appendRemaining()"
• "Add defer stdout.flush() catch {}; after writer creation"
• "Change list.append(val) to list.append(allocator, val)"
• "Change "{}" to "{s}" (or appropriate specifier)"
• "Replace a / b with @divTrunc(a, b) for signed integers"
• "Replace std.mem.tokenize with std.mem.tokenizeAny"
• "Replace std.process.args() with std.process.argsAlloc"
• "Change for (items) |x, i| to for (items, 0..) |x, i|"
• "Replace std.json.Parser with std.json.parseFromSlice"